UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Sublethal effects of fenitrothion on forest passerines Millikin, Rhonda Lorraine 1987

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1988_A6_7 M54.pdf [ 6.54MB ]
Metadata
JSON: 831-1.0097625.json
JSON-LD: 831-1.0097625-ld.json
RDF/XML (Pretty): 831-1.0097625-rdf.xml
RDF/JSON: 831-1.0097625-rdf.json
Turtle: 831-1.0097625-turtle.txt
N-Triples: 831-1.0097625-rdf-ntriples.txt
Original Record: 831-1.0097625-source.json
Full Text
831-1.0097625-fulltext.txt
Citation
831-1.0097625.ris

Full Text

SUBLETHAL EFFECTS OF FENITROTHION ON FOREST PASSERINES By RHONDA LORRAINE MILLIKIN B.Sc, Car-let on University, 1978 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS IN SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of Zoology) We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA December 1987 ® Rhonda Lorraine M i l l i k i n , 1987 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. r Department of <^,?r*s 1/j ^  The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 ABSTRACT A five-year study was carried out to test a sensitive, nondestructive, new method for determining sublethal and long-term consequences of fenitrothion applications on forest songbirds. I used censuses and t e r r i t o r y mapping of singing males to provide indices of r e l a t i v e abundance on sprayed and control p l o t s . Mist-netting was used to colour-band i n d i v i d u a l s of 3 i n d i c a t o r species (the chestnut-sided warbler, magnolia warbler and white-throated sparrow), to determine "their breeding condition, and to follow t h e i r fates aft e r a f e n i t r o t h i o n a p p l i c a t i o n . Time-budget observations were made of the behaviour of some marked in d i v i d u a l s . Fenitrothion was applied a e r i a l l y i n 1985, and by ground i n 1986. I f i r s t studied the e f f e c t of f e n i t r o t h i o n on the songbird community; comparing treatment and control plots, before and a f t e r the application. Data on the b i r d populations showed that fewer young were caught i n 1985, and birds returned at a lower rate the year following treatment; a lower proportion of the 1986 catch i n mist nets were males. Nonetheless, other factors (budworm cycles, for example) had a greater influence on population trends than the treatment. Behavioural observations indicated that i n d i v i d u a l s of the 3 i n d i c a t o r species did not abandon the treated area after either a p p l i c a t i o n , although white-throated sparrows and magnolia i i w a r b l e r s moved away from f o l i a g e r e g i o n s with h i g h e r d e p o s i t s of spray. There was no s i g n i f i c a n t change i n the a l l o t m e n t of time t o s o c i a l , maintenance, or f e e d i n g behaviours, f o r any of the i n d i c a t o r s p e c i e s . T h i s o b s e r v a t i o n i s not c o n s i s t e n t with the known symptoms of organophosphate p o i s o n i n g ( i . e . i n c r e a s e d time spent s i t t i n g , b i l l - w i p i n g , and p r e e n i n g ) . C h e s t n u t - s i d e d w a rblers and w h i t e - t h r o a t e d sparrows continued t o forage a c t i v e l y on sprayed p l o t s or nearby. Magnolia warblers decreased t h e i r f o r a g i n g e f f o r t a f t e r both a p p l i c a t i o n s . In p a r t 2 of the t h e s i s , I s t u d i e d the e f f e c t of f e n i t r o t h i o n on the i n v e r t e b r a t e food of f o r e s t songbirds. Branch samples were taken as a measure of the food a v a i l a b l e t o f o l i a g e - g l e a n i n g b i r d s . Drop t r a y s were pl a c e d under sample t r e e s t o measure the amount of food f a l l e n from the t r e e a f t e r the a p p l i c a t i o n . F o l l o w i n g treatment, t h e r e was a lower d e n s i t y of i n v e r t e b r a t e s on white b i r c h and balsam f i r branches than on c o n t r o l t r e e s . T h i s r e d u c t i o n was not observed u n t i l 5 days a f t e r the a p p l i c a t i o n , although drop t r a y samples i n d i c a t e d an immediate k i l l of i n v e r t e b r a t e s . These techniques sampled d i f f e r e n t types of i n v e r t e b r a t e s such t h a t a l a r g e p r o p o r t i o n of the drop t r a y samples were not a s s o c i a t e d with the t r e e (eg. f l y i n g D i p t e r a ) . In a d d i t i o n t o a decreased abundance, a l a r g e p o r t i o n of the remaining i n v e r t e b r a t e s on white b i r c h t r e a t e d t r e e s were dead. T h i s suggests a f u r t h e r decrease i n food a v a i l a b i l i t y t o b i r d s l i k e w a r b l e r s t h a t s p e c i a l i z e on moving prey. i i i The d e p r e s s i o n o f f o o d a v a i l a b l e t o b i r d s was p r o b a b l y s h o r t - l i v e d , a s suming movement o f i n v e r t e b r a t e s i n t o d e p o p u l a t e d a r e a s f rom u n s p r a y e d f o l i a g e n e a r b y . B e h a v i o u r a l r e s p o n s e s o f b i r d s t o s p r a y i n g were a l s o s h o r t - l i v e d , a p p a r e n t o n l y w i t h i n 5 days o f t h e a p p l i c a t i o n . A t t h e maximum a l l o w a b l e s i n g l e d o s e , f e n i t r o t h i o n appea r s t o have l i t t l e e f f e c t on f o r e s t s o n g b i r d s , even when t e s t e d w i t h a h i g h l y - s e n s i t i v e method . i v T A B L E O F C O N T E N T S Page ABSTRACT i i TABLE OF CONTENTS v L I S T OF TABLES v i L I S T OF FIGURES v i i ACKNOWLEDGMENTS i x INTRODUCTION 1 C H A P T E R 1 S U B L E T H A L E F F E C T S O F F E N I T R O T H I O N O N F O R E S T P A S S E R I N E S 4 INTRODUCTION 4 METHODS 10 RESULTS 25 DISCUSSION 53 CONCLUSION 62 C H A P T E R 2 E F F E C T S O F F E N I T R O T H I O N O N T H E T E R R E S T R I A L F O O D B A S E O F F O R E S T P A S S E R I N E S 64 INTRODUCTION 64 METHODS 66 RESULTS 71 DISCUSSION 82 CONCLUSION 89 GENERAL DISCUSSION 91 REFERENCES 95 APPENDIX I 101 APPENDIX I I 107 v L I S T OF TABLES 1.1 F e n i t r o t h i o n d e p o s i t s on f o l i a g e at d i f f e r e n t l o c a t i o n s of the t r e e crown f o l l o w i n g both a p p l i c a t i o n s 16 1.2 L o c a t i o n and b e h a v i o u r a l c a t e g o r i e s used i n the time-budget o b s e r v a t i o n s 24 1.3 Long-term changes i n the number of t e r r i t o r i e s of the c h e s t n u t - s i d e d warbler, magnolia warbler, and w h i t e - t h r o a t e d sparrow 27 1.4 Gross area of moderate to severe d e f o l i a t i o n by spruce budworm from 1983 to 1986 30 1.5 Change i n p o p u l a t i o n s t r u c t u r e on p l o t T, and on p l o t C, from 1983 t o 1987, as determined by m i s t - n e t t i n g 34 1.6 Frequency of w h i t e - t h r o a t e d sparrows observed f e e d i n g i n t r e a t e d and c o n t r o l p l o t s b e f o r e , immediately a f t e r , and l a t e r a f t e r the 1985 and 1986 a p p l i c a t i o n 46 1.7 Number of w h i t e - t h r o a t e d sparrows observed c a r r y i n g food 46 1.8 P r o p o r t i o n of b i r d s t h a t were observed c a r r y i n g food without p r e v i o u s l y f e e d i n g i n the spray b l o c k 49 1.9 Comparison of the mean weights of the t h r e e i n d i c a t o r s p e c i e s on t r e a t e d and c o n t r o l p l o t s 49 1.10 Comparison of the p r o p o r t i o n of a d u l t i n d i v i d u a l s caught i n mist nets d u r i n g the postspray n e t t i n g p e r i o d s of 1985 and 1986, on t r e a t e d and c o n t r o l p l o t s 51 2.1 Change i n the r e l a t i v e number of i n v e r t e b r a t e s c o l l e c t e d from sample t r e e s from be f o r e the a p p l i c a t i o n t o 15 days a f t e r the a p p l i c a t i o n 77 2.2 P r o p o r t i o n of D i p t e r a , Hymenoptera, and f e e d e r s i n drop t r a y samples from white b i r c h 82 2.3 R e l a t i o n s h i p between branch and drop t r a y samples 84 2.4 Comparison of the i n v e r t e b r a t e c o m p o s i t i o n of branch samples t o t h a t of drop t r a y samples 86 v i L I S T OF FIGURES 1.1 L o c a t i o n of treatment and c o n t r o l p l o t s f o r the a e r i a l and ground a p p l i c a t i o n s 12 1.2 P o p u l a t i o n trends of t e r r i t o r i a l b i r d s on t r e a t e d and c o n t r o l p l o t s , from 1983 to 1987 26 1.3 P o p u l a t i o n trends of the major b i r d groups on treatment and c o n t r o l , from 1983 to 1987 28 1.4 Change i n abundance of budworm-associated b i r d s p e c i e s , and b i r d s p e c i e s known to have a ne g a t i v e n u m e r i c a l response t o budworm numbers, from 1983 to 1987, on t r e a t e d and c o n t r o l p l o t s 32 1.5 Change i n abundance of b i r d s p e c i e s u n r e l a t e d t o budworm numbers 33 1.6 Comparison of changes i n the p r o p o r t i o n of o b s e r v a t i o n s taken i n which c h e s t n u t - s i d e d warblers were observed, on the t r e a t e d and c o n t r o l p l o t s , f o r both a p p l i c a t i o n y e a r s 37 1.7 Comparison of changes i n the p r o p o r t i o n of o b s e r v a t i o n s taken i n which magnolia warblers were observed, on the t r e a t e d and c o n t r o l p l o t s , f o r both a p p l i c a t i o n years . 39 1.8 Comparison of changes i n the p r o p o r t i o n of o b s e r v a t i o n s taken i n which w h i t e - t h r o a t e d sparrows were observed, on the t r e a t e d and c o n t r o l p l o t s , f o r both a p p l i c a t i o n y e a r s 40 1.9 Comparison of the p r o p o r t i o n of time magnolia warblers spent i n s o c i a l , maintenance, and f e e d i n g behaviours, over the 1985 study p e r i o d , on t r e a t e d and c o n t r o l p l o t s 42 1.10 Comparison of the p r o p o r t i o n of time magnolia warblers spent i n maintenance behaviour, over the 1985 study p e r i o d , on t r e a t e d and c o n t r o l p l o t s 43 1.11 Comparison of the p r o p o r t i o n of time c h e s t n u t - s i d e d warblers spent s e a r c h i n g f o r food over the study p e r i o d , on t r e a t e d and c o n t r o l p l o t s , i n 1985 48 2.1 Diagrammatic r e p r e s e n t a t i o n of balsam f i r and white b i r c h sampling r e g i o n s 69 2.2 Diagrammatic i l l u s t r a t i o n of the placement of i n v e r t e b r a t e drop t r a y s under the f o l i a g e t i p s of balsam f i r and white b i r c h 72 v i i 2.3 D i s t r i b u t i o n of i n v e r t e b r a t e s i n the 5 canopy r e g i o n s , on treatment and c o n t r o l white b i r c h t r e e s 73 2.4 Comparison of the p r o p o r t i o n of i n v e r t e b r a t e s c o l l e c t e d from branches that were a l i v e at d i f f e r e n t time p e r i o d s on t r e a t e d and c o n t r o l sample t r e e s 79 2.5 P r o p o r t i o n of D i p t e r a , Hymenoptera, and f e e d e r s i n drop t r a y samples 81 2.6 I n v e r t e b r a t e s c o l l e c t e d from drop t r a y s below balsam f i r on treatment and c o n t r o l 83 2.7 I n v e r t e b r a t e s c o l l e c t e d from drop t r a y s below white b i r c h on treatment and c o n t r o l 83 v i i i ACKNOWLEDGMENTS Many people have helped during t h i s study, and I am g r a t e f u l t o them a l l . Those people most c r i t i c a l t o the study were: B. Laughton, K. Holder, S. Keane, D. Ryckman, W. Cameron, D. Syme, D. P o i r i e r , G. Logan, S. G u i l l i l a n d , T. Poldmaa, and P. S a r i c h , who provided e n d l e s s hours of f i e l d work and d a t a t a b u l a t i o n , o f t e n beginning b e f o r e dawn; and S. Holmes who was a constant source of encouragement and advice. F u r t h e r thanks must go t o : J . Beveridge f o r p r o v i d i n g the m e t e o r o l o g i c a l equipment, and f o r h e l p i n g manufacture the sampling equipment; B. Z y l s t r a f o r mixing the f o r m u l a t i o n ; L. P o l l o c k and S. Holmes f o r c a l i b r a t i n g the spray equipment and a p p l y i n g the i n s e c t i c i d e ; N. Payne f o r a d v i c e concerning the ground a p p l i c a t i o n method; P. deGroot and A. Obarymskyj f o r a s s i s t a n c e with the ground a p p l i c a t i o n method, c a l i b r a t i o n , and f o r p r o v i d i n g equipment; K.M.S. Sundaram f o r r e s i d u e a n a l y s i s ; A. Sundaram f o r d r o p l e t s p e c t r a ; and K. Mortenson f o r d r y i n g the i n s e c t samples. I am i n d e b t e d t o the Fo r e s t Pest Management I n s t i t u t e , i n p a r t i c u l a r P.D. Kingsbury, f o r p r o v i d i n g the r e s o u r c e s necessary t o c a r r y out t h i s r e s e a r c h , and f o r g i v i n g me the o p p o r t u n i t y t o pursue t h i s degree. I am most g r a t e f u l t o my s u p e r v i s o r , Dr. J.N.M. Smith who has pr o v i d e d me d i r e c t i o n , advice, and guidance. F i n a l l y , I would a l s o l i k e t o thank the graduate students of UBC's Animal Resource Ecology f o r making i t a l l worthwhile. i x 1 INTRODUCTION For 30 years, chemical spraying of spruce budworm CChoristoneura f u m i f e r a n a (Clem.)) has been a f a c t of l i f e i n New Brunswick, and a major t h r u s t of f o r e s t pest management i n E a s t e r n Canada as a whole. Not s u r p r i s i n g l y , t h e r e has been concern over the environmental consequences of these p r a c t i c e s . The r e s e a r c h spurred by t h i s concern has been summarized i n s e v e r a l e x c e l l e n t reviews (Pearce 1971; NRCC 1975; Pearce 1975; V a r t y 1975; Bart and Hunter 1978; Grue et a l . 1983; P e a k a l l and Bart 1983; P e a k a l l 1985). Des p i t e t h i s volume of rese a r c h , the exact e f f e c t s of f o r e s t r y i n s e c t i c i d e s , s p e c i f i c a l l y f e n i t r o t h i o n , on f o r e s t s ongbirds s t i l l remain a mystery; as does the long-term r e s u l t of t h e i r use. N e v e r t h e l e s s , two p o s s i b l e f a c t o r s r e d u c i n g the abundance of b i r d s i n t r e a t e d areas, have been i d e n t i f i e d : 1) d i r e c t exposure through behaviours t h a t b r i n g b i r d s i n t o c l o s e c o n t a c t w i t h the chemic a l (Pearce and P e a k a l l 1977; Buckner and S a r a z i n 1975; Pearce et a l . 1979); and 2) i n d i r e c t e f f e c t s through decreased food a v a i l a b i l i t y , or the con t a m i n a t i o n of food (Doane and Schaefer 1971; Hunter and Witham 1985). These two f a c t o r s are the s u b j e c t of t h i s t h e s i s . In chapter 1, the p o s s i b i l i t y of d i r e c t exposure i s examined. Measurements of chemical r e s i d u e were taken i n d i f f e r e n t canopy r e g i o n s t o determine where the maximum d e p o s i t of f e n i t r o t h i o n o c c urred, and 2 therefore, the potential exposure of the birds. I then examined the e f f e c t s of exposure to spraying on: long-term population trends, the behaviours of individuals present during the application, and t h e i r reproductive success. Behaviours of three b i r d species were examined for possible changes i n : a) movement within the canopy; or b) allotment of time to s p e c i f i c behaviours. Chapter 2 deals with i n d i r e c t e f f e c t s on the bird's food source. Branch samples were taken before and after treatment, i n order to measure changes i n the amount of food available to birds. Drop trays were used to measure the amount of food removed from the tree subsequent to the treatment. S p e c i f i c questions addressed were: 1) What was the magnitude and duration of insect drop from treated trees? 2) Was t h i s increased drop related to a s i g n i f i c a n t reduction of a v a i l a b l e food? 3) Was there a greater e f f e c t on invertebrates inhabiting areas of higher deposit? Exist i n g methods for determining sublethal and long-term e f f e c t s on forest songbirds are not adequate. By using a combination of methods (census-mapping, mist-netting to mark and recapture in d i v i d u a l s , and time-budget analyses of t h e i r behaviours) over a five-year f i e l d study, t h i s thesis addresses the need for a s e n s i t i v e , nondestructive method for measuring sublethal and long-term consequences of i n s e c t i c i d e usage. This technique can be applied to other chemical and b i o l o g i c a l i n s e c t i c i d e s . Although b i o l o g i c a l control agents are l e s s l i k e l y to cause a d i r e c t e f f e c t on birds, i n d i r e c t e f f e c t s through 3 decreased food a v a i l a b i l i t y c o u l d r e s u l t . These e f f e c t s c o u l d be assessed with time-budget analyses and captures of f l e d g e d young by m i s t - n e t t i n g . 4 SUBLETHAL EFFECTS OF FENITROTHION ON FOREST PASSERINES INTRODUCTION A. Old Methods Insecticides aimed at spruce budworm control occur during the breeding season of forest songbirds, coinciding with peaks i n avian abundance and reproduction. Conventional censusing techniques to monitor pesticide impacts involve monitoring the singing a c t i v i t y of t e r r i t o r i a l males before and a f t e r treatment, on both treated and untreated control p l o t s . A r e l a t i v e decrease i n singing a c t i v i t y on treated plots i s assumed to indicate a detrimental impact. Monitoring of singing a c t i v i t y may be a suitable method when chemicals are used at high dosages. Songbird censuses (supplemented by carcass searches) i n the 1960's showed that f e n i t r o t h i o n and phosphamidon, applied at rates recommended then (280-560g/ha and 280-1260g/ha res p e c t i v e l y ) , adversely affected birds (Fowle 1965, Finley 1965, McLeod 1968, Pearce 1968, Buckner 1974, Bart and Hunter 1978). During the l a s t 10 years, however, les s toxic i n s e c t i c i d e s have been used, and through refined a p p l i c a t i o n technology, the a p p l i c a t i o n rates of i n s e c t i c i d e s used previously (eg. aminocarb, 5 f e n i t r o t h i o n ) , have been reduced. Together, these factors have lowered the environmental hazards to birds. Consequently, methods geared at detecting immediate l e t h a l e f f e c t s need to be replaced with methods that measure sublethal and more long-term e f f e c t s . Song censuses are incapable of detecting such subtle or minor impacts (Peakall and Bart 1983). Problems with monitoring singing a c t i v i t y include: 1) large sample v a r i a b i l i t y due to weather and migration which may mask insecticide-induced e f f e c t s ; 2) an i n a b i l i t y to d i s t i n g u i s h between emigration, mortality and behavioural changes that influence conspicuousness; and 3) immigration of birds from untreated areas into the treated area. It i s not therefore clear what changes i n census re s u l t s should follow spray-induced e f f e c t s . B. New Conditions Organophosphate i n s e c t i c i d e s reduce brain cholinesterase (ChE) l e v e l s i n songbirds (Zinkl et a l . 1979; Busby et a l . 1981; Fleming and Grue 1981). The Canadian W i l d l i f e Service now routinely use the ChE assay developed by H i l l and Fleming (1982) as a monitoring t o o l to measure exposure of songbirds to forestry i n s e c t i c i d e sprays. In t h e i r i n t e r p r e t a t i o n of changes i n ChE a c t i v i t y l e v e l s following a e r i a l i n s e c t i c i d e applications, they have adopted the standards set by Ludke et a l . (1975), that 20% ChE depression indicates exposure, and by Z i n k l et a l . (1979) 6 that 50% GhE depression s i g n i f i e s a l i f e - t h r e a t e n i n g s i t u a t i o n . There are, however, 3 problems with t h i s method: 1) because singing birds are collected, there may be a bias towards healthier i n d i v i d u a l s i n the samples; 2) c o l l e c t i o n may be of i n d i v i d u a l s that immigrated into the treated area after treatment; and 3) the method i s destructive, requiring the s a c r i f i c e of 100 or more birds. Furthermore, the b i o l o g i c a l s i g n i f i c a n c e (effects on behaviour and reproductive success) of d i f f e r e n t l e v e l s of ChE depression are not well known. C. Background on the Program Design Fenitrothion has been used i n Canada since the l a t e 1960's, and has been applied to m i l l i o n s of hectares of forest. It continues to be the major chemical i n s e c t i c i d e for forest insect pests i n Canada. In 1986, 300,000 hectares of Canadian forest were sprayed with fenitrothion (P.D. Kingsbury, pers. comm.)1. The t o x i c i t y curves (mortality of birds verses dosage) for f e n i t r o t h i o n are steep (NRCC 1975). Thus, small increases i n the e f f e c t i v e a p p l i c a t i o n rate, due to multiple swathing for example, may cause a sharply increased impact. In addition, the time scale of response may vary considerably with small changes i n dosage. Immediate e f f e c t s on adult mortality are expected at application 1. Project leader, Environmental Impact, Forest Pest Management Inst i t u t e , Sault Ste. Marie, Ontario. 7 rates greater than 275gAI/ha (NRCC 1975; Peakall and Bart 1983). Breeding f a i l u r e through juvenile mortality i s expected between 206 to 275gAI/ha. Other sublethal e f f e c t s on behaviour (e.g. changes i n foraging, singing, and movements), are detected at rates greater than 138gAI/ha. The dosage rate at which long-term ef f e c t s occur i s unknown. A dosage of 280gAI/ha was chosen for the present study because: 1) i t i s the maximum dose for for e s t r y applications i n Canada, and 2) from the above information i t appears to be "borderline" i n terms of i t s "safety" ( i . e . lack of e f f e c t s ) on forest songbirds. A water formulation was chosen because studies by the Canadian W i l d l i f e Service on ChE depression have involved t h i s formulation, and i t i s the major formulation i n use. S t r a t i f i c a t i o n of the spray cloud may have an important eff e c t on exposure of songbirds to „erial sprays. Warblers and kinglets, because they inhabit tree crowns, are thought to be highly susceptible to forest spraying (Pearce 1968; Buckner and Ray 1973; Busby et a l . 1987). Most of the descending spray cloud i s intercepted by the crown canopy of a dense forest (NRCC 1975). Ground-living birds may be less affected (Moulding 1976; Peakall and Bart 1983). Despite these conjectures, no one has attempted to relate songbird responses to deposit concentrations i n s p e c i f i c regions of trees following the a p p l i c a t i o n of a chemical i n s e c t i c i d e . I have shown that exposure does vary with canopy region (Appendix I I ) . 8 Organophosphate exposure i n birds i s associated with decreased food intake and subsequent loss of body weight (Grue 1982). Birds are thought to search outside of the treated area for food only when the area treated i s small enough that the bordering unsprayed area i s nearby (Hunter and Witham 1985). Ef f e c t s on food seeking behaviour (Adams 1977) may af f e c t parental care, thereby influencing breeding success. Direct e f f e c t s of fenitrothion on invertebrates l a s t 2 to 4 days when large numbers of non-target insects are k i l l e d (Varty 1974; Chapter 2), and residual effects may l a s t up to 30 days afte r spraying (NRCC 1975). Since even seed-eating birds may eat large numbers of insects during the breeding season, changes i n feeding behaviour of songbirds should be a good measure of sublethal exposure to an organophosphate. D. Feeding Behaviour Many birds depend on insects during the breeding season as they are an e s s e n t i a l food source for the young. Most wood warblers (Parulidae) eat a l l major orders of arboreal arthropods (MacArthur 1958). However, certain food items are preferred due to t h e i r c a l o r i c value, and ease of handling or capture (MacArthur 1958; Royama 1970; Garton 1979). Under conditions of low food abundance, however, a greater range of food items may be taken, and search time per item should increase (Schoener 1971). Travel time per item between patches should also increase i f patches are reduced i n size or number. Birds can r e a d i l y f i n d and 9 consume o n l y a s m a l l percent of the t o t a l food present due to the i n c r e a s e d e f f o r t r e q u i r e d to f i n d s carce prey (Kendeigh 1947). By d e p r e s s i n g the abundance of i n s e c t s with a p e s t i c i d e ( c a r b a r y l ) Hunter and Witham (1985) found t h a t 77 percent fewer warblers foraged i n the sprayed area, and t h a t they foraged lower i n the canopy, and i n a g r e a t e r v a r i e t y of t r e e s . Doane and Schaefer (1971) found t h a t a 99 percent k i l l of gypsy moth l a r v a e f o r c e d b i r d s to forage o u t s i d e of the sprayed p l o t s . Increased d e p o s i t s i n the t r e e crown can cause a d i f f e r e n t i a l decrease i n i n s e c t abundance (Moulding 1976) which i s thought t o l e a d t o i n c r e a s e d e f f e c t s on canopy f e e d i n g b i r d s p e c i e s (Hunter and Witham 1985). To f e e d i n areas of lower d e p o s i t , b i r d s might need t o change t h e i r f o r a g i n g behaviour. Niche p a r t i t i o n i n g may decrease c o m p e t i t i o n both w i t h i n and between s p e c i e s (MacArthur 1958; Morse 1976). Therefore, movement of b i r d s i n t o new f o r a g i n g s i t e s may i n c r e a s e c o m p e t i t i o n . When c o m p e t i t i o n becomes i n t e n s e e f f o r t may be d i v e r t e d from necessary r e p r o d u c t i v e a c t i v i t i e s , or a d u l t s may r a i s e t h e i r young to independence, but these young may s u f f e r i n c r e a s e d m o r t a l i t y a f t e r they become independent (Kendeigh 1947). E. Objectives The o b j e c t i v e s of my study were: 10 - 1) t o assess the short-term s u b l e t h a l e f f e c t s of f o r e s t s p r a y i n g on n a t i v e songbirds through: a) changes i n the h o r i z o n t a l and v e r t i c a l s t r a t i f i c a t i o n of 3 common s p e c i e s of b i r d s i n r e l a t i o n to c o n c e n t r a t i o n of the d e p o s i t ; b) changes i n t h e i r f e e d i n g behaviour; and c) i n c r e a s e d time spent i n behaviours a s s o c i a t e d with organophosphate p o i s o n i n g such as preening and b i l l - w i p i n g ; - 2) t o assess long-term s u b l e t h a l e f f e c t s through a comparison of: a) annual r e t u r n r a t e s ; and b) annual f l e d g i n g success, over c o n s e c u t i v e years i n the t r e a t e d and u n t r e a t e d c o n t r o l areas. My o v e r a l l goal was to develop a s e n s i t i v e method t h a t c o u l d be used r o u t i n e l y i n monitoring s t u d i e s . METHODS 1. Site Description: A 200 ha s e c t i o n of second growth b o r e a l f o r e s t , l o c a t e d 13 km NE of Searchmont, On t a r i o , i n the Icewater Greek watershed, La Verendrye Township, was a u t h o r i z e d by the O n t a r i o M i n i s t r y of N a t u r a l Resources f o r long-term r e s e a r c h i n t o the environmental impact of f o r e s t i n s e c t i c i d e a p p l i c a t i o n s . In 1983, an 8 ha study p l o t , i n the centre of the proposed spray b l o c k (49.2 ha), was s e l e c t e d f o r d e t a i l e d o b s e r v a t i o n s of f o r e s t s o n g b i r d s ( P l o t T ) . A c o n t r o l p l o t f o r the 1985 a p p l i c a t i o n (4 ha), was s e t up i n 1984, a f u r t h e r 5 km NE of t h i s area, to e l i m i n a t e the 11 p o s s i b i l i t y of d r i f t from the a e r i a l treatment ( P l o t C). T h i s p l o t was s m a l l e r because of manpower l i m i t a t i o n s . However, the 3 s p e c i e s of i n t e r e s t ( c h e s t n u t - s i d e d warbler, Dendroica  p e n s y l v a n i c a ( L . ) , magnolia warbler, IL_ magnolia ( W i l s o n ) , and wh i t e - t h r o a t e d sparrow, Z o n o t r i c h i a a l b i c o l l i s (Gmelin)) were common w i t h i n the p l o t . A second treatment p l o t of approximately 3 ha was e s t a b l i s h e d i n 1986 ( P l o t T2). A p o r t i o n of the f i r s t treatment p l o t was used as a c o n t r o l .for the 1986 ground a p p l i c a t i o n . Due to the reduced d r i f t a s s o c i a t e d w i t h a ground a p p l i c a t i o n , the t r e a t e d and c o n t r o l areas c o u l d be w i t h i n the same v a l l e y . Consequently, o b s e r v a t i o n s i t e s on P l o t T2 and the c o n t r o l were c l o s e l y matched i n 1986 ( F i g u r e 1.1). H a b i t a t a n a l yses were conducted i n a l l 3 areas u s i n g the James and Shugart (1970) method (Appendix I, Tables 1,2 and 3). The o r i g i n a l treatment p l o t was r e a n a l y s e d i n 1986 due t o an apparent s u c c e s s i o n a l change (Appendix I, Table 4), which c o u l d have i n f l u e n c e d b i r d p o p u l a t i o n trends i n the area. Shrub growth i n c r e a s e d c o n s i d e r a b l y over the 3 years on p l o t T (ground cover i n c r e a s e d from 73 percent t o 92 p e r c e n t ) . A l a r g e p o r t i o n of the stand i n a l l 3 areas was cut 10 to 19 ye a r s ago. T h i s was a p a r t i a l cut, l e a v i n g s e c t i o n s of spruce and f i r t h a t are now 45 to 65 ye a r s o l d . Rough c a l c u l a t i o n s (Appendix I, Tab l e 5) of the volume of balsam f i r and white spruce f o l i a g e i n the 3 areas ( p l o t T, p l o t T2, and p l o t C) were 554m 3, 718m 3, and 1483m 3, r e s p e c t i v e l y . Figure 1.1. Location of treatment and control plots for the a e r i a l and ground applications. A E R I A L A P P L I C A T I O N 13 Budworm p o p u l a t i o n s p r i o r to t h i s study had i n c r e a s e d from the l a t e 1960's to cause the t h i r d and most severe outbreak i n E a s t e r n Canada s i n c e 1909 ( K e t t e l a 1983). In the study r e g i o n , budworm d e c l i n e d from about 1800 l a r v a e / m 2 f o l i a g e i n 1983, and 240/m 2 i n 1984, to 0 i n 1987 (M. AppleJohn pers. comm.2; see a l s o Table 1.4). None of the 3 areas were sprayed p r i o r t o t h i s study. The treatment p l o t s had n a t u r a l borders to the southeast ( G o u l a i s R i v e r ) and southwest (change i n topography) which c o u l d l i m i t movement i n and out of the spray b l o c k ; a problem i n a number of impact s t u d i e s ( P e a k a l l and Bart 1983). The h a b i t a t was second growth b o r e a l f o r e s t (mean canopy height of 9 m ) . Although t h i s was not a t y p i c a l budworm f o r e s t , i t was more amenable to study than a mature f o r e s t . Furthermore, b i r d s i n h a b i t i n g open areas and the upper crown of second growth t r e e s , can r e c e i v e a s i m i l a r exposure to that of canopy-dwelling b i r d s i n a t y p i c a l budworm f o r e s t (Moulding 1976; Pearce et a l . 1979). The 3 areas were s i m i l a r i n t r e e s p e c i e s c o m p o s i t i o n . Predominant s p e c i e s of the f i r s t treatment p l o t ( p l o t T) were Thuja o c c i d e n t a l i s . Abies balsamea. and B e t u l a p a p y r i f e r a . Those of the second treatment p l o t ( p l o t T2) were Abies balsamea. P i c e a  g l a u c a . B e t u l a p a p y r i f e r a . and Populus t r e m u l o i d e s . Predominant s p e c i e s of the c o n t r o l p l o t ( p l o t C) were Abies balsamea. P i c e a  g l a u c a . and B e t u l a p a p y r i f e r a . S e c t i o n s of P l o t T were p o o r l y 2. C h i e f , F o r e s t I n s e c t and Disease Survey, Great Lakes F o r e s t Research Centre, S a u l t Ste. Marie, O n t a r i o . 14 d r a i n e d . Only the d r i e r p o r t i o n , i d e n t i c a l i n h a b i t a t t o P l o t T2, was used as a c o n t r o l f o r the second a p p l i c a t i o n . P l o t C was d r i e r than the other p l o t s , and the t r e e s were g e n e r a l l y more mature (1 percent over 18 m). 2. Application of the i n s e c t i c i d e : S i g n i f i c a n t l y h i g h e r l e v e l s of p e s t i c i d e are d e p o s i t e d on the upwind s i d e of the t r e e and i n areas not f i l t e r e d by other f o l i a g e (Armstrong and Yule 1978; Barry 1984). T h i s produces a v e r t i c a l g r a d i e n t or s t r a t i f i c a t i o n of d e p o s i t where lower canopy l e v e l s r e c e i v e l e s s d e p o s i t ( S p i l l m a n and Joyce 1978; Sundaram and Nott 1984). H o r i z o n t a l s t r a t i f i c a t i o n has a l s o been r e p o r t e d where l e s s d e p o s i t reaches the i n s i d e f o l i a g e (Armstrong and Yule 1978; Sundaram et a l . 1985). In order to r e l a t e changes i n b i r d behaviour to c o n c e n t r a t i o n s of d e p o s i t , deposit samplers were s i t u a t e d i n each of the 5 canopy r e g i o n s used f o r b e h a v i o u r a l s t u d i e s . D e t a i l s of the method are g i v e n i n Appendix I I . A. A e r i a l a p p l i c a t i o n At 0730 on 14 June, 1985, f e n i t r o t h i o n was a p p l i e d with a Cessna 188 a i r c r a f t equipped with 4 M i c r o n a i r AU3000 atomizer u n i t s , at a blade angle of 35°, as an emulsion i n water at a t o t a l volume of 1.5 l i t r e s / h e c t a r e . The tank mix c o n s i s t e d of 15 15 percent t e c h n i c a l f e n i t r o t h i o n (Sumithion*0, 1.5 percent s o l v e n t (Dowanol TPM), 1.5 percent e m u l s i f i e r (Atlox®3409F), 1 percent t r a c e r dye (Rhodamine B) and 81 percent water. The spray was a p p l i e d 15 m above the t r e e canopy at a f l y i n g speed of 160 km/h w i t h a swath width of 45 m. The dosage was 280 g a c t i v e i n g r e d i e n t ( A l ) of f e n i t r o t h i o n per hectare. M e t e o r o l o g i c a l c o n d i t i o n s at the time of spray were: temperature 15 ± 1°C, r e l a t i v e humidity 80 percent, wind speed 2 ± 0.5 km/h and no c l o u d cover. R e s u l t s of chemical analyses on the f a t e and d i s t r i b u t i o n of f e n i t r o t h i o n f o l l o w i n g the a p p l i c a t i o n (Appendix I I ) , i n d i c a t e d a d e f i n i t e g r a d i e n t i n d e p o s i t c o n c e n t r a t i o n s w i t h i n balsam f i r , d e c r e a s i n g from top to bottom and from p e r i p h e r y to i n n e r t r e e canopy, presumably due t o f i l t r a t i o n of spray d r o p l e t s by the needles. The r a t i o of d e p o s i t c o n c e n t r a t i o n from top to lower canopy l e v e l s was 1.7:1.3:1 f o r balsam f i r . I n s i d e f o l i a g e r e c e i v e d approximately the same d e p o s i t as lower o u t s i d e f o l i a g e . T h i s s t r a t i f i c a t i o n of d e p o s i t was not observed f o r white b i r c h ( T a b l e 1.1). More d e p o s i t was r e c e i v e d i n mid and lower canopy r e g i o n s of white b i r c h , probably due to the geometry of the t r e e . Poor weather c o n d i t i o n s i n 1985 f o r 3 days f o l l o w i n g the a p p l i c a t i o n ( r a i n ) prevented adequate sampling of b i r d behaviour, and may have enhanced d e g r a d a t i o n of the c h e m i c a l . Consequently, the a p p l i c a t i o n was repeated i n 1986. 16 Table 1.1. Fenitrothion deposits on foliage at d i f f e r e n t locations of the tree crown following the a e r i a l and ground app l i c a t i o n . AERIAL1 GROUND2 SAMPLER LOCATION FIR 3 BIRCH3 FIR 3 BIRCH3 top 75 + 20 66±22 61±12 38±13 mid-outside 54±16 90±25 43±13 46±12 low-outside 43± 8 71±20 41±14 36± 8 mid-inside 41 + 13 72±17 32±10 36± 9 low-inside 30± 4 64±17 18± 6 33± 8 o v e r a l l mean±SD 49±23 73±27 39±15 38±15 for the 6 sample trees; samples from 2 trees were pooled to provide 3 composite samples for analysis. 2 nine sample trees were analysed separately. 3 analysis of the amount of deposit per surface area of foli a g e , expressed as ng per cm. 17 B. Use of a ground application to simulate the 1985 a e r i a l a p p l i c a t i o n In A p r i l of 1986, the O n t a r i o M i n i s t e r of N a t u r a l Resources d e c i d e d not to allow any a e r i a l a p p l i c a t i o n s of chemical i n s e c t i c i d e s to O n t a r i o crown f o r e s t s . T h i s ban i n c l u d e d a p p l i c a t i o n s f o r e i t h e r r e s e a r c h or pest c o n t r o l . I t was t h e r e f o r e necessary to r e s o r t t o a ground a p p l i c a t i o n . For a v a l i d comparison between a p p l i c a t i o n years, both the dosage and s t r a t i f i c a t i o n of the d e p o s i t had to be r e p l i c a t e d . In the area s e l e c t e d ( P l o t T2), 64 percent of the t r e e s were l e s s than 15 cm i n diameter, and 86 percent were l e s s than 23 cm i n diameter (a height of l e s s than 12 meters). T h e r e f o r e , a ground a p p l i c a t i o n c o u l d p r o v i d e the coverage needed f o r t r e e s of t h i s s i z e . There are two p o s s i b l e ways of conducting a ground a p p l i c a t i o n t o simulate an a e r i a l spray. Hopewell (1974) developed a technique f o r a p p l y i n g a s i m u l a t e d a i r c r a f t spray to i n d i v i d u a l t r e e s u s i n g a s p i n n i n g d i s c n o z z l e . A s t a t i c or d i r e c t e d a p p l i c a t i o n such as t h i s does not, however, allow f o r s t r a t i f i c a t i o n of the d e p o s i t . On the other hand, spr a y i n g i n swaths through the f o r e s t a l l o w s the d e p o s i t t o be c a r r i e d i n t o the t r e e s as i t would be from an a e r i a l a p p l i c a t i o n . S t r a t i f i c a t i o n occurs because of 18 d i f f e r i n g wind speeds w i t h i n the d i f f e r e n t canopy h e i g h t s (N. Payne pers. comm.)3. As with a e r i a l a p p l i c a t i o n s , some wind movement was necessary f o r a p r e d i c t a b l e movement of the spray c l o u d . The s p r a y i n g of i n d i v i d u a l t r e e s i n a d i r e c t e d f a s h i o n , was a l s o r e j e c t e d due to the problem of immigration of i n s e c t s from the surrounding v e g e t a t i o n onto the sprayed t r e e , g i v i n g d i f f e r e n t r e c o l o n i z a t i o n r e s u l t s from t h a t of an a e r i a l l y t r e a t e d b l o c k . I t h e r e f o r e used a Solo port 423 backpack mistblower (70 ml engine c a p a c i t y ) with the n o z z l e p o i n t i n g s t r a i g h t up i n the a i r , i n order t o take the spray above the canopy. The mistblower was f i t t e d w i t h a 2 meter e x t e n s i o n tube and a booster pump which i n c r e a s e d the v e r t i c a l throw of the spray t o about 15 meters. In t h i s way, the spray cloud d i f f u s e d back down over the canopy, i m i t a t i n g an a e r i a l a p p l i c a t i o n . The e x t e n s i o n tube was f i t t e d w i t h a d i f f u s e r n o z z l e to c o n t r o l d r o p l e t s i z e . P a r a l l e l t r a i l s were cut 20 meters apart throughout the area. These swath l i n e s were o r i e n t e d p e r p e n d i c u l a r t o the p r e v a i l i n g wind d i r e c t i o n t o allow the wind t o d i s s i p a t e the spray c l o u d and thereby even out the d e p o s i t . A l l overhead branches were removed and the path was cut wide enough t o permit 3. P r o j e c t l e a d e r , Spray Cloud Behaviour, F o r e s t Pest Management I n s t i t u t e , S a u l t Ste. Marie, O n t a r i o . 19 u n o b s t r u c t e d walking so that a constant walking speed could be maintained. The equipment was c a l i b r a t e d , u s i n g a f o r m u l a t i o n to mimic the s p e c i f i c g r a v i t y and v i s c o s i t y of f e n i t r o t h i o n ( t r i e t h y l phosphate 4.3 percent, A t l o x 3409F 1.5 percent, Dowanol TPM 1.5 percent, Rhodamine B 1.5 percent and water 91.7 p e r c e n t ) , to determine the a c t u a l flow r a t e of the mistblower w i t h the e x t e n s i o n tube. The f o r m u l a t i o n was then a d j u s t e d f o r the mistblower a p p l i c a t i o n r a t e to maintain a dosage of 280 g Al/ha. The tank mix c o n s i s t e d of 4.5 percent f e n i t r o t h i o n (.224 l i t e r s ) , 1.5 percent A t l o x 3409F (.075 l i t e r s ) , 1.5 percent Dowanol TPM (.075 l i t e r s ) , 1.0 percent Rhodamine B dye (.05 l i t e r s ) , and 91.5 percent water (4.576 l i t e r s ) . With both the f o r m u l a t i o n (the amount of A l / h a of tank mix), and the volume e m i s s i o n r a t e (dependent on the mistblower flow r a t e ) f i x e d , o n l y the walking speed c o u l d be a d j u s t e d . Therefore, having c a l i b r a t e d the flow r a t e to be 312 ml/min, and knowing both the swath width (20 meters) and the area to be covered (2.434ha), the r e q u i r e d walking speed would be 0.52 m/sec. C. The Ground a p p l i c a t i o n F e n i t r o t h i o n was a p p l i e d between 1107 and 1156 on 18 June, 1986. One person s e t the walking pace u s i n g 20 m f l a g g e d s t a t i o n s . The a p p l i c a t o r f o l l o w e d behind h o l d i n g the n o z z l e 20 v e r t i c a l l y upwards, e m i t t i n g the spray at the maximum flow r a t e (312 ml/min). A t h i r d person recorded the time e l a p s e d f o r each l i n e . M e t e o r o l o g i c a l c o n d i t i o n s d u r i n g the spray a p p l i c a t i o n were: wind speed 9.6 ± 1.0 km/h, temperature 21 ± 1°C, RH 50 percent, and no c l o u d cover. From the t o t a l volume emitted (12.667 l i t e r s ) and the area t r e a t e d (2.434 ha), the a c t u a l a p p l i c a t i o n r a t e was 5.2 l i t e r s / h a or 292.5 g A l per h e c t a r e (about 4% h i g h e r than e s t i m a t e d ) . S t r a t i f i c a t i o n of the deposit was s i m i l a r t o t h a t of the a e r i a l a p p l i c a t i o n where the maximum d e p o s i t was r e c e i v e d i n t r e e crowns and i n the p e r i p h e r a l f o l i a g e of balsam f i r (Table 1.1). The s m a l l e r d r o p l e t s produced by the mistblower a p p l i c a t i o n were p o o r l y c o l l e c t e d by white b i r c h f o l i a g e . T h i s was probably due to the low humidity d u r i n g the a p p l i c a t i o n (A. Sundaram pers. comm.)4. Very l i t t l e d e p o s i t reached the ground (1.7 g/ha) compared t o the a e r i a l a p p l i c a t i o n (73 g/ha), suggesting a more e f f e c t i v e c o l l e c t i o n of the mistblower spray by the f o l i a g e . 3. B i r d populations of Icewater Creek: The b i r d communities of Icewater Creek were c h a r a c t e r i z e d d u r i n g the summers of 1983 and 1984. Stages of the breeding c y c l e were determined u s i n g the breeding c o n d i t i o n of i n d i v i d u a l s 4. P r o j e c t l e a d e r , P e s t i c i d e Formulations, F o r e s t Pest Management I n s t i t u t e , S a u l t Ste. Marie, O n t a r i o . 21 caught i n mist nets, changes i n s i n g i n g a c t i v i t y over the season, and o b s e r v a t i o n s of breeding behaviour ( a c t i v i t y at the nest, f o r example). The b r e e d i n g season extends from mid-May t o the end of J u l y , when the young have f l e d g e d , and t e r r i t o r i e s have broken up. D i v e r s i t y of b i r d s i n the area was h i g h (34 s p e c i e s of t e r r i t o r i a l b i r d s ) . P o p u l a t i o n s of the 3 i n d i c a t o r s p e c i e s averaged 1.8 per ha f o r c h e s t n u t - s i d e d warblers, 2.5 per ha f o r magnolia warblers, and 2.8 per ha f o r w h i t e - t h r o a t e d sparrows. F o r t y percent of a l l t e r r i t o r i a l b i r d s counted belonged t o the 3 i n d i c a t o r s p e c i e s . 4. E f f e c t s of f e n i t r o t h i o n on forest songbirds: A. Long-term E f f e c t s : Censuses were conducted using a p l o t method (Kendeigh 1947) t o r e c o r d a l l s i n g i n g and s i g h t e d b i r d s . A 40 m g r i d was f l a g g e d f o r p l o t t i n g b i r d l o c a t i o n s . The l o c a t i o n of each i n d i v i d u a l observed was mapped f o r d e l i n e a t i n g t e r r i t o r i e s . Two observers sampled each area i n o p p o s i t e d i r e c t i o n s t o remove the e f f e c t s of observer b i a s , and t o c o n t r o l f o r e f f e c t s of time of day on a c t i v i t y . One 8 ha p l o t ( p l o t T) was censused from 1983 t o 1987. A second 4 ha p l o t ( p l o t C) was censused from 1984 t o 1987, and a t h i r d 3 ha p l o t ( p l o t T2) was censused only i n 1986 and 1987. Censuses f o r the t h i r d p l o t i n 1986 were taken from time-budget 22 o b s e r v a t i o n s i t e s . Changes i n r e l a t i v e abundance were a l s o e s t i m a t e d by mist n e t t i n g . Nets were sampled simultaneously i n t r e a t e d and un t r e a t e d c o n t r o l areas. They were d i s p e r s e d throughout the study areas. The r e t u r n of i n d i v i d u a l s t o each a r e a was determined from r e c a p t u r e s of i n d i v i d u a l s i n mist nets the f o l l o w i n g year. B. Medium-term E f f e c t s : A l l i n d i c a t o r s p e c i e s were common to the area, easy t o observe, and p o t e n t i a l l y s e n s i t i v e t o a e r i a l a p p l i c a t i o n s . Some i n d i v i d u a l s of these s p e c i e s were colour-banded t o f a c i l i t a t e i d e n t i f i c a t i o n . D i f f e r e n t c o l o u r s were used t o i d e n t i f y males and females. White-throated sparrows occupy open h a b i t a t s where they may r e c e i v e a s i m i l a r spray exposure t o c r o w n - i n h a b i t i n g s p e c i e s t h a t are more d i f f i c u l t t o study (Busby et a l . 1983). The magnolia warbler i s a l s o an edge s p e c i e s i n h a b i t i n g mainly balsam f i r at the mid-canopy l e v e l . C h e s t n u t - s i d e d w a r b l e r s a l s o forage i n mid-canopy, but mainly i n deciduous t r e e s p e c i e s . P r e l i m i n a r y o b s e r v a t i o n s of a l l 3 s p e c i e s r e v e a l e d i n t r a s p e c i f i c d i f f e r e n c e s i n behaviour. Females were more a c t i v e l a t e r i n the morning, tended t o be lower i n the t r e e and f u r t h e r i n s i d e the canopy (see a l s o Morse (1968)), and they apportioned 23 t h e i r t i m e d i f f e r e n t l y from males o f t h e i r s p e c i e s . Fema le s were no t i n c l u d e d i n d e t a i l e d a n a l y s e s as t h e y c o u l d no t be o b s e r v e d i n l a r g e enough numbers . P r e l i m i n a r y s t u d i e s a l s o showed t h a t t h e ma in a c t i v i t y p e r i o d was a 4 hour p e r i o d b e g i n n i n g a h a l f hour a f t e r s u n r i s e . B e h a v i o u r a l o b s e r v a t i o n s were t a k e n a t e v e n l y - d i s t r i b u t e d s i t e s t h r o u g h o u t t r e a t e d and u n t r e a t e d c o n t r o l a r e a s o v e r t h e s t u d y p e r i o d (9 June t o 3 J u l y i n 1986, and 28 May t o 26 J u l y i n 1 9 8 5 ) . S i t e s were c h o s e n where v i s i b i l i t y o f b i r d s was good , and where a l l canopy r e g i o n s were v i s i b l e . These s i t e s were sampled i n random o r d e r , and were r andomly a s s i g n e d among o b s e r v e r s . O b s e r v a t i o n s were c o n d u c t e d s i m u l t a n e o u s l y i n t h e t r e a t e d and u n t r e a t e d c o n t r o l a r e a s . O b s e r v a t i o n s a t e a c h s i t e l a s t e d f o r 20 m i n u t e s . D u r i n g t h i s t i m e , e ach b i r d seen was r e c o r d e d f o r as l o n g as i t was p r e s e n t , and t h e s t a r t and f i n i s h t i m e s o f e ach b e h a v i o u r and move t h e b i r d made were n o t e d on a d a t a s h e e t . The l o c a t i o n and b e h a v i o u r a l c a t e g o r i e s u sed a r e l i s t e d i n T a b l e 1 .2 . To e l i m i n a t e t h e e f f e c t o f t r e e h e i g h t on f o r a g i n g h e i g h t , I e x p r e s s e d f o r a g i n g h e i g h t as a p r o p o r t i o n o f t r e e h e i g h t . F o r a g i n g h e i g h t s were t h u s c o n v e r t e d t o t h e canopy r e g i o n u t i l i z e d ( t o p , m i d , o r l o w ) . A l l o b s e r v a t i o n s were r e l a t e d t o c h e m i c a l r e s i d u e measurements , t a k e n i n the same canopy r e g i o n s . S t r a t i f i c a t i o n o f t h e d e p o s i t was e x p e c t e d t o i n f l u e n c e b i r d b e h a v i o u r t h r o u g h Table 1.2. L o c a t i o n and b e h a v i o u r a l c a t e g o r i e s used i n the time-budget o b s e r v a t i o n s . LOCATIONS: 0 * ou ts ide 1 * inside BEHAVIOURS: S o c i a l Maintenance Feeding S i n g i n g and t e r r i t o r i a l defense C o u r t i n g C a l l (Alarm or other) Nest b u i l d i n g S i t t i n g and l o o k i n g Preening B i l l wiping F l y c a t c h i n g Hawking Hover-gleaning Gleaning Peck and Hammer Probe C a r r y i n g food Searching 25 avoidance of the chemical and/or d e p l e t i o n of food a v a i l a b l e through a chemical-induced k i l l of i n v e r t e b r a t e s . Reproductive success was estimated by: a) the number of f l e d g l i n g s caught i n mist nets i n t r e a t e d and u n t r e a t e d areas; b) ob s e r v a t i o n s of nests found w i t h i n both areas; and c) ob s e r v a t i o n s of a d u l t b i r d s f e e d i n g t h e i r young. The capture date of f l e d g l i n g s was a l s o compared f o r t r e a t e d and c o n t r o l areas. C. Immediate E f f e c t s : Immediate e f f e c t s were determined by changes i n s i n g i n g a c t i v i t y , and by movement of i n d i v i d u a l s out of the t r e a t e d area. RESULTS E f f e c t s of fe n i t r o t h i o n on forest songbirds: A. Long-term population trends: 1) Census r e s u l t s and t e r r i t o r y analysis: Abundance of t e r r i t o r i a l b i r d s i n c r e a s e d on the c o n t r o l p l o t ( P l o t C) before sp r a y i n g , but d e c l i n e d s l i g h t l y on the t r e a t e d p l o t ( P l o t T) ( F i g u r e 1.2). Abundance on both the c o n t r o l and t r e a t e d p l o t s d e c l i n e d at about the same r a t e i n the year f o l l o w i n g treatment. 26 Figure 1.2. P o p u l a t i o n t r e n d s of t e r r i t o r i a l b i r d s ( a l l s p e c i e s ) on t r e a t e d ( P l o t T) and c o n t r o l ( P l o t C) p l o t s , from 1983 t o 1987. The number of b i r d s (x±SD) are expressed per h e c t a r e . F e n i t r o t h i o n was a p p l i e d i n 1985 on P l o t T. 27 Numbers of warblers were s i g n i f i c a n t l y lower (p<.005, r e g r e s s i o n , slope=-3.6, df=5) i n 1986 than 1985 on the t r e a t e d p l o t , but not on c o n t r o l (p>.05). P o p u l a t i o n s of a l l other groups of b i r d s on the t r e a t e d p l o t f l u c t u a t e d as expected from the c o n t r o l trends ( F i g u r e 1.3). P o p u l a t i o n s of the t h r e e i n d i c a t o r s p e c i e s were not s i g n i f i c a n t l y reduced w i t h i n the year of treatment (p>.05, ANOVA, d f = l , l 5 ) . Although the number of t e r r i t o r i e s of these 3 s p e c i e s d e c l i n e d over the study p e r i o d , a s i m i l a r p r o p o r t i o n of the o r i g i n a l t e r r i t o r i e s were s t i l l occupied i n 1987 on treatment and c o n t r o l p l o t s . The most notable d e c l i n e was f o r the c h e s t n u t - s i d e d warbler between 1986 and 1987 ( T a b l e 1.3). Table 1.3. Long-term changes i n the number of t e r r i t o r i e s of the c h e s t n u t - s i d e d warbler, magnolia warbler, and w h i t e - t h r o a t e d sparrow. 1983 1984 1985 1986 1987 PLOT T S p e c i e s : c h e s t n u t - s i d e d 13 13 9 8 3 magnolia 12 12 12 11 9 w h i t e - t h r o a t 13 8.5 7 7 6 PLOT C Sp e c i e s : c h e s t n u t - s i d e d _ 11 12 10 4 magnolia - 8 10 9 6 w h i t e - t h r o a t — 9.5 6 6 4 2) Change i n budworm-feeding species: 28 f ± C O N T R O L • • T R E A T M E N T ~T 1 1 1 1 1 1 1 1 1 -1983 1984 1985 1986 1987 1983 1984 1985 1986 1987 YEARS Figure 1.3. P o p u l a t i o n t r e n d s of the major b i r d groups (A= wa r b l e r s , B= th r u s h e s , C= f l y c a t c h e r s , D= k i n g l e t s , E= v i r e o s , F= w h i t e - t h r o a t e d sparrows) on treatment ( P l o t T) and c o n t r o l ( P l o t C), from 1983 to 1987. The number of b i r d s (x±SD) i s expressed per h e c t a r e . F e n i t r o t h i o n was a p p l i e d i n 1985 on P l o t T. 29 One e x p l a n a t i o n f o r the general d e c r e a s i n g t r e n d i n b i r d abundance on both p l o t s (Figure 1.2), i s t h a t c y c l i c d e c l i n e s i n abundance of spruce budworm may cause budworm-feeding b i r d s p e c i e s to decrease i n numbers ( M o r r i s et a l . 1958). Since budworm p o p u l a t i o n s i n Northeastern O n t a r i o have been d e c r e a s i n g from 1981 (Table 1.4), one might expect budworm-associated b i r d s p e c i e s to have decreased i n abundance over the study p e r i o d (1983 to 1987). C o n t r o l r e s u l t s are c o n s i s t e n t w i t h t h i s h y p o t h e s i s , as t h e r e has been a s i g n i f i c a n t r e d u c t i o n i n numbers of budworm-feeding s p e c i e s (the tennessee, Vermivora p e r e g r i n a (Wilson), b l a c k b u r n i a n , EL. f u s c a ( M u l l e r ) , bay-breasted, D.  castanea (Wilson), and cape-may , IL. t i g r i n a (Gmelin), warblers, and the evening grosbeak, Hesperiphona v e s p e r t i n a (Cooper); p<.005, r e g r e s s i o n , df=23, slope= - . 7 ) . Numbers of these s p e c i e s were i n i t i a l l y low on p l o t T, and d i d not change over the study p e r i o d . H a b i t a t d i f f e r e n c e s on the 2 p l o t s may have c o n t r i b u t e d to the d i f f e r i n g responses to budworm. The h a b i t a t f o r budworm and the a s s o c i a t e d b i r d s p e c i es was more s u i t a b l e on p l o t C ( 1% t r e e s of g r e a t e r than 12m), and i n the f o r e s t adjacent to t h i s p l o t . An i n v e r s e n u m e r i c a l response i s expected f o r the magnolia, yellow-rumped, Eh. coronata ( L . ) , and b l a c k - t h r o a t e d green, D.  v i r e n s (Gmelin) warblers because they are outcompeted by budworm s p e c i a l i s t s ( M o r r i s et a l . 1958). There was a s l i g h t o v e r a l l (1984 to 1987) i n c r e a s e (.53 b i r d s per h e c t a r e ) of these s p e c i e s on p l o t C. The i n c r e a s e from 1984 to 1986 (p<.01, r e g r e s s i o n , df=19, slope=1.22) was 2.48 b i r d s per h e c t a r e ; c o r r e s p o n d i n g to a Table 1.4. Gross area (ha) of moderate-to-severe d e f o l i a t i o n (current) by spruce budworm from 1983 to 1986 1. Area of moderate-to-severe d e f o l i a t i o n Region D i s t r i c t 1983 1984 1985 1986 Northeastern Sault Ste. Marie 669,875 30,255 7,875 A l l d i s t r i c t s 4,533,718 2,203,389 1,522,757 14,504 North Central A l l d i s t r i c t s 2,039,030 3,879,876 6,211,392 North Western A l l d i s t r i c t s 774,634 1,667,801 3,403,547 Tota l 9,039,862 8,747,852 12,332,365 8,855,687 1 adapted from Thomson et a l . 1985 o 31 decrease of 2.15 b i r d s per hectare of budworm-related s p e c i e s over the same p e r i o d . T h i s i n c r e a s e was not observed on p l o t T, and was not expected s i n c e there was no change i n numbers of budworm-related s p e c i e s ( F i g u r e 1.4). C o n t r o l r e s u l t s suggest t h a t a response to budworm p o p u l a t i o n s o c c u r r e d i n the Icewater Creek area where there was a p p r o p r i a t e h a b i t a t . F l u c t u a t i o n s i n budworm numbers do not seem to have i n f l u e n c e d b i r d p o p u l a t i o n t r e n d s on p l o t T, however. Abundance of other b i r d s p e c i e s , not i n f l u e n c e d by budworm p o p u l a t i o n s , f o l l o w e d the same t r e n d on c o n t r o l and treatment p l o t s ( F i g u r e 1.5). T h i s suggests that other f a c t o r s (environmental c o n d i t i o n s on the w i n t e r i n g grounds or d u r i n g m i g r a t i o n , f o r example) had a g r e a t e r i n f l u e n c e on p o p u l a t i o n t r e n d s than the treatment. 3) Relative abundance of species as determined by mist netting: Contrary to the trends e x h i b i t e d i n the census r e s u l t s , the number of b i r d s caught per net hour on treatment ( p l o t T) was not lower i n 1986 than 1985 (Table 1.5). The p r o p o r t i o n of males caught i n 1986 was lower than i n any other year on e i t h e r p l o t , however (38 percent on p l o t T i n 1986 v e r s u s an average i n other y e a r s of 44 percent on p l o t T and 42 percent on p l o t C; Table 1.5). As the males have a g r e a t e r p o t e n t i a l f o r exposure t o i n s e c t i c i d e sprays than females, t h i s suggests a reduced r e t u r n of males r e l a t e d to the treatment. 32 ~T 1 1 I I 1983 1984 1985 1986 1987 YEARS Figure 1.4. Change i n abundance of budworm-associated b i r d s p e c i e s (A), and b i r d s p e c i e s known to have a n e g a t i v e numerical response to budworm numbers (B), from 1983 t o 1987, on t r e a t e d ( P l o t T) and c o n t r o l ( P l o t C) p l o t s . Numbers of b i r d s (x±SE) are expressed per h e c t a r e . 33 Figure 1 . 5 . Population trends of b i r d species not i n f l u e n c e d by budworm populations, from 1983 to 1987, on t r e a t e d ( P l o t T) and c o n t r o l ( P l o t C) p l o t s . Numbers of b i r d s (x±SE) are expressed per hectare. Table 1.5. Change in population structure on plot T, from 1983 to 1987, and on plot C, from 1984 to 1986, as determined by mist -net t ing. Numbers represent or ig inal captures for the respective year, expressed per 100 net hours. The categories for each group are: the total number of birds caught (T) , number of males CM), number of females (F ) , and the number of juveni les ( J ) . 1983 1984 1985 1986 1987 P lo t T T M F J T M F J T M F J T M F J T M F F1ycatchers 2.8 0.7 1.9 0.2 3.1 1.0 1.5 0.6 2.4 0 1.9 0.2 2.5 .3 1.8 .3 2.4 .9 1.3 Thrushes 6.0 3.0 1.8 1 .3 5.1 2.3 1.2 1.2 3.5 1.6 1.4 0.3 4.5 1.3 1.7 1.0 3.3 1.9 1.4 Red-eyed vireo 0.7 0.1 0.4 0 1.6 0.8 0.6 0.2 1.0 0.2 0.5 0.1 0.9 0.5 0.2 0 0.9 0 0.9 Warb1ers 18.1 9.7 5.9 2.0 24.9 9.8 8.4 5.6 26.3 11.1 9.2 4.3 27.4 1 1.0 8.6 7.6 1 7.9 10.3 8.0 Purple finch 0.5 0.3 0.1 0.1 1.0 0.2 0.2 0.4 0.3 0 0.2 0 0.3 0.1 0.1 0 0 0 0 White-throated sparrow 4.8 1.5 1.2 1.8 3.2 1.3 0.4 1 .2 2.1 1.3 0.5 0.3 2.7 1.1 1.1 0.5 3.8 2.4 1.4 Al1 te r r i to r la l birds 33.7 1 5.4 1 1.6 5.8 39.6 15.7 12.5 9.4 36.3 14.3 13.9 5.4 39.2 14.4 14.0 9.5 28.2 15.5 13.1 Proportion of catch 1 46.9 35.3 1 7.3 41.8 33.1 23.9 42.4 41.4 15.0 37.9 36.7 24.6 - -1984 1985 1986 Plot C T M F J T M F J T M F Flycatchers 0.1 0.1 0 0 0.4 0.1 0.3 0 1.4 1.1 0.4 Thrushes 3.8 1.0 1.1 1.1 4.5 1.4 2.0 0.7 1.4 1.1 0.4 Red-eyed vireo 0.7 0.1 0.1 0.1 0 0 0 0 0 0 0 Warblers 22.2 8.4 6.8 4.8 22.0 9.6 8.6 3.3 17.5 11.2 6.3 Purple finch 0.1 0.1 0 0 0 0 0 0 0 0 0 White-throated sparrow 4.1 1.8 1.1 1.1 3.9 1.5 1.4 1.1 2.8 2.1 0.7 Al1 t e r r i t o r i a l birds 31.0 11.9 9.12 7.1 30.8 12.6 12.2 5.0 23.1 15.4 0.1 Proportion of catch 1 42.3 32.5 25.2 42.3 40.9 16.8 - -Only adults that could be sexed were Included in th is ca lcu la t ion . 35 The lowest p r o p o r t i o n of young caught (15 percent) o c c u r r e d on p l o t T i n 1985 (Table 1.5). T h i s agrees with a h y p o t h e s i s of reduced f l e d g i n g success i n the year of the a p p l i c a t i o n . However, a low p r o p o r t i o n of young was a l s o obtained on the c o n t r o l p l o t i n 1985 (16.8 p e r c e n t ) , suggesting that t h i s was a poor year f o r breedi n g . The number of f l e d g l i n g w h i t e - t h r o a t e d sparrows caught on p l o t T d u r i n g 1985 and 1986 was lower than 1983 or 1984 and lower than c o n t r o l . The number of male w h i t e - t h r o a t e d sparrows r e t u r n i n g i n 1986 was a l s o lower than other y e a r s and lower than c o n t r o l . The number of f l e d g l i n g magnolia and c h e s t n u t - s i d e d warblers was not, however, lower i n the year of treatment nor were the numbers of warblers as a whole. A b e t t e r index of the e f f e c t s of s p r a y i n g i s the r e t u r n r a t e of marked b i r d s . I f the a p p l i c a t i o n had a s i g n i f i c a n t e f f e c t , the number of r e c a p t u r e s on the treatment p l o t i n the year a f t e r s p r a y i n g should have been u n u s u a l l y low. I n d i v i d u a l s of t e r r i t o r i a l s p e c i e s caught the year of the a p p l i c a t i o n (1985), on p l o t T, r e t u r n e d the next year at a lower r a t e (7.4 p e r c e n t ) than those f i r s t caught i n 1983 or 1984 (16.3 percent and 19.3 percent, r e s p e c t i v e l y ) . The r e t u r n r a t e f o r 1985 capt u r e s on treatment was a l s o lower than t h a t of c o n t r o l f o r any year (range of 14.2 t o 21.8 p e r c e n t ) . B . Med ium- t e rm r e s p o n s e : 1) Movement o f b i r d s : 36 To examine the p o s s i b i l i t y t h a t b i r d s avoided the spray, time-budget o b s e r v a t i o n s of the 3 i n d i c a t o r s p e c i e s were analyzed s e p a r a t e l y to t e s t f o r changes i n occurrence of b i r d s a f t e r the a p p l i c a t i o n . Data were gathered s i m u l t a n e o u s l y i n the c o n t r o l area. These data were analyzed f o r the 5 canopy r e g i o n s (top, mid-outside, low-outside, m i d - i n s i d e , l o w - i n s i d e ) . Only males are c o n s i d e r e d i n the a n a l y s i s , because they were more obse r v a b l e than females. Data were presented as the number of times a banded i n d i v i d u a l was observed, d i v i d e d by the t o t a l number of o b s e r v a t i o n s taken. The t o t a l number of o b s e r v a t i o n s was c a l c u l a t e d as the number of s i t e s v i s i t e d per day, m u l t i p l i e d by the number of days of o b s e r v a t i o n . These p r o p o r t i o n s were compared b e f o r e s p r a y i n g , immediately a f t e r s p r a y i n g , and more than 5 days a f t e r s p r a y i n g , f o r both t r e a t e d and c o n t r o l areas. There was no i n d i c a t i o n from the p r o p o r t i o n of i n d i v i d u a l s observed, t h a t c h e s t n u t - s i d e d warblers l e f t the t r e a t e d p l o t a f t e r e i t h e r a p p l i c a t i o n ( F i g u r e 1.6 A ) . In f a c t , i n 1986 i n d i v i d u a l s were observed more o f t e n a f t e r the treatment. C o n t r o l r e s u l t s i n 1986 d i d not show t h i s i n c r e a s e i n a c t i v i t y , except f o r i n c r e a s e d o b s e r v a t i o n s i n the top canopy r e g i o n ( F i g u r e 1.6 B). Treatment r e s u l t s from 1985 e x a c t l y f o l l o w t r e n d s on the c o n t r o l ( i . e . c h e s t n u t - s i d e d warblers became l e s s v i s i b l e over the study p e r i o d on both p l o t s ) . More i n d i v i d u a l s were observed i n areas of lower c o n c e n t r a t i o n of d e p o s i t a f t e r treatment, 37 z o i-< > cc UJ </> 00 o u. o z g i-or O o. o cc Q. I FENITROTHION TREATMENT CONTROL ALL CANOPY REGIONS • T R E A T M E N T •CONTROL M I D - L O W - M I D - LOW-B TOP OUT OUT IN IN + .05-z o I-< > cc LL (0 CO o LL O z o H CC 2 o cc 0. LU O z < I o 0 . -.05 M O .15-+ .10-+ .05 .05 .10 -JL T I M E PERIOD H I G H LOW CONCENTRATION OF DEPOSIT F i g u r e 1.6. Comparison of changes i n the p r o p o r t i o n of o b s e r v a t i o n s taken (x±SE) i n which i n d i v i d u a l c h e s t n u t - s i d e d warblers were observed, on the t r e a t e d and c o n t r o l p l o t s , from b e f o r e treatment (T^) to a f t e r treatment ( T 3 ) , f o r both a p p l i c a t i o n y e a r s . A= a l l canopy r e g i o n s . B= i n d i v i d u a l canopy r e g i o n s . 38 r e l a t i v e t o c o n t r o l . But areas of higher c o n c e n t r a t i o n of deposit d i d not have fewer i n d i v i d u a l s , r e l a t i v e t o changes on c o n t r o l . T h i s suggests t h a t c h e s t n u t - s i d e d warblers d i d not move to avoi d t h e d e p o s i t . U n l i k e the c h e s t n u t - s i d e d warblers, magnolia warblers were g e n e r a l l y l e s s v i s i b l e immediately f o l l o w i n g both a p p l i c a t i o n s ( F i g u r e 1.7 A). C o n t r o l and treatment t r e n d s f o r each canopy r e g i o n ( F i g u r e 1.7 B) were q u i t e s i m i l a r f o r both y e a r s , the e x c e p t i o n being t h a t more i n d i v i d u a l s were observed m i d - i n s i d e a f t e r the a p p l i c a t i o n on the t r e a t e d p l o t s . T h i s i s c o n s i s t e n t w i t h a p r e f e r e n c e f o r l e s s exposed ( i n terms of d e p o s i t ) regions of the t r e e , but the i n c r e a s e was not s i g n i f i c a n t d i f f e r e n t from the change on c o n t r o l (p>.05, z - t e s t ) . There i s no i n d i c a t i o n t h a t magnolia w a r b l e r s l e f t the t r e a t e d area i n e i t h e r a p p l i c a t i o n year. White-throated sparrows were a l s o observed more f r e q u e n t l y i n l e s s exposed canopy r e g i o n s ( i . e . low-outside and m i d - i n s i d e ) on the t r e a t e d p l o t s a f t e r a p p l i c a t i o n than i n c o n t r o l p l o t s ( F i g u r e 1.8 B). T h i s movement was s i g n i f i c a n t l y d i f f e r e n t from t h a t of c o n t r o l i n both years f o r low-outside, but o n l y i n 1986 f o r m i d - i n s i d e (p<.05, z - t e s t f o r change i n p r o p o r t i o n ) . A d d i t i o n a l l y , fewer i n d i v i d u a l s were observed i n more exposed canopy r e g i o n s ( i . e . mid-outside f o r both a p p l i c a t i o n years, and t o p f o r 1986 o n l y ) . T h i s suggests movement away from areas of h i g h e r d e p o s i t . The t r e n d was c o n s i s t e n t f o r mid-outside and top 3 9 \ FENITROTHION TREATMENT CONTROL Z g < > cc ai w CO o LL o z o h-CC O a O cc a A. ALL CANOPY REGIONS CC o a. O cc a. LU a z < X u •TREATMENT • CONTROL M I D - L O W - M I 0 - LOW-B. TOP O U T O U T IN IN ^ro +.10 + .05 z g < > cc LU W CO o u. o -.05 .10-z O +.104 + .05--.05 --.10-oo o. •O OD T I M E PERIOD HIGH LOW CONCENTRATION OF DEPOSIT F i g u r e 1.7. Comparison of changes i n the p r o p o r t i o n of o b s e r v a t i o n s taken (x±SE) i n which i n d i v i d u a l magnolia w a r b l e r s were observed, on the t r e a t e d and c o n t r o l p l o t s , from b e f o r e treatment (T]_) to a f t e r treatment ( T 3 ) , f o r both a p p l i c a t i o n y e a r s . A= a l l canopy r e g i o n s . B= i n d i v i d u a l canopy r e g i o n s . 40 \ FENITROTHION Z g < > CC ID (/> CO o LL O z g CC o a O cc a. •TREATMENT •CONTROL ALL CANOPY REGIONS Z g i-< > cc LU (/) CO O u. O z g u. cc o a o cc a LU a z < X o — — T R E A T M E N T . . . . . . CONTROL M I D - L O W - M I D - LOW-B. TOP OUT OUT IN IN +.10 H _ + . 0 5 -- . 0 5 .10-+ .10 + .05 -. 0 5 -.10 -00 o 00 TIME PERIOD H I G H LOW CONCENTRATION OF DEPOSIT F i g u r e 1.8. Comparison of changes i n the p r o p o r t i o n of o b s e r v a t i o n s taken (x±SE) i n which i n d i v i d u a l w h i t e - t h r o a t e d sparrows were observed, on the t r e a t e d and c o n t r o l p l o t s , from bef o r e treatment (T^) to a f t e r treatment ( T 3 ) , f o r both a p p l i c a t i o n y e a r s . A= a l l canopy r e g i o n s . B= i n d i v i d u a l canopy r e g i o n s . 41 canopy r e g i o n s , but not s i g n i f i c a n t l y d i f f e r e n t from c o n t r o l (p>.05, z - t e s t ) . 2) Behavioural changes within the spray block To assess whether i n d i v i d u a l s remaining i n the b l o c k changed t h e i r behaviour a f t e r s praying, a n a l y s i s was d i r e c t e d at how i n d i v i d u a l s present a l l o c a t e d t h e i r time. O b s e r v a t i o n s were t h e r e f o r e expressed as a p r o p o r t i o n of the b i r d ' s time spent i n v a r i o u s behaviours. For s i m p l i c i t y , behaviours were grouped as s o c i a l , maintenance, and feeding behaviours. Only males were c o n s i d e r e d i n the a n a l y s i s . I n d i v i d u a l s of the 3 i n d i c a t o r s p e c i e s d i d not a l l o c a t e t h e i r time d i f f e r e n t l y among the 3 b e h a v i o u r a l c a t e g o r i e s a f t e r e i t h e r a p p l i c a t i o n on the t r e a t e d p l o t as compared t o o b s e r v a t i o n s taken b e f o r e the a p p l i c a t i o n , or o b s e r v a t i o n s taken s i m u l t a n e o u s l y on c o n t r o l ( f o r example, F i g u r e 1.9). There was an i n c r e a s e i n the average p r o p o r t i o n of time spent f e e d i n g a f t e r the 1986 a p p l i c a t i o n f o r both c h e s t n u t - s i d e d w a r b l e r s and w h i t e - t h r o a t e d sparrows, but t h i s i n c r e a s e was not s i g n i f i c a n t (p>.05, K r u s k a l - W a l l i s t e s t ) . S i m i l a r l y , Magnolia warblers spent an i n c r e a s e d p r o p o r t i o n of t h e i r time i n maintenance behaviours a f t e r the 1986 a p p l i c a t i o n , beyond t h a t expected from c o n t r o l ( F i g u r e 1.10), but a g a i n t h i s d i f f e r e n c e was not s i g n i f i c a n t (p>.05, K r u s k a l - W a l l i s t e s t ) . 42 2 A .2 0 -O 1.0 .8 -O ^ H .4 H rr O a. .2 O oc a o -1.0 .4 .2 -0 CONTROL 8 5 —p-T i outliers a —r— T 2 TREATMENT 1(5 14 4 V g — T — — J 1 r~—•—-j— T 3 T , lz T3 TIME PERiOD j s o % of median j 50 % of the observations » extreme outlifir O o 03 UJ O z < z UJ < 2 o z Q UJ IU LL F i g u r e 1.9. Comparison of the p r o p o r t i o n of time magnolia w a r b l e r s spent i n s o c i a l , maintenance, and f e e d i n g behaviours, over the 1985 study p e r i o d , on t r e a t e d and c o n t r o l p l o t s . Time p e r i o d s T]_, Tg, and T 3 , r e p r e s e n t the o b s e r v a t i o n s : prespray, immediate pos t s p r a y , and l a t e r p ostspray, r e s p e c t i v e l y . rrrmi C O N T R O L D T R E A T M E N T B E F O R E IMMEDIATELY A F T E R L A T E R A F T E R F i g u r e 1 . 1 0 . Comparison of the p r o p o r t i o n of time magnolia warblers spent i n maintenance behaviour b e f o r e treatment, immediately a f t e r treatment, and l a t e r a f t e r treatment, on t r e a t e d ( P l o t T ) , and c o n t r o l ( P l o t C) p l o t s , i n 1986. 44 Changes i n f e e d i n g behaviour were analyzed i n more d e t a i l . Warblers spent l e s s time f o r a g i n g immediately f o l l o w i n g treatment (a decrease of 42 % i n the p r o p o r t i o n of a v a i l a b l e o b s e r v a t i o n time spent f o r a g i n g ; versus an i n c r e a s e of 266 % on c o n t r o l i n 1986; a decrease of 61 % on treatment and a decrease of 6 % on c o n t r o l i n 1985), i n both deciduous and c o n i f e r o u s t r e e s . The p r o p o r t i o n of warblers feeding i n c o n i f e r o u s t r e e s on the t r e a t e d p l o t d i d not d i f f e r from that on the c o n t r o l p l o t i n 1985, and d i d not change a f t e r treatment i n 1986. Of the t h r e e i n d i c a t o r s p e c i e s , the magnolia warbler was the o n l y s p e c i e s to decrease i t s use of c o n i f e r o u s t r e e s a f t e r both a p p l i c a t i o n s (a decrease of 54 % i n 1985 and 64 % i n 1986). The c o r r e s p o n d i n g r e s u l t s f o r c o n t r o l were an i n c r e a s e of 100 % i n 1985 and a decrease of 5 % i n 1986. T h i s decreased use was a l s o apparent f o r deciduous t r e e s , however, and consequently, the decreased use of c o n i f e r s may merely r e f l e c t decreased f o r a g i n g a c t i v i t y of magnolia warblers i n g e n e r a l . White-throated sparrows showed no change i n t r e e s p e c i e s use f o l l o w i n g the 1986 a p p l i c a t i o n , but a s l i g h t decrease (25 %) i n the p r o p o r t i o n of f o r a g i n g o b s e r v a t i o n s i n c o n i f e r s f o l l o w i n g the 1985 a p p l i c a t i o n ( c o n t r o l o b s e r v a t i o n s i n c r e a s e d but the sample s i z e was s m a l l ) . C h e s t n u t - s i d e d warblers d i d not u t i l i z e c o n i f e r s i n the t r e a t e d areas. Magnolia w a r b l e r s foraged mainly i n mid-canopy, but a l s o i n the tops of both c o n i f e r o u s and deciduous t r e e s . I n d i v i d u a l s f o r a g i n g immediately a f t e r s p r a y i n g i n both a p p l i c a t i o n y e ars 45 moved from the o u t s i d e to i n s i d e f o l i a g e of the deciduous t r e e s (no i n d i v i d u a l s were observed top or mid-outside a f t e r e i t h e r a p p l i c a t i o n on treatment, whereas, 4/5 and 5/5 i n d i v i d u a l s u t i l i z e d these canopy r e g i o n s before the 1985 and 1986 a p p l i c a t i o n s r e s p e c t i v e l y ; no i n d i v i d u a l s were observed f e e d i n g i n deciduous t r e e s on c o n t r o l i n 1985, but 7/16 i n d i v i d u a l s c o n t i n u e d t o feed i n top or mid-outside r e g i o n s immediately a f t e r the 1986 a p p l i c a t i o n on c o n t r o l ) . I n d i v i d u a l s continued t o forage i n the top and mid-outside of c o n i f e r o u s t r e e s a f t e r both a p p l i c a t i o n s on both p l o t s . There were no o b s e r v a t i o n s of a t t a c k maneuvers i n e i t h e r t r e e s p e c i e s on the t r e a t e d p l o t immediately a f t e r the 1986 a p p l i c a t i o n , yet 9/14 i n d i v i d u a l s on c o n t r o l were observed i n these behaviours. A f t e r the 1985 a p p l i c a t i o n , the t o t a l p r o p o r t i o n of time magnolia warblers spent i n a t t a c k maneuvers decreased by 71 % on treatment; on c o n t r o l , the t o t a l p r o p o r t i o n of time decreased by 13 %. White-throated sparrows f e d over the e n t i r e t r e e , but mainly i n the mid-canopy of both c o n i f e r o u s and deciduous t r e e s . The l o c a t i o n of f o r a g i n g maneuvers was not n o t i c e a b l y d i f f e r e n t a f t e r the treatment. More i n d i v i d u a l s were observed f e e d i n g immediately a f t e r the 1986 a p p l i c a t i o n ; no i n c r e a s e was observed on the c o n t r o l i n 1986, or on e i t h e r p l o t i n 1985 (Table 1.6). The i n c r e a s e d frequency of f e e d i n g o b s e r v a t i o n s was mainly a d i f f e r e n c e i n the frequency and p r o p o r t i o n of time spent c a r r y i n g food (Table 1.7). I t i s p o s s i b l e that food was c a r r i e d from o u t s i d e the sprayed area, as i n d i v i d u a l s were observed f l y i n g 46 Table 1.6. Numbers of white-throated sparrows observed f e e d i n g i n t r e a t e d and c o n t r o l p l o t s before, immediately a f t e r , and l a t e r a f t e r the 1985 and 1986 a p p l i c a t i o n . The number i n brackets i s the frequency expressed as a p r o p o r t i o n of the number of o b s e r v a t i o n samples taken d u r i n g t h a t time p e r i o d . NUMBER OF INDIVIDUALS OBSERVED FEEDING APPLICATION PRESPRAY IMMEDIATE LATER ( T l ) POSTSPRAY(T2) POSTSPRAY(T3) 1986-treatment 5 (.045) 12 (.125) 15 (.165) - c o n t r o l 10 (.089) 10 (.102) 7 (.082) 1985-treatment 6 (.061) 6 (.050) 9 (.076) - c o n t r o l 2 (.035) 2 (.032) 1 (.015) Table 1.7. Number of whi t e - t h r o a t e d sparrows observed c a r r y i n g food. The number i n bracke t s i s the p r o p o r t i o n of time spent c a r r y i n g food, out of the a v a i l a b l e time, expressed as a percent. APPLICATION PRESPRAY IMMEDIATE LATER ( T l ) POSTSPRAY(T2) POSTSPRAY(T3) 1986-treatment 1 (.008) 6 (.365) 3 (.06) - c o n t r o l 1 (.007) 0 (0) 0 (0) 1985-treatment - c o n t r o l 0 (0) 0 (0) 1 (.011) 0 (0) 3 (.047) 0 (0) 47 a c r o s s the spray block boundary. However, b i r d s may a l s o have f o r a g e d o u t s i d e the c o n t r o l p l o t . C h e s t n u t - s i d e d warblers fed throughout deciduous t r e e s ; most commonly i n white b i r c h . They p r e f e r the mid-canopy where i n s e c t i c i d e d e p o s i t s concentrate. F o l l o w i n g the 1985 a p p l i c a t i o n , i n d i v i d u a l s no longer f e d i n the tops of deciduous t r e e s but s t i l l f e d i n the mid-outside. In 1986 a l s o t h e r e was no s i g n i f i c a n t d i f f e r e n c e i n the p r o p o r t i o n of time spent f e e d i n g i n areas of p o t e n t i a l l y h i g h r e s i d u e (top and mid-outside of c o n i f e r s ; top, mid-outside, and low-outside of deciduous) on treatment or c o n t r o l , f o r any time p e r i o d . There were fewer o b s e r v a t i o n s of f e e d i n g behaviour i n the 1985 t r e a t e d p l o t . However, those i n d i v i d u a l s observed immediately a f t e r the 1985 a p p l i c a t i o n d i d i n c r e a s e the p r o p o r t i o n of time they spent s e a r c h i n g ( F i g u r e 1.11). In 1986, i n d i v i d u a l s spent more time f o r a g i n g immediately a f t e r spraying; t h i s may have been r e l a t e d t o i n c r e a s e d demands of the young. The p r o p o r t i o n of time spent i n s e a rch maneuvers i n c r e a s e d 2.3 f o l d on c o n t r o l , and 2.5 f o l d on treatment. The p r o p o r t i o n of b i r d s observed c a r r y i n g food on the t r e a t e d p l o t t h a t were not f i r s t observed f e e d i n g i n the p l o t , was higher immediately f o l l o w i n g the 1986 a p p l i c a t i o n than f o r any other time p e r i o d on e i t h e r p l o t (Table 1.8). There were too few o b s e r v a t i o n s of c a r r y i n g behaviour on the c o n t r o l p l o t i n 1985 t o compare between y e a r s . 48 F i g u r e 1.11. Comparison of the p r o p o r t i o n of time c h e s t n u t - s i d e d warblers spent s e a r c h i n g f o r food b e f o r e treatment, immediately a f t e r treatment, and l a t e r a f t e r treatment, on t r e a t e d ( P l o t T) and c o n t r o l ( P l o t C) p l o t s , i n 1985. 49 Table 1.8. P r o p o r t i o n of b i r d s that were observed c a r r y i n g food without p r e v i o u s l y f e e d i n g i n the spray b l o c k . The data are expressed as a p r o p o r t i o n of the obs e r v a t i o n s taken. The number of o b s e r v a t i o n s of c a r r y i n g behaviour are g i v e n i n b r a c k e t s . PRESPRAY IMMEDIATE LATER POSTSPRAY POSTSPRAY 1986: TREATMENT .40(5) .60(15) .38(13) CONTROL .33(3) .43(7) .40(5) Table 1.9. Comparison of the mean (±SE) f l e d g l i n g weights of the t h r e e i n d i c a t o r s p e c i e s on t r e a t e d and c o n t r o l p l o t s . F e n i t r o t h i o n was a p p l i e d i n 1985 and again i n another l o c a t i o n i n 1986; 1983 and 1984 were prespray years. 1983 1984 1985 1986 CHESTNUT-SIDED WARBLER Treatment 10.2 9.5+0.3 9.4±0.3 9.8±0.2 C o n t r o l - 10.4+0.4 9.5±0 9.8±0.2 MAGNOLIA WARBLER Treatment 8.2±0.4 9.1±0.4 8.6±0.4 8.4±0.2 C o n t r o l - 9.3±0.6 8.6±0.3 8.3±0.1 WHITE-THROATED SPARROW Treatment 23.9±.5 19.7+2.1 23.9+1.3 21.9±0.4 C o n t r o l - 22.9+1.3 23.9±0.4 23.1±0.5 50 3) Numbers and weights of f l e d g l i n g s on c o n t r o l and treatment p l o t s There was no apparent r e d u c t i o n i n weights of young magnolia w a r b l e r s , c h e s t n u t - s i d e d warblers, or w h i t e - t h r o a t e d sparrows, f l e d g e d from the t r e a t e d p l o t , i n e i t h e r a p p l i c a t i o n year (Table 1.9). These young were caught i n mist nets. A comparison of the number of young f l e d g e d was given with the long-term e f f e c t s . I f n e s t i n g attempts had f a i l e d , I expected i n d i v i d u a l s to remain i n breeding c o n d i t i o n longer than those i n d i v i d u a l s t h at s u c c e s s f u l l y f l e d g e d t h e i r f i r s t brood. Breeding c o n d i t i o n was measured by brood patch development, and c l o a c a l protuberance. A comparison of the breeding c o n d i t i o n of b i r d s mist n e t t e d i n treatment and c o n t r o l i n 1985, shows t h a t i n d i v i d u a l s of t e r r i t o r i a l s p e c i e s came out of breeding c o n d i t i o n s l i g h t l y e a r l i e r on c o n t r o l , which may i n d i c a t e t h a t more i n d i v i d u a l s r e n e s t e d on treatment (5 of 13 females caught on c o n t r o l d u r i n g the p e r i o d from 18 t o 20 J u l y had f i n i s h e d breeding as judged from r e f e a t h e r i n g of the brood patch, while only 5 of 43 females were f i n i s h e d on treatment; 8 of 14 males caught on c o n t r o l d u r i n g the same time were not breeding as compared t o 7 of 23 males on t r e a t m e n t ) . C. Immediate response I observed no immediate m o r t a l i t y , r e d u c t i o n i n s i n g i n g 51 a c t i v i t y , or movement of i n d i v i d u a l s out of the t r e a t e d area. B i r d s banded b e f o r e the a p p l i c a t i o n were observed again i n the are a afterwards. The p r o p o r t i o n of new b i r d s caught i n mist nets a f t e r treatment was lower i n the t r e a t e d area than the c o n t r o l i n both a p p l i c a t i o n years (Table 1.10). T h i s suggests t h a t t h e r e was no e m i g r a t i o n from the spray block; i f t e r r i t o r i e s w i t h i n the sprayed area were abandoned, they might have been r e o c c u p i e d by n o n - t e r r i t o r i a l males from elsewhere. T a b l e 1.10. Comparison of the p r o p o r t i o n of a d u l t i n d i v i d u a l s caught i n mist nets a f t e r s p r a y i n g i n 1985 and 1986, on t r e a t e d and c o n t r o l p l o t s . NETTING PERIOD TREATMENT CONTROL 1985 18-21 June .33 .55 3-5 J u l y .51 .61 17-19 J u l y .61 .76 1986 8-9 J u l y .63 .72 16-18 J u l y .49 .73 Two male common y e l l o w t h r o a t s , caught i n mist nets 4 days a f t e r the 1985 a p p l i c a t i o n on the t r e a t e d p l o t , e x h i b i t e d i n v o l u n t a r y muscle c o n t r o l f o l l o w e d by t e r m i n a l wing-beat c o n v u l s i o n s ( s i g n s of i n t o x i c a t i o n by f e n i t r o t h i o n (Hudson et a l . 1984)). T h e i r ChE l e v e l s were 12.46 and 14.45 Ltmoles/min/g b r a i n t i s s u e . The normal range of u n i n h i b i t e d ChE v a l u e s i s 25 to 30 Mmoles/min/g b r a i n t i s s u e (D. Busby pers. comm.)5. I n h i b i t i o n of 5. B i o l o g i s t , Canadian W i l d l i f e S e r v i c e , F r e d r i c t o n , New Brunswick. 52 over 50 percent i n d i c a t e s death from p e s t i c i d e p o i s o n i n g (Ludke et a l . 1975). Assuming the lowest u n i n h i b i t e d l e v e l , these common y e l l o w t h r o a t s were 42 and 50 percent i n h i b i t e d . In t h i s i n s t a n c e , p e s t i c i d e p o i s o n i n g and the s t r e s s of n e t t i n g may have combined to cause death. SUMMARY OF RESULTS 1) Long-term p o p u l a t i o n t r e n d s of t e r r i t o r i a l b i r d s were not a f f e c t e d by treatment; 2) although warblers on treatment and c o n t r o l showed d i f f e r e n t p o p u l a t i o n t r e n d s , t h i s was mainly because b i r d s on c o n t r o l responded t o changing budworm p o p u l a t i o n s , whereas, b i r d s on the t r e a t e d p l o t d i d not; 3) a lower p r o p o r t i o n of young were caught i n mist nets on the t r e a t e d p l o t i n 1985 than expected from c o n t r o l numbers or from other y e a r s on the t r e a t e d p l o t ; 4) a lower p r o p o r t i o n of the c a t c h on the t r e a t e d p l o t were males i n 1986; 5) b i r d s r e t u r n e d at a lower r a t e the year f o l l o w i n g treatment on the t r e a t e d p l o t ; 6) none of the i n d i c a t o r s p e c i e s abandoned the t r e a t e d area a f t e r e i t h e r a p p l i c a t i o n , although, t h e r e was some i n d i c a t i o n t h a t w h i t e - t h r o a t e d sparrows and magnolia warblers moved away from f o l i a g e r e g i o n s w i t h h i g h e r d e p o s i t s ; 7) t h e r e was no s i g n i f i c a n t change i n a l l o t m e n t of time t o s o c i a l , maintenance, or f e e d i n g behaviours, f o r any of the i n d i c a t o r s p e c i e s ; 8) c h e s t n u t - s i d e d w a r b l e r s and w h i t e - t h r o a t e d sparrows continued to forage a c t i v e l y on sprayed p l o t s or nearby; 9) magnolia warblers decreased t h e i r f o r a g i n g e f f o r t on the t r e a t e d p l o t a f t e r both a p p l i c a t i o n s . 53 DISCUSSION A. A new approach for assessing impacts of i n s e c t i c i d e spraying on forest birds The main o b j e c t i v e of t h i s study was t o develop a method f o r measuring s u b l e t h a l and long-term consequences of i n s e c t i c i d e usage. The method o u t l i n e d here i s a workable monitoring t o o l , but r e q u i r e s c o n s i d e r a b l e e x p e r t i s e . Mist n e t t i n g i s v a l u a b l e f o r e s t i m a t i n g : 1) the number of f l e d g l i n g s i n t r e a t e d versus c o n t r o l areas; 2) the approximate date of c e s s a t i o n of breeding (e.g. due t o i n t e r r u p t i o n by s p r a y i n g ) ; 3) movement of b i r d s i n t o and out of the sprayed area; and 4) long-term p o p u l a t i o n t r e n d s . B e h a v i o u r a l o b s e r v a t i o n s are of v a l u e i n a s s e s s i n g short-term impacts such as: 1) response to changes i n food a v a i l a b i l i t y ; and 2) movements r e l a t e d t o i n s e c t i c i d e d e p o s i t (exposure). For b e h a v i o u r a l changes to be d e t e c t e d , o b s e r v a t i o n s must be taken w i t h i n 5 days a f t e r the a p p l i c a t i o n . In ducks, si g n s of f e n i t r o t h i o n i n t o x i c a t i o n can appear as soon as 30 minutes a f t e r treatment; deaths u s u a l l y occur between 1 hour and 4.5 days (Hudson et a l . 1984). Small songbirds a l s o respond r a p i d l y when o r a l l y dosed w i t h f e n i t r o t h i o n ; the e f f e c t s u s u a l l y l a s t l e s s than 24 hours i f the b i r d s u r v i v e s (S. Holmes pe r s . comm.)6. In the f i e l d , however, a d d i t i o n a l exposure may occur a f t e r the 6. T o x i c o l o g i s t , F o r e s t Pest Management I n s t i t u t e , S a ult Ste. Marie, O n t a r i o . 54 a c t u a l spray (e.g. through e a t i n g contaminated f o o d ) . Secondary e f f e c t s of decreased a v a i l a b i l i t y of food c o u l d a l s o be man i f e s t e d over a longer p e r i o d . For these reasons, behaviour samples geared at d e t e c t i n g i n i t i a l exposure should be c o n c e n t r a t e d over the f i r s t 2 days f o l l o w i n g the a p p l i c a t i o n , but samples designed to measure the e f f e c t of a decreased food source or c o n t i n u e d exposure, should be extended t o at l e a s t 5 days a f t e r s p r a y i n g . The c e r t a i n t y of some c o n c l u s i o n s of t h i s study are l i m i t e d by f o u r problems: - 1) Small sample s i z e . Although the area was p r o d u c t i v e f o r b i r d s , the number of r e s i d e n t s per p l o t t h a t c o u l d be sampled was s t i l l s m a l l ; - 2) Short time windows. Sampling e f f o r t was co n c e n t r a t e d over a 2 month p e r i o d . Any e f f e c t s of treatment may be dampened by the l o n g e r t i m e - s c a l e e f f e c t s of m i g r a t i o n p r e s s u r e s and the s i t u a t i o n on the w i n t e r i n g grounds; - 3) Poor weather c o n d i t i o n s immediately f o l l o w i n g the 1985 a p p l i c a t i o n . A s u f f i c i e n t number of behaviour samples c o u l d not be c o l l e c t e d immediately a f t e r the treatment. As 50 percent of r e s i d u e s on f o l i a g e w i l l be l o s t w i t h i n the f i r s t 4 t o 8 days (NRCC 1975), b e h a v i o u r a l responses d u r i n g the i n i t i a l p o s t s p r a y samples i n 1985 may have been s i m i l a r t o those seen i n the l a t e r p o s t s p r a y time p e r i o d of the 1986 a p p l i c a t i o n ; 55 - 4) The s m a l l area t r e a t e d i n 1986 may have allowed i n d i v i d u a l s t o forage outside the spray b l o c k , or to immigrate r a p i d l y from outside the p l o t . There was, however, no evidence of immigration from o b s e r v a t i o n s of marked b i r d s . Some of these problems could be overcome through s l i g h t m o d i f i c a t i o n s of the method. I t would be p o s s i b l e t o i n c r e a s e the number of o b s e r v a t i o n s per s e s s i o n by f o l l o w i n g i n d i v i d u a l s . However, p r e l i m i n a r y work with t h i s method showed t h a t : 1) i t caused c o n s i d e r a b l e i n t e r f e r e n c e by the observer; and 2) i t s e l e c t e d f o r conspicuous i n d i v i d u a l s and conspicuous behaviours, and t h e r e f o r e , d i d not provide an equal chance of observing i n d i v i d u a l s i n l e s s exposed r e g i o n s of the t r e e . I t h e r e f o r e chose to use, and recommend, f o c a l - a n i m a l sampling with a s t a t i o n a r y observer. In t h i s way, the s t o p p i n g r u l e i s both independent of behaviour and independent of the observer's m o t i v a t i o n . Sample s i z e s c o u l d be i n c r e a s e d by s e l e c t i n g i n d i v i d u a l t e r r i t o r i e s f o r o b s e r v a t i o n , r a t h e r than sampling areas that may c o n t a i n few i n d i v i d u a l s of each s p e c i e s . B e h a v i o u r a l o b s e r v a t i o n s c o u l d a l s o be improved by c o n c e n t r a t i n g the time-budgeting e f f o r t on f e e d i n g behaviour. Most e f f e c t s should occur w i t h i n 5 days of treatment. T h i s r e q u i r e s i n t e n s i v e e f f o r t s d i r e c t e d over a short time, but would work w e l l i n a p r o v i n c e such as New Brunswick where p l o t s i n the n o r t h c o u l d be as much as 2 weeks behind the south i n phenology. T h i s c o u l d then be supplemented with mist 56 n e t t i n g , b e f o r e and a f t e r b e h a v i o u r a l o b s e r v a t i o n s , f o r the marking of i n d i v i d u a l s , to determine f l e d g i n g success, and to determine the r e t u r n of i n d i v i d u a l s the f o l l o w i n g year. B. Immediate and medium-term e f f e c t s B i r d s d i d not abandon t e r r i t o r i e s w i t h i n the sprayed area f o l l o w i n g e i t h e r a p p l i c a t i o n . I n d i v i d u a l s banded be f o r e the a p p l i c a t i o n s , were observed again afterwards. In 1985, i n d i v i d u a l s remained, but there was evidence t h a t t h e i r f l e d g i n g success decreased. In 1986 however, f l e d g i n g success was not a f f e c t e d , p o s s i b l y because i n d i v i d u a l s were a b l e t o forage i n unsprayed areas. At l e a s t some i n d i v i d u a l s c a r r i e d food i n from o u t s i d e the spray b l o c k . I d i d not however, measure movement ac r o s s p l o t boundaries s y s t e m a t i c a l l y . I expected t h a t b i r d s f o r a g i n g w i t h i n the t r e a t e d p l o t would have been f o r c e d t o change t h e i r behaviour t o o b t a i n s u f f i c i e n t food. None of the i n d i c a t o r s p e c i e s p a r t i t i o n e d t h e i r time d i f f e r e n t l y between s o c i a l , maintenance, and f e e d i n g behaviours a f t e r treatment. F o r a g i n g e f f o r t s were, however, r e d i r e c t e d by: 1) more movement t o l o c a t e prey D i f f e r e n c e s i n abundance, d i s t r i b u t i o n , and the k i n d of prey a v a i l a b l e i n each canopy r e g i o n i n f l u e n c e p a t t e r n s of b i r d locomotion (Paszkowski 1982). An i n s e c t i c i d e - i n d u c e d change i n abundance sh o u l d a l t e r p a t t e r n s of locomotion. Graber and Graber (1983) found t h a t b i r d s moved 57 more at decreased l a r v a l d e n s i t y as they foraged. I observed i n c r e a s e d s e a r c h i n g a c t i v i t y only f o r the c h e s t n u t - s i d e d warbler. 2) f o r a g i n g i n areas of lower d e p o s i t Movement from areas of h i g h e r d e p o s i t to areas of lower d e p o s i t was observed f o r the w h i t e - t h r o a t e d sparrow and the magnolia warbler. Ches t n u t - s i d e d w a r b l e r s , on the other hand, showed no movement w i t h i n the canopy. Out of 8 s p e c i e s of f o l i a g e - g l e a n i n g b i r d s , Greenberg (1983) found the c h e s t n u t - s i d e d warbler t o be the most s p e c i a l i z e d i n i t s s e l e c t i o n of m i c r o l i a b i t a t s . T h i s may e x p l a i n the observed l a c k of movement by t h i s s p e c i e s , and t h e i r i n c r e a s e d s e a r c h i n g a c t i v i t y , assuming t h a t i n v e r t e b r a t e p o p u l a t i o n s would be more depressed i n areas of h i g h e r i n s e c t i c i d e d e p o s i t . 3) s e a r c h i n g a l a r g e r area The area searched c o u l d be i n c r e a s e d by f o r a g i n g on a g r e a t e r number of t r e e s p e c i e s . B e h a v i o u r a l changes imposed on a b i r d s p e c i e s that f o r a g e s mainly on one i n s e c t s p e c i e s , i n a l i m i t e d number of t r e e s p e c i e s , should be more pronounced. Reports of i n c r e a s e d t r e e s p e c i e s use (Hunter and Witham 1985) have i n v o l v e d budworm-associated b i r d s p e c i e s f o r a g i n g mainly on one i n s e c t s p e c i e s (budworm), which was a f f e c t e d by the spray. In c o n t r a s t , the Icewater Creek area l a c k e d a dominant i n s e c t s p e c i e s . Consequently, an i n c r e a s e i n t r e e s p e c i e s use was l e s s probable. There was, however, a t r e n d f o r b i r d s i n the t r e a t e d area to forage i n more t r e e s p e c i e s . 58 C . Long-term p o p u l a t i o n t r e n d s In examining the consequences of p e s t i c i d e a p p l i c a t i o n s on f o r e s t s o n g b i r d p o p u l a t i o n s , i t i s important t o know how changes w i t h i n one season compare to longer p o p u l a t i o n t r e n d s . During 1983 t o 1987, b i r d p o p u l a t i o n s i n the study area seem to have been d e c r e a s i n g o v e r a l l ( F i g u r e 1.2). There have been no other long-term s t u d i e s of b i r d p o p u l a t i o n s i n N o r t h e a s t e r n O n t a r i o . But s t u d i e s conducted i n Northwestern O n t a r i o (Black Sturgeon Lake) (Kendeigh 1947; Sanders 1970; and more r e c e n t l y , D. Welsh p e r s . comm.''') suggest t h a t p o p u l a t i o n s of budworm-associated s p e c i e s have f o l l o w e d c y c l e s of budworm p o p u l a t i o n s with a de l a y of 1 or 2 br e e d i n g seasons. P o p u l a t i o n s of the Icewater Creek ar e a have responded to decreases i n budworm p o p u l a t i o n s of the No r t h e a s t e r n d i s t r i c t of O n t a r i o (Table 1.4). The 1986 budworm s i t u a t i o n c o n t r a s t s that of 1982 and d i f f e r s markedly from the outbreak s i t u a t i o n of 1980. Some s p e c i e s of b i r d s i n c r e a s e i n numbers i n response t o i n c r e a s e s i n budworm numbers (MacArthur 1958; M o r r i s et a l . 1958; Crawford and Jennings 1982). D e n s i t y of thes e s p e c i e s can i n c r e a s e from 5 t o 9 p a i r s per h e c t a r e . Other b i r d s show an i n v e r s e response. In d e c r e a s i n g budworm p o p u l a t i o n s t h i s p a t t e r n i s r e v e r s e d (Sanders 1970). The observed change of 2.5 b i r d s per h e c t a r e (1.3 p a i r s ) on p l o t C was low compared t o t h a t r e p o r t e d 7. B i o l o g i s t , Canadian W i l d l i f e S e r v i c e , Ottawa, O n t a r i o . 59 by M o r r i s et a l . (1958; 7.5 p a i r s ) . H i s r e s u l t was over a 10 year p e r i o d ; c o v e r i n g an 8,000 f o l d change i n budworm p o p u l a t i o n s . Although the outbreak M o r r i s (et a l . 1958) s t u d i e d was l e s s severe than t h a t preceding my study ( K e t t e l a 1983), budworm numbers had d e c l i n e d b e f o r e my censuses were i n i t i a t e d . T h e r e f o r e , f l u c t u a t i o n s i n budworm numbers were pro b a b l y l e s s pronounced d u r i n g my study. Nonetheless, i t i s reasonable to assume t h a t budworm p o p u l a t i o n s a f f e c t e d b i r d p o p u l a t i o n s at Icewater Creek i n the appropiate h a b i t a t . The l a c k of response on p l o t T may have been due t o : a) a masking e f f e c t of the treatment; b) the marginal h a b i t a t f o r budworm, and t h e r e f o r e , budworm-related s p e c i e s of b i r d s ; or c) any change r e l a t i v e t o budworm may have o c c u r r e d b e f o r e my study began. Y e a r l y f l u c t u a t i o n s may a l s o be r e l a t e d t o h a b i t a t changes. Decreases were noted i n the ovenbird, c h e s t n u t - s i d e d warbler, common y e l l o w t h r o a t , and the w h i t e - t h r o a t e d sparrow, but there were no corres p o n d i n g i n c r e a s e s i n other s p e c i e s t o suggest that a change i n h a b i t a t composition, f a v o u r i n g one s p e c i e s over another, o c c u r r e d . Census r e s u l t s show a decrease i n the number of s p e c i e s , from a mean of 33 i n 1983 and 1984, t o a mean of 26 i n 1986 and 1987. Species not recorded i n l a t e r y e a r s were uncommon to the area, e i t h e r n e s t i n g at the edge of t h e i r range ( g r e a t - c r e s t e d f l y c a t c h e r , wood th r u s h , and Wilson's w a r b l e r ) , or i n marginal h a b i t a t ( r e d - b r e a s t e d nuthatch, s o l i t a r y v i r e o ) . Numbers of these s p e c i e s may have peaked p r i o r t o t h i s study with i n d i v i d u a l s p o s s i b l y occupying l e s s s u i t a b l e t e r r i t o r i e s . A 60 r e d u c t i o n due to h a b i t a t change i s u n l i k e l y . The p o p u l a t i o n trends on p l o t s T and C i n d i c a t e t hat p e s t i c i d e treatment caused medium-term b e h a v i o u r a l changes t h a t a f f e c t e d b r e e d i n g success through: 1) a lower p r o p o r t i o n of young f l e d g e d on the t r e a t e d p l o t during the year of treatment; and 2) a reduced r e c r u i t m e n t of i n d i v i d u a l s the year f o l l o w i n g the treatment. The p r o p o r t i o n of f l e d g l i n g s and males captured i n mist nets was a l s o lower than that r e p o r t e d by Lehoux et a l . (1982); x±SE = 27.4±.3 f l e d g l i n g s and x±SE = 43±.3 males. These medium-term e f f e c t s d i d not r e s u l t i n an o v e r a l l change i n abundance. P o p u l a t i o n t r e n d s were i n f l u e n c e d more by environmental f a c t o r s other than treatment. D. Exposure D i f f e r e n t i a l impact on canopy-feeding b i r d s compared to ground-feeding b i r d s (Moulding 1976; Pearce and P e a k a l l 1977; P e a k a l l and Bart 1983) suggests a r e l a t i o n s h i p between exposure and e f f e c t , however, i t does not e s t a b l i s h the cause to be a decreased abundance of food as Hunter and Witham (1985) have proposed. Areas of i n c r e a s e d d e p o s i t have more p o t e n t i a l f o r d i r e c t dermal exposure as w e l l as g r e a t e r i n d i r e c t e f f e c t s through decreased food a v a i l a b l e . The magnolia warbler feeds almost e x c l u s i v e l y on c o n i f e r o u s i n s e c t s , and are t h e r e f o r e , at g r e a t e r r i s k from a p p l i c a t i o n s d i r e c t e d at a c o n i f e r o u s pest such as budworm. In the present study, the magnolia was the o n l y 61 i n d i c a t o r s p e c i e s to decrease i t s use of c o n i f e r s a f t e r both a p p l i c a t i o n s . C h e s t n u t - s i d e d warblers forage i n deciduous t r e e s which r e c e i v e d , i n 1986, l e s s d e p o s i t than the c o n i f e r o u s t r e e s u t i l i z e d by the magnolia warbler and the w h i t e - t h r o a t e d sparrow. Magnolia w a r b l e r s were l e s s v i s i b l e a f t e r the a p p l i c a t i o n ( F i g u r e 1.7), and w h i t e - t h r o a t e d sparrows moved from l o c a t i o n s of h i g h exposure t o a lower exposure ( F i g u r e 1.8). C h e s t n u t - s i d e d w a r b l e r s on the other hand, were more v i s i b l e f o l l o w i n g the 1986 a p p l i c a t i o n ( F i g u r e 1.6). Yet i n 1985, vhen deciduous t r e e s r e c e i v e d as much d e p o s i t as the c o n i f e r s , c h e s t n u t - s i d e d warblers d i d not i n c r e a s e t h e i r a c t i v i t y . Although d e p o s i t s were lower i n deciduous t r e e s f o l l o w i n g the 1986 a p p l i c a t i o n , behaviour changes were more apparent. T h i s may be due to the i n s u f f i c i e n t immediate p o s t s p r a y samples i n 1985, but i t may a l s o be due to the d i f f e r e n c e i n a r e a t r e a t e d . In 1986 w i t h only 3 ha t r e a t e d , b i r d s were perhaps a b l e t o forage o u t s i d e the spray b l o c k without having to t r a v e l f a r from t h e i r t e r r i t o r i e s . In 1985 however, with a l a r g e r a r e a t r e a t e d (49 ha), the o p t i o n to forage o u t s i d e the spray b l o c k was l e s s a v a i l a b l e . The energy expended to i n c r e a s e f o r a g i n g d i s t a n c e might not compensate f o r the i n c r e a s e d energy i n t a k e . The l a r g e r b l o c k s i z e i n 1985 may have r e s u l t e d i n reduced r e p r o d u c t i v e success as observed a f t e r t h i s a p p l i c a t i o n only. 62 Hunter and Witham (1985) observed no change i n the number of war b l e r s f o r a g i n g or t h e i r f o r a g i n g niche on a t r e a t e d area, r e l a t i v e t o a c o n t r o l , when the e n t i r e area was t r e a t e d . However, when only 30 percent of the area was t r e a t e d , b e h a v i o u r a l changes were observed. The d i f f e r e n c e , they proposed, was t h a t w i t h complete coverage, b i r d s don't have the o p p o r t u n i t y t o s h i f t t h e i r f o r a g i n g area. Presumably, these b i r d s would have t o make do. The expected e f f e c t would be a lower b r e e d i n g success due to l e s s food a v a i l a b l e , but no change i n f o r a g i n g l o c a t i o n . Whereas w i t h spray refuges, the expected r e s u l t would be b e h a v i o u r a l changes t o compensate, and l i t t l e or no change i n r e p r o d u c t i v e success. CONCLUSION The main r e s u l t s of t h i s study are: 1) when b i r d s cannot e a s i l y forage i n unsprayed areas (e.g. i n 1985, and most o p e r a t i o n a l s p r a y s ) , t h e i r f l e d g i n g success i s dec r e a s e d (Table 1.5); and 2) they r e t u r n at a lower r a t e the f o l l o w i n g year ( T a b l e 1.5). However, when b i r d s can e a s i l y f o r a g e i n unsprayed areas nearby as i n 1986, f l e d g i n g success i s u n a f f e c t e d . B e h a v i o u r a l changes were mainly c o n f i n e d t o f e e d i n g behaviour. These changes were u n r e l a t e d t o o v e r a l l p o p u l a t i o n t r e n d s , but they i n d i c a t e how i n s e c t i c i d e s p r a y s a f f e c t f o r e s t s o n g b i r d s , and sho u l d t h e r e f o r e be i n c l u d e d i n a m o n i t o r i n g method. The method d e s c r i b e d here r e q u i r e s c o n s i d e r a b l e e x p e r t i s e 63 but i s s e n s i t i v e and n o n d e s t r u c t i v e . Long-term p o p u l a t i o n s trends were u n a f f e c t e d by treatment. At 280 gAI/ha, f e n i t r o t h i o n appears to have l i t t l e e f f e c t on f o r e s t s o n g b i r d s . For an i n d i c a t i o n of long-term p o p u l a t i o n t r e n d s , a census program with t e r r i t o r y mapping c o u l d p r o v i d e an adequate measure of p o p u l a t i o n changes i f c a r r i e d out over enough l o c a t i o n s t o c o n t r o l f o r environmental f a c t o r s such as h a b i t a t d i f f e r e n c e s , and weather e f f e c t s . 64 E F F E C T S O F F E N I T R O T H I O N O N T H E T E R R E S T R I A L I N V E R T E B R A T E F O O D O F F O R E S T S O N G B I R D S I N T R O D U C T I O N Chemical i n s e c t i c i d e s are i n d i s c r i m i n a t e k i l l e r s of t e r r e s t r i a l arthropods; a f f e c t i n g both t a r g e t and nontarget s p e c i e s . One such i n s e c t i c i d e , f e n i t r o t h i o n , i s commonly used f o r c o n t r o l of spruce budworm ( C h o r i s t o n e u r a f u m i f e r a n a (Clem.)) and hemlock l o o p e r (Lambdina f i s c e l l a r i a f i s c e l l a r i a (Guen.)) i n E a s t e r n Canada (Anon. 1987), and pine beauty moth ( P a n o l i s  flammea D. and S.) i n S c o t l a n d (Spray et a l . 1987). When used i n f o r e s t i n s e c t c o n t r o l o p e r a t i o n s , the d i r e c t e f f e c t s of f e n i t r o t h i o n g e n e r a l l y l a s t from 2 t o 5 days, when l a r g e numbers of nontarget i n v e r t e b r a t e s are k i l l e d ( V a r t y 1974; V a r t y 1977). R e s i d u a l l e v e l s of f e n i t r o t h i o n , (up to 10% of the i n i t i a l d e p o s i t ) , may remain a v a i l a b l e t o d e f o l i a t i n g i n s e c t s up t o 30 days a f t e r a p p l i c a t i o n due to accumulation i n the f o l i a g e (NRCC 1975). I n s e c t s are the p r i n c i p a l food of f o r e s t s o n g b i r d s , and as such, a r e d u c t i o n i n the abundance of i n s e c t s might a d v e r s e l y a f f e c t s o n g b i r d p o p u l a t i o n s . Spruce budworm l a r v i c i d e s l i k e f e n i t r o t h i o n are a p p l i e d d u r i n g the breeding season of f o r e s t s o n g b i r d s , at a time when a d e p l e t i o n of a v a i l a b l e f o o d should be c r i t i c a l . During the bree d i n g season, even the young of 65 s e e d - e a t i n g b i r d s may r e q u i r e i n s e c t s i n t h e i r d i e t s . B i r d s respond t o a decrease i n i n s e c t abundance w i t h a change i n f o r a g i n g s t r a t e g y or emi g r a t i o n from the area (Macdonald and Webb 1963; Doane and Schaefer 1971; Moulding 1976; Bart 1979; Hunter and Witham 1985). I n s e c t i c i d e - i n d u c e d decreases i n i n s e c t abundance have r e s u l t e d i n fewer warblers f e e d i n g i n sprayed areas (Hunter and Witham 1985; Doane and Schaefer 1971). In a d d i t i o n , those warblers which c o n t i n u e d t o forage i n the sprayed areas u t i l i z e d more t r e e s p e c i e s , and decreased t h e i r use of spruce. Such changes i n f o r a g i n g behaviour might reduce f o r a g i n g e f f i c i e n c y . Most warblers eat a l l major orders of a r b o r e a l arthropods but s e l e c t food of g r e a t e r biomass y i e l d or c a l o r i c v a l u e per u n i t of f e e d i n g time (MacArthur 1958). L e p i d o p t e r a n l a r v a e , the t a r g e t i n s e c t s i n most c o n t r o l o p e r a t i o n s , are the p r e f e r r e d food f o r meeting the h i g h energy demands of young b i r d s (Royama 1970; Knapton 1984). Under c o n d i t i o n s of low food abundance, a g r e a t e r range of food items w i l l be taken (Schoener 1971). When i n s e c t s become s c a r c e , b i r d s can f i n d and consume only a s m a l l p o r t i o n of the food a v a i l a b l e due to i n c r e a s e d e f f o r t s r e q u i r e d t o l o c a t e widely spaced items (Kendeigh 1947). Both mean hunting time per item, and t r a v e l l i n g time between patches of prey, should i n c r e a s e (Schoener 1971). I t i s l i k e l y t h e r e f o r e , t h a t a spray-i n d u c e d 66 r e d u c t i o n i n prey a v a i l a b i l i t y would a f f e c t the for a g i n g e f f i c i e n c y of f o r e s t songbirds. Deposit of sprayed chemicals i n the f o r e s t canopy i s uneven both h o r i z o n t a l l y and v e r t i c a l l y (Armstrong and Yule 1978; Spillman and Joyce 1978; Barry 1984). Hence, e f f e c t s on the i n v e r t e b r a t e community are a l s o uneven (V a r t y 1974). Exposure to a e r i a l i n s e c t i c i d e s i s greatest i n the crown of the t r e e s where the l a r g e s t d e p o s i t s occur (NRCC 1975). This d i f f e r e n t i a l deposit r e s u l t s i n d i f f e r e n c e s i n i n s e c t abundance at v a r i o u s canopy l e v e l s and may cause increased e f f e c t s on canopy feeding b i r d species (Moulding 1976, Hunter and Witham 1985). The p o t e n t i a l f o r e f f e c t s on f o r e s t songbirds, through a d e p l e t i o n of food, would t h e r e f o r e depend on the canopy r e g i o n i n which the b i r d s feed, and the d e p l e t i o n of food a v a i l a b l e i n that niche. The o b j e c t i v e s of t h i s study are: a) t o determine i f the a p p l i c a t i o n of f e n i t r o t h i o n causes a change i n r e l a t i v e abundance of i n v e r t e b r a t e s , and hence, a change i n food a v a i l a b l e to f o r e s t songbirds; b) t o determine how t h i s change i s r e l a t e d to the amount and s p a t i a l l o c a t i o n of i n s e c t i c i d e deposited; and c) to determine the d u r a t i o n of any r e d u c t i o n i n i n v e r t e b r a t e numbers. METHODS To measure the e f f e c t of spraying w i t h f e n i t r o t h i o n on the 67 b i r d s ' food source, samples were taken t o determine a) changes i n i n s e c t abundance on sprayed t r e e s ; and b) the q u a n t i t y of food ( i n s e c t s ) removed from the t r e e s by s p r a y i n g . T h i s study was conducted i n 1986 when a ground a p p l i c a t i o n was used t o simulate an a e r i a l spray; d e t a i l s of the a p p l i c a t i o n are g i v e n i n Chapter 1. The two most common t r e e s p e c i e s i n the area, and those most f r e q u e n t l y used by the b i r d s p e c i e s of i n t e r e s t , were balsam f i r and white b i r c h . Nine sample t r e e s of each s p e c i e s were s e l e c t e d i n the treatment area, and i n the u n t r e a t e d c o n t r o l area. A l l t r e e s were between 6 and 8 meters i n h e i g h t . A d e t a i l e d h a b i t a t d e s c r i p t i o n i s gi v e n i n Chapter 1. A. Changes i n i n s e c t abundance on sprayed trees: To measure the change i n r e l a t i v e abundance of i n v e r t e b r a t e s on sample t r e e s , branch samples were c o l l e c t e d by p o l e pruning b e f o r e and a f t e r the a p p l i c a t i o n . T h i s t e c h n i q u e has been u t i l i z e d e x t e n s i v e l y f o r spruce budworm p o p u l a t i o n s t u d i e s , and to determine the spray e f f i c a c y of i n s e c t i c i d e a p p l i c a t i o n s ( M o r r i s 1955; Sanders 1980). To adapt t h i s method f o r my study, a l l i n v e r t e b r a t e s were c o l l e c t e d from the branches r a t h e r than j u s t the t a r g e t i n s e c t s . Samples were taken 13 June (5 days b e f o r e the a p p l i c a t i o n ) , 20 June (2 days a f t e r the a p p l i c a t i o n ) , 23 June (5 days a f t e r the a p p l i c a t i o n ) , and 3 J u l y (15 days a f t e r the a p p l i c a t i o n ) . 68 Measurements of r e s i d u e taken f o l l o w i n g the a e r i a l a p p l i c a t i o n i n 1985 confirmed the expected c o n c e n t r a t i o n of chemical d e p o s i t i n the upper canopy r e g i o n ( T a b l e 1.1). C o n i f e r crowns r e c e i v e d approximately 2.5 times the c o n c e n t r a t i o n of the d e p o s i t r e c e i v e d on i n n e r f o l i a g e or on o u t s i d e f o l i a g e of the lower canopy r e g i o n . White b i r c h f o l i a g e however, d i d not i n t e r c e p t the d e p o s i t i n the same way, probably due t o the d i f f e r i n g geometry of the 2 t r e e s p e c i e s . Nonetheless, a l a t e r a l s t r a t i f i c a t i o n of dep o s i t s t i l l o c c u r r e d where the inn e r f o l i a g e r e c e i v e d l e s s chemical than o u t s i d e f o l i a g e f o r the same canopy r e g i o n . For t h i s reason, some d i f f e r e n t i a l e f f e c t on i n s e c t abundance would be expected f o r both s p e c i e s of t r e e s . Branches were randomly chosen from 5 separate canopy r e g i o n s t o measure t h i s d i f f e r e n t i a l e f f e c t . The re g i o n s were i d e n t i f i e d as top (0-2 m from the crown t i p ) , mid-outside (a 46 cm branch t i p 2-4 m below the crown t i p ) , and m i d - i n s i d e (the next 46 cm of the same branch), l o w e r - o u t s i d e ( g r e a t e r than 4 m below the crown t i p ) , and l o w e r - i n s i d e (the next 46 cm of the same branch) ( F i g u r e 2.1). Each sample was put i n a separate paper bag and s t o r e d i n a c o l d room where the i n s e c t s c o u l d be kept a l i v e but t o r p i d u n t i l the branches were p i c k e d . I n s e c t s were removed from the branches u s i n g the method developed by Deboo et a l . (1973). A l l i n v e r t e b r a t e s were p i c k e d from the branch samples w i t h i n a week of c o l l e c t i o n . I n v e r t e b r a t e samples were p r e s e r v e d i n a s o l u t i o n of 70 percent water, 28 percent methanol and 2 percent g l y c e r i n . F i g u r e 2 .1 . Diagrammatic r e p r e s e n t a t i o n of balsam f i r and white b i r c h sampling r e g i o n s . t> o u t s i d e , I = i n s i d e , m=meters. 70 They were l a t e r counted and i d e n t i f i e d to f a m i l y . Samples were taken f o r a n a l y s i s of r e s i d u e s from the same canopy r e g i o n s , to r e l a t e changes i n i n s e c t abundance t o i n s e c t i c i d e d e p o s i t . Although the l e n g t h of branch was constant f o r a l l samples, the number of buds (balsam f i r ) or leaves (white b i r c h ) v a r i e d c o n s i d e r a b l y (CV = 58% f o r white b i r c h , and 57% f o r balsam f i r ) . G e n e r a l l y , fewer buds or l e a v e s were found on the i n s i d e branches (about two t h i r d s the number found on top branches). As the abundance of new growth may i n f l u e n c e the abundance of r e s i d e n t arthropods ( V a r t y 1977), I t e s t e d f o r a r e l a t i o n s h i p between the number of new buds/leaves and the number of f e e d i n g i n s e c t s . I found no d e f i n i t e r e l a t i o n s h i p f o r e i t h e r t r e e s p e c i e s on e i t h e r p l o t . I t h e r e f o r e , d i d not c o r r e c t f o r the number of buds or l e a v e s . A l l samples were a l s o c o n v e r t e d to biomass to b e t t e r r e l a t e numbers of i n v e r t e b r a t e s to the amount of fo o d a v a i l a b l e t o b i r d s . R e s u l t s are presented f o r both numbers of i n v e r t e b r a t e s and sample weights. Samples were r i n s e d 3 times f o r 3 days each i n 70 percent a l c o h o l to remove any g l y c e r i n r e s i d u e s t h a t may have pe n e t r a t e d the i n s e c t s a f t e r storage i n the 2 percent g l y c e r i n - a l c o h o l s o l u t i o n . These samples were then oven d r i e d at 50°C to constant weight. Food abundance was then expressed as mg dry wt per 46 cm branch. 71 B. Abundance of invertebrates i n drop trays below sprayed trees: To measure the q u a n t i t y of i n s e c t food f a l l i n g from the t r e e s a f t e r the spray, nylon-screened drop sheets (1/4 m x 1/4 m) were p l a c e d under the f o l i a g e t i p s of each sample t r e e ( F i g u r e 2.2). These t r a y s were r a i s e d about 20 cm above the ground t o reduce p r e d a t i o n on the k i l l e d i n v e r t e b r a t e s . I n v e r t e b r a t e s were c o l l e c t e d d a i l y . Drop samples were t r e a t e d ( i . e . preserved, counted, and i d e n t i f i e d ) i n a manner s i m i l a r t o branch samples. RESULTS Relative abundance and d i s t r i b u t i o n of invertebrates: T h i r t y - t w o f a m i l i e s were i d e n t i f i e d from branch samples of balsam f i r and 31 from white b i r c h . The most common i n v e r t e b r a t e s i n both t r e a t e d and un t r e a t e d c o n t r o l areas, were e i t h e r sucking p l a n t f e e d e r s (Homoptera), f o l i a g e f e e d e r s ( L e p i d o p t e r a , Hymenoptera, C o l e o p t e r a ) , or browsers of l i c h e n or p o l l e n (Psocoptera, C o l e o p t e r a ) . I n v e r t e b r a t e s f e e d i n g upon the t r e e s ( f e e d e r s ) were d i s t i n g u i s h e d from those t h a t merely perched (non-feeders) and sought prey ( p r e d a t o r s ) on the t r e e s . The d i s t r i b u t i o n of these three groups of i n v e r t e b r a t e s among canopy r e g i o n s , was s i m i l a r f o r treatment and c o n t r o l t r e e s ( f o r example, F i g u r e 2.3). The fe e d e r s were presen t over a l l canopy r e g i o n s , but were l e s s common on i n s i d e branches of white b i r c h . Predatory i n v e r t e b r a t e s (mainly Araneida and Hemiptera) were more 72 iJTOt e 2Mtp DJ;SJT n a t i 0 ^ ^ t r a t l o n of the placement of whl?e b i r S d P 0 P t r a y S U n d 6 r t h e f o l i a g e ^ of balsam f i r and 73 F i g u r e 2.3. D i s t r i b u t i o n of i n v e r t e b r a t e s (F=feeders, N=nonfeeders, p=predators) i n the 5 canopy r e g i o n s , on treatment and c o n t r o l white b i r c h t r e e s . These samples were taken b e f o r e the a p p l i c a t i o n . 74 common on balsam f i r than on white b i r c h . On balsam f i r they were found throughout the t r e e , but on white b i r c h they were most commonly found on the i n s i d e branches. Nonfeeding i n v e r t e b r a t e s (mainly D i p t e r a ) were only i n f r e q u e n t l y c o l l e c t e d i n branch samples. Samples i n c l u d e d both adul t and immature forms; pupae and cocoons were e l i m i n a t e d from a n a l y s i s . In f a m i l i e s where feed i n g h a b i t s changed w i t h development of the i n s e c t , they were separated a c c o r d i n g l y . Consequently, "feeders" i n c l u d e both a d u l t and l a r v a l i n v e r t e b r a t e s . E f f e c t of Treatment: A. Branch samples To address the q u e s t i o n of an e f f e c t of d e p o s i t on t o t a l food a v a i l a b i l i t y , I f i r s t t e s t e d f o r an i n t e r a c t i o n between zone (areas of h i g h e r and lower d e p o s i t ) and time ( p o s t s p r a y v e r s e s p r e s p r a y ) . An a n a l y s i s of v a r i a n c e was conducted on l o g transformed numbers of i n v e r t e b r a t e s , u s i n g the model: log(N+l)= t r e e + time + zone + t r e e * t i m e + zone*time + t r e e * z o n e + tree*time*zone ( e r r o r ) . For balsam f i r , the r e s u l t s i n d i c a t e d a s i g n i f i c a n t n a t u r a l decrease over time (p=.01 f o r c o n t r o l t r e e s ) , w i t h a more pronounced r e d u c t i o n over time i n the t r e a t e d area (p< . 0 0 1 ) . More v a r i a t i o n i n the c o n t r o l area was between t r e e s than between times, zones, or the i n t e r a c t i o n of t h e s e (p< . 0 0 1 ) . 7 5 In the t r e a t e d area, most v a r i a t i o n o c c u r r e d over time. The i n t e r a c t i o n between zone and time was only s i g n i f i c a n t i n the t r e a t e d area (.02<p<.05) i n d i c a t i n g a treatment e f f e c t . However, the zones of g r e a t e s t r e d u c t i o n were not c o n s i s t e n t l y the zones of h i g h e s t d e p o s i t , suggesting no r e l a t i o n s h i p between the amount of d e p o s i t and r e d u c t i o n of i n s e c t s i n the t r e e . R e s u l t s f o r white b i r c h i n d i c a t e d a s i g n i f i c a n t n a t u r a l change over time on both p l o t s (p<.001 f o r c o n t r o l ; p=.001 f o r treatment). The only time p e r i o d s i g n i f i c a n t l y d i f f e r e n t on treatment from c o n t r o l (p<.05, t - t e s t , df=64) was 5 days a f t e r the a p p l i c a t i o n , when c o n t r o l numbers i n c r e a s e d 2 f o l d from p r e v i o u s samples, w i t h no corresponding i n c r e a s e on treatment. There was a s i g n i f i c a n t e f f e c t of zone on both p l o t s (p<.001 f o r c o n t r o l ; p=.002 f o r treatment), where i n v e r t e b r a t e s were more abundant i n the o u t s i d e canopy r e g i o n s , but no s i g n i f i c a n t i n t e r a c t i o n between zones and time f o r e i t h e r t r e a t e d or c o n t r o l t r e e s . Variance between t r e e s was h i g h l y s i g n i f i c a n t f o r c o n t r o l (p<.001) but not s i g n i f i c a n t f o r treatment. F e n i t r o t h i o n r e s i d u e s were l e s s s t r a t i f i e d i n white b i r c h than i n balsam f i r . Deposit r e c e i v e d i n top, mid-outside and low e r - o u t s i d e branches was 1.3, 1.5 and 1.1 times, r e s p e c t i v e l y , t h a t r e c e i v e d on i n s i d e f o l i a g e (Table 1.1). The areas where d e p o s i t c o n c e n t r a t e d were those where biomass decreased most. There was a s i g n i f i c a n t decrease over time i n both areas of highe r d e p o s i t (p<.001) and areas of lower d e p o s i t (p<.01), but 76 the r e g r e s s i o n was only s i g n i f i c a n t f o r areas of higher d e p o s i t (p<.05, df=33)). Some t r e e s had many more i n v e r t e b r a t e s than others ( f o r example, the average number of i n v e r t e b r a t e s b e f o r e s p r a y i n g on balsam f i r t r e e 1 was about 3 times that on t r e e 4). I t h e r e f o r e analyzed percent p o p u l a t i o n change by t r e e , then c a l c u l a t e d the mean of these 9 v a l u e s f o r each p l o t and each t r e e s p e c i e s . C o n s i d e r i n g feeders only, the mean percent p o p u l a t i o n r e d u c t i o n on balsam f i r was 30% f i v e days a f t e r the a p p l i c a t i o n , and a f u r t h e r 25% f i f t e e n days a f t e r s p r a y i n g ( T a b l e 2.1). The c orresponding n a t u r a l m o r t a l i t i e s on the c o n t r o l p l o t were 0 and 13 percent r e s p e c t i v e l y . The o v e r a l l p o p u l a t i o n r e d u c t i o n was 48% on treatment and 9% on c o n t r o l . Cadogan (1986) r e p o r t e d a r e d u c t i o n of 67 t o 84 percent with f e n i t r o t h i o n a p p l i e d twice at 210 g A l / h a , and a c o n t r o l m o r t a l i t y of 0 t o 33 percent. H i s numbers r e f e r r e d only to spruce budworm. Trends on white b i r c h were s i m i l a r i n the t r e a t e d and u n t r e a t e d areas, although there was c o n s i d e r a b l y more v a r i a t i o n over time i n c o n t r o l t r e e s (Table 2.1). Numbers of i n v e r t e b r a t e s c o l l e c t e d b e f o r e s p r a y i n g and 3 days a f t e r the spray were s i m i l a r i n t r e a t e d and u n t r e a t e d samples. However, l a r g e i n c r e a s e s (T2 to T3; between 3 and 5 days a f t e r the a p p l i c a t i o n ) i n the number of i n v e r t e b r a t e s sampled from t r e e s 1, 4 and 7 on c o n t r o l , f o l l o w e d by e q u a l l y l a r g e decreases (T3 to T4; between 5 and 15 days a f t e r the a p p l i c a t i o n ) made the a n a l y s i s d i f f i c u l t t o i n t e r p r e t . The 77 Table 2.1. Changes i n the r e l a t i v e number of -inver t e b r a t e s ( ( T j _ + 1 - T i ) / T i , where Tj_ i s the time p e r i o d i ) c o l l e c t e d from each sample t r e e , from b e f o r e the a p p l i c a t i o n t o 15 days a f t e r the a p p l i c a t i o n . T]_ = bef o r e spraying; T2 = 3 days a f t e r s p r a y i n g , T3 = 5 days a f t e r s p r a y i n g , and T4 = 15 days a f t e r s p r a y i n g . TREATMENT CONTROL TIME PERIOD T1-T2 T2-T3 T3-T4 T1-T2 T2-T3 T3-T4 BALSAM FIR: TREE 1 0, .35 -0. .80 -0. 27 -0.41 0 -0. 56 2 1. .36 -0 .35 -0. 82 0.29 -0.36 -0. 55 3 -0, .71 -0. .33 -0. 58 4. 50 -0.27 -0. 38 4 0, .75 -0 .64 0. 20 -0.67 1.83 1. 29 5 -0, .46 0 .86 -0. 92 0.33 -0.43 -0. 69 6 -0 . 14 0 . 13 -0. 33 0.79 -0.48 -0. 04 7 0 . 17 -0 .80 0. 67 0.47 -0. 57 0. 50 8 0 .47 -0 . 13 -0. 43 -0.42 0.39 0 9 0 .61 -0 .64 0. 25 -0. 10 0.32 -0. 78 x±SE .27±.21 • -.3: i. 18 -.25±.18 .62±.51 .14±.25 --. 13± . 1 o v e r a l l change: x±SE= = — .48± . 17 x±SE= -.09±.29 WHITE BIRCH: TREE 1 -0 . 19 -0 .79 0. , 18 0.36 3.00 -0. ,63 2 0 .04 1 .52 -0. .87 -0.07 0.39 -0. .44 3 2 .08 -0. .70 -0.42 2.29 -0. . 57 4 -0 .08 -0 . 18 1, .33 0.22 8.36 -0. .90 5 0 .67 -0 .24 -0, . 11 -0.59 1.23 -0, .35 6 -0 .05 0 .67 -0, .73 -0.53 0. 33 -0, .20 7 0 . 53 -0 .22 -0. . 17 0.91 2.48 -0 .83 8 -0 .24 -0 .06 -0 .40 -0.29 1.25 -0 .80 9 -0 .33 1 .62 -0 .94 2.12 0.26 -0 .92 x±SE .27: t .25 .29 ± .31 -.11±.25 . 19±.29 2.18±.84 o v e r a l l change: x±SE = - . 30± . 18 x±SE = -.17±.18 78 o v e r a l l percent p o p u l a t i o n r e d u c t i o n from prespray t o 15 days a f t e r was 30% on treatment and 17% on c o n t r o l , but the confidence i n t e r v a l s of these two values overlap. I f the i n s e c t s were k i l l e d but remained on the branches, any e f f e c t of s p r a y i n g would be v i s i b l e only as a decrease i n the p r o p o r t i o n of l i v i n g i n s e c t s i n each sample. The p r o p o r t i o n of l i v e i n s e c t s was not reduced by 3 days a f t e r the a p p l i c a t i o n ( F i g u r e 2.4). T h i s suggests that a l a r g e p r o p o r t i o n of the i n s e c t s not removed from the t r e e , remained a l i v e f o r up t o 3 days a f t e r the a p p l i c a t i o n . However, by 5 days a f t e r treatment the m a j o r i t y of i n s e c t s remaining on the branches were dead. Any i n s e c t s a l i v e at sampling were kept a l i v e . There was a s i g n i f i c a n t l y lower p r o p o r t i o n of l i v i n g i n s e c t s on branches between prespray and 5 days a f t e r the a p p l i c a t i o n on the t r e a t e d p l o t (a 10% r e d u c t i o n per sample p e r i o d ; p<.005, r e g r e s s i o n , df=133) but not on c o n t r o l . A steeper r e d u c t i o n o c c u r r e d on the t r e a t e d p l o t (p<.001, ANCOVA, df=266). Dead i n s e c t s would not be a v a i l a b l e t o b i r d s t h a t r e q u i r e movement t o d e t e c t t h e i r prey. Greenberg (1983) found that warblers were not i n t e r e s t e d i n mealworms as food u n l e s s these prey were a l i v e . I n c r e a s e s i n the p r o p o r t i o n of l i v e i n s e c t s 15 days a f t e r the a p p l i c a t i o n ( F i g u r e 2.4) may have been due t o a removal of dead i n s e c t s from the t r e e , or t o the movement of l i v e i n s e c t s w i t h i n the t r e e . The p r o p o r t i o n of l i v e i n s e c t s i n white b i r c h branch samples was u n a f f e c t e d by the treatment ( F i g u r e 2.4). I n s e c t s not removed 79 i r~ T2 T 3 T I M E P E R I O D T 4 ^ i ? ^ r e . 2 ^ 4 ; C o m P a r i s o n of the p r o p o r t i o n of i n v e r t e b r a t e s (9*^ ^ e f T e ^ a t d i ? f 1 r e n f Till frills a f t P ? % V d a y f . a " e r (T 2), 5 days a f t e r (T 3), and 15 days ( b a l s a ^ r 111 wSt'eMrchl! ° a t r 9 a t e d " * C ° n t r o 1 t - e s 80 from the t r e e would, t h e r e f o r e be s u i t a b l e as prey f o r b i r d s l i k e w a r b lers t h a t s e l e c t l i v i n g i n s e c t s . Changes i n r e l a t i v e abundance may be u n r e l a t e d t o the amount of energy a v a i l a b l e to b i r d s . A n a l y s i s of changes i n dry weights of food a v a i l a b l e on balsam f i r suggest a s i g n i f i c a n t decrease i n biomass of i n v e r t e b r a t e s on t r e a t e d t r e e s (p<.001, r e g r e s s i o n , df=33) and c o n t r o l t r e e s (p<.01, r e g r e s s i o n , df=32). T h i s r e d u c t i o n was not r e s t r i c t e d to the canopy r e g i o n s r e c e i v i n g h i g h e r d e p o s i t . Biomass c a l c u l a t i o n s from white b i r c h show a s i g n i f i c a n t (p<.001, r e g r e s s i o n , df=33) dec r e a s i n g t r e n d i n the amount of i n v e r t e b r a t e food a v a i l a b l e f o l l o w i n g treatment. In c o n t r a s t , the c o n t r o l r e s u l t s show an i n c r e a s i n g t r e n d over the same time p e r i o d (p<.05, r e g r e s s i o n , df=33). B. Drop tray samples The drop t r a y samples from balsam f i r suggest t h a t f e n i t r o t h i o n had an immediate e f f e c t on D i p t e r a and Hymenoptera, and an extended e f f e c t on feeders ( F i g u r e 2.5). T h i s agrees with the NRC (1975) r e p o r t on f e n i t r o t h i o n which found the peak k i l l f o r D i p t e r a t o be 2 days e a r l i e r than t h a t of d e f o l i a t o r s . The abundance of dead i n s e c t s was h i g h e s t 1 day a f t e r the a p p l i c a t i o n , f a l l i n g o f f to b a s e l i n e l e v e l s by 4 days a f t e r s p r a y i n g ( F i g u r e 2.6). T h i s suggests an e x p o n e n t i a l l y d e c r e a s i n g 81 "T~ 3 1 2 D A Y S A F T E R T H E A P P L I C A T I O N F i g u r e 2.5. P r o p o r t i o n of D i p t e r a , Hymenoptera, and f e e d e r s i n drop t r a y samples taken 1 t o 3 days a f t e r the a p p l i c a t i o n , from balsam f i r (x±SE) of 9 sample t r e e s ) . 82 m o r t a l i t y r a t e , with the g r e a t e s t k i l l o c c u r r i n g almost immediately. R e s u l t s f o r white b i r c h again show a l a r g e immediate k i l l of i n v e r t e b r a t e s ( D i p t e r a , Hymenoptera and f e e d e r s ) with some extended k i l l (mainly f e e d e r s ) up to 3 days a f t e r the a p p l i c a t i o n ( F i g u r e 2.7, Table 2.2). Table 2.2. P r o p o r t i o n of D i p t e r a , Hymenoptera, and f e e d e r s i n drop t r a y samples from white b i r c h t r e e s (x±SE of 9 sample t r e e s ) . DAYS AFTER THE APPLICATION + 1 +2 + 3 D i p t e r a .25±.07 .21± . 08 . 30± . 11 Hymenoptera .18±.05 . 19± . 08 .09± . 04 f e e d e r s .55±.11 .62± . 10 . 53± . 11 There was no apparent r e l a t i o n s h i p between the i n c r e a s e d number of i n v e r t e b r a t e s t h a t dropped onto t r a y s and the reduced number of i n v e r t e b r a t e s i n the branches f o r e i t h e r t r e e s p e c i e s (Table 2.3). Although the b i r c h t r e e with the l a r g e s t drop was the t r e e with the b i g g e s t change i n i n s e c t numbers, t h i s does not apply f o r the b i r c h t r e e with the next l a r g e r drop. DISCUSSION My r e s u l t s from drop t r a y s below white b i r c h were s i m i l a r to F r a s e r ' s (1983) r e s u l t s f o l l o w i n g an a p p l i c a t i o n of f e n i t r o t h i o n at 210 g/ha. His found a 30.5±7.37 (x±SE) % k i l l of a l l i n v e r t e b r a t e s compared to my 42.4±15.49. In F r a s e r ' s study, the 83 03 UJ < ca UJ r-cc UJ > z o cc UJ CD 5 Z 20 n 15 -10 -5 -- A T R E A T M E N T « ¥ - A C O N T R O L A P P L I C A T I O N O F F E N I T R O T H I O N T — r T— i— t— f—!—H"T— i—r—T— i— i—i— r 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 D A Y S I N J U N E F i g u r e 2.6. Abundance of i n v e r t e b r a t e s c o l l e c t e d from drop t r a y s below balsam f i r (x±SE of 9 sample t r e e s ; l/4m 2 sampler) on treatment and c o n t r o l . F i g u r e 2.7. Abundance of i n v e r t e b r a t e s c o l l e c t e d from drop t r a y s below white b i r c h (x±SE of 9 sample t r e e s ; l/4m 2 sampler) on treatment and c o n t r o l . 84 Table 2.3. R e l a t i o n s h i p between branch and drop t r a y samples u s i n g the p r o p o r t i o n of prespray i n v e r t e b r a t e s s u r v i v i n g to 5 days a f t e r the a p p l i c a t i o n (T 3/T]_), compared t o the cummulative number of i n v e r t e b r a t e s c o l l e c t e d from drop t r a y s 1, 2, and 3 days a f t e r treatment. T h i s number was then expressed as a p r o p o r t i o n of the average number before s p r a y i n g ( ( N 1 + N 2 + N 3 ) / N p r e ) . PROPORTION SURVIVING (T3/T1) ON BRANCHES CUMMULATIVE DROP ( ( N 1 + N 2 + N 3 ) / N p r e ) BALSAM FIR: TREE 1 2 3 4 5 6 7 8 9 0.28* 1.00 0.86 0.63 1.00 1.00 0.17* 0.47 0. 14* 27.9** 18.0 27.9** 14.4 14.5 33.8* * 11.7 14.7 15.0 WHITE BIRCH: TREE 1 2 3 4 5 6 7 8 9 0. 17* 1.00 0.92 0.75 1.00 1.00 1.00 0.71* 1.00 62.0** 54.8* * 12.6 17.2 9.2 7.5 18.3 8.2 2.8 * l a r g e s t r e d u c t i o n i n number of i n v e r t e b r a t e s per branch ** l a r g e s t cummulative drop 85 c o r r e s p o n d i n g k i l l of budworm was 22.5 % and he found a s i m i l a r s p e c i e s composition i n h i s branch and drop t r a y samples. I know of no comparable s t u d i e s f o r balsam f i r . The numbers of i n s e c t s f a l l i n g onto drop t r a y s suggests a l a r g e r e f f e c t than that measured by branch sampling. Although the same t r e e s were used f o r both drop t r a y and branch sampling, the two methods were not s t r i c t l y comparable. T h i s i s due to the predominance of D i p t e r a i n the t r a y s and t h e i r s c a r c i t y on branch samples. Branch samples were composed of mostly i n v e r t e b r a t e s a s s o c i a t e d with the t r e e . Consequently, t i e two sampling procedures s e l e c t e d q u i t e d i f f e r e n t organisms. Table 2.4 l i s t s the p r o p o r t i o n of the major i n s e c t groups found i n branch samples b e f o r e s p r a y i n g , and immediately (1 to 3 days) a f t e r s p r a y i n g i n drop t r a y s . The removal of l a r g e numbers of D i p t e r a probably had l i t t l e e f f e c t on the i n s e c t p o p u l a t i o n of the t r e e . Drop t r a y s under white b i r c h sampled a g r e a t e r number of f e e d e r s than balsam f i r drop t r a y s , and there was some correspondence between the e f f e c t on branches and the drop sample r e s u l t s , whereas, no correspondence was found on balsam f i r . For any p a r t i c u l a r t r e e , the number of i n s e c t s i n drop t r a y s was not a good p r e d i c t o r of changes i n the i n v e r t e b r a t e p o p u l a t i o n on i t s branches. The magnitude of drop may have depended on whether the branches above the t r a y r e c e i v e d a heavy d e p o s i t or not. The number of branches sampled by the drop t r a y s was not known, but the t r a y s remained i n the same p l a c e 86 Table 2.4. Comparison of the i n v e r t e b r a t e composition of branch samples t o th a t of drop t r a y samples. PROPORTION OF BRANCH SAMPLES PROPORTION OF DROP TRAY SAMPLES BALSAM FIR: D i p t e r a aphids Hymenoptera s p i d e r s C o l e o p t e r a L e p i d o p t e r a f e e d e r s .03 .37 .03 . 14 .05 .01 .76 .45 .27 . 15 0 .06 .01 .39 WHITE BIRCH: D i p t e r a aphids Hymenoptera s p i d e r s C o l e o p t e r a L e p i d o p t e r a f e e d e r s .01 .40 .03 .02 . 17 .02 .95 .22 .45 . 15 0 .03 .03 .59 1 c a l c u l a t e d as a p r o p o r t i o n of the prespray t o t a l number of i n v e r t e b r a t e s . 2 c a l c u l a t e d as a p r o p o r t i o n of the t o t a l drop from 1, 2, and 3 days a f t e r the a p p l i c a t i o n . 87 throughout the study. For branch sampling, however, a d i f f e r e n t branch was randomly s e l e c t e d each time. Branches were never taken from the f o l i a g e column above the drop t r a y (to prevent sampling d i s t u r b a n c e of the i n v e r t e b r a t e s ) . Thus, d e p o s i t on the branches above the drop t r a y c o u l d have d i f f e r e d s i g n i f i c a n t l y from t h a t on the branches taken f o r a n a l y s i s of i n v e r t e b r a t e p o p u l a t i o n changes. V a r i a b i l i t y between branch samples, due to the patchy nature of i n s e c t i c i d e d e p o s i t s , c o u l d a l s o e x p l a i n the d i s c r e p a n c y between the magnitude of drop from t r e e s and the reduced number of i n v e r t e b r a t e s on t h e i r branches. By randomly s e l e c t i n g branches, one sample c o u l d have had a d i f f e r e n t l e v e l of d e p o s i t than another. Branches r e c e i v i n g l i t t l e d e p o s i t c o u l d mask an e f f e c t on neighbouring branches r e c e i v i n g more d e p o s i t . From t h i s study and others ( V a r t y 1977), i t i s apparent t h a t refuges of unsprayed f o l i a g e (such as the i n s i d e f o l i a g e or the downwind s i d e of the t r e e ) e x i s t i n any spray b l o c k , and a p r o p o r t i o n of any i n v e r t e b r a t e s p e c i e s ' p o p u l a t i o n i s l i k e l y t o a v o i d c o n t a c t with the chemical ( V a r t y 1977). T h i s i s why c o n t r o l of the t a r g e t , spruce budworm, i s incomplete (70-80%, Varty 1977). Mobile arthropods tend to invade empty n i c h e s , and r e c u p e r a t i o n i s g e n e r a l l y r a p i d . V a r t y (I.W. p e r s . comm.8) used a permethrin wash t o measure the i n s e c t p o p u l a t i o n remaining i n 8. Research S c i e n t i s t , Maritimes F o r e s t Research Centre, F r e d r i c t o n , New Brunswick (now r e t i r e d ) . 88 balsam f i r t r e e s a f t e r a double a p p l i c a t i o n of 210g Al/ha of f e n i t r o t h i o n . He found no s i g n i f i c a n t spray impact on the aphid p o p u l a t i o n d e s p i t e a l a r g e k i l l of aphids onto the drop t r a y s . T h e r e f o r e , u n l e s s b i r d s f e e d only i n h i g h l y exposed regions of the t r e e , they should be able to f i n d refuges of i n s e c t s w i t h i n t h e i r t e r r i t o r y or c l o s e by. This may r e q u i r e a change i n f o r a g i n g s i t e , but not f o r a l l i n d i v i d u a l s , and t h i s may s i g n i f i c a n t l y dampen any e f f e c t of treatment on r e p r o d u c t i o n or s u r v i v a l . D i f f e r e n c e s i n i n v e r t e b r a t e k i l l between canopy regions were not marked, nor was t h e r e a strong r e l a t i o n s h i p of k i l l t o d e p o s i t of f e n i t r o t h i o n ; i n balsam f i r , t h e r e was no i n d i c a t i o n t h a t i n c r e a s e d d e p o s i t had an i n c r e a s e d e f f e c t on the i n v e r t e b r a t e s . T h i s r e s u l t may be a consequence of an inadequate sampling i n t e n s i t y . N e v e r t h e l e s s , because spray i s d e p o s i t e d unevenly over i n d i v i d u a l t r e e s , some v a r i a b i l i t y i n e f f e c t i s i n e v i t a b l e . Branch sampling p r o v i d e d an adequate index of p o p u l a t i o n changes on t r e a t e d and c o n t r o l t r e e s . The i n i t i a l i n v e r t e b r a t e p o p u l a t i o n on the t r e e c o u l d not, however, be determined. Branch sampling d i d not pr o v i d e an accurate measure of the t o t a l i n v e r t e b r a t e p o p u l a t i o n due to the uneven d i s t r i b u t i o n of the i n v e r t e b r a t e s and the subsequent v a r i a b i l i t y between branches. A p r e f e r a b l e d e s i g n would be to supplement sample t r e e s with a known p o p u l a t i o n of budworm, f o r example, i n order t o a c c u r a t e l y 89 determine the magnitude of e f f e c t on the i n v e r t e b r a t e p o p u l a t i o n of the t r e e . D e s p i t e these problems, the r e s u l t s obtained i n t h i s study agree with those r e p o r t e d elsewhere. F e n i t r o t h i o n has been found to cause a l a r g e , immediate ( w i t h i n the f i r s t 4 days) k i l l of l a r v a l L e p i d o p t e r a , sawfly l a r v a e , aphids and p e r c h i n g f l i e s ; D i p t e r a n s are k i l l e d d i r e c t l y a f t e r the spray (Sumitomo 1978; F r a s e r 1983). Buckner (1974) proposed that prolonged m o r t a l i t y of f e e d e r s might occur f o l l o w i n g f e n i t r o t h i o n treatment, and t h a t t h i s c o u l d be a t t r i b u t e d t o d i f f e r i n g exposure r o u t e s ( c o n t a c t v e r s e s i n g e s t i o n ) . The o p p o r t u n i t y f o r exposure through contact decreases r a p i d l y a f t e r the a p p l i c a t i o n , whereas p o i s o n i n g by i n g e s t i o n may be prolonged through the p r o g r e s s i v e c o n c e n t r a t i o n of t o x i n s . CONCLUSION The f e n i t r o t h i o n treatment i n 1986 k i l l e d mainly D i p t e r a ( i n the drop t r a y r e s u l t s ) , and f e e d i n g i n v e r t e b r a t e s ( i n both drop t r a y s and branch samples). There was, however, l i t t l e e f f e c t on the t o t a l i n v e r t e b r a t e community of e i t h e r balsam f i r or white b i r c h . Since t h e r e was no dominant i n s e c t s p e c i e s i n the area I expected b i r d s to forage approximately e q u a l l y on a l l a v a i l a b l e i n s e c t groups. There may have been a s l i g h t r e d u c t i o n i n food a v a i l a b i l i t y , but t h i s r e d u c t i o n would have been s h o r t - l i v e d i f i n s e c t s moved i n from unsprayed areas nearby. Furthermore, i f 90 t h i s r e d u c t i o n i n food a v a i l a b i l i t y was of s u r p l u s food, there would be no e f f e c t on breeding success. 91 GENERAL DISCUSSION A p p l i c a t i o n s f o r spruce budworm have c o n t i n u e d f o r 30 years, over m i l l i o n s of he c t a r e s of f o r e s t , yet budworm continues t o be a problem. Those budworm not contacted by the spray (20-30 % of the p o p u l a t i o n ) , s u r v i v e to i n c r e a s e the p o p u l a t i o n the f o l l o w i n g year ( P r e b b l e 1950; Varty 1977). Annually repeated a p p l i c a t i o n s are t h e r e f o r e necessary t o p r o t e c t the new f o l i a g e (Grimble and M o r r i s 1983). Repeated use of i n s e c t i c i d e s c o u l d cause a d d i t i o n a l s t r e s s on song b i r d p o p u l a t i o n s , beyond t h a t measured i n my study, through a continued r e d u c t i o n of food a v a i l a b l e or continued e f f e c t s on r e p r o d u c t i v e success. L a r g e - s c a l e (100-1000 ha) spray b l o c k s c o u l d a l s o i n c r e a s e the p o t e n t i a l f o r e f f e c t s on b i r d s by l i m i t i n g : 1) the movement of b i r d s t o feed o u t s i d e the t r e a t e d area, and 2) immigration of i n v e r t e b r a t e s i n t o the sprayed area. The e f f e c t on food a v a i l a b i l i t y to b i r d s would t h e r e f o r e be enhanced i n o p e r a t i o n a l sprays of t h i s s c a l e . Under o p e r a t i o n a l c o n d i t i o n s , f e n i t r o t h i o n i s t y p i c a l l y a p p l i e d twice at 210 gAI/ha with a 5-6 day i n t e r v a l . In t h i s experiment, f e n i t r o t h i o n was a p p l i e d once at 280 gAI/ha. A double a p p l i c a t i o n may impact more h e a v i l y on the i n v e r t e b r a t e community by r e a c h i n g those i n v e r t e b r a t e s not c o n t a c t e d w i t h the f i r s t a p p l i c a t i o n ; thereby f u r t h e r reducing the t o t a l i n v e r t e b r a t e community of the t r e e . T h i s may e x p l a i n the r e l a t i v e l y low impact observed on the i n v e r t e b r a t e community (compared to m o r t a l i t i e s r e p o r t e d by Cadogan (1986), f o r example), and i n t u r n , the s l i g h t 92 response from f o r e s t songbirds. At the maximum a l l o w a b l e s i n g l e dose, f e n i t r o t h i o n appears t o have l i t t l e e f f e c t on f o r e s t s o n g b i r d s , even when t e s t e d with a h i g h l y - s e n s i t i v e method. The method d e s c r i b e d i n t h i s t h e s i s was developed s p e c i f i c a l l y to answer an important, but unresolved, q u e s t i o n i n f o r e s t pest management: What are the medium and long-term, s u b l e t h a l e f f e c t s of chemical i n s e c t i c i d e s on f o r e s t songbird p o p u l a t i o n s ? The r e s u l t s suggest t h a t at l e a s t some of the te c h n i q u e s used c o u l d be adapted f o r monitoring programs at the o p e r a t i o n a l l e v e l , and f o r candidate i n s e c t i c i d e s c r e e n i n g i n s m a l l s c a l e f i e l d t r i a l s . There i s no reason t o r e s t r i c t the method t o chemical i n s e c t i c i d e s t h a t d i r e c t l y , though i n a d v e r t e n t l y , p o i s o n b i r d s . Even b i o l o g i c a l i n s e c t i c i d e s (B.t. or v i r u s e s ) , which are much more pest s p e c i f i c , can a f f e c t b i r d s through a r e d u c t i o n of the food base r e q u i r e d f o r maintenance and r e p r o d u c t i v e success. The method d e s c r i b e d should d e t e c t t h i s impact. On the whole, the monitoring method used i n t h i s study, should p r o v i d e a s e n s i t i v e measure of the impact of i n s e c t i c i d e s , c h e m i c a l or b i o l o g i c a l , on f o r e s t songbird p o p u l a t i o n s . Even though the method i s adaptable, a major problem remains t h a t i s c h a r a c t e r i s t i c to any monitoring program. The study area may not be r e p r e s e n t a t i v e of other spray areas ( r e c e i v i n g the same a p p l i c a t i o n ) , due to v a r i a b i l i t y i n : h a b i t a t , phenology, amount of spray d e p o s i t e d , and the b i r d p o p u l a t i o n . Even w i t h i n a sprayed area, t h e r e i s a problem of v a r i a b i l i t y i n d e p o s i t . Due 93 t o the uneven d e p o s i t , and the r e s u l t i n g uneven e f f e c t on i n v e r t e b r a t e food of b i r d s , v a r i a b i l i t y i n response t o the a p p l i c a t i o n of an i n s e c t i c i d e such as f e n i t r o t h i o n i s i n e v i t a b l e . T h i s i s the nature of the beast, and i s p r e c i s e l y why c o n t r o l of e a s t e r n spruce budworm has not been p o s s i b l e . I t i s l i k e l y t h a t i n any f o r e s t r y a p p l i c a t i o n of i n s e c t i c i d e s (due to v a r i a b l e wind c o n d i t i o n s , s t r u c t u r e of the f o r e s t , and m i c r o m e t e o r o l o g i c a l c o n d i t i o n s at the time of s p r a y ) , some i n d i v i d u a l b i r d s w i l l r e c e i v e l i t t l e exposure while other i n d i v i d u a l s , occupying the same niche, c o u l d r e c e i v e more. Consequently, the average response w i l l l i k e l y be dampened by b i r d s l e s s exposed to the i n s e c t i c i d e . T h i s v a r i a b i l i t y i n p o t e n t i a l e f f e c t cannot be improved by i n c r e a s e d sample s i z e . ( I n c r e a s e d sample s i z e would, however, c o n t r o l f o r v a r i a b i l i t y of response among i n d i v i d u a l s exposed to the same d e p o s i t . ) The average e f f e c t i s a l l t h a t can be achieved. With t h i s i n mind, measurable changes i n b i r d behaviour, and the b i r d p o p u l a t i o n , should not be underestimated as these e f f e c t s would undoubtedly be dampened. To understand how i n s e c t i c i d e a p p l i c a t i o n s a f f e c t b i r d s , l e s s emphasis should be p l a c e d on ChE i n h i b i t i o n i t s e l f . For ChE i n h i b i t i o n t o be meaningful, i t must be coupled w i t h b e h a v i o u r a l responses t o t h a t i n h i b i t i o n . With the c u r r e n t move to b i o l o g i c a l i n s e c t i c i d e s , i t i s even more c r i t i c a l t h a t an a l t e r n a t i v e method be developed. 94 The impact of i n s e c t i c i d e s on f o r e s t songbirds i s a h i g h l y complex problem which may be b e t t e r approached through c o n t r o l l e d experiments where a known de p o s i t i s a p p l i e d on a l l l o c a t i o n s of the t r e e w i t h a known i n i t i a l p o p u l a t i o n of i n v e r t e b r a t e s . T h i s would p r o v i d e a more ac c u r a t e measure of changes i n food a v a i l a b i l i t y and how t h i s a f f e c t s behaviour. T h i s i s the d i r e c t i o n I would l i k e t o pursue. 95 REFERENCES Adams, P.M. 1977. E f f e c t s of a n t i c h o l i n e r g i c and c h o l i n e s t e r a s e b l o c k i n g drugs on a p p e t i t e behaviour under d i f f e r e n t d e p r i v a t i o n c o n d i t i o n s . L i f e S c i . 21:129-136. Anon. 1987. I n s e c t i c i d e s r e g i s t e r e d f o r f o r e s t and woodlands management. T e c h n i c a l r e f e r e n c e , Canadian Pulp and Paper A s s o c i a t i o n , and The F o r e s t Pest Management I n s t i t u t e . Armstrong, J.A. and W.N. Yule 1978. The d i s t r i b u t i o n of a e r i a l l y - a p p l i e d spray d e p o s i t s i n spruce t r e e s . Can. Ent. 110:1259-1267. Barry, J.W. 1984. D e p o s i t i o n of chemical and b i o l o g i c a l agents i n c o n i f e r s . In Chemical and B i o l o g i c a l C o n t r o l s i n F o r e s t r y , eds. Garner, W.Y. and J . Harvey ( J r . ) , Am. Chem. Soc. Symp. S e r i e s No. 238:117-138. B a r t , J . 1979. E f f e c t s of acephate and s e v i n on f o r e s t b i r d s . J . W i l d l . Manage. 43:544-549. B a r t , J . and L. Hunter, 1978. E c o l o g i c a l impacts of f o r e s t i n s e c t i c i d e s : an annotated b i b l i o g r a p h y . Canada-U.S. Spruce Budworm Program Report, 128pp. Buckner, C H . 1974. The b i o l o g i c a l s i d e - e f f e c t s of f e n i t r o t h i o n i n f o r e s t ecosystems. Chem. Cont. Res. I n s t i t . Rep. CC-X-67. Buckner, C H . and D.G.H. Ray 1973. Songbird p o p u l a t i o n s i n the spruce budworm c o n t r o l area, northwestern New Brunswick p r i o r to treatment with phosphamidon. Report to NRC A s s o c i a t e Committee on S c i e n t i f i c C r i t e r i a f o r Environmental Q u a l i t y . Buckner, C H . and R. S a r a z i n 1975. S t u d i e s of the environmental impact on the 1974 spruce budworm c o n t r o l o p e r a t i o n i n Quebec. Chem. Cont. Res. I n s t . , I n f . Rept., CC-X-93, 106pp. Busby, D.G., Pearce, P.A., and N.R. G a r r i t y 1981. B r a i n c h o l i n e s t e r a s e response i n songbirds exposed t o experimental f e n i t r o t h i o n s p r a y i n g i n New Brunswick. Canada. B u l l . E n v i r o n . Contam. T o x i c o l . , 26:401-406. Busby, D.G., Pearce, P.A., and G a r r i t y , N.R. 1987. E f f e c t of u l t r a U L V f e n i t r o t h i o n s p r a y i n g on b r a i n chE a c t i v i t y i n f o r e s t s o n g b i r d s . B u l l . E n v i r o n . Contam. T o x i c o l . 39:304-311. Busby, D.G., Pearce, P.A., G a r r i t y , N.R., and L.M. Reynolds 1983. E f f e c t of an organophosphate i n s e c t i c i d e on b r a i n c h o l i n e s t e r a s e a c t i v i t y i n w h i t e - t h r o a t e d sparrows exposed t o a e r i a l f o r e s t s p r a y i n g . J . Appl. E c o l . , 20:255-263. Cadogan, B.L. 1986. R e l a t i v e f i e l d e f f i c a c i e s of Sumithion 20% f l o w a b l e and Sumithion t e c h n i c a l f o r m u l a t i o n s a g a i n s t spruce 96 budworm, C h o r i s t o n e u r a fumlferana ( L e p i d o p t e r a : t o r t r i c i d a e ) . Can. Ent. 118: 1143-1149. Crawford, H.S. and D.T. Jennings 1982. R e l a t i o n s h i p s of b i r d s and spruce budworms- l i t e r a t u r e review and annotated b i b l i o g r a p h y . USDA For. Serv. B i b l i o g r a p h i e s and L i t e r a t u r e of A g r i c . 23:38pp. Deboo, R.F., L.M. Campbell, and A.G. Copeman 1973. A sampling technique f o r e s t i m a t i n g numerical trends i n l a r v a l p o p u l a t i o n s of i n s e c t d e f o l i a t o r s on c o n i f e r s . P h y t o p r o t e c t i o n 54: 9-22. Doane, C C . and P.W. Schaefer 1971. A e r i a l a p p l i c a t i o n s of i n s e c t i c i d e s f o r c o n t r o l of the gypsy moth: with s t u d i e s of e f f e c t s on non-target i n s e c t s and b i r d s . Conn. A g r i c . Exp. Stn. B u l l . 724 23pp. F i n l e y , R.B. 1965. Adverse e f f e c t s on b i r d s of pnosphamidon a p p l i e d to a Montana f o r e s t , J . Wild. Manage., 29:580. Flemming, W.J., and C.E. Grue 1981. Recovery of c h o l i n e s t e r a s e a c t i v i t y i n f i v e a v i a n s p e c i e s exposed t o d i c r o t o p h o s , an organophosphorus p e s t i c i d e . P e s t i c . Biochem. P h y s i o l . , 16:129-135. Fowle, C D . 1965. A p r e l i m i n a r y r e p o r t on the e f f e c t s of phosphamion on b i r d p o p u l a t i o n s i n c e n t r a l New Brunswick. Canadian W i l d l i f e S e r v i c e O c c a s i o n a l Paper No. 7, 54pp. F r a s e r , R.G. 1983. The e f f e c t of a e r i a l s p r a y i n g of f e n i t r o t h i o n f o r spruce budworm c o n t r o l on the non-target i n s e c t community on white b i r c h . F a c u l t y of F o r e s t r y , Univ. of N.B., 31pp. Garton, E.O. 1979. I m p l i c a t i o n s of optimal f o r a g i n g theory f o r i n s e c t i v o r o u s f o r e s t b i r d s , pg 107 In J.G. Dickson ed. The r o l e of i n s e c t i v o r o u s b i r d s i n the f o r e s t ecosystems, 381 pp. Graber, J.W. and R.R. Graber 1983. Feeding r a t e s of warblers i n s p r i n g . Condor 85(2) : 139-150. Greenberg, R. 1983. The r o l e of neophobia i n determining the degree of f o r a g i n g s p e c i a l i z a t i o n i n some migrant warblers. Am. Nat. 122(4):444-453. Grimble, D.G. and O.N. M o r r i s 1983. R e g i o n a l e v a l u a t i o n of B.t. f o r spruce budworm c o n t r o l . USDA Info . B u l l . No. 458, 9pp. Grue, C.E. 1982. Response of common g r a c k l e s to d i e t a r y c o n c e n t r a t i o n s of f o u r organophosphate p e s t i c i d e s , Arch. E n v i r o n . Contam. T o x i c o l . , 11:617-626. Grue, C.E., W.J. Flemming, D.G. Busby, and E.F. H i l l 1983. A s s e s s i n g hazards of organophosphate p e s t i c i d e s to w i l d l i f e . 97 T r a n s a c t i o n s of 48th N.Am. W i l d l . and Nat. Res. Conf., pp.200-220. H i l l , E.F. and W.J. Fleming 1982. A n t i c h o l i n e s t e r a s e p o i s o n i n g of b i r d s : f i e l d monitoring and d i a g n o s i s of acute p o i s o n i n g . E n v i r o n . T o x i c o l . Chem., 1:27-38. Hopewell, W.W. 1974. E v a l u a t i o n of commercial p r e p a r a t i o n of B a c i l l u s t h u r i n g i e n s i s with and without c h i t i n a s e a g a i n s t spruce budworm. Env. Canada, For. Serv., Chem. Cont. Res. I n s t . , Inf. Rept., CC-X-59, Sect B, 14pp. Hudson, R.H., R.K. Tucker, and M.A. Haegele 1984. Handbook of t o x i c i t y of p e s t i c i d e s t o w i l d l i f e . U.S. F i s h and W i l d l i f e Serv. Res. Publ. No. 153, 91pp. Hunter, M.L. and J.W. Witham 1985. E f f e c t s of c a r b a r y l - i n d u c e d d e p r e s s i o n of arthropod abundance on the behaviour of P a r u l i d a e warblers, Can. J . Z o o l . , 63:2612-2616. James, F.C. and H. Shugart 1970. A quanti"fcative method of h a b i t a t d e s c r i p t i o n . Audubon F i e l d Notes 24(1):727-736. Kendeigh, S.C. 1947. B i r d p o p u l a t i o n s t u d i e s i n the c o n i f e r o u s f o r e s t biome d u r i n g a spruce budworm outbreak. Ont. Dep. Lands and For. B i o l . B u l l . , 1, 100pp. K e t t e l a , E.G. 1983. A c a r t o g r a p h i c h i s t o r y of spruce budworm d e f o l i a t i o n 1967 to 1981 i n E a s t e r n North America. In f o . Rept. DPC-X-14, 8pp. Knapton, R.W. 1984. P a r e n t a l f e e d i n g of n e s t l i n g n a s h v i l l e w a r b l e r s : The e f f e c t s of food type, b r o o d - s i z e , n e s t l i n g age and time of day. Wilson B u l l . 96(4):594-602. Lehoux, D., R. O u e l l e t , and P. Laporte 1982. Etude comparative des d i f f e r e n t e s methodes de s u r v e i l l a n c e des oiseaux f o r e s t i e r s s u i t e a des epandages experimentaux d ' i n s e c t i c i d e s . S e r v i c e canadien de l a faune, Ste-Foy, Quebec, 92pp. Ludke, J.L., E.F. H i l l , and M.P. D i e t e r 1975. C h o l i n e s t e r a s e (ChE) response and r e l a t e d m o r t a l i t y among b i r d s f e d ChE i n h i b i t o r s . Arch. E n v i r o n . Contam. T o x i c o l . 3(1):1-21. MacArthur, R.H. 1958. P o p u l a t i o n ecology of some warblers of n o r t h e r n c o n i f e r o u s f o r e s t s . Ecology 39:487-494. Macdonald, D.R. and F.E. Webb 1963. I n s e c t i c i d e s and the spruce budworm. In The dynamics of epidemic spruce budworm p o p u l a t i o n s . Ed. R.F. M o r r i s . Mem. Entomol. Soc. Can. 31:288-310. 98 MoLeod, J.M. 1968. R e s u l t s of an a e r i a l s p r a y i n g o p e r a t i o n a g a i n s t the swaine jack pine sawfly, N e o d i p r i o n swainei Middelton, i n Quebec u t i l i z i n g the i n s e c t i c i d e pnosphamidon, For. Chon., 44:14-20. M o r r i s , R.F. 1955. Development of sampling techniques used f o r f o r e s t i n s e c t d e f o l i a t o r s , with s p e c i a l r e f e r e n c e to the spruce budworm. Can. J. Z o o l . 33:225-294. M o r r i s , R.F., W.F. C h e s i r e , C.A. M i l l e r and D.G. Mott 1958. The numerical response of a v i a n and mammalian p r e d a t o r s during a g r a d a t i o n of the spruce budworm. E c o l . 49(4)-.487-494. Morse, D.H. 1968. A q u a n t i t a t i v e study of f o r a g i n g of male and female spruce-woods warblers. Ecology 49(4):779-784. Morse, D.H. 1976. V a r i a b l e s a f f e c t i n g the d e n s i t y and t e r r i t o r y s i z e of b r e e d i n g spruce-woods warblers. Ecology 57:290-301. Moulding, J.D. 1976. E f f e c t s of a l o w - p e r s i s t e n c e i n s e c t i c i d e on f o r e s t and b i r d p o p u l a t i o n s . Auk 93:692-708. N a t i o n a l Research C o u n c i l of Canada, 1975. F e n i t r o t h i o n : the e f f e c t s of i t s use on environmental q u a l i t y and i t s chemistry, Publ. NRCC 14104, 162pp. Paszkowski, C.A. 1982. V e g e t a t i o n , ground, and f r u g i v o r o u s f o r a g i n g of the American Robin. Auk 99:701-709. P e a k a l l , D.B. 1985. B e h a v i o u r a l responses of b i r d s t o p e s t i c i d e s and other contaminants. Residue Reviews 96:46-77. P e a k a l l , D.B. and J.R. Bart 1983. Impacts of a e r i a l a p p l i c a t i o n of i n s e c t i c i d e s on f o r e s t b i r d s , CRC C r i t i c a l Reviews i n Environmental C o n t r o l , 13(2):165pp. Pearce, P.A. 1968. E f f e c t s on b i r d p o p u l a t i o n s of phosphamidon and Sumithion used f o r spruce budworm c o n t r o l i n New Brunswick, Canadian W i l d l i f e S e r v i c e I n t e r d e p a r t m e n t a l Committee on f o r e s t s p r a y i n g o p e r a t i o n s . Pearce, P.A. 1971. Side e f f e c t s of f o r e s t s p r a y i n g i n New Brunswick. T r a n s a c t i o n s of the 36th N.Am. W i l d l . Conf., pp.163-170. Pearce, P.A. 1975. E f f e c t s on f o r e s t b i r d s , pp.55-62 Ifi NRCC, F e n i t r o t h i o n : the e f f e c t s of i t s use on environmental q u a l i t y and i t s c h e m i s t r y . Publ. NRCC 14104. Pearce, P.A. and D.B. P e a k a l l 1977. The impact of f e n i t r o t h i o n on b i r d p o p u l a t i o n s i n New Brunswick, pp.299-306 I n Proceedings of a symposium on f e n i t r o t h i o n : the long-term e f f e c t s of i t s use i n f o r e s t ecosystems, NRCC, 16073. 99 Pearce, P.A., P e a k a l l ,D.B., and A.J. E r s k i n e 1979. Impact on f o r e s t b i r d s of the 1975 spruce budworm spray o p e r a t i o n i n New Brunswick, Canadian W i l d l i f e S e r v i c e Progress Note, 97:1-15. Prebble, M.L. 1950. The b a t t l e of the budworm. Pulp and Paper Magazine of Canada. June, pp.149-155. Rogers, CM. 1985. Foraging success and t r e e s p e c i e s use i n the l e a s t f l y c a t c h e r . Auk 102:613-620. Royama, T. 1970. F a c t o r s governing the hunting behaviour and food s e l e c t i o n of the great t i t (Parus major ( L . ) ) . J . Anim. E c o l . 39:619. Sanders, C.J. 1970. Po p u l a t i o n s of breeding b i r d s i n the s p r u c e - f i r f o r e s t s of northwestern O n t a r i o . Can. F i e l d - N a t . 84:131-135. Sanders, C.J. 1980. A summary of cu r r e n t t e c h n i q u e s used f o r sampling spruce budworm p o p u l a t i o n s and e s t i m a t i n g d e f o l i a t i o n i n E a s t e r n Canada. Can. For. Serv., S a u l t Ste. Marie, Ont., Report O-X-306, 33pp. Schoener, T. 1971. Theory of fe e d i n g s t r a t e g i e s . Ann. Rev. E c o l . Syst. 2:369-404. S p i l l m a n , J . J . and R.J.V. Joyce 1978. Low-volume and ultra-low-volume spray t r i a l s from a i r c r a f t over T h e t f o r d F o r e s t . In C o n t r o l of Pine Beauty Moth by F e n i t r o t h i o n i n Sc o t l a n d 1978, eds. Holden, A.V. and D. Bevan, For.Comm., U.K. pp.31-52. Spray, C.J., H.Q.P. C r i c k and A.D.M. Hart 1987. E f f e c t s of a e r i a l a p p l i c a t i o n s of f e n i t r o t h i o n on b i r d p o p u l a t i o n s of a S c o t t i s h pine p l a n t a t i o n . J . Appl. E c o l . 24:29-47. Sundaram, K.M.S. and R. Nott 1984. F e n i t r o t h i o n r e s i d u e s i n s e l e c t e d components of a c o n i f e r f o r e s t f o l l o w i n g a e r i a l a p p l i c a t i o n of tank mixes c o n t a i n i n g T r i t o n X-100. A g r i c . Canada, Can. For. Serv., I n f . Rept. FPM-X-65, 14pp. Sundarum, K.M.S., P.D. Kingsbury, C. Feng, R. M i l l i k i n , and J . Broks 1985. D i s t r i b u t i o n and d e p o s i t i o n of f e n i t r o t h i o n i n s e c t i c i d e i n a b o r e a l f o r e s t near Searchmont, O n t a r i o , d u r i n g an ex p e r i m e n t a l spray program conducted i n 1985. A g r i c . Can., CFS, For. Pest Manage. I n s t i t . , S a u l t Ste. Marie, Canada, 47pp. Sumitomo 1978. Impact of f e n i t r o t h i o n (Sumithion ) on the whole environment i n c l u d i n g humans. Sumitomo Chemical Co., Lt d . , Osaka, Japan. 100 Thomson, M.J., M. Applejohn, and G.M. Howse 1985. F o r e s t i n s e c t and desease c o n d i t i o n s i n On t a r i o . Survey B u l l e t i n , Great Lakes F o r e s t Research Centre, S a u l t Ste. Marie, 31pp. Vart y , I.W. 1974. E f f e c t s on f o r e s t i n v e r t e b r a t e s , pp.39-54 In NRCC, F e n i t r o t h i o n : the e f f e c t s of i t s use on environmental q u a l i t y and i t s chemistry. Publ. NRCC 14104, 162pp. Var t y , I.W. 1975. Side e f f e c t s of pest c o n t r o l p r o j e c t s on t e r r e s t r i a l arthropods other than the t a r g e t s p e c i e s , pp.266-275 In M.L. Prebble ed., A e r i a l c o n t r o l of f o r e s t i n s e c t s i n Canada. Dept. of the Env., Ottawa, Canada. Varty, I.W. 1977. Long-term e f f e c t s of f e n i t r o t h i o n spray programs on non-target t e r r e s t r i a l arthropods, pp.343-376 In Proceedings of a symposium on f e n i t r o t h i o n : the long-term e f f e c t s of i t s use i n f o r e s t ecosystems, NRCC, 16073. Z i n k l , J.G., Henny, C.J., and P.J. Shea 1979. B r a i n c h o l i n e s t e r a s e a c t i v i t i e s of p a s s e r i n e b i r d s i n f o r e s t s sprayed w i t h c h o l i n e s t e r a s e i n h i b i t i n g i n s e c t i c i d e s , pp.356-365 In Animals as Monitors of Environmental P o l l u t a n t s , N a t i o n a l Academy Science, Washington, D.C. 101 APPENDIX I HABITAT ANALYSES 102 T a b l e 1. H a b i t a t a n a l y s i s of p l o t T, 1984. Number of c i r c l e s Numoer of t rees in a i l c i r c l e * by diameter af s u e c l a s i T r e e s / h e c t a r e R e l a t i v e d e n s i t y ' 7-13. > 1 J . 3-19. J 19.3-29 5 29.5-38 38-46 46-52.t 52 .8 -60 .3 60. T o t a l (by s p e c i e s ) tby s p e c i e s ffaeula papgriftra 1 1 3 5 1 20 6.4 12.2 Ainu* mgota J J 1.0 1 .S Abiaa bal'amaa 27 6 1 34 10.9 20.7 Aaar mbm* 1 1 2 0.6 1.2 a"««r maaanarvn 1 1 2 4 1.3 2.4 F raxi nut nigra 1 1 2 4 '• > 2.4 Tnuja oaaidnntalIt 1 ) 21 52 0 1 71 22.7 4J. J Tivga aanadanai* 1 1 O.J 0.6 Piata glavaa 4 2 1 1 a 2.6 4.9 Prunat rirginiana 8 8 2.6 4.8 Batula Ivtta 1 i 0. I 0. 6 Popttlua trtnuloliaw 7 1 8 2.6 4 . a 10'ALS 77 n 44 5 1 2 - 164 52.5 100S Tr re a/ hec I are (by a w e c L i i ' i ) R e l a t i v e dens i ty (by s w e c l a 2 5.3 M . 2 ) 17 21 . ) 14.1 26.3 I .6 3.0 0.3 0.6 0.6 1.2 I SEE Si BASAt. AREA 5 fREOUCNCT 8 Crosa s e c t i o n a l area of the trunW at t o t a l No. Of breaat height ( d . b . h ) basa l c i r c l e s . .. — . area R e l a t i v e in which SPECIES A 6 a C 0 E f C H (by s p e c i e s doninanc e' spec ies R e l a t i v e ( .009) ( .027) (.072) (.162) (.279) (.441) ( .6)9) ( .0005 d 2 i aq «ii (by s p e c i e s ) occurred f r equenc 9*tula papyriftra .099 .081 .36 .162 .70 3 10.4 7 58 itnui rugota .027 .02 7 0.4 2 1 6 Abia* baltamaa .24) .162 .072 .477 7.0 8 66 katr rubra* .009 .072 .081 1.2 2 16 tetr aaaaharum .009 .027 . 144 .18 2.7 1 8 F raxinut nigra .009 .027 . 1 44 .18 2.7 2 16 Tnuja a a a i i t n t a l i t .117 .56 7 2.304 .643 .441 4.077 60.2 6 50 Tauga aanajtnaia .009 .009 0.1 1 3 Pi eta glauaa .036 .054 .072 .279 .441 6.5 4 33 PrinNi virginiana .072 .072 1 . 1 1 8 8a tula lu e«a .441 .441 6.5 1 3 Fopulua tramuleiiat .063 .027 .09 1.3 2 16 T0IAL5 .693 .945 3.168 .81 .279 .889 .522 6.778 1005 Basal area (by a w e c l a s a ) .558 . 756 2.5)9 .648 .225 .702 R e l a t i v e basal area (by a w e c l a s s ) 10.2 1 3.9 46.9 12.0 4. 1 1 3.0 SHRUBS: Total shrub stems in a l l t r a n s e c t s (2 per c i r c l e ) * 1000, d i v i d e d by the number of t r a n s e c t s a 2 l , 4 8 * snrub sterna per hectare (1289 st e-n s) G«OU*0 C0VCR: t o t a l p l u s e s (*) recorded (20 s i g h t i n g s per c i r c l e ) « TOO, d i v i d e d by the t o t a l number o f s i g h t i n g s s 67,35 ground c o v e r . CANOPY COVE*: Tota l p luses (•) recorded (20 s i g h t i n g s per c i r c l e ) « 100. d i v i d e d by the t o t a l number o f s i q h t i n q s = 60.3% canopy c o v e r . CANOPT HEIGHT ( O . S . / ' J . S . ) : Average: 12/? Sanqe = 7-24/1-3 NOTES: Cutover 4 second growth o . S . * JO" dry o v e r a l l , f a l l e n t rees as dead underbrush throughout U .S . = &Q* Number per un i t area Tota l t rees counted « 0.32 R e l a t i v e d e n s i t y i s the percent of the t o t a l number of t rees which are the s p e c i e s in q u e s t i o n G i v e est imated diameter 9asal area i s the c r o s s s e c t i o n a l area o f the trunk of a tree at T.4 meters (dbh) M u l t i p l y th« number of t rees in a l l c i r c l e s in s w e C l a s s A t imes .009 (average area in square meters for t h i s 3. -e c l a s s ) To ta l basa l area of the s p e c i e s 1 00 t o t a l basal area of a l l s p e c i e s frequency i n d i c i t e s the evenness o f d i s t r i b u t i o n o f a s p e c i e s Nuwcer of c i r c l e s in « n j c h t^e 3Decies occurred f a t a l numoer o f c i r c l e s iaa M a j o r v p p S h r u b s - *9*r r a i y u * , Abit* >JII)»«J, Pie si gIJU * a , Papulu* t r 9ful)\J * » , 9ubu t iduiv , B* iul j papyriftra, Sorbut d f t r t s a n a , Prumut ptitylvtiniiQ, H i m ttrobut, Coryl*t noriutJ, lettr tpisat***, < 4 m « l a * a J i i e r sp . , S&mbuau* s o . Laniaira -jp. 103 T a b l e 2. H a b i t a t a n a l y s i s of p l o t C. Number of c i r c l e s = 6 m a s t O E N S t l t ' Number of t rees in a l t c i r c l e s by diameter or s i r e c l a s * SPECIES A B C 0 C F G H* T r e e s / h e c t a r e R e l a t i v e dens i ty^ 7-13,3 13 .3 -19 .3 19.3-29.5 29.5-38 38-46 46-52.8 52 .8 -60 .3 60.3 T o t a l (by s p e c i e s ) (by species} 4a{«e aalaewaa 43 21 2 66 42.2 • 55.0 11 6 8 25 16.0 20.8 ffaeule papyrif*F9 9 2 1 1 1 U 9.0 11 .7 fia*a mariama I ik 5 » 5.8 7.5 Pinua *trobu9 . t 1 1 3 1.9 2.5 fru*H» panty taan iaa 2 - 2 1 . 3 1.7 Aear Fdiruii - 1 - 1 0.6 0.8 I0TAL5 67 35 15 1 1 - 1 120 76.8 1CO.0 I r e e s / h e c t e r e (by i w e c l a s s / 42.1 22.H 9.6 0.6 0.6 - - 0.6 R e l a t i v e dens i ty (by s i t e c l a s s ) 55.8 29.2 12.5 0.8 0.8 - - 0.8 TREES: BASAL AREA 5 fREQUENC' 8 C r o s s s e c t i o n a l area of the trunk at breaat height ( d . b . h . ) SPECIES (.009) (.0005 d 2 ) t o t a l No. of b a s a l c i r c l e s area R e l a t i v e in which (by a p e c i e s dominance' apec ies R e l a t i v e ' aq <a) (by s p e c i e s ) occur red fr equenc y 1.098 30.5 6 100 .837 23.25 5 83 .648 18.0 5 83 .351 9.8 3 50 .621 17.25 3 50 .018 0.5 1 16 .027 0.8 1 16 3.600 100.1 - -Abi*« baltamta ,387 tio*a glauox ,fj"?l> S f t u l a p a p i r i f t r a .081 M e * a m<tri-a«a .018 finua atrobut • Frunut ptniyIvanioa ,018 t1««p rubrum fOTALS .567 .162 .054 .117 .027 .0 .027 .945 , 144 .576 .072 .216 .072 .162 .522 .279 Basal area (by i i i * e l a s s ) R e l a t i v e basal area (by s i / * c l a s s ) 1.512 1.728 16.8 26.3 JO.O 4.5 .450 7.8 SHftuBSi To ta l shrub sterna in a l l t r a n s e c t s (2 per c i r c l e ) * 1000, d i v i d e d by the number of t r a n s e c t s * S0t)H per hectare (910 stens) GR0UNO COVCSt Tota l p l u s e s (*) recorded (20 s i g h t i n g s per c i r c l e ) « 100, d i v i d e d by the t o t a l number o f s i g h t i n g s * ground c o v e r . CANOPy COVERt Tota l p l u s e s (*) recorded (20 s i g h t i n g s per c i r c l e ) x 100, d i v i d e d by the t o t a l number g f s i g h t i n g s * canopy c o v e r . CANOPY H U G H ! ( 0 . 5 . / U . S . ) . Average. 12/2 Sange * 7 - 2 4 / 1 . i NO(£S: Cutaver 4 second g r o - t h O . S . * 30% dry o v e r a l l , ' a l i e n t rees as dead underbrush throughout U .S . s 40* shrub s t e * a 67.5% 60.8% Number per un i t area ? l o t a l t r e e s counted * 0.64 * R e l a t i v e dens i ty la the percent of the t o t a l number o f t rees which are the s p e c i e s in q u e a t i o n 4 Give est imated diameter ' B a i a l area i s the c r o s s s e c t i o n a l area or the trunk of a tree at 1.4 -netert (dbh) 6 M u l t i p l y the number of t rees m a l l c i r c l e s in s u e C l a s s A t imes .009 (average area in square meters for t h i s a w e * b a s a l area of the s p e c i e s ^ ^ t o t a l basal area of a l l s p e c i e s ' f requency i n d i c a t e s the evenness of d i s t r i b u t i o n of a s p e c i e s ' Number o f c i r c l e s in «hic»> the s o e c i e s occur red • • • •. ; • * 100 Tota l number of c i r c l e s Major SpO shrubs - rvbrumt 4 D i « « i a l n » « a , >*t««<2 j l«i»d<t, Popttlut t i-»«>u t aid a • , tub** i i a t u * . Va lu ta papyri far*, Sorb** amsrieana, Prunut pen* y t e a i i a a , P i i m ttrabu*, Car-glut aornuta, Aenr 9pieatumt Ammla^ahitr 3 p . , Sambuou* s p . , i.0>ti««ea s p . 104 T a b l e 3. H a b i t a t a n a l y s i s of p l o t T2. Number o f c i r c l e * * 6 Number of t rees in a l l c i r c l e s by diameter o f s u e c l a s s A 8 C D C F G 7-13.^ 13.3-19.3 19 .3 -29 .5 29.5-38 38-46 46-52.8 5 2 . 8 - 6 0 . J T r e e s / h e c t a r e {by s p e c i e s ) R e l a t i v e d e n s i t y ' (by s p e c i e s ) tlaaa alauaa 1 3 2 3 18 11.5 18.2 Finis* atrobum . - - - - 1 1 0.6 - 1.0 T\nja oaoii#«ta[{a 1 1 1 2 - 3.2 5.1 i b i a l baltamsa 22 10 . - 32 20.5 32.3 3 3 1 - - 7 4.5 7.1 Primus ai r j i ana 1 - - 1 0.6 1 .0 Prunua p a n a u I i » a i iaa 1 - - - - - 1 0.6 1 .0 4 l * u « rujoaa 2 - . - 2 1.3 2.0 Batula paaypiftra 8 3 2 2 1 - U 10.2 16.2 Batula lutta . - - 1 1 0.6 1 .0 Papulae e r « * u l a { J « « 11 3 - 14 9.0 14.1 Saebu* anariaana 1 - - - - - 1 0.6 1 .0 T01AIS 63 22 7 4 2 1 99 63.4 1005 T r e e s / h e c t a r . (by s i r e c l a s s ) 40. 3 14.1 4. .5 2.6 1.1 0.4 R e l a t i v e d e n s i t y (by s i r e c l a s s ) * J . 6 22.2 7, .2 4.0 2.0 1 .0 -TREES: 8A5AL AREA* FREQUENCY8 Cross s e c t i o n a l ares of the trunk at breast height ( d . b . h . ) SPECIES A 4 a C ( .009) (.027) (.072) P{««« fftda.93 .117 .054 .216 P(«u« ttrobuw -Thuja 9<soiJ*ntali* .009 .027 .072 Abia* bataamta .198 .2 70 Aaar mbrum .027 .081 .072 f m o i i i ui rglniana .009 - -PI-MHMS psnaytvaniaa .009 - -J I « u a rugeta .018 -ttttttla p4pyrif*ra .072 .081 .144 aa tu ld lutma . -Fop*t** tr*muloi4*t .099 .081 -SorbuM am*ritana .009 - -TOTALS .567 .594 .504 Basal area (by i w e c 1 ass ) .909 .954 .810 0 (.162) E (.279) r (.441 ) G ( .659) H (.0005 t o t a l No. Of b a s a l c i r c l e s area R e l a t i v e in which (by s p e c i e . dominenc s p e c i e s R e l a t i v e 9 sq m) (by s p e c i e s ) occur red frequency .387 11.0 5 83.3 .6 59 18.2 1 16.7 .432 12. J 3 50.0 .468 13.3 6 100.0 .180 5.1 3 50.0 .009 0. 3 1 16.7 .009 0.3 1 16.7 .018 0 .5 1 16.7 .900 25.6 4 66.7 .279 7.9 1 16.7 .180 5. 1 2 33.3 .009 0.3 1 16.7 .279 .279 .553 R e l a t i v e b a s a l are (by s u e c l a s s ) 16.1 16.9 14.4 1.0*5 18.5 .891 15.9 ,639 1 .026 18.2 SHfiU85t Tota l shrub stems i hectare (765 stems) GROUND COVER: Total p luses (*) recorded (20 s i g h t i n g s per c i r c l e ) CANOPY COVER: Tota l p l u s e s (*) recorded (20 s i g h t i n g s per c i r c l e ) CANOPY HEIGHT ( 0 . S . / U . S . ) : Average: 12/2 Sange * 11 -15 / . 3 -5 NOTES: Cutover 4 second growth O .S . * 51* dry o v e r a l l Mi«ed stand U .S . = 48% a l l t r a n s e c t s (2 per c i r c l e ) * 1000, d i v i d e d by th# number o f t r a n s e c t s » 25,500 shrub stems per » 100, d i v i d e d by the t o t a l number of s i g h t i n g s * 36.7% ground cover . « 100, d i v i d e d by the t o t a l number o f s i g h t i n g s * 40.9% canopy c o v e r . Number per un i t area Tota l t rees counted x 0.64 R e l a t i v e dens i ty i s the percent o f the t o t a l number o f t rees which are th« s p e c i e s in q u e s t i o n G i v e est imated diameter Basal area i s the c r o s s s e c t i o n a l ares of the trunk of a t ree at 1.4 meters (dbn) M u l t i p l y t h * number o f t rees in a l l c i r c l e s in s i z e C l a s s A times .009 (average area Tota l b a s a l area af the s p e c i e s , _ _ ' CO square meters for t h i s s i z e c l a s s ) Tota l basal area o f a l l goec ies frequency i n d i c a t e s the evenness of d i s t r i b u t i o n o f m s p e c i e s Number of c i r c l e s in « h i c h the s o e c i e s occur red l o t a l numoer of c i r c l e s 100 Major SOO shruOs - Ainu § rvgota , 41-im n r r a i i e i , 9« £ u la oapyriftra, Sorbu* a.m* rioa* a, P r u i u i pittylvaniaa, PI-NXKI v i r y i * i i n a t I b i #t ba'.$am0a , ?\uj 3 oo 9 i i t n t a I i t, *a*r r u i n . * , *<n r J n i j u t u * , ia*r tae sS<s"vm , »c ipu [ u « t r * - * u l 3 \ i t s , Frttzi TK « P * i i # y i 3 a - i i j a Sambuattm ainaitnti » , Pi ana jl iuo<t, Cornu* al 11 mi f ol i-j , i r s p . , Sal ix s p , , Lomiytra SQ.. 5? i r a « a 105 T a b l e 4. H a b i t a t a n a l y s i s of p l o t T, 1986, Number of c i r c l e s Number of t rees in a l l c i r c l e s by diameter o f s w e c l j s s -15 .5 13 .3 -19 .3 19 .3 -29 .5 29.5-38 18-16 16-52.8 5 2 . 8 - 6 0 . ) 60. 5 T r e e s / h e c t a r e (by s p e c i e s ) R e l a t i v e d e n s i t y ' (by s p e c i e s ) A b i t t ba'.tatta 9 ffatuta p a p g r l f t r a 5 P l a t a glauaa ?\uja o a a l i t n t a l i * Aaar rubrum ) Alnut rugata a Prunut p t n t y l o a n i a a 2 Populut t r t ^ u l s l i t t 2 5op5aa a<**rl :ana 2 T r e e s / h e c t a r e (by s w e c l a s u ) 16.6 R e l a t i v e dens i ty (by s w e c l a s s ) 59.1 ).S 1 ).6 1 .9 6.8 5.1 4 .5 1.3 7.7" 2.6 2.6 1. 3 1.9 1.3 28.2 18. ) 15.9 4.5 2 7.3 9.1 9.1 4.5 6.3 4.5 100 C r o s s s e c t i o n a l area of the trunk at To ta l No. or breast height ( d . b . h . ) baaa l c i r c l e s — area R e l a t i v e in which SPf.CICS A B C 0 E r C H (by s p e c i e s d om i nanc e^ s p e c l e s Re I a 11. e° .009) (.027) ( .072) ( .162) (.279) (.441) ( .6)9) (.0005 d J ) sq m) (by s p e c i e s ) occur red frequency A b l t t baltamta . 0 7 ; - _ - .072 4.6 2 33.3 ffaeula papgrifara .04 5 .02 7 - .162 - .234 15.3 J 50.0 P l a t a glauaa - .027 .072 - .099 6.5 1 16.7 Thuja o o a l i t n t a l I t - .081 . 504 .324 - .909 59.4 2 3). 3 Aatr rubpum .027 - .072 - .099 6.5 2 3 5.3 A l t u * rugata .036 - - - - .036 2.4 1 16.7 Prunut p t * t g l v e * l a a .018 - - - .018 1.2 2 3).3 Pppulut t r t m u l a i d t t .0)8 .027 - - .045 2.9 2 33.3 Sorbu* amtrlaana .018 - - - - .018 1.2 2 33.3 TOTALS .2 34 .162 .648 .486 - 1.53 - -Basal area (by a w e c l a s s ) .3744 .261 1 .0)5 .774 - -R e l a t i v e basa l area (by s w e c l a s s ) 15.3 10.6 42.4 31 .7 - - - - -SHRUBS! Total shrub stems in a l l t r a n s e c t s (2 per c i r c l e ) * 1000, d i v i d e d by the number of t r a n s e c t s » 23,600 shrub stems per hectare (708 stems) GR0UN0 COVER: Total p luses (*) recorded (20 s i g h t i n g s per c i r c l e ) t 100, d i v i d e d by the t o t a l number of s i g h t i n g s = 91.75 ground c o v e r . CANOPY COVER: Total p l u s e s (•) recorded (20 s i g h t i n g s per c i r c l e ) « 100, d i v i d e d by the t o t a l number o f s i g h t i n g s a 36.75 canopy c o v e r . CANOPY HEIGHT tO.S./U..5.) t Average: NQIES: Cutover 4 second growth dry o v e r a l l , f a l l e n t rees aa dead underbrush throughout 9 / i Range = 2-1>/2-6 0 . 5 . * as U.S. ftQ*. Number per un i t area l o t a l t rees counted * 0,64 R e l a t i v e d « n » i t y i t the percent of the t o t a l number of t rees which ate t h « soec jes in q u e s t i o n Give est imated diameter Basal area i s the c r o s s s e c t i o n a l area of the trunk of a tree at 1.4 meters tdbh) M u l t i p l y the number of t r e e s in a l l c i r c l e s in a w e C l a s s A times .009 (average area ^ota l b a s a l area of the s p e c i e s . „„ I I . . . , . — - I, - • — . — — • • , x 1 00 Tota l basal area of a i l s p e c i e s frequency i n d i c a t e s the evenness of d i s t r i b u t i o n of a s p e c i e s Number of c i r c l e s in which the s o e c i e s occur red square meters for t h i s s i z e c l a s s ) To ta l number of c i r c l e s 100 Ha jo r spp shrubs - n r r u l a t a , Abimi bal*a*t\a, i<s*r ap taa t i i * , S a l i x j P t i Pm*y# pen* y l n i n i o a , Sorb a* am*riaana, Pepulua t r a i u l o i S a a , Fratinwa pmsyloaniaa, Lcniaara s p. , v i r g i n i a n a . Ha art f l o u a i , Batula p a p y r i f t t r a , Finn ntrobua, AI nut P t j o t a , Aatr rub rum, Thuja o a o i i s n t a l i t , Cormi* a l t t r n i f o l i a 106 Tabl e 5 . Rough c a l c u l a t i o n s of T2, and p l o t C. f o l i a g e volume f o r p l o t T, p l o t S i z e C l a s s of T r e e 1 T o t a l 4 A B C F o l i a g e v o l u m e / t r e e 2 9.82m3 22.7m 3 34.Om3 T o t a l f o l i a g e volume 3 p l o t T p l o t T2 p l o t C 304 344 530 182 272 613 68 102 340 554 718 1483 1 see Appendix I , Tables 1-4. 2 IIr 2h/3: a c t u a l measurements taken from s i z e c l a s s A =6m, r=1.25m); v a l u e s e s t i m a t e d f o r s i z e c l a s s B (h=7.5m, r=1.7m), and f o r s i z e c l a s s C (h=9m, r=1.9m) # of t r e e s * f o l i a g e volume/tree: a c t u a l # of t r e e s f o r each s i z e c l a s s t o t a l m 3 f o l i a g e f o r a l l s i z e c l a s s e s 107 APPENDIX II DETAILS OF THE CHEMICAL RESIDUE STUDY 108 PESTICIDE DEPOSITS OVER FORESTS: AERIAL VS. MISTBLOWER APPLICATION OF SPRAYS Kanth M.S. SUNDARAM, Rhonda MILLIKIN and Alam SUNDARAM AGRICULTURE CANADA, CANADIAN FORESTRY SERVICE, FOREST PEST MANAGEMENT INSTITUTE, 1219 QUEEN STREET EAST, P.O. BOX 490, SAULT STE. MARIE, ONTARIO P6A 5M7 CANADA ABSTRACT Spray deposition patterns on simulated and l i v e f o l i a g e of balsam f i r and white birch were determined at different heights and at p e r i -phery and i n t e r i o r locations of the tree crown, following a e r i a l and mistblower applications of formulations containing f e n i t r o t h i o n , over a boreal forest near Searchmont, Ontario. Droplet s i z e spectra and deposits of A l were assessed at ground l e v e l using Kromekote card/glass plate units. A e r i a l application was made with a Cessna 188 a i r c r a f t f i t t e d with Micronair AU3000 atomisers. For mistblower application, a Soloport 423 backpack mistblower f i t t e d with an extension tube and a diffuser nozzle at the t i p was used. Deposit data on the ground samplers indicated s i g n i f i c a n t l y larger droplets and greater deposits i n the a e r i a l spray t r i a l than i n the mistblower treatment. However, f o l i a r deposits at tree canopy l e v e l were only s l i g h t l y higher i n the former spray t r i a l than i n the l a t t e r , indicating that the two delivery systems can provide s i m i l a r f o l i a r deposits i f the operational conditions were optimized i n c a l i b r a t i o n t r i a l s . 109 Analysis of spray deposits on the simulated and l i v e f i r foliage showed d e f i n i t e gradients i n deposit l e v e l s , decreasing from top to bottom crown, and from periphery to inner tree crown. In the birch tree crown, such gradients were not observed. Generally the simulated leaves acted as better collectors of spray droplets than the natural leaves. The overall mean deposit values, expressed i n ng/cm^, showed a wide var-i a t i o n , although there was generally a good relationship between the deposits on the simulated and natural surfaces. 1. Introduction The use of an a i r c r a f t for forestry spraying of pesticides has demonstrated to be the most competitive means of tree protection i n Canada since the areas to be treated are large.* However, for spraying small young trees, a i r - c a r r i e r sprayers, such as the knapsack mist-blowers, are p a r t i c u l a r l y useful for projecting the droplets up into trees by means of a high-velocity air-stream ( 60 m.s.~l). The a i r -stream v e l o c i t y improves penetration and even-distribution of sprays into dense canopies and f a c i l i t a t e s impaction of small droplets on the target with turbulence,^ and minimizes f a l l o u t and ground contamina-t i o n . ^  ^ However, data are sparse i n the l i t e r a t u r e on the comparative aspects of canopy penetration, v e r t i c a l and r a d i a l d i s t r i b u t i o n of sprays i n tree canopy, and f o l i a r and ground deposition following a e r i a l and mistblower applications onto small forest trees. The use of simulated samplers for deposit c o l l e c t i o n provides many advantages. The pesticide chemical w i l l not metabolize as fast on simu-lated samplers as i n b i o l o g i c a l ones, so that a more accurate picture of 110 the active Ingredient (Al) deposits can be obtained. Secondly, the extraction and column cleanup procedures for gas-liquid-chromatographic (GLC) determination of the A l deposits are much simpler because of the absence of i n t e r f e r i n g materials present i n the b i o l o g i c a l samples. Therefore, a study of the relationship between the deposits on simulated and l i v e f o l i a r surfaces would provide information on the s u i t a b i l i t y of using such surfaces for deposit c o l l e c t i o n . The present study was designed to examine i f a mistblower applica-t i o n from ground l e v e l can provide f o l i a r deposits s i m i l a r to those obtained from an a i r c r a f t , and was a part of a larger project to invest-igate the impact of i n s e c t i c i d e spraying on forest song birds ( M i l l i k e n , personal communication). The design included investigation of spray deposition patterns on simulated and liv.e f oliage of balsam f i r , Abies balsamea (L.) M i l l . , and white birch, Betula papyrifera (Marsh.), at different crown heights and at periphery and i n t e r i o r locations of the trees, following a e r i a l and mistblower applications of a formulation containing f e n i t r o t h i o n , and to determine the ground deposits re s u l t i n g from the two treatments. The objectives were to investigate ( i ) the differences i n droplet s i z e spectra, ground deposits and f o l i a r concen-trations between the a e r i a l and mistblower applications, ( i i ) the r e l a -tionship between deposits on simulated and l i v e f o l i a g e , and ( i i i ) the v e r t i c a l and r a d i a l d i s t r i b u t i o n s i n deposits on f o l i a g e of balsam f i r and white birch trees. I l l 2. Experimental 2.1 Materials 2.1.1 A e r i a l application study The a e r i a l application study was conducted i n 1985. The spray formulation consisted of technical fenitrothion (Sumithion , Sumitomo Chemical Co., Osaka, Japan) 15% (v/v), mixed with Atlox 3409F (Atkemix, Brantford, Ont., Canada) 1.5%, Dowanol TPM (Dow Chemical, Sarnia, Ont., Canada) 1.5%, Rhodamine B ( A l l i e d Chemical, Morristown, New Jersey, USA) 1%, and water 81%. 2.1.2 Mistblower application study The -mistblower application study was conducted i n 1986. The ingredients of the spray formulation used i n this study were the same as those described i n 2.1.1., but their percentage compositions were d i f -ferent: technical fenitrothion 4.5% (v/v), Atlox 3409F 1.5%, Dowanol TPM 1.5%, Rhodamine B 1% and water 91.5%. 2.2 Methods 2.2.1 Spray block descriptions The spray block (B85, 49 ha) used for the a e r i a l application study was selected i n a boreal forest area about 10 km north of Searchmont (coordinates, N 46"52', W 84"00') i n Township 24 R l l , Algoma D i s t r i c t , Ont., Canada. The block was dominated by cedar and alder as wel l as by young balsam f i r and white birch trees. The mean canopy height of a l l tree species was around 8 m. An area (8 ha) was established approxi-mately i n the middle of the spray block (Fig. 1) for selecting sample trees and for placing a r t i f i c i a l samplers to assess spray deposits. 112 The spray block (B86, 2.43 ha) used for the mistblower application study was located approximately 1 km north of the 1985 s i t e . The topo-graphy of the block was very si m i l a r to the one used for the a e r i a l application study. Nine spray l i n e s , each 20 m wide, were established In the spray block (Fig. 2) for fenitrothion application. 2.2.2 Sampling trees For the a e r i a l application study, s i x trees, each of balsam f i r and white birch [ t o t a l height 7 ± 1 m; crown height 6 ± 0.5 m; crown d i a -meter (base) 2.5 ± 0.5 m; and diameter at breast height 11 ± 3 cm; for both 6pecies], were selected randomly within the 8 ha sampling area (Fig. 1)." For the mistblower application study, however, nine sampling trees i n each of balsam f i r and white birch, s i m i l a r to those used i n the 1985 study with respect to height and shape, were selected approxi-mately i n the middle of the spray block (Fig. 2). Three f i r / b i r c h pairs were located at 2 i 0.1 i , three pairs at 10 ± 0.1 m and the l a s t three pairs at 18 i 0.1 m, away from the spray l i n e s . 2.2.3 Simulated samplers For simulating f i r fo l i a g e , aluminum c o i l clusters (Individual c o i l s having a diameter si m i l a r to that of mature balsam f i r needles) were used.5 These were placed on the f i r tree crown using a pole pruner at 1, 3 and 5 m heights, s t a r t i n g from the crown t i p . These heights represented the top, middle and bottom sampling s i t e s (Table 1) of the tree crown. At each of the mid and bottom crown l e v e l s , one cluster was placed horizo n t a l l y near the stem of each tree representing respec-t i v e l y , the mid-Interior and bottom-interor sampling s i t e s of the tree. 113 Aluminum branches containing 10 to 15 aluminum leaves, having the same dimensions as the natural birch leaves, were placed on the birch trees, at the same heights and locations as those on the f i r trees. 2.2.4 Ground sampling units The conventional Kromekote card/glass plate units** were used for determining the ground deposit levels and droplet s i z e spectra. For the a e r i a l application study, 12 such units were placed i n locations shown i n Fig. 1, each on an aluminum stand 15 cm above the forest f l o o r , at 1 h prior to spray application. For the mistblower application study, however, 30 such units were placed i n locations shown i n Fig. 2. 2.2.5 Spray application and meteorological conditions For the 1985 study, a Cessna' 188 a i r c r a f t equipped with four Micronair AU3000 atomizer units with blade angles set at 3 5 % applied the spray at a dosage rate of 280 g A l i n 1.5 L/ha and at a emission rate of 18 L/min, f l y i n g at a speed of 160 km/h with a swath i n t e r v a l of 45 m. Spray was applied at a height of 15 m above the tree canopy and at right angles to the prevailing wind, on June 14/1985, between 0715 and 0800 h. The meteorological conditions that existed at the time of spraying were: wind speed 2 ± 0.5 km/h, temperature 15 ± 1*C, r e l a t i v e humidity (RH) 80% and the cloud cover 0/10. For the 1986 study, a Soloport 423 backpack mistblower (70 mL engine capacity) f i t t e d with an extension tube and a d i f f u s e r nozzle (Solo Incorporated, P.O. Box 5030, 5100 Chestnut Ave., Newport News, V i r g i n i a , USA) was used to apply the spray on June 18/1986, between 1107 and 1156 h, at a dosage rate of 293 g A l i n 5.2 L/ha. P r i o r to the actual study, the mistblower was calibrated using a simulant having the 114 same physical properties as those of the fenitrothion formulation used to determine the operational parameters required ( d e t a i l s of c a l i b r a t i o n procedures are given elsewhere; M i l l i k i n , personal communication). The operator walked along each spray l i n e at an even space (0.5 m/s), hold-ing the nozzle v e r t i c a l l y upwards and emitting the spray uniformly at 0.312 L/min. The meteorological conditions that prevailed during spray application were: wind speed 9.6 ± 1.0 km/h, temperature 21 ± l^C, RH 50% and the cloud cover 0/10. 2.2.6 Sampling and storing procedures A l l samples, both natural and simulated, were collected at 1 h a f t e r spfay application. For investigating the v e r t i c a l -distribution of f e n i t r o t h i o n i n the peripheral f o l i a g e , one branch 30 cm long, was clipped from the location adjacent to the simulated sampler, from each of the top, mid and bottom crown l e v e l s . For determining the r a d i a l d i s t r i b u t i o n , s u f f i c i e n t branch segments were taken from the mid-interior and bottom-interior l e v e l s , adjacent to the positions of the simulated samplers. A l l samples were placed immediately i n portable coolers and stored at O^C The simulated aluminum branches on the f i r and birch trees, and the glass plates of the ground sampling units were a l l collected and immedi-ately transported to the nearby f i e l d laboratory (improvised), where the fenitrothion deposits were extracted at once from the samplers using ethyl acetate as the solvent. The extracts were placed i n amber-colored bottles and stored i n coolers at 0*C. At the end of the f i e l d t r i a l s , the f i r and birch f o l i a g e samples, and the extracts of the simulated samplers, were a l l transported to the U 5 Sault Ste. Marie laboratory, where they were stored i n freezer at -2CTC u n t i l analysis by (GLC). The Kromekote cards were collected, wrapped i n aluminum f o i l and stored i n dark i n a desiccator. 2.2.7 Sample preparation, extraction, column cleanup and GLC analysis of deposits on natural and simulated f o l i a g e In the a e r i a l application study, samples of the natural and simu-lated birch f o l i a g e , collected from si m i l a r locations of the s i x trees, were divided into three sets for t r i p l i c a t e measurements, i . e . , those from tree No. 1 were combined with those of No. 11 (Fi g . 1), No. 4 with 10 and No. 5 with 7, to form three sets of composite samples. Simi-l a r l y , the f i r f o l i a g e samples from tree No. 2 were combined with those of No. 12, No. 3 with 9, and No. 6 with 8, to form three sets of compos-i t e samples. In the mistblower application study, however, samples from the nine trees of each species were analysed i n d i v i d u a l l y to provide nine sets of deposit data. Procedures used for extraction, column cleanup and GLC analysis of the l i v e f o liage were the same as those described by Sundaram and Sundaram^, except that neutral aluminum oxide ( M e r c k — A c t i v i t y Stage I , supplied by Canlab Chemicals, Toronto, Ont., Canada) was used for column cleanup instead of the Nuchar SN charcoal). The data were expressed i n ng/g (mean ± SD) of fresh foliage (Table 1). The minimum detection l i m i t of the measurement technique was 50 ng/g. The data was also con-verted into ng/cm2 (mean ± SD) using the surface area and mass of a leaf, and the number of leaves per g fresh weight (Table 1). 116 Fenitrothion deposits on the simulated f i r and birch f o l i a g e , which were extracted i n the f i e l d laboratory, were analysed d i r e c t l y by GLC without any column cleanup procedures. The A l deposits were converted into ng/cm^ (Table 1) using the surface area of the samplers. 2.2.8 Analysis of spray deposits on ground sampling units 2.2.8.1 Droplet analysis on Kromekote cards Droplet stains on the Kromekote cards were analysed by the National Aeronautical Establishment (NAE) of the National Research Council of Canada (NRCC), Ottawa, using the Flying Spot Scanner. 8 The data obtained from the 12 cards (Fig. 1) used i n the a e r i a l application study were pooled, the s t a i n diameters were converted into the corresponding spherical droplet diameters by using a correction factor for droplet spreading,^ and the number and volume, median diameters (DJJ.5 and Dy.5 respectively), maximum diameter ( D m a x ) and droplet density (drop-l e t s per cm^) were evaluated.^ The data were also used to compute the percentage frequency and volume d i s t r i b u t i o n according to diameter classes and presented as histograms i n Fig. 3. Similar calculations were carried out for the 30 Kromekote cards placed i n the mistblower application study to obtain the droplet parameters and histograms (Fig. 3) for the 1986 study. The minimum detection l i m i t of the droplet s i z i n g technique was 10 m. 2.2.8.2 Deposit analysis on glass plates The deposits on glass plates, which were extracted i n the f i e l d laboratory, were analysed for fenitrothion by the GLC technique without 117 any column cleanup, and the data were expressed i n g Al/ha and percent recovery of the applied fenitrothion (Fig. 3). 3. Results and discussion 3.1 Droplet s i z e spectra and deposits on ground samplers—aerial vs. mistblower application The DJJJJJX, D J J . 5 and Dy .5 values, and the frequency and volume d i s t r i b u t i o n histograms (Fig. 3) indicated unequivocally that spray droplets deposited on the ground samplers i n the a e r i a l application study were markedly larger than those observed i n the mistblower study. Since f l a t samplers placed at ground l e v e l have been shown to c o l l e c t predominantly the upper end of the droplet s i z e spectrum emitted, i t can be assumed that the mistblower had emitted smaller droplet sizes than the a i r c r a f t . On the other hand, both delivery systems could have emitted s i m i l a r large droplet sizes at the release point; but under the high RH conditions (90%) observed i n the a e r i a l application study, the droplets probably underwent minimal evaporation i n - f l i g h t , thus main-taining the same large sizes at the ground l e v e l as w e l l . However, under the low RH conditions (50%) that existed i n the mistblower application study, the released large droplets could have evaporated considerably i n - f l i g h t , thus decreasing i n sizes upon reaching the ground l e v e l . Both processes could have caused the observed differences i n the droplet s i z e spectra of the two spray clouds. The large droplets found at ground l e v e l i n the a e r i a l application study, must have had s u f f i c i e n t energy to impact on the f l a t ground samplers, thus resulting i n a higher droplet density on the Kromekote 118 cards, and greater deposition on the glass plates (Fig. 3) than those observed i n the mistblower study. 3.2 Average fenitrothion deposits on canopy f o l i a g e — a e r i a l vs. mist-blower application The data i n Table 1 show that the average fe n i t r o t h i o n concentra-tions i n canopy f o l i a g e ( i . e . , i n both f i r and birch f o l i a g e ) , expressed i n ng/g or ng/cm^, were s l i g h t l y higher i n the a e r i a l spray t r i a l than i n the mistblower treatment, although no s i g n i f i c a n t difference was noted between the data i n the two applications (ANOVA P 0.05) due to the large standard deviations obtained. The higher a e r i a l spray deposits were noticeable even with the simulated surfaces. This trend was due to the larger droplets present at the canopy l e v e l i n the a e r i a l spray t r i a l , as compared to the smaller, droplets present i n the mist-blower study. Large droplets [ i . e . , those with a Dv.5 °f about 60 m (see Fig. 3)] are expected to impact on foliage more e f f i c i e n t l y than small droplets (with a Dy.5 of about 30 m), resulting i n higher f o l i a r concentrations. The comparable mean canopy deposits obtained i n the a e r i a l and mistblower applications, i n spite of the markedly different drop sizes present, can be attributed to the wind speeds that prevailed during the two treatments. In the a e r i a l spray t r i a l , the wind speed was low ( 2 km/h), compared to the higher value ( 10 km/h) observed i n the mist-blower study. Higher wind speeds were known to increase the turbulence i n the v i c i n i t y of canopy fol i a g e , provide the required k i n e t i c energy to the small droplets and enhance f o l i a r impaction i n forestry applica-t i o n s . 1 1 119 In the case of a e r i a l application, the average deposits ( i n ng/cm2) on l i v e or simulated f o l i a g e were s l i g h t l y higher on birch leaves than on f i r needles, although there was no s i g n i f i c a n t difference between the two surfaces. In the mistblower application, however, the average deposits were s l i g h t l y lower (but not s i g n i f i c a n t l y lower) on birch leaves than on f i r needles. The reason for t h i s trend l i e s i n the shape of the birch leaves, since f l a t surfaces are known^2 to c o l l e c t lower number of the smaller droplets than the needle-shaped f i r leaves. 3.3 Relationship between deposits on simulated and l i v e surfaces In both studies, the simulated surfaces received s i g n i f i c a n t l y higher AI deposits (ANOVA P 0.05) than the natural surfaces. This trend was evident on both f i r and 'birch leaves, and at a l l sampling locations of the canopy (Table 1). This observation i s i n agreement with that reported previously^ i n a e r i a l spray t r i a l using mexacarbate. It appears that b i o l o g i c a l samples, irrespective of t h e i r surface char-a c t e r i s t i c s , tend to receive lower deposits than m e t a l l i c objects. The reason could be that a b i o l o g i c a l surface i s a weaker conductor of e l e c t r i c a l charges than a metal surface. As a r e s u l t , the metal surface might have received a greater number of spray droplets than the b i o l o g i -c a l samples. On the other hand, the chemical might have degraded partly during the f i r s t hour post-spray before the f o l i a g e samples were c o l -lected, a phenomenon which could not have occurred on the m e t a l l i c samplers. These aspects, however, require further investigations. 120 3.4 V e r t i c a l distributions of deposits i n the periphery of the tree crown From the deposit levels l i s t e d i n Table 1, i t i s evident that the top portion of the f i r tree crown received the maximum deposits, i n both a e r i a l and mistblower application studies. This behavior was observed In both simulated and l i v e f i r f o l i a g e . This finding i s i n agreement with that reported by others, 5 13-18 a n ( j ± B <jue to the f i l t r a t i o n of spray droplets by the conifer canopy. However, such v e r t i c a l gradients i n deposits were not apparent i n the birch tree crown, since no marked differences were noticeable i n the mean deposits from top to bottom i n either of the two studies. Such differences between the two tree species could be due to the d i s t r i b u t i o n of fo l i a g e within the tree crown and also due to the different shapes of leaves of the two tree species. As a r e s u l t , different micrometeorological factors could be associated with the two tree crowns, causing differences i n droplet deposition patterns and canopy f i l t r a t i o n of droplets. 3.5 Radial d i s t r i b u t i o n of deposits i n the tree crown Similar to the v e r t i c a l d i s t r i b u t i o n of the chemical i n the tree crown, the r a d i a l d i s t r i b u t i o n also showed considerable differences i n the deposits between the mid-crown periphery and mid-interior of the tree i n both a e r i a l and mistblower applications. Such a trend also existed i n the bottom periphery and bottom-interior levels (Table 1). However, none of these r a d i a l gradients were noticeable i n the birch tree crown i n either of the two studies, since the deposit values were quite s i m i l a r i n a l l r a d i a l locations. The reason for these differences could be the same as those mentioned i n Section 3.4. 121 3.6 The usefulness of aluminum surfaces for deposit c o l l e c t i o n i n forestry spraying In spite of the marked differences observed i n the deposits between the simulated and l i v e f o l i a r surfaces, there was a general trend for proportional v a r i a t i o n i n the deposits at si m i l a r sampling locations; i . e . , when the deposit was high on an aluminum sampler i n a location, there was a correspondingly high deposit on the b i o l o g i c a l sample c o l -lected from the same location. This implies that the aluminum samplers can provide a r e l a t i v e picture of the d i s t r i b u t i o n of spray deposits i n different components of the forest ecosystem, although they cannot pro-vide a picture of the actual residues present i n the b i o l o g i c a l samples. Acknowledgements The authors are Indebted to N. Payne, P. de Groot and A. Obarymskyj for their assistance i n the ground application method; L. Pollock and S.B. Holmes for c a l i b r a t i o n and application i n the a i r c r a f t and mist-blower studies respectively; A.M. Drummond of the National Aeronautical Establishment, National Research Council Canada, Ottawa, for analysing the Kromekote cards; P.D. Kingsbury for his assistance i n spray block preparation; B. Z y l s t r a for mixing the spray formulations; and C. Feng, R. Nott, J . Broks, J.W. Leung, N. Boyonoski, R.W. Wing, K.L. Hyyrlainen, and J. Hatherley f o r th e i r technical help i n the f i e l d and laboratory investigations. 122 Ref erences 1. Prebble, M.L. In: Aerial Control of Forest Insects in Canada (Prebble, M.L., Ed.), Information Canada Publ., Catalogue No. Fo23/19/1975, Ottawa, Canada, 1975, pp. 77-84. 2. Randall, J.M. J. Agric. Engng. Res. 1971, 16, 1-31. 3. Matthews, G.A. In: Pesticide Application: Principles and Practice (Haskell, P.T., Ed.), Clarendon Press, Oxford, England, 1985, pp. 95-117. 4. Matthews, G.A. Pesticide Application Methods* Longman Inc., New York, 1979. 5. Sundaram, K.M.S.; Sundaram, A.; Nott, R. Trans. ASAE 1986, 29, 382-388, 392. 6. Randall, A.P. Environ. Can. For. Serv. Res. Notes 1980, 36, 23. 7. Sundaram, K.M.S.; Sundaram, A. Pestic. Sci. 1987, 18, 259-271. 8. Drummond, A.M. The Effect of droplet Density and Sample Area on Variability of Results by the Flying Spot Scanner, Natl. Res. Council Can., Nat l . Aeronaut. Establ. Lab. Tech. Rep. LTR-FR-76, 1980, 38 pp. 9. Rayner, A.C.; Haliburton, Wm. Rev. Sci. Instr. 1955, 26, 1124-1127. 10. Johnstone, D.R. BCPE Monograph No. 22, B r i t . Crop Prot. Council, Croydon, 1978, pp. 35-42. 11. Joyce, R.J.V.; Beaumont, J. In: Control of Pine Beauty Moth by Fenitrothion in Scotland 1978, (Holden, A.V.; Bevan, D., Eds.), Forestry Commission, U.K., 1978, pp. 63-80. 123 12. Matthews, G.A. Pest Management Longman Inc., England, 1984. 13. Carman, G.E.; Jeppson, L.R. J. Econ. Entomol. 1974, 67, 397-402. 14. Yates, W.E.; Ogawa, J.M.; Akesson, N.B. Tvans ASAE 1974, 17, 633-639. 15. Spillman, J . J . ; Joyce, R.J.V. In: Control of Pine Beauty Moth by Fenitrothion in Scotland 19783 (Holden, A.V.; Bevan, D., Eds.), Forestry Commission, U.K., 1978, pp. 31-52. 16. Armstrong, J.A.; Yule, W.N. Can. Ent. 1978, 110, 1259-1267. 17. Barry, J.W.; Kenney, P.; Wong, J . ; Barber, L.; Ekblad, R.; Dumbald, R.; Flake, H. Aerial Application to Southern Pine Seed Orchards, USDA For. Serv., Southern Region, Forest Pest Management, A s h v i l l e , North Carolina, USA, 1982. 18. Barry, J.W. In: Chemical and Biological Controls in Forestry, ASC Symposium Series No. 238, American Chemical Society, Washington, D.C., 1984, pp. 117-137. 124 1985 STUDY PLOT ( 8 ha ) J L E G E N D ROAD J = i BRIDGE RIVER OR STREAM FOREST TRAIL BALSAM FIR •D CD ® ® ® H WHITE BIRCH C D ® ® ® ® © • K - CARD A GP Fig. 1. Locations of the sampling trees and Kromekote® card/glass plate units in the 8 ha sampling area (aerial application study). 125 LEGEND SPRAY LINE RIVER OR STREAM FOREST TRAIL O BALSAM FIR & WHITE BIRCH 2 m - ®(D © 10 m - (4) (J) (6) 18 m - ® (D @ • K - CARD A. GP Fig. 2. Locations of the sampling trees and Kromekote card/glass plate units in the 2.43 ha spray block (mistblower application study). 126 Aerial Appl. Drop No. 1985 " N . 5 3 6 um Dm., 1 1 7 u m Aerial Appl. Drop Vol . 1 985 D V 5 5 8 u m Mistblower Appl. Drop No. 1986 " N . S 1 8 u m " max 8 3 u m Mistblower Appl Drop Vol . 1 986 ~T— 25 —r— 50 75 —r-100 0 25 50 Droplet Diameter (um) 100 12 3. Frequency and volume distribution percentages according to size category. The deposit levels on ground sampling units were: droplets/cm 2 14, AI de-posit 73 g/ha, and percent recovery 26 for ae r i a l application; droplets per cm 5, AI deposit 1.7 g/ha, and percent recovery 0.6 for mistblower application. 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.831.1-0097625/manifest

Comment

Related Items