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Factors affecting orchard pheasant populations in the Okanagan Valley of British Columbia, with special… Rye, Darrell 1952

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FACTORS AFFECTING ORCHARD PHEASANT POPULATIONS IN THE OKANAGAN VALLEY OF BRITISH COLUMBIA, ¥/ITH SPECIAL REFERENCE TO ORCHARD INSECTICIDES by DARRELL RYE A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS .FOR.THE DEGREE_OF MASTER OF ARTS IN THE DEPARTMENT OF ZOOLOGY We accept this thesis as conforming to the standard required from candidates for the DEGREE OF MASTER OF ..ARTS Members of the Department of Zoology THE UNIVERSITY OF BRITISH COLUMBIA April,195Z. A* Ft ABSTRACT Pheasant chicks were tested under both f i e l d and laboratory conditions"for susceptibility to both inhalation and ingestion of DDT, parathion, methoxychlor, aramite, sulfanone, and #4049 (an organic phos-phate). An attempt was made to correlate chemical analysis for DDT in the tissues of dead birds with death from known amounts of DDT. The effect of concentrate spray machines as opposed to hand-gun machines was tested, and an attempt made to evaluate the factors controlling popula-tions of pheasants in the Okanagan Valley, B r i t i s h Columbia. Both DDT and parathion were found to cause considerable mortality under ideal conditions, but i t is thought that such conditions are seldom realized. In the f i e l d , parathion acts chiefly through inhala-tion toxicity, while the reverse is true of DDT. Concentrate machines apply only 30-40 percent as much insecticide to the cover crop in an orchard as do hand-gun machines. The increasing use of such machines may result in a decreased effect of poisons such as-DDT, which acts through ingestion; the finer mist produced by concentrate machines however, may enhance the effect of inhalation poisons such as parathion. Methoxychlor, aramite, sulfanone and # 4049 were found to be non-toxic to pheasant chicks in the concentration employed for the control of orchard pests. These materials are expected to replace DDT and parathion in the Okanagan Valley in the near future. The chemical analysis of dead birds for the presence of DDT has not proven satisfactory to date. &7N - // The qualitative reduction of pheasant habitat i n the Okanagan, as a result of intensive orchard cultivation, is believed to be the greatest single factor affecting pheasant populations in this area. Much of this intensive cultivation is due to the increasing use of sprinkler irrigation, permitting frequent mowing-, discing, or other disturbance of the orchard cover crop. CONTENTS Page INTRODUCTION '. 1 ACKNOWLEDGEMENTS 3 HISTORY • •• 5 The Settlement of the Okanagan Valley, and its development as an Orchard Area 5 The Introduction of the Ring-necked Pheasant. Its Rise and Decline 5 Studies in the Ecology of the Ring-necked Pheasant in the Okanagan Valley 6 THE ORCHARD AS PHEASANT HABITAT. 7 RECENT CHANGES IN ORCHARD AGRICULTURAL. PRACTICES 10 Sprinkler Irrigation 10 Mowing and Discing of cover 12 Spraying 13 New insecticides 13 DDT (dichloro-diphenyl-triohlorethane.) ..... 13 PARATHION (0,0-diethyl-O-p-nitrophenyl-thiophosphate) 15 METHOXYCHLOR'.(Dimethoxy-diphenyl-trichlor-ethane) 17 ARAMITE (B-chloraethyl-B-(p-tert.hutylphenoxy) -methyl ethyl sulphite) 17 SULFANONE (R-242) (p.chlorophenyl phenyl sulphone) 18 CONTENTS continued Page Spray Machinery 18 Turbo-mist 19 Bes-spray 20 Trump Conversion Unit 21 Bes-kil 22 FACTORS AFFECTING OKANAGAN PHEASANT POPULATIONS 23 General 23 Climate 23 Hunting pressure 24 Disease and parasites 26, Predation 27 Orchard Populations 27 Sprinkler irrigation and cover treatment 27 Reduction of pheasant habitat 28 Insecticides 31 methods: 1. field experiments 31 2. laboratory experiments 33 Effect of different types of machinery ......... 34 Chemical analysis of cover 36 Experiments 38 DDT Inhalation and ingestion 38 Ingestion 39 CONTENTS continued Page Experiments Chemical analysis of birds ki l l e d by DDT ...... 42 PARATHION Inhalation and ingestion 43 Inhalation compared with that of DDT 44 METHOXYGHLOR Inhalation and Ingestion 47 "Ingestion 48 ARAMITE Ingestion and inhalation 49 Ingestion 50 SULFANONE Ingestion and inhalation . 51 Ingestion 52 #4049 . Ingestion and inhalation ........ 53 Ingestion .* 53 Summary of insecticides 54 Non-orchard Populations 56 SUMMARY AND CONCLUSIONS 57 SUGGESTIONS, FOR FURTHER STUDY 60 MANAGEMENT RECOMMENDATIONS 60/ LITERATURE CITED V 63 FACTORS AFFECTING ORCHARD PHEASANT POPULATIONS IN THE OKANAGAN VALLEY OF BRITISH COLUMBIA, WITH SPECIAL REFERENCE TO ORCHARD INSECTICIDES A - - -INTRODUCTION Benson (1950) has summarized the literature up to 1949 on the effect of commercial insecticides, particularly DDT, on bird l i f e . In his own paper he presents certain experimental data which he obtained in 194$ during his study of the effects of orchard spraying on pheasants in the Okanagan Valley, together with general considera-tions concerning the problem of the decline of pheasant populations in this region.(i) The present study, sponsored jointly by the University of B r i t i s h Columbia and the B r i t i s h Columbia Game Commission, was designed as a continuation and extension of Benson's work. The introduction and possible widespread use of new insecticides necessitated the test-ing of these materials for possible toxic effect; moreover, further information concerning the action of DDT and parathion, previously tested by Benson, was desired. This study was conducted at the Dominion Entomological laboratory, Summerland, B. C., during the summer months of 1950 and - 2 1951, with the following aims in view. 1. The extension of knowledge of the effects of previously tested insecticides. 2. An evaluation of the effects on pheasants of insecticides, introduced since 1949, whose use on a large scale is contemplated in the near future. 3. An attempt to correlate chemical analysis of pheasant tissues with death from DDT poisoning. 4. An investigation of factors, other than orchard spraying, which might have an effect upon pheasant numbers in orchard areas of the Okanagan Valley. - 3 -ACKNOWLEDGEMENTS * ^ This study was sponsored jointly by the B r i t i s h Columbia Game Commission; and the University of B r i t i s h Columbia. The work reported herein was conducted under the guidance of Dr.. Ian McTaggart Cowan, Department of Zoology, University of B r i t i s h Columbia, to whom I am grateful for help both in the actual study and in the preparation of the manuscript. Dr. P. A. Larkin, Mr. James Hatter, and Mr. E. Taylor, of the same department, furnished much helpful advice and information. I am also greatly indebted to Dr. S&frfes Marshall, who donated space and equipment at the Dominion Entomological Laboratory, Summerland, Bri t i s h Columbia, of which he i s in charge. Without his cooperation in this and in many other ways this study i n it3 present form ,would have " A been impossible. A l l members of his'staff cooperated in various ways, that materially aided the progress of this endeavour. I am particularly grateful to Gordon Halvofson, who did most of the/experimental spraying, to Dr. J. M. MacArthur, Ralph Miles, and Kenneth'Williams, who worked many hours on techniques for analyzing poisoned birds, and to D.B.Waddell, who took the photographs contained herein. Messrs. G. Morgan, E. Tait, and J . Towgood, a l l of Summerland, donated the use of their orchards for the f i e l d experiments, and I am most appreciative of their generosity in this regard. Considerable help was also given me by Robert Bowman, and Donald Reid, of the Canadian Wildlife Service, by J . MacLachlan, of Summerland, who procured the pens used in the field experiments, and by Alec Watt, District Horticulturist, who supplied me with much information on local conditions. To them I extend my thanks. Finally, I should like to thank Glen Smith, who assisted me most ably during the month of June, 1951, and my wife, for her help in preparing many of the pheasant chicks for chemical analysis, and for her continual encouragement and support. 5 -HISTORY The Settlement of the Okanagan Valley, and i t s Develop-ment as an Orchard Area.(/$") The Okanagan Valley f i r s t appears i n B r i t i s h Columbia history as the home of Indians of the Okanagan Nation, and later as a route for trade and exploration. Land was f i r s t taken out by settlers in 1859. Cattle ranching, gold mining, wheat growing and other enter-prises were attempted i n the Okanagan, but none proved successful on a permanent basis. In 1892, however, the f i r s t commercial f r u i t orchard was planted, and from this small beginning grew the industry that i s now the mainstay of the valley. As early as 1913, thirty thousand people were dependent on the success or failure of the apple crop. Until 1921 average annual production was 1,500,000 boxes; i n the next ten years i t rose to 3,156,000 boxes, and i n 1950 reached the impressive total of 8,008,073 boxes. The Introduction of the Ring-necked Pheasant; Its Rise and Decline. Pheasants f i r s t appeared i n the Okanagan in 1910, when five birds were sent to Okanagan F a l l s . The report of the B r i t i s h Columbia Game Commission for 1912 states: A few birds of the Mongolian breed were turned out i n the vi c i n i t y of Okanagan Landing, and although they appear to have wintered, no broods have been seen. Farther south in the vic i n i t y of Okanagan F a l l s five birds were kept in captivity and bred with.success. The whole stock was turned out in the f a l l of 1911, and wintered well. This f a l l i t is estimated that there are two hundred birds in this v i c i n i t y . - 6 -These birds appear to have done remarkably well. A three day season was declared in 1913, during which from thirty to forty birds were shot. The following year a "few" birds were sent to Kelowna. By 1934, when the next introductions were made, the birds were well established. Subsequent introductions each year by the Game Commission (except 1942-44, and 1951) established a mongrel stock composed of the Mongolian Pheasant (Phasianus colchicus mongol-icus) and the Ring-necked Pheasant (P.c.torquatus), with the torquatus strain predominating. (4) The rapid increase of pheasant populations in the Okanagan culminated in a peak of unknown density in 1942. A gradual decline then began, followed by a crash in 1946. Since then, although no regular censuses on a large scale have been taken, the population appears to have levelled off, and indeed to have shown a slight increase in 1951. Studies in the Ecology of the Ring-necked Pheasant in the Okanagan Valley. Only two studies of this nature have been made prior to that reported in the present paper. Cowan (1942) reported on the economic status of the ring-necked pheasant in the Okanagan. He found l i t t l e serious damage to fruit and vegetable crops, except in localized areas. He estimated the pheasant population at about one bird per acre; this was at the peak of pheasant abundance.(V) Reference has already been made to the work of Benson (1950) - 7 -He tested the effect on pheasant chicks, under controlled conditions, of several insecticides in use i n the Okanagan in 1949. Several of these, notably DDT and parathion, were observed to have a toxic effect. Details of Benson's results w i l l be discussed in the section on insect-icides. Benson also discussed the pheasant decline in the Okanagan. He does not believe this to have been caused by orchard insecticides, although they may have accelerated the decline once i t began. Since 1949 several studies have been made in other areas which are of interest to workers in the Okanagan. Post (1949 and 1951) con-ducted f i e l d experiments, and made observations on the effect of f i e l d spraying of toxaphene, chlordane and aldrin in a grasshopper control programme in Wyoming. He obtained mortality of pheasants and other gallinaceous birds with a l l three insecticides, small chicks being particularly susceptible. Small amounts of aldrin were found to cause cessation of laying in hen pheasants. None of these materials is used in the Okanagan. Mohr, et a l . , (1951) studied the effect of DDT, parathion, and tetraethyl pyrophosphate (TEPP) on pheasants i n Eastern Washington. ('*) Since this study has elements in common with that of Benson and of the present author, the results reported therein w i l l be discussed i n detail in the section on insecticides. THE ORCHARD AS PHEASANT HABITAT Okanagan orchards, at the peak of pheasant abundance, provided excellent habitat for these birds. Most of these orchards were com-posed of trees placed at regular intervals of about thirty feet; the ground between the trees was allowed to become covered with a dense growth of various indigenous weeds and grasses. This cover provided food in abundancefor the pheasants l i v i n g in i t . Insects were numerous, and 3ince much of the growth consisted of weeds there was a large supply of seeds, which form the main part of the pheasant's diet. Water was ready to hand in the irrigation ditches which ran i n parallel rows across the orchards. Escape cover was automatically provided. The canopy of f r u i t trees, together with the dense ground cover, made capture by both avian and t e r r e s t r i a l predators d i f f i c u l t . Some use was made of orchards for roosting purposes, but many birds l e f t the orchards in the evening, and roosted in the dense brush which was often found in their immediate v i c i n i t y . Orchards were used to some extent for nesting, though probably not so much as a l f a l f a and hay f i e l d s . No reliable data exist on the relative use by pheasants of orchard and non-orchard areas at the peak of abundance in 1942. It i s known, however, that the bulk of the Okanagan pheasant harvest at this time came from the region around Vernon, in which more than half the irrigated land i s devoted to ground crops. (Figure 7) In 1949, Benson found a significantly higher proportion of pheasants in non-orchard areas in the Kelowna d i s t r i c t , and reported that this was probably the case elsewhere in the valley. Crowing counts - 9 -made by the writer in May, 1951, a.t Summerland and Kelowna, are in agree-ment with these findings. In view of the present reduction of orchard cover in the Oka-nagan (which w i l l be discussed), i t seems reasonable to suppose that relatively few pheasants would be found in such habitat. It should be pointed out, however, that exact information cannot be obtained in the Okanagan by crowing count censuses, owing to the d i f f i c u l t y of noting the precise position of crowing birds. Censusing of representative areas with the use of dogs, (the method used by Benson), i s probably the most satisfactory method of obtaining the necessary information. Benson believes "... that the part of pheasant population resident in the orchards has always been small, and that the bulk of the harvest ... has always come from the non-orchard areas given over to mixed farming, grain and vegetables, which have sufficient dispersion of cover types." The present intensive use of many orchards has certain-l y aggravated this tendency. Orchard habitat i s often only marginal pheasant range, and populations of any size in such areas may only result from increasing density of pheasants in more favourable non-orchard areas. This paper deals chiefly with factors affecting pheasants in orchard areas. An examination of present-day orchard agricultural practices in the Okanagan supplies evidence as to why these areas can no longer support the pheasant populations that they once did. This is not to imply that changes of equal importance have not occurred in farm-ing practices in non-orchard areas. A consideration of such changes, however, l i e s outside the scope of the present study. - 10 -RECENT CHANGES IN ORCHARD AGRICULTURAL PRACTICES Sprinkler Irrigation When pheasant populations were at their peak in the Okanagan Valley, most of the orchards i n that region were irrigated by the ditch, or furrow, method. A main flume or ditch was constructed along the high side of an orchard, and from i t ran small ditches, parallel to each other and about ten feet apart. These small ditches extended to the bottom of the orchard, supplying water to the trees adjacent to them. Under this system, cover - usually indigenous weeds - was allowed to grow more or less unchecked. Discing was carried out in the spring and f a l l , but could not be undertaken during the summer with-out some considerable d i f f i c u l t y , since i t would be necessary to replace the irrigation ditches after each discing. Insofar as irrigation was concerned, the only disturbance to pheasants in the orchards was occasioned by workers walking along the ditches to keep them free from clogging. Most of the orchard area was completely undisturbed. In the early 1930's a few growers experimented with sprinklers, in an effort to avoid much of the work and constant patrolling necessary for successful ditch irr i g a t i o n . Because of the weight and clumsiness of the equipment, however, the method was not highly thought of by most growers. Dr. J . C. Wilcox, of the Summerland Experimental Station, has this to say with regard to the increasing use of orchard sprinklers in the Okanagan: - 11 -"Sprinkler irrigation did not become popular in the Okanagan Valley un t i l about 1945, when aluminum'tubing and the new types o f quick coupler became available here. Since then sprinkler irrigation has gone ahead by leaps and bounds. It has been replacing much of the furrow irrigation in the Valley, and most of the new projects are also being irrigated by this method. I estimate that over 50% of the irrigated f r u i t and vegetable land in the southern interior i s now irrigated by the sprinkler method. The variation from d i s t r i c t to d i s t r i c t , however, i s very great. (23) Sprinkler systems commonly in use in the Okanagan at the pres-ent time consist of a f a i r l y large guage (2 i n . or more) pipe of some' aluminum-alloy, in thirty foot sections fastened together by one of several patented rapid coupling devices. At the end of each section is an upright pipe to which is attached a sprinkler nozzle. These nozzles are of various types, but usually are set so that the spray of water emerging from them describes a complete circ l e about once every minute. Most growers have sufficient pipe to cover the width of the orchard being irrigated; the pipes are l a i d between the f i r s t two rows of trees, and sprinkling continued for twelve hours. The pipes are then moved over two rows, and l e f t for another twelve hours, and so on down the length of the orchard. On each setting, a strip i s watered, in length equal to the width of the orchard, and i n width to the circum-ference of the circles covered by the revolving spray from the nozzles. This method of irrigation has several advantages over the older furrow method. One man i s able to attend to the irrigation of the whole orchard in about one hour per day, instead of having to patrol the orchard every hour or two to clear obstructions in the ditches. Erosion and leaching of the s o i l is greatly reduced. The volume of water required is less than is necessary for furrow irrigation, and the - 12 -grower is permitted to run his sprinklers on a 24 hour basis, instead of being limited to two or three days per week, as is the case for users of ditch systems. Finally, the use of easily removable sprink-lers permits the planting and regulation of a suitable cover crop. Most growers feel that these advantages more than outweigh the i n i t i a l cost of installation; hence the increasing popularity of sprinkler systems. Figure 1. Sprinkler irrigation in operation i n an Okanagan orchard. Mowing and discing of cover Growers using sprinkler irrigation systems have found i t convenient to treat orchard cover in a different manner than was possible formerly. Many keep the ground between the trees free of a l l vegetation by periodic discing. Others plant various cover crops, usually a variety of clover, and keep the growth down to a convenient - 13 -height by periodic mowing or discing. Too profuse a growth of cover interferes with the operation of sprinkler systems, and hinders workers engaged in thinning and picking. The percentage of orchards which are kept free of cover, or in which the cover is mowed at intervals during the summer, varies con-siderably from one d i s t r i c t to another. In general the percentage of orchards i n which intensive cultivation of the cover crop is carried on is greatest in areas which have the greatest proportion of sprinkler ir r i g a t i o n . The effect of these practices upon pheasantr.populations is considerable, and w i l l be considered shortly. Spraying New insecticides One of the major changes i n the agriculture of the Okanagan , has been the introduction of new insecticides for the control of various orchard pests. The introduction of DDT to replace various arsenic and aluminum compounds (1947) and the introduction of parathion the next year to control the woolly aphis and various species of mites has been reported by a number of authors. Some information regarding these familiar sub-i , • stances, however,. of. interest. (22),. • DDT (dichloro-diphenyl-trichlorethane. Toxicologists have used DDT as a standard by which to measure the effect of other commercial insecticides. Lehman, for example, states that the m.l.d. of DDT for (1C rats i s about 250 mg. per kg., and rates other insecticides on this basis'. The effect of this substance is upon the nervous system, affecting chiefly the acetylcholine-cholinesterase balance of the nerves - 14 -controlling the voluntary muscles. In pheasants the most character-istic sign of poisoning is the trembling of the whole body of the bird. These tremors are f i r s t detectable in the t a i l , and progress rapidly; the most violent tremors are to be seen in the legs and wings. The tremors vary in intensity, becoming most violent just before death ensues. Although a fair number of studies on the effect of DDT on warm-blooded animals have been made, l i t t l e work has been done on g a l l i -naceous birds. Jackson (1950) was unable to k i l l pheasants by feeding DDT. chlordane or toxaphene mixed with feed in an amount "calculated to be about the maximum that a bird might find in a field after a heavy spraying." No birds died under"this treatment, although slight liver damage was reported. Benson (1950) exposed penned birds to inhalation and ingestion of DDT at concentrations ranging from 10 to 18 lb. per acre of 50$ powder. He reported mortality up to 100$, and thought that inhalation of the insecticide was more toxic to pheasants than was ingestion,. He postulated 7 lb. per acre as the threshold of tolerance of his experimental birds.(') Mohr, et al., (1951) obtained no symptoms of poisoning when they injected 1.0 cc. of a 1/100 suspension of 50$ DDT intravenously into 4-week old Leghorn chicks. They also failed to k i l l adult pheas-ants by exposing the birds to DDT spray in amounts up to 50 lb. of actual DDT per acre, applied by ground duster, and smaller amounts applied by aircraft (20 lb./acre), and steam generator (15 lb./acre). These same investigators also tested the effect of chronic DDT poisoning on adult pheasants by feeding the birds 1/1000 and 1/3200 - 15 -DDT i n their food at seven day intervals for a period of 39 days. At the end of that time one bird i n the 1/100G group had died, another had become sick but recovered, and a l l had lest weight. The suggestion is made that chronic poisoning may be more dangerous to pheasants than a single large dose. PARATHION (0,0-diethyl-O-p-nitrophenyl-thiophosphate) Lehman rates this material as 70 times as toxic to warm bloods as DDT. It has been used in the Okanagan since 1948 for the control of pear psylla, woolly aphis, and several species of mites. Good control i s obtained, but the toxic nature of the insecticide makes i t s use hazardous to care-less operators. Respirators and rubber clothing are essential i f para-thion is to be handled safely, and these impedimenta are extremely uncomfortable i n hot weather. More by luck than by good management there have been no deaths from parathion in B r i t i s h Columbia (excluding one case of suicide by drinking the spray), but several non-fatal cases of poisoning have been reported, and i t w i l l probably be only a matter of time before a f a t a l i t y occurs. The Department of Agriculture has therefore discontinued the recommendation of parathion for commercial orchard spraying, although supplies are s t i l l available for growers who wish to use i t at their own risk. According to Lehman, parathion affects the postganglionic cholinergic nerves, that i s , the nerves supplying smooth muscles and glands. This has been termed the muscarinic effect, and i t s principal symptoms are lacrimation, salivation, sweating, nausea, vomiting, diarrhea, respiratory distress, and disturbance of vision. - 16 -There is also an effect on the preganglionic and somatic motor nerves. This is termed the nicotinic effect, and is char-acterized by flushing of the skin, throbbing of the head, effects on blood pressure, various grades of heart block, and muscle tremors of peripheral origin. (11) Experimental birds suffering from parathion poisoning dis-played light tremors, especially in the region of the head and neck, progressive weakness of the legs, and marked salivation. This last was not always noticeable at the time of death but could be discovered by opening the mouth of the dead bird. Benson reported excessive preening as a characteristic symp-tom, but this was not conclusively demonstrated by the writer. Preen-ing occurred in some cases, but by no means in a l l . He obtained a 50% k i l l in a group of ten pheasant chicks with the use of 16 lb./acre of 15% parathion, in both ingestion and inhalation tests. Mohr, et al. found no toxic effects when Leghorn chicks were placed in a covered box 30 x 30 x 30 inches in size, and sprayed with parathion for thirty minutes at a concentration of ^  lb of 15% powder in 100 gal. of water. Likewise, no signs of poisoning were observed when penned adult pheasants were exposed to field spraying of 4.5 lb of actual parathion per acre. 0+) Parathion is rapid in its action, death usually occurring within a few hours after exposure. Repeated sub-lethal doses may have a cumulative effect, owing to a continued reduction of the cholinesterase level. - 17 'METHOXYCHLOR (Dimethoxy-diphenyl-trichlorethane). This i s one of several new insecticides being tested at the present time for commercial use i n the Okanagan Valley. These tests are being carried out by Dr. James Marshall and his staff at the Dominion Entomological Laboratory, Summerland, B. C , with the aim of finding substances which are efficient i n k i l l i n g as many species of orchard pests as possible, and at the same time are harmless to man and other warm-blooded animals. Described as the methoxy analog of DDT, methoxychlor is rated by Lehman as being 1/24 as toxic to warm bloods. (10) The material being tested i s in the form of 50$ wettable powder, and i s applied at the same rate as DDT. Marshall states that methoxychlor i s being tested as a substi-tute for DDT i n the control of codling moth, leaf hoppers, and the peach twig borer. The future outlook for i t s commercial use depends largely upon the price, which i s high at present, but is expected to drop rapidly in the near future. (13) ARAMITB (B-chloraethyl-B-(p-tert. butylphenoxy) -methyl  ethyl sulphite)., Aramite i s being used to a limited extent in the control of the Willamette mite. Scott and Madsen (1950) reported that this material showed great promise in the control of a l l species of mites, but Marshall has found i t effective only against the Willamette mite. It is reportedas being non-toxic to humans in the dosage employed i n California (1-2 l b . per gallon of water), but because of i t s relatively high price and restricted toxicity i s not likely to find extensive use in the Okanagan. - 18 -SULFANONE (R-242) (p.chlorophenyl phenyl sulphone) i s being used i n the Okanagan for the control of the Two-spotted mite and the Pacific mite. It is put out as 40/£ wettable powder by Stauffer Chem-i c a l Co., which reports i t as being 1/15 as toxic as DDT to mice. The price has been high, but is expected to drop sharply this year. Marshall thinks that sulfanone may find widespread use i n the Okanagan for several years. #4049 (S-(1.2,-dicarbethoxyethyl)o,o,-dimethyl dithio-phos- phate'). This material, which has the empirical formula CIQ H19 06 P S2 is manufactured by the American Cyanamid Co. of New York as a 25$ wet-table powder. I t i s reported by the manufacturers to be cholinester-ase-inhibiting, with a brief duration of action, and l i t t l e cumulative effect. I t i s said to be 50-rlOO times less toxic than parathion, with a low order of inhalation toxicity. Its .present use in the Okanagan is experimental. Control i s obtained of pear psylla, aphids, and a l l species of mites. It w i l l probably be used on a practical basis by 1953, since i t combines low human toxicity with a wide range of effect on orchard pests. With regard to the use of other materials, Marshall says, "I doubt i f there w i l l be wide-spread use of any other insecticides or acaricides i n the near future, but eventually I think systemic compounds w i l l be developed to the point of general use — perhaps in five or ten years." (13) Spray Machinery Until 1945, most orchard spraying was carried on in the Oka-nagan by means of "hand gun" outfits. These consisted of a tank to - 19 hold the spray mixture, a compressor to build up pressure i n the tank, and two hoses f i t t e d with nozzles, attached one on each side of the tank. The whole machine was mounted on wheels and towed behind a tractor or truck. The nozzles of the spray guns were large, the usual size being 8/64 i n . , and consequently the volume of liquid was considerable, running from about 350-800 gal. per acre. One man was required to handle each hose, and as a result at least three men were required for maximum efficiency. The rate of coverage was about 3-5 acres per day. Since their introduction about six years ago, concentrate sprayers have largely replaced hand spraying outfits in most parts of the Okanagan. These machines permit one man to do the same job that formerly required three operators, and in a very much shorter time. Concentrate machines are usually towed behind a tractor, and consist of a tank to hold the insecticide, a system of nozzles through which the spray emerges, and a fan, turbine or other device by means of which the material i s blown into the foliage of the trees. Several different types of these machines are currently in use i n the Okanagan. Turbo-mist This machine f i r s t appeared in 1§46 as the "Okanagan Experi-mental Sprayer". Designed and later modified by Dr. James Marshall, i t now consists of an insecticide tank to which is attached a turbine powered by a 22 h.p. "Wisconsin" air-cooled motor, operating at 2500 r.p.m. The turbine, 12 i n . in diameter, is terminated by a four f t . " f i s h t a i l " , through which an a i r blast of 7500 cu. f t . per minute - 20 -emerges at a velocity of about 115 m.p.h. Seven nozzles inject the insecticide mixture into the air stream through "whirl-plate" tungsten carbide-cobalt discs. The insecticide is stored in a 125 gal. tank, from which i t i s forced to the nozzles by a pump operated by the turbine motor, at a pressure of 300 l b . per sq. i n . , and a rate of 2.45 gal. per min. 80 gallons are required to spray an acre of apple trees of average size and planting. The whole machine is mounted on four wheels, and is towed behind a tractor at a speed of 1 m.p.h. or more, depending upon prevail ing conditions. (Figure 2.) Figure 2. Turbo-mist Sprayer. Metal rods keep foliage from catching on " f i s h - t a i l " . Bes-spray Manufactured by the Besler Corporation of California, the Bes spray works on much the same principle as the Turbo-mist. Instead of - 21 -turbine, however, there is a large fan, with an arc-of-circle vent, mounted on the end of the insecticide tank. The fan is driven by a 13 h.p. motor at 1800 r.p.m. A smaller motor, of ijf h.p. powers the pump which forces insecticide to the nozzles. There are six of these nozzles, equipped with "whirl-plate" discs, set in the centre of the vent. (Figure 3.) This machine has a lower a i r velocity (100 m.p.h.) than the Turbo-mist, and a slightly larger a i r volume (8000 cu. ft./min.) About 85 gal. are required per acre. Figure 3. Bes-spray sprayer Trump Conversion Unit The Trump Co., Penticton, B r i t i s h Columbia, puts out a unit somewhat similar to the Bes-spray, designed for attachment to hand-gun machines. The blower fan operates at 1750 r.p.m. from a 25 h.p. motor, producing an a i r stream of low velocity (65 m.p.h.) and large volume (19,000 cu. ft./min.). The output of insecticide i s 4^ - gal./min, with application of about 100 gal./acre. 22 -The popularity of this machine is due to i t s comparative cheapness, since i t consists only of a blower unit. Many growers have hand-gun machines that are s t i l l serviceable, and by attaching a Trump unit are able to modernize their equipment at minimum cost. Bes-kil This machine appeared somewhat earlier than the last two mentioned, and is considerably more complex in design. Like the others, i t has a fan and an insecticide tank. In addition i t has a steam generator, fired by coal o i l , which produces steam at 275°F. Three jets blow the s^eam into the ai r stream produced by the fan, which i s turned by a five h.p. motor at 2500 r.p.m. Insecticide at 16 times the hand-gun concentration is pumped into the steam linej the resulting blast emerges at 75 m.p.h. The particle sizes of the spray can be varied by changing the steam pressure. (Figure 4). This machine i6 expensive to buy, and somewhat d i f f i c u l t to operate. The high concentration of insecticide increases hazard to operators when agents such as parathion are employed. - 23 -Various manufacturers claim superiority for their particular machines,, but at present definite information is not available. When evaluating machines of this type, the most important consideration is the effectiveness with which they apply the insecticide to the foliage of the trees being treated. A study to determine the relative effect-iveness of these different sprayers is being carried on at Summerland by D. B. Waddell. Although the study is not yet complete, i t appears that considerable differences in performance exist. F i n a l results may be expected next year. The relative efficiency of these different machines results in. a variation between the amount of insecticide applied to the foliage and that f a l l i n g upon the cover crop in each case. The effect of such differences on pheasants w i l l be discovered i n the section on experiments. FACTORS AFFECTING.OKANAGAN PHEASANT POPULATIONS General r Climate Benson came to the conclusion that there was no evidence in Okanagan temperature and precipitation records to indicate that climate played a part in the decline i n pheasant numbers. It is possible, how-ever, that weather conditions may have a considerable bearing on the course of such a decline. It i s well known that pheasant chicks are very susceptible to cold and damp for the f i r s t few weeks after hatching. Two weeks of such weather in late May or early June may result in con-siderable losses of young birds. Moreover, under such circumstances - 24 -renesting w i l l riot occur. Such conditions of weather do not appear, except in extreme cases, in average monthly temperature and precipita-tion records. The depressing effect of these conditions, however, is none the less real. The same may be said of unfavourable winter conditions. These occur when low temperatures combine with deep snow to make feed-ing by the birds d i f f i c u l t or impossible. This combination of circum-stances may likewise f a i l to be reflected in averages found in meteoro-logical records. It i s well known to local observers, however, that considerable mortality to pheasants has occurred under such conditions. This mortality may be quite rapid i f a few days of unusual cold follow a prolonged period of deep snow. Detailed information i n this connec-tion would be most valuable, but is at present not available. Temper-ature and snowfall readings would have to be taken daily in each area under consideration, together with observations on pheasant behaviour, before accurate conclusions could be drawn. - Hunting pressure Numbers of hunters have increased markedly in the Okanagan in recent years. Figure 5 shows that the number of resident firearms licenses sold in Kelowna, Oliver, Penticton, Salmon Arm and Vernon rose from a total of 2000 in 1940 to 7,550 in 1949. It is of interest to note that a sharp increase in 1945, coincident with the return of many hunters from service with the armed forces, also coincides with a reported'drop in pheasant abundance. However, a much sharper increase in license sales is to be noted in 1949, and no decline in pheasant - 25 population was noted in that year. It follows that an increase i n the numbers of hunters, coincident with a decrease in the numbers of birds, would tend to accentuate this decrease in the eyes of the casual observer, since there would be fewer birds per hunter available. I t i s not suggested that increased hunting pressure i t s e l f brought about the pheasant decline, but i t is postulated that this made the decline appear worse than i t actually was. Unfortunately, no quantitative data exist as to the actual pheasant decline; the only information available is the reports of local observers, who state that such a crash did occur in 1946. It has been observed in many cases that the opening few days of pheasant hunting see the harvesting of most of the season t o t a l . Taylor states that between 67 and 90 percent of the 1950 pheasant k i l l in the Fraser Delta area of B r i t i s h Columbia occurred on the f i r s t two days of the open season. (20) ; It has never been demonstrated that hunting can reduce the cock t hen ratio below that necessary for reproductive success. Har-per, et a l . , (1950), for example, report post-season ratios in the Sacramento Valley of as low as 3.4 cocks per 100 hens, with no detect-able adverse effects upon reproductive success. It seems highly unlikely that deleterious effects wo^^ld be obtained in the Okanagan. The only manner in which increased hunting pressure could conceivably reduce1pheasant abundance is by i l l e g a l k i l l of hens. This may run quite high, and may be expected to increase as larger - 26 numbers of hunters compete for the available supply of birds. Harper et a l . report a hen k i l l of 5$, but estimates of workers in other areas run much higher. Taylor estimates a 25$ i l l e g a l hen k i l l on the Fraser delta. In view of the fact that the annual turnover of pheasants, reported by Leopold, et a l . (1943) as 70$ in Wisconsin, probably applies in the Okanagan, i t i s doubtful i f the i l l e g a l k i l l of hens in this region has more than a minor depressing effect on the population* More information, however, i s desired i n this connection. i • 7 • • ' •• O | 3 ' —I— 193? 19*0 •+- -+- -t-i9*' 11*2. '9*3 19** /9fS /7*6 '1*7 /I*? /f*9 Y E A R Figure 5. Sale of Resident Firearms Licences in the Okanagan Valley, 1939-1949. Disease and Parasites Although outbreaks of Newcastle disease, and infestations of various parasites such as gapeworm are known to occur in pheasants in some l o c a l i t i e s , these agencies have not been reported as affecting pheasant populations in the Okanagan. - 27 -Predation * Some pheasants are undoubtedly destroyed each year by pre-dators, but the number is not believed to be great. The most common predators reported are domestic cats and dogs; the latter sometimes cause considerable local disturbance in the nesting season. Goshawks and owls (Great horned and Long-eared) probably take a few birds. Although no study of predation has been made, i t has never been believed by local observers to be a serious factor in controlling pheasant numbers. This is the conclusion reached by Benson in his study, and results of a similar nature are reported by Taylor, who says that although some predation by crows, dogs and cats on wild-raised pheasants occurs on the Fraser Delta, i t i s probably of minor importance. (20) Orchard Populations Sprinkler Irrigation and Cover Treatment I t has been suggested earlier i n this paper that an orchard under sprinkler irrigation i s generally much less suitable as pheasant habitat than one which is irrigated by the ditch or furrow method, owing both to a greatly increased amount of disturbance, and to reduced and frequently treated cover crop. Actual wetting with water spray may also be a" factor in discouraging pheasants, although hen pheasants have been observed sittin g on eggs directly in the path of a sprinkler, and have remained in such a position for twelve hours or more. Should such a bird be forced to leave the nest, however, the subsequent c h i l l i n g of the eggs would probably cause mortality. Chicks hatching under such - 27 -conditions would also be adversely affected. Dr. J. Wilcox has been quoted as estimating the percentage area under sprinkler irrigation as being i n the neighbourhood of 50 percent. Recent figures are not available, but Figure 7 shows that percentages ranged from 7 percent in Vernon to 60 percent in the Oyama-Winfield area in 1949, with an average of 30 percent. (18) In Summerland, of 35 orchards sampled, 15 were mowed or disced with sufficient frequency during the summer to make successful nesting by pheasants unlikely. Seventeen were disced once or twice a year, and three were untouchedj i n these cases damage to nesting pheasants probably occurs very infrequently, i f at a l l . Reference to Table I shows that a difference between sprinkler and ditch i r r i -gation i s suggested. This sample of 35 orchards involves 402 acres, or slightly less than 10 per-cent of the irrigated area in Summerland. Of orchardists who employed ditch irrigation, five out of seventeen or 30$ mowed or disced their orchard cover during the summer months. (May, June July and August.) The average frequency was ; li'2 treatments per season. Of orchardists using sprinkler irrigation, eleven out of eighteen, or 61 percent, treated their orchard cover in some manner during the summer months, with an average frequency of treatment of 3.2. Although the following sample i s of a limited area only, and not necessarily representative of the Okanagan Valley as a whole, the suggestion is made that sprinkler irrigation has a definite and adverse, effect on pheasants, both by disturbance and by actual mechanical injury to nesting birds, eggs and young. Thorough mowing of an orchard in which -28 -the cover is f a i r l y short and even, as is often the case in sprinkler-irrigated orchards, results i n the destruction of nearly a l l nests present i n the area. " Discing is probably somewhat less destructive, but may also cause heavy losses. The use of sprinkler irrigation is increasing steadily in the Okanagan, and we may expect an intensification of these effects in the next few years. TABLE I. Cover Treatment under Ditch and Sprinkler Irrigation. Ditch % Sprinkler % Mowing or discing. in summer months 5 30 11 6!l> Frequency of treatment 1.2 3.2 No mowing or disc-ing in summer 12 70 7 40 months Reduction of Pheasant Habitat In addition to the loss of suitable habitat owing to increased sprinkler irrigation and subsequent disturbance, a considerable area that is now uncultivated w i l l sooner or later be placed under irrigation. Reference to Figure 8. shows that l i t t l e change in t o t a l acreage under irrigation has taken place in the ten year period 1939-49, with the exception of the Oliver-Osoyoos area, but that considerable land remains that i s considered potentially irrigable, particularly in the Kelowna - 29 -and Vernon areas. The total figures for the Okanagan ares 47, 948 acres irrigated, 30,600 additional acres irrigable. The percentage of this area that is good pheasant habitat is unknown, but i t seems li k e l y that i t i s f a i r l y high. It i s not possible to predict how many years i t w i l l be before the bulk of this land is u t i l i z e d for agricultural purposes, but most of i t w i l l probably be irrigated sooner or later. While this may produce better pheasant habitat for a limited time, inten-sive cultivation by modern methods may well render i t more unsuitable than i t is at present. This Is a large unknown factor, but one which must be kept in mind. percentage area Vernon Area Oyama, Winfield & Okanagan. Centre .. Kelowna Area....... J Summerland Area ..... Penticton Oliver-Osoyoos. sprinkler i r r i g : Apples Other tree f r u i t s Ground crops and others. Livestock Figure 7. Percentage use of i r r i -gated land in the Okanagan Valley. - 30 -Vernon. 6ooc Oyama, Winfield & Okanagan Centre .. Kelowna. == _ IS^qop = ~ 1 IS, 4,/6 WW*0 000 Summerland = ¥069 ^ -¥3.07 Penticton 5 1^ /3.^  — Oliver-Osoyoos. -i rmw 60S 9 \l<t7¥j 1939 - 1949 irrigable Figure 8 Acreage irrigated in 1939 and 1949, and additional irrigable acreage, in the Okanagan Valley. - 31 -Insecticides Many people have attributed the decline in Okanagan pheasant populations to the use, i n recent years, of highly toxic insecticides in controlling orchard pests. As has been noted, Benson thought that these new sprays, while capable of causing pheasant mortality, were not directly responsible for the decline, chiefly for the reason that they did not come into widespread use u n t i l the decline was well under way. It was considered desirable, however, to obtain further i n -formation as to the possible damage these materials might i n f l i c t , and accordingly experiments were designed to this end, both to supplement information obtained by Benson, and to supply data on other insecticides introduced since he conducted his study in 1949. Methods Most of the experiments on pheasants were conducted on chicks from four to fifteen days of age. The majority of these birds were supplied as day-old stock, by W. Greenslade, of Vancouver; a few were obtained locally from deserted nests, and nests damaged by mowing. (1) F i e l d experiments: During f i e l d experiments, chicks were kept i n pens with broody hens. The pens used were of two types. For tests of ingestion only, pens were constructed with wooden sides and ends, and a wire top with a small wooden l i d . For inhalation, and combined inhalation and ingestion experiments, pens were constructed entirely of wire f l y screen on a wood frame. Both types were of the same size; v i z . 5 f t X 32 i n . X 15 i n . Figure 9 shows the plan of the ingestion type pens. - 32 p—is"— — S' w i r e , top I inch mesh 1 Figure 9. Plan of pens used in f i e l d experimentsj ingestion type. A l l pens were without bottoms, and were moved as soon as the cover they enclosed was eaten or destroyed by trampling. For tests of inhalation only, birds were "placed in inhalation type pens, and l e f t therenfor one hour after spraying. They were then trans-ferred to ingestion type pens in a clear area for observation. For tests of ingestion only, birds were placed in ingestion type pens on a sprayed plot after spraying was completed. For com-bined inhalation and ingestion tests, birds were placed in inhalation type pens during spraying, and then transferred to ingestion pens on the same plot. Birds were kept supplied with food in the form of commercial turkey starter, and with water. Broody hens were fed, mixed grainj they also ate some of the turkey starter. For ingestion tests food and water were placed on the test plot before spraying was begun. Control pens were placed i n the same orchard as were the test pens, but in currently unsprayed areas. Thus any toxic material remaining from previous spraying by the owner would have an equal effect on both groups. Test plots were located in the centre of blocks of trees of average size. These blocks were sufficiently large to ensure the - 33 -test plots receiving a maximum amount of d r i f t . Unless otherwise noted, the turbo-mist machine previously described was used for spray-ing. Birds were assumed to have died from the effects of the insecticide only i f they showed definite signs of poisoning. A l l dead oirds were taken for chemical analysis. An observation period of at least two weeks was allowed on a l l experiments. It was f e l t that confinement on the sprayed area for that time represented at least the maximum exposure to which a bird would be subjected under natural conditions. When sprinkler i r r i g a -tion was carried on by the owner of the orchard i n the v i c i n i t y of the pens, they were covered with waterproof building paper. This averaged about one twelve-hour period once a week. (2) Laboratory experiments: For laboratory feeding experi-ments pheasant chicks were kept in a "duplex" brooder designed by the writer. This is shown belov/ (Fig. 10) • Test birds were placed in one side of the brooder, and control birds in the other. The tempera-ture in the heated portion of the brooder was maintained thermostatic-all y at 35°C. A l l birds were weighed daily for a period of two -weeks. Figure 10 (a) Duplex brooder* Cover on' one side removed. - 34 Fig 10 (b). Duplex brooder. Detail pf heating unit The insecticide being tested was mixed mechanically with the turkey starter with which the birds were fed. Food and water were available at a l l times. Effect of different types of machinery, (experi-ments on pheasants.) Before testing the effects of various insecticides i t was considered desirable to ascertain the effect of different types of spray machinery. It has been stated that concentrate machines are replacing the older hand-gun outfits in the Okanagan. The possibil-i t y existed that this change might have an effect on the concentration of insecticide remaining in an orchard after spraying. Sixty pheasant chicks, five days old, were exposed to combined inhalation and ingestion of DDT and Parathion, applied with both turbo-mist and hand-gun machines. Spraying was conducted on -35-three separate occasions, using DDT at the rate of 12, 18, and 24 lb/acre of 50$ wettable powder, and parathion at 8, 12, and 16 l b / acre of 15$ wettable powder. The lowest figure in each case rep-resents the recommended orchard concentration. Twenty control birds were exposed to spraying with water only. Table II shows that there was no difference mortality i between the two machines when DDT was used, but that in the case of parathion mortality was higher with the turbo-mist. Because of the / d i f f i c u l t y of ascertaining the cause of death in a bird which is found dead, and because pheasant chicks'are subject to considerable mortality from inadvertent c h i l l i n g , and from trampling by the broody hen, only those birds which showed definite signs of poisoning are considered in this table. Table I I . Result of applying DDT and parathion with hand-gun and Turbo-mist machines - j Treatment Number of Deaths* Turbo-mist Hand-gun No. $ No. . $ DDT 3 20 3 20 Parathion 4 26.6 2 13.3 *Died with definite signs of poisoning. Dampening by water seemed to have no effect in either case. i - 36 -Chemical analysis of cover An accurate method of comparing the concentration of insecticide on the cover after spraying with the two machines was desired. The following test was carried out by Dr. J . M. MacArthur, assisted by the author. Two plots, each containing six good-sized apple trees, were selected. Samples of the cover crop (Ladino clover) were taken before and after spraying, in the manner indicated i n Figure 11. Fourteen samples, each weighing 100 grams (wet) were taken from each plot the day before spraying, and again after.spraying as soon as the spray deposit had dried on the cover. DDT 50% wettable powder was used for the test, and applied at the regular orchard concentration of 12 lb./acre. This amounted to 0*116 l b . per tree i n the hand-gun plot, and 0.085 l b . per tree in the turbo-mist plot. Samples were stripped in benzene, and analysed for DDT by the Stiff-Cast JTIIo method (modified) (3) . The results are shown i n Table III. >'*) (?) b-» a b (k.* periphery of btanclies. Figure 11. Location of samples in test plots; cover deposit test Table III. Amount of DDT deposited on.cover with handrgun and turbo mist machines Turbo-mist* Hand-gun Average of "a" samples . 789 p.p.m. 2790 p.p.m. Average of "b" samples 843 " 2360 " Average of "x" and "y" samples ... 877 - " 970 * corrected to amount applied equivalent to hand-gun. Both machines applied approximately the same amount of DDT to the cover in the spaces between the trees. Immediately under the trees, however, the hand-gun applied approximately three times as much spray as did the turbo-mist. This difference i s undoubtedly due to heavy dripping from the branches after a tree has been sprayed. These figures offer an explanation for the results obtained in the previous experiment, (p.34) The pens in this test were placed between the trees, and therefore received approximately equal amounts of insecticides from the two machines. In the case of DDT, which has l i t t l e inhalation toxicity, but remains toxic on the cover crop for some time j~ approximately equal numbers of birds died in each group, i n the case of parathion, which has a high order of inhalation toxicity, but breaks down rapidly after being deposited, the turbo-mist, with i t s fine spray particles, caused greater mortality than did the hand-gun. - 38 -The increased use of the turbo-mist, and other concentrate machines, and a corresponding decrease in the use of machines of the hand-gun type would probably result in a--decreased effect oh pheasants of insecticides-with high ingestion toxicity potential, and a possible increased effect of those with high inhalation toxicity. Differences between the various concentrate machines, although probably significant, are very unlikely to be as great as the difference between the hand-gun and turbo-mist, as shown above. Experiments DDT. Inhalation and ingestion Benson reported that inhalation of DDT was more toxic to pheasant chicks than was ingestion of this material. Since the oppo-site effect has been noted in connectionuwith human susceptibility, as reported by Webster (1950), an experiment was set up to attempt to evaluate the difference between these two types of exposure. Pheasant chicks, 4 days old, were exposed to inhalation and ingestion of DDT at concentrations of 12, 18, 24, and 30 lb/acre of 50$ wettable powder. : Results were obscured by rain two days after the experiment. Table IV shows the mortality in the different groups. In total these were: control, 66.6$; DDT ingestion, a l l groups, 77.5$. DDT inhal-ation, a l l groups, 40.7$. Only birds in the 24 lb./acre and the 30lb./acre ingestion groups showed any signs characteristic of DDT poisoning. The high percentage of deaths in the 12 lb./acre pen was due to the indifference - 39 -of the broody hen during a period of cool, damp weather, and most of the other deaths, with the exception of those in the two groups noted, probably resulted from similar causes. Table IV. Inhalation and Ingestion of DDT under F i e l d conditions.-. Number of deaths* Amt. of DDT Ingestion Inhalation Control No. |" | m | < m | • .No. | j No j , 12 lb ./acre 9 90 5 50 18 lb ./acre 7 70 3 30 24 lb./acre 6 60 3 42.8 30 lb./acre 9 90 Not tested Control - - - - 6 66.6 •Deaths from a l l causes. This experiment f a i l e d to demonstrate any observable suscept-i b i l i t y of pheasant chicks to inhalation of DDT. For further information in this regard, see section on para-thion inhalation. DDT. Ingestion Twelve pheasant chicks, 10 days old, were fed DDT in the form of b% powder, mechanically mixed with their food, at rates of 200,600, and 800. p.p.m. actual DDT. A measurement was made of the amount of food - 40 -eaten by each group. The results obtained are shown in Table V. Table V. Ingestion of DDT Group Cone, of DDT F i r s t Symptoms A l l dead Amt Eaten A 200 p.p.m. 12th day 13th day - 0.048 g. B 600 " 6th day 7th day 0.045 g. C 800 " 5th day 10th day 0.068 g. These results are not conclusive, because of the small number of birds employed, but they raise some very interesting points. There would appear to be considerable individual difference in the reaction of pheasant chicks to DDT. Table V. shows that five days elapsed between the onset of poisoning, and the death of the last bird in Group G. This lag was caused by the high resistance of one bird in the group. These individual differences may possibly have been caused by failure of certain individuals to eat as much food, and consequently as much insecticide, as the others. However i t i3 l i k e l y that individual differences i n susceptibility do exist. From this test, and from DDT ingestion results i n comparison with methoxychlor. (q.v.), i t becomes apparent that even when the turbo-mist machine i s used, DDT may be deposited on the cover in sufficient quantity to cause the death of birds eating this cover. DDT at the - 41 -rate of 500 p.p.m. was invariably f a t a l , i f the birds had to subsist entirely on food containing the poison. In f i e l d tests, however, even when the birds were retained within a very circumscribed area, and subjected to double the above concentration of DDT, losses were less than 50$. The explanation appears to be that in the f i e l d pheasants do not eat sufficient poison to be so seriously affected. This may be due to several factors. 1. Movement of birds Partly because of the natural movements of the species, and partly because of more or less con-tinual disturbance i n the orchards, the birds do not remain in one place for any considerable length of time, during the greater part of the day. Most of the orchards i n the Okanagan do not exceed. 25 acres in size, and i n most cases there is waste .land, or f i e l d s in close enough proximity to attract pheasants. The birds thus seldom remain in an area of high .insecticide concentration for very long. 2. Removal of insecticide from.cover Although there i s no quantitative data to this effect, i t has been observed by the. writer, and others that deposits of DDT, which appear on the leaves of the cover crop as a white powder, wash -off when the cover is subjected to rain or to soaking by irrigation sprink-le r systems. The amount of DDT which a pheasant w i l l ingest in any area w i l l therefore depend in part upon the amount of r a i n f a l l and irrigation sprinkling taking place in that area after the insecticide has been applied. 3. Type of Cover crop Many orchards in the Okanagan are clean cultivated. Others are sown with a variety of cover crops, of which various species of clovers (Trifolium) are the most common. In s t i l l others natural weeds may be allowed to grow, but orchards with this type of cover are be-coming increasingly rare. Couch grass (Agropyron repens) however, occurs in a l l , or portions of, many orchards.-- 42 -The writer has found some evidence to suggest that pheasants find various species of Trifolium more palatable than couch grass, and would tend to consume less cover in orchards in which the latter species predominates. Couch grass, with i t s more or less perpendicular leaves, and relatively small surface area, would probably receive less spray deposit than would the many horizontal leaves of the clovers. The weed seeds which form a considerable proportion of the pheasants' diet are not found in appreciable quantities in many orchards, and would have to be sought elsewhere. Chemical analysis of birds k i l l e d by DDT Several investigators have thought i t desirable to be able to analyze dead pheasants for the presence of DDT i n their tissues, as a means of supplementing information obtained by controlled experiments. Many orchardists and farm workers have assumed that any dead pheasants found in the v i c i n i t y of spraying operations have died from the effect of the insecticide, and a precise method of analysis would be of value in answering questions proposed by these and other interested parties. Benson had a series of test and control birds analyzed for DDT by the total chlorine method, and came to the conclusion that no significant difference could be detected between the test and control groups by this method.(1)'..'.) Mohr, et a l . , using the method of Clabom (3), were able to obtain significant differences between birds treated with DDT and those fed on normal rations. The test birds received 0.1$ DDT in their food for a period of 39 days; one cock bird died on the 23rd. day, and showed 8,109 p.p.m. of DDT in adipose tissue, - 43 -and 44 p.p.m. in hepatic tissue. Other birds showing slightly less (14) than 4000 p.p.m. in adipose tissue f a i l e d to show signs of poisoning; Dr. J . M. MacArthur and his associates at Summerland analyzed a series of treated and control pheasant chicks for the writer, using the techniques reported by Mohr, et a l . (14) They were unable to obtain significant differences between the two groups, owing chiefly to the clouding effect of f a t 3 , which they were unable to eliminate to their satisfaction. They are currently trying new techniques which they hope may eliminate this d i f f i c u l t y . Analysis for parathion is only possible on fresh specimens, or those which have been frozen very shortly after death", since this material normally breaks down rapidly by hydrolysis. For this reason the analysis of birds found dead in the f i e l d is not considered practic-able insofar as the detection,of lethal amounts of parathion is concerned. PARATHION Inhalation and ingestion Twenty pheasant chicks, 15 days old, were exposed to ingestion and inhalation of parathion, in the form of 15$ wettable powder, at the rates of 8 lb. and 16 l b . per acre. Table VI shows that 50$ of the birds exposed in the 16 lb./acre group died. Death occurred in 20$ of the 8 lb./acre inhalation group, while 10$ (one bird) died in each of the ingestion groups. It is possible that these last birds died from causes other than parathion poisoning, possibly from being chilled by the heavy rain that f e l l two days after spraying. In the inhalation groups, however, a l l but one of the affected - 44 -birds were observed with characteristic 'parathion tremors 1. Table VI. Parathion 15$ Ingestion 8 lb./acre 16 lb/acre Inhalation 8 lb/acre 16 lb/acre Date No. dead Date No. dead Date No. dead Date No. . j.dead J u l . 26 G 0 0 4* J u l . 27 0 0 2* 0 J u l . 28 0 1 0 0 J u l . 29 0 0 0 0 Aug. 2 0 0 0 1 Aug. 7 1 0 0 0 Total 1 1 2 Percent 10 10 20 50 * Observed with symptoms of parathion poisoning. During the observation period two birds died i n the control group, probably owing to c h i l l i n g . PARATHION Inhalation compared with that of DDT. In order to compare the effect of inhalation of DDT and parathion, pheasant chicks 16 days old were placed in a closed box of about 7-|- cu. f t . capacity. The insecticide being tested was then - 45 -introduced by means of a hand sprayer of the "fly-tox" type. 25 cc. of spray mixture was applied every 15 minutes un t i l a total of 100 cc. was reached. Birds were removed from the box two hours after the beginning of the test, and kept under observation in the "duplex" brooder. Five birds were used i n each group. The parathion spray contained 16.8 gm. actual parathion per l i t e r of water, and the DDT spray 33.6 gm. actual DDT per l i t e r . These amounts were calculated so as to be approximately twice the amount used i n concentrate machines. The size of the container in which the birds were held was such, however, that the f i n a l concentration of insecticides was very much higher than would be the case i f these mix-tures were used under orchard conditions. Table VII. Inhalation of parathion vs. DDT Parathion DDT Concentration 16.8 gm./liter 33.6 g . / l i t e r Amt. applied 100.0 cc. 100.0 cc. No. of deaths 4 0 Time for 1st death 2-_- hrs. Time for last death... 6 hrs. - — -% mortality .. 80% 0% Birds in the parathion group were observed with tremors typical of parathion poisoning. Marked salivation also occurred, but was not evident u n t i l the b i l l s of the dead birds were opened. _ 46-As shown in Table VII, four out of five birds in this group died within six hours of the beginning of the test, while none,of those in the DDT group showed any signs of poisoning. Once again we note great individual differences in reaction; one of the birds in the parathion group was apparently unaffected, and showed no signs of poisoning during the observation period. These last two experiments suggest that inhalation of para-thion is more dangerous to pheasants than is the ingestion of this material. This, of course, would not necessarily be true in the laboratory i f measured doses of parathion were fed to the birds. In the f i e l d , however, the insecticide does not remain on the cover in sufficient quantity, or for a sufficient length of time, to present a serious hazard. MacArthur (1949) has found that two days after spray-ing, the percentage of parathion on apples i s reduced to 54$. This: drops to 15$ at the end of a week, and by 28 days has been reduced to merely a trace.Y«) This is shown graphically in Figure 12. p 100 e 90 r 80 70 c 60 e 50 n 40 t 30 20 r e s i - 10 due 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 days after spraying Figure 12. Parathion residue on apples. - 47 A much more rapid disappearance would probably occur on the cover, owing to. the washing influence of rain and sprinkling previously considered. I t therefore appears that, in the case of parathion, inha-lation rather than ingestion is the important agent of mortality to., pheasants. The reverse seems to be true in the case of DDT. "Benson, however, claims that DDT also has a high inhalation toxicity. . This the writer was unable to demonstrate. It 'is thought that parathion may have been the lethal agent in at least some of Benson's tests, since he used a mixture of the two insecticides. The rapid action of the poison, and the behaviour of the affected birds, also suggest this explanation. In one of his experiments, however, he reported death of a l l of ten birds within 24 hours of spraying with DDT at 10 lb./acre. The explanation of so great a difference in results is not known. The writer repeats, however, that he was unable to demonstrate definite inhalation toxicity of DDT at concentrations of up to 30 l b . / acre. METHOXYCHLOR Inhalation and Ingestion Teh chicks,. 17 days old, were exposed to combined ingestion and inhalation of methoxychlor 50$ wettable powder at the rate of 24 l b / acre. Reference to Table VIII. shows that no deaths attributable to methoxychlor poisoning were observed. - 48 -Table VIII Ingestion and inhalation of 50$ methoxychlor at the rate of 24 lb./acre Bate Aug. 21 Aug. 22 Aug. 23 Aug. 24 Aug.;125 Aug. 26 Aug. 27 Aug. 29 Total Percent Number of deaths Cause of death Test group Control group 0 . 0 ; 0 0 0 1 believed wetting 0 1 not known 0 0 2 * 0 not known 1 * 1 not known 0 1 not known 3 30 4 40 # No signs of poisoning. METHOXYCHLOR Ingestion Eight birds, eight weeks old, were fed 50$ methoxychlor mixed with their food at the rate of 500 p.p.m. actual methoxychlor. Ano-ther eight birds of the same age were fed a similar amount of DDT. - 49 -Table IX. Comparative ingestion of DDT and methoxychlor at "the rate of 500 p.p.m. Date Number of deaths DDT Methoxychlor Control Sept 0 0 0 Sept 5* 0, 0 Sept 3* 0 0 Total 8 0 0 Percentage 100 0 0 .aDied with tremors typical of DDT poisoning Methoxychlor does not appear to have any toxic effect on pheasant chicks at concentrations of 24 lb./acre of 50$ powder, or 500 p.p.m. in food. Under the same conditions DDT produced mortal-i t y up to 100$. ARAMITE Ingestion and inhalation Twenty chicks, six days old, were exposed to combined ingestion and inhalation of aramite 15$ wettable powder at the rate of 12 l b . / acre. Table X. shows that within the two week observation period only one bird died, apparently owing to mechanical injury. Two others - 50 -died two days later, but once again mechanical injury i s believed to have been responsible. No evidence of toxic effect was noted. Table X. Ingestion and inhalation of 15$,Aramite-at the rate of 12 l b . /acre. Date Number of deaths,: Test group "A" Test group "B" Control 0 0 0 0 1* 0 2* 0 0 * death due to mechanical injury ARAMITE Ingestion 1. During the course of the preceding experiment 10 chicks of the same age and stock were kept in a clear area and fed aramite at the rate of 500 p.p.m. actual aramite mixed i n their food. No deaths or any signs of i l l effects were noted in this group. 2. Ten chicks, 2 days old, were placed in the "duplex" brooder on a diet of mash containing 500 p.p.m. actual aramite. Teh birds in the other half of the brooder served as a control group. A l l birds were weighed daily whenever possible. No symptoms of poisoning or any i l l effects were noted in the test group. There was no significant difference in the weight of birds in the test group, and approximately June 13 June 19 July 3 - 51 -equal amounts of food were consumed. See Table XI. Pheasant chicks showed no deleterious effects from ingestion and inhalation of aramite in concentrations at least as great as any to which they would be exposed under commercial application of this material. So far as is known, aramite can be safely used as an or-chard insecticide without affecting pheasant populations. Table XI. Weights of pheasant chicks fed aramite at the rate of 500 p.p.m. Date Test (gm.) Control (gin.) June 26 204.0 196.5 June 27 219.7 224.4 June 28 231.9 241.2 June 29 257.4 284.6 July 1 321.5 352.5 July 3 401.8 430.1 July 4 442.0 504.4 July 5 470.3 537.3 July 6 533.7 , 579.3 July 7 588.5 642.6 July 8 655.7 707.9 July 9 721.0 777.2 -Each variate i s the total weight of ten birds SULFANONE (R-242) Ingestion and inhalation Twenty pheasant chicks, 11 days old, were exposed to inhala-tion and ingestion of sulfanone at the rate of 16. l b . per acre of 40$ wettable powder. Ten birds of the same age and stock served as controls. A l l birds were observed feeding during the course of spraying. One bird died i n the control pen during the observation period. - 52 -No signs of poisoning or deaths were observed in the test group. Some birds appeared definitely smaller than others, but this phenomena is frequently observed i n almost any group of growing pheasant chicks, and cannot be attributed to the action of sulfanone on the basis of this experiment. SULFANONE Ingestion Ten birds were tested i n the "duplex" brooder, with ten others as controls, i n the same manner as in the aramite test (q.v.) 500 p.p.m. actual sulfanone was mixed with their food, and observations were made over a two week period. No signs of poisoning were observed, but Table XII shows that there was a slight lowering of the growth rate. Table XII. Weights of pheasant chicks fed sulfanone at the rate of 500 p.p.m. Date Test (gm.) Control (gm.) July 10 255.6 262.3 July 11 276.8 289.8 July 12 303.3 327.5 July 13 322.7 353.2 July 14 355.9 407.4 July 16 432.1 508.3 July 17 428.5 547.6 July 18 507.5 581.1 July 19 548.9 671.4 July 20 615.3 726.0 July 23 773.4 926.3 Each variate i s the total weight of ten birds. Sulfanone may cause a slight retardation of growth i n pheasant chicks under experimental conditions, but there i s no indication that commercial - 53 -application of" this insecticide would cause any harm to wild birds in the f i e l d . #4049 Ingestion and inhalation Twenty birds, eight days old, were exposed in f i e l d pens to combined ingestion and inhalation of #4049 at the rate of 12 l b . of 25$ wettable powder per acre. No deaths or signs of poisoning were noted during the observation period. #4049 Ingestion Ten pheasant chicks ingested 500 p.p.m. #4049 i n their food for two weeks, as in the aramite and sulfanone laboratory experiments. Table XIII shows that the test group grew at the same rate as the experimental group. No signs, of poisoning were observed at any time. Table XIII Weights of pheasant chicks fed the rate of 500 p. p. m. Date Test (gm) Control (gm) July 26 450.0 424.0 July 27 492.3 471.9 July 29 522.9 435.4 July 31 624.3 606.5 Aug. 1 673.3 640.4 Aug. 2 723.5 703.2 Aug. 4 812.5 791.9 Aug. 6 1001.3 970.4 Aug. 7 1076.5 1017.3 Aug. 8 1130.3 1081.7 Each variate i s the total weight of ten birds Available evidence indicates that no harm to pheasants would - 54 -result from the commercial application of #4049 in the concentrations now being recommended. Summary of Insecticides In summarizing the Okanagan insecticide situation, i t is the conclusion of the writer that these agents cannot be demonstrated as having been, or being at present a limiting factor in the numbers of pheasants i n the Okanagan Valley. Some of the more toxic chemicals, notably DDT and parathion, are capable of causing considerable mortal-i t y under certain conditions, but these conditions, for reasons previously discussed, axe seldom realized. This fact, together with the evidence that the pheasant decline was well under way before DDT and parathion were in use, suggests that toxic sprays are, at most, a depressing factor which might accelerate a decline, but which would not l i k e l y be the cause of i t . Present indications are that the deleterious effects of orchard insecticides w i l l be greatly reduced within the next few years. The probable replacement of DDT by methoxychlor, and of parathion by sulfanone and #4049, w i l l mean that the bulk of the insect control pro-gramme w i l l be carried out with agents whose toxicity to pheasants is low or non-existent. This may be expected to eliminate most losses now caused by chemical sprays. Several unknown and untested factors remain, however. F i r s t , does the use of two insecticides at the same time produce a greater effect than the use of both agents separately? Benson suggests this pos s i b i l i t y , but as yet no studies have been made. Some growers in - 55 -the Okanagan have been applying a mixture of DDT and parathion, i n order to control both coddling moths and mites with a single treat-ment. This practice is not followed by a l l operators, however; many find i t preferable to apply a parathion spray prior to treatment with DDT. The poss i b i l i t y does exi3t that aramite, sulfanone and #4049, or any one of these, may have an enhanced toxic effect i n combination with each other or with methoxychlor, but since the Okanagan spray recommendations are specific in warning against the mixture of insect-icides which may combine chemically, and since none of these agents is more than slightly toxic to pheasants, the possibility of such increased effect seems small. The second unknown is the effect, i f any, which moderate amounts of these materials may have upon the reproductive mechanisms of pheasants. Post found that hen pheasants stopped laying when they were being administered experimental dosages of aldrin, (17) and the possibil-i t y exists that effects of this kind may also be realized i n cases where birds ingest moderate amounts of insecticides which otherwise produce no i l l effects. At present nothing i s known in this regard. Further studies may also reveal further information on the effect of the type of food being consumed on toxic reactions, and on the results of starvation upon birds that have received sub-lethal doses of insecticides which have a cumulative effect. Benson was unable to demonstrate any effect of this nature i n the case of DDT, although he f e l t that his dosages were possibly too low. This factor may well be - 56 --unimportant, especially in the case of organic phosphates, whose action i s of short duration, and also of methoxychlor, which is very much less toxic than DDT. Non-orchard Populations Although this study has been concerned almost entirely with orchard populations, i t must be borne i n mind that pheasants appear to be more numerous in non-orchard areas, owing at least in part, as we have said, to the unsuitability of present-day orchard conditions. Less than half the land under cultivation in the Okanagan is devoted to tree f r u i t s . The Census of Canada for 1941 gives the total tree f r u i t area as 25,884 acres, and that for a l l f i e l d crops as 69,044 acres. Until the complete figures for the 1951 census are released i t i s not possible to obtain comprehensive information on changes in land use i n non-orchard areas. Some recent data are available, however, for the region bounded by Okanagan Mission i n the south and Enderby in the north^i) Since this comprises 96$ of the cattle raising and mixed farming area of the valley, these figures are shown in contrast to those for the whole Valley in 1941. F a l l wheat A l f a l f a Timothy Figure 13. Acreage in ground crops in the Okanagan Valley, 1941 and 1949. - 57 -These data suggest that certain changes in agriculture have taken place i n this area. The most significant of these i s in the acreage devoted to the two chief hay crops, a l f a l f a and timothy, from a total of 24,130 in 1941 to 7,100 in 1949. . If this difference actually exists, i t may mean that a considerable area of good pheasant nesting cover no longer remains. These figures are merely cited to indicate the poss i b i l i t y that significant changes may have taken place in non-orchard areas i n the Okanagan. Since these areas are large, deleterious effects on pheasant populations may well have resulted. Whether or not this, i s the case w i l l only be determined by a careful study of this habitat. SUMMARY AND CONCLUSIONS The present study was undertaken to add to information already available concerning the effect of DDT and parathion on pheas-ants, to ascertain whether or not any differences existed between the action of different types of spray machinery, and to test for possible toxic effects of new insecticides currently being considered for com-mercial application in the Okanagan Valley of B r i t i s h Columbia. Consideration was also given to other factors which might have played a part i n the pheasant decline in this region. Both DDT and Parathion w i l l cause pheasant mortality under suitable conditions; parathion has an immediate inhalation toxicity, but because of i t s rapid hydrolyzation does not remain in sufficiently high concentrations to cause serious effects more than a few days after i t s application. DDT, on the other hand, has l i t t l e or no inhalation toxicity, but may remain on the cover in lethal amounts for some time. Other insecticides tested, v i z . methoxychlor, aramite, sulfa-none and #4049, showed no appreciable toxic effects. So far as i s known, the contemplated commercial use of some or a l l of these materials w i l l have the effect of reducing existing pheasant mortality from "~ orchard spraying. It i s expected that the above mentioned materials w i l l replace DDT and parathion in the Okanagan Valley within the next few years. No other insecticides are being considered for general use at the present time. Concentrate spraying machines, which are becoming increasingly numerous in the Okanagan, deposit only about one third as much insecti-cide on the cover as do the hand gun machines. This may result in an increased toxicity of inhalation poisons such as parathion, (owing to the finer spray put out by concentrate machines,) and a decreased effect of ingestion poisons- such as DDT. Birds exposed to f i e l d application of DDT showed a much lower rate of mortality than did birds which were fed the same concentrations in the laboratory. This difference is believed to be due largely to the fact that a deposit of insecticide in an orchard does not remain available to pheasants for a sufficient length of time to exert i t s maximum effect. This may be brought about by a number of factors, including movements and food preferences of the birds themselves, and the mechanical removal of the insecticide by rain and sprinkler i r r i -gation . - 59 -The chemical analysis of dead birds has so far proven unsatisfactory as a means of demonstrating DDT poisoning as a cause of death. Sprinkler i r r i g a t i o n has increased rapidly since 1945, an estimated 50$ of the orchards i n the Okanagan being thus irrigated. There is evidence to show that the use of this type of irrigation tends to render orchards unsuitable as pheasant habitat, both because of the greatly increased disturbance resulting from the operation and moving of the sprinkler systems, and also from the more intensive cover treatment which this method of irrigation permits. Orchard sprinklers may also exert a certain beneficial effect by the removal of deposits of insecticide from the cover crop. This reduction of suitable pheasant habitat i s believed by the writer to be the most serious of the factors whioh are known to affect pheasants in this region. Poisoning by orchard insecticides, while i t undoubtedly has caused a certain amount of mortality, cannot be demonstrated as having been of sufficient severity to be classed as a limiting factor. The effect of weather cannot be precisely determined. Unsuit-able weather conditions are known to have caused pheasant mortality, but the seriousness of cold winters with deep snow, and of wet periods in the summer, cannot yet be analysed. More accurate and local weather information, combined with biological studies, is necessary before con-clusions can be drawn. Hunting pressure has increased very considerably i n the past ten years, but the effect of such an increase is probably more apparent than real. Predation, especially by domestic dogs and cats, may cause some losses, but i t i s not believed to be of significant importance. Other factors, such as possible cyclic fluctuations, and the recession of a species on a new range, have been considered by Benson, but to date no evidence has been presented which would throw light on these p o s s i b i l i t i e s . , In dealing with the problem of the pheasant decline in the Okanagan Valley we are hampered by the lack of information concerning population sizes and productivity before and during the decline. In studying a similar decline i n the Dakotas, Kimball (1948) was able to narrow the causes down to factors resulting in juvenile mortality. No data on reproductive success are available for the Okanagan, and there i s no evidence to indicate whether or not juvenile mortality has been significantly higher in this area during the years of the decline than i t was during the height of pheasant abundance. The qualitative reduction of pheasant habitat previously referred to, however, would be expected to exert i t s chief influence upon reproductive success. Further studies on juvenile mortality i n diverse areas may support this view. SUGGESTIONS FOR FURTHER STUDY As an outcome of the present study, the writer makes the following recommendations for further study: 6a -1. That tests be conducted to determine the effect of methoxychlor, aramite, sulfanone, and #4049 upon the reproduction of pheasants. 2. That pheasants be tested for reaction to com-binations of these materials. 3. That complete and regular censuses of representative areas be taken, together with detailed meteorological information, in order to obtain infor-mation on population trends, and on the effect of weather upon adult mortality and reproductive success. 4. That tests be made of any new insecticides whose widespread use i n the Okanagan Valley is contemplated. None exist at present, but i t is possible that the need for such materials may arise. Dr. James Marshall, Dominion Entomological Laboratory, Summerland, B.C., should be consulted periodically in this regard. 5. That in view of the fact that more than half the agricultural land i n the Okanagan Valley is not devoted to f r u i t growing, and since this area has not been subject to investigation with regard to pheasant populations within recent years, that a study he under-taken to obtain information on factors affecting pheasants on these lands, which have been producing the bulk of the Okanagan pheasant harvest. MANAGEMENT RECOMMENDATIONS There seems to be l i t t l e hope for practical pheasant manage-ment in orchard areas of the Okanagan Valley. Such practices as would benefit the birds are often at variance with the interests of the f r u i t grower, to whom his orchard i s his livelihood, and pheasants at best a source of relaxation i n which he has l i t t l e time to indulge, and at worst a cause of considerable annoyance and possibly injury. The leaving of cover patches in which pheasants might nest undisturbed by mowing or discing would be of considerable value, but most - 62 -growers interviewed did not think such a scheme would be practical, or worth the effort involved. Many orchardists resent the intrusion of hunters who frequently invade their property without permission, damaging f r u i t trees, and endangering the safety of workers in the orchard. While this situation prevails i t is not surprising that the grower is not  particularly interested i n increasing pheasant numbers on his land-Public education, and possibly some system whereby the f r u i t grower may reap a l i t t l e p rofit from the-pheasants on his property would go a long way towards solving this problem. The use of flushing bars has not been attempted in the orchard areas of the Okanagan. It would probably not be practical, because of the d i f f i c u l t y of cutting close to the trees, and of manoevering in circumscribed areas. Adherence to the law forbidding hunting dogs being allowed to roam at large during the nesting season would probably be beneficial. The use of non-toxic insecticides in the control of orchard pests w i l l be helpful. Since the use of these materials is being and w i l l be recommended by the Department of Agriculture, this matter should take care of i t s e l f . I t should be realized that Okanagan orchard areas w i l l probably never again produce the pheasant populations that formerly existed there. Management, at least for the present, should, i n the writer's opinion, be restricted to accurate censusing from year to year, and regulation of the take accordingly, together with public education with the aim of obtaining this harvest with a maximum of cooperation among a l l concerned. - 63 -LITERATURE CITED Benson, W. A. 1950 The effect of orchard spraying on pheasants in the Okanagan Valley with observations on bird-l i f e in orchard areas. M.A.Thesis, University of B r i t i s h Columbia. Br i t i s h Columbia Provincial Game Department. 1912 Annual Reports. 1949 Claborn, H. 1946 V. The determination of DDT in the presence of DDD. J. Assoc. O f f i c i a l Agr. Chemists, 29; 330-33.7,'. Cov/an, I. MoT. 1942. . Economic status of the pheasant on the cultiva-ted lands of the Okanagan Valley, B r i t i s h Columbia, Report of the B r i t i s h Columbia Provincial Game  Commission, :49-63. « Dominion Bureau'of S t a t i s t i c s . 1941. Eighth Census of Canada. Harper, H. T., 1951.. Hart, C M . and Shaffer, D.C Effects of hunting pressure and game farm stocking on pheasant populations in the Sacramento Valley, California, 1946-1949. California Fish and Game, 37 (2) : 141-176. Jackson, W. B. 1950. Wisconsin Conservation Bulletin, 15 (9) s 38. Kimball, J . W. 1948 Pheasant population characteristics and trends in the Dakotas. Trans. North American Wildlife Con-ference, 13; 291-314. - 6'4 -LITERATURE CITED continued 9. Leopold, A., Sperry, J. M., Fenney, W. S.,»iiand Catenhuser, J. A. 1943. Population turnover on a Wisconsin pheasant. refuge. J. Wildlife Mangt. 7 (4) :383-394 10. Lehman, A. J. 1948.. Toxicology of the new agricultural chemicals. Bulletin of the Association of Food and Drug  O f f i c i a l s . 12 (3) 11. Lehman, A. J. 1949.. The major toxic action of insecticides. Bulletin of the New York Academy of Medicine 25 (6)j 382-387. 12. MacArthur, J. / 1949 . Annual report of the Dominion Entomological Laboratory, Summerland, B. C , 1 pp. r 199^122i 13. Marshall, James. 1952. Officer-in-Charge, Dominion Entomological Laboratory, Summerland, B. C., Personal correspondence. 14. Mohr, R. W., Telford, H. S., Peterson, E. H., Walker, K. C. 1951. Toxicity of orchard insecticides to game birds in eastern Washington. Stations Circular  No. 170, Washington Agricultural Experiment  Stations, Pullman, Washington. 15. Ormsby, Margaret A. 1931. M. A. Thesis, University of B r i t i s h Columbia 16. Post, G. 1949. Two new insecticides. Wyoming Wild L i f e , 13 (4) $8. 17. Post, G. 1951.' A study of aldrin insecticide - i t s effects on birds and other w i l d l i f e . Wyoming Wild L i f e , 15 (9) * 4. LITERATURE, CITED continued . . . 18. Provincial Department of Trade and Industry. 1950.. Facts about irrigation and irrigable lands in the tree-fruits area of the.Okanagan and Similkameen Valleys. Publication of the Depart-ment . 19 Scott, C. E., and Madsen, H. 1950. Review of new miticides. California Fruit and  Grape Grower, 4:23. 20 Taylor, E.W. 1950. A study of factors affecting reproduction and survival of the ring-necked pheasant in the lower Fraser River Valley of B r i t i s h Columbia. M.A.Thesis, University of B r i t i s h Columbia. 21. Watt, A. W. 1950. D i s t r i c t Horticulturist, Summerland, B.C. Personal correspondence. 22. Webster, R. L. 1950 New insecticides: their use, limitations, and hazard to human health. Stations Circular No. 64 (Third Revision), Washington Agricultural Experiment  Stations, Pullman, Washington. 23. Wilcox, J. C. 1952. Dominion Experimental Station, Summerland, B. C. Personal correspondence. 


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