UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Comparative analysis of the feeding behaviour of two salamander populations in Marion Lake, B.C. Neish, Iain Charles 1970

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

Item Metadata

Download

Media
831-UBC_1970_A1 N43.pdf [ 6.15MB ]
Metadata
JSON: 831-1.0102232.json
JSON-LD: 831-1.0102232-ld.json
RDF/XML (Pretty): 831-1.0102232-rdf.xml
RDF/JSON: 831-1.0102232-rdf.json
Turtle: 831-1.0102232-turtle.txt
N-Triples: 831-1.0102232-rdf-ntriples.txt
Original Record: 831-1.0102232-source.json
Full Text
831-1.0102232-fulltext.txt
Citation
831-1.0102232.ris

Full Text

A COMPARATIVE ANALYSIS OP THE FEEDING BEHAVIOUR OP TWO POPULATIONS IN MARION LAKE, B.C.  by IAIN CHARLES NEISH B.Sc.(Hon.) D a l h o u s i e U n i v e r s i t y  (1967)  A THESIS SUBMITTED IN PARTIAL FULFILMENT OP THE REQUIREMENTS FOR THE DEGREE OP DOCTOR OP PHILOSOPHY  in  t h e Department  of Zoology  We a c c e p t t h i s to the required  THE  t h e s i s &P c o n f o r m i n g standard.  UNIVERSITY OP BRITISH COLUMBIA O c t o b e r , 1970.  SALAMANDER  In  presenting  this  an a d v a n c e d  degree  the  shall  I  Library  f u r t h e r agree  for  scholarly  by h i s of  this  written  thesis at  the U n i v e r s i t y  make  that  it  may  representatives. for  freely  permission  purposes  thesis  in p a r t i a l  financial  is  of  British  Canada  Columbia,  British  by  for  gain  Columbia  shall  the  that  not  requirements I  agree  r e f e r e n c e and copying  t h e Head o f  understood  Depa r t m e n t  The U n i v e r s i t y  of  for extensive  permission.  V a n c o u v e r 8,  of  available  be g r a n t e d  It  fulfilment  of  or  that  study.  this  thesis  my D e p a r t m e n t  copying  for  or  publication  be a l l o w e d w i t h o u t  my  ABSTRACT  A  comparative  behaviour  and  populations neotenous were of  to  the  of  two  Marion  estimated  lake  (Baird).  information  relevant  of  Lake.  that  The  i n the  Ambystoma.  of  The  for  either  and  constant  substratum.  animals  returned  2449  larvae  A.  gracile  the  s p r i n g and areas  granulosa  were  summer.  with  changed  through  their  home r a n g e s  "wandering" October.  lake  i n mid-summer Fifty  percent  they  in April and  of  left  adult  and the  A.  was  changed  lake  gracile  the  for  dispersed, and  size  vegetation  been  May,  of  total  the  was  displaced  originally through  showed in  and  lake  Although  had  was  determined  within  time.  It  kgm.  Density  different  distribution  popula-  young  409  not  population  positions of  of  gracile  1969  observed  gracile  and  The  the  and  for Taricha  where  entered  and  14,500.  and  A.  areas  granulosa  A.  dynamics  computer  1968  trapped  and  the  T.  and  During  a  and  study  population  represent  between  to  the  populations  young  and  of  construct  were  B.C.,  (Skilton)  These  of  contagious  Lake,  45,500  numbers  T.  feeding  about  kgm.  through  to  granulosa  18  The  and  aims  the  feeding.  about  highly  the  were  lake.  varied  to  Ambystoma T.  the  Marion  The  r e s p e c t i v e l y at  species.  composition  and  adult  there  biomasses  caught  salamander  estimated  year  populations  Taricha  the  of  Taricha granulosa  gracile  model of  b e e n made  structure of  salamanders  salamander  were  second  the  provide  populations  tions  population  Ambystoma  simulation  in  a n a l y s i s has  time.  evidence  September  seen  during  the  breeding  s e a s o n were metamorphosed and  only during A p r i l lake a l l year,  and  May.  were f o u n d i n the  Neotenous a d u l t s remained  as d i d l a r v a e o f the  first  Those l a r v a e which, metamorphosed d i d so early but  September.  no  f o u n d on  s e e n i n T.  m o r t a l i t y was  p r e y e d on by  fish  and  the l a k e  o f the  scent  tadpoles.  this.  T h e r e was  Amphipods and  f e e d i n g Ambystorna.  The  for  6j>"/o  The  salamanders r e a c t e d  with  visual,  no  food  tactile  i n the  A . g r a c i l e were  nocturnal on  the  predators  benthos  distinct  types  and  of  feeders,  that  volume o f T a r i c h a and Sida  crystallina  volume o f w a t e r column f e e d i n g with  feeding  or chemical  b e h a v i o u r when  stimuli.  I t was  such  Ambystorna  d i p t e r a n l a r v a e accounted  cladooeran  o f s a l a m a n d e r had  i n d e p e n d e n t o f the  T a r i c h a o f 5.9  T.  for benthic  accounted Ambystorna. stimulated  concluded  were r e s p o n d e d t o by  animals  lake.  Both s p e c i e s which was  lake  dead s p e c i m e n s were  evidence  that a combination of these s t i m u l i feeding  and  to l o c a t e h i g h d e n s i t i e s of prey  t o t a l stomach c o n t e n t s  of the  but  T a r i c h a were p r i m a r i l y b e n t h i c  capable of u t i l i z i n g  64^  d i v i n g bugs and  i n the w a t e r column had  behaviour.  do  found i n the l a k e  source of  T a r i c h a . Ambystorna f e e d i n g  Ambystorna f e e d i n g  could  No  Ambystorna were f o u n d t o be  i n Marion Lake.  as h a t c h i n g  year.  i n l a t e August  granulosa.  the  bottom.  T a r i c h a and  feeding  second  in  Ambystorna g r a o i l e grew r a p i d l y i n the  g r o w t h was  granulosa  and  lake  - 6.3  cm.  a constant  amount o f f o o d  rate of d i g e s t i o n  i n the  body l e n g t h d i g e s t e d  stomach.  horse heart  at  Male a  iv.  rate  of 0 27 cc/day.  Pemale T a r i c h a 5.2  o  Ambystoma cc/day.  6.1  cm.  food  t i m e s the  d i g e s t i n one  five  The  mean volume o f stomach c o n t e n t s  fed  day  and  amount w h i c h t h e y c o u l d  amount w h i c h c o u l d  i n the  be  digested  at a high  were m a x i m a l l y r e s p o n s i v e between p r e y  Ambystoma  digest  from l a k e  l a b o r a t o r y behaved i n the  were t h e r e f o r e h u n t i n g  period  and  T a r i c h a were c a p a b l e o f e a t i n g s i x t i m e s the  eat  t h a n the  long  0.22  they could  l o n g had  cm.  a d i g e s t i o n rate of  volume t h a t  - 7.7  - 5«6  i n one  day.  same way.  The  t o p r e y and  day.  a n i m a l s was  i n one  level  could  less  Taricha animals  o f h u n g e r when t h e y had  a short r e f r a c t o r y  ingestions.  T a r i c h a were p r e s e n t e d  with  0.042 c c . p i e c e s  of  horse  2 heart  a t d e n s i t i e s o f 8,  daily  r a t i o n and  the  ficantly different  30,  200  /m  on  the  r e s u l t s of the feeding  on  Richardson)  ( i n p r e p . ) and  produced.  equation"  (1959),  by  The  (8/m  .  The  the  signi-  days. 2  (l00/m  When  ), a f t e r eating  s t u d y were combined  rainbow t r o u t  with  b a s e d on H o l l i n g s 1  expanded t o i n c l u d e and  Ware's  (Salmo g a i r d n e r i  a computer s i m u l a t i o n model o f  o f hunger, p r e y v u l n e r a b i l i t y  a  day.  model was  w h i c h was  mean  salamanders  ) t h e y r e s p o n d e d by  first  present  information  a t i o n was  f o r s i x consecutive  to a h i g h prey d e n s i t y  prey density  l a r g e volume o f f o o d The  and  between t h e s e d e n s i t i e s when the  T a r i c h a were s w i t c h e d a t low  100  t i m e between i n g e s t i o n s were n o t  were i^ed a t a g i v e n d e n s i t y  feeding  60,  temperature.  pred-  "disc  some e f f e c t s  V  P r e d i c t i o n s by t h e model were compared five  experiments  horse h e a r t .  i n w h i c h T a r i c h a f e d on t a d p o l e s and p i e c e s o f  The o b s e r v e d  and p r e d i c t e d p r o p o r t i o n s e a t e n  by a mean v a l u e o f 0,9%.  differed  to the r e s u l t s o f  When a p r e y  t y p e was p r e s e n t  i n h i g h p r o p o r t i o n and a t h i g h d e n s i t y t h e model t e n d e d t o slightly and prey  underestimate  tended  to s l i g h t l y  numbers o f t h e more numerous p r e y o v e r e s t i m a t e numbers o f t h e l e s s  eaten numerous  eaten. P r e d a t i o n by T a r i c h a and Ambystorna i n M a r i o n  simulated  L a k e was  f o r t h e months o f May, J u n e , J u l y and A u g u s t .  d e s c r i b i n g seven prey  t y p e s were used  Lake t h e s e p r e y a c c o u n t e d  i n t h e model.  Data  I n Marion  f o r a t o t a l o f 79S& o f t h e volume o f  T a r i c h a stomach c o n t e n t s and 13°/° o f b e n t h i c f e e d i n g Ambystorna stomach c o n t e n t s .  P r e d i c t e d proportions o f prey types  by T a r i c h a were a mean o f 5*3 p e r c e n t a g e  eaten  p o i n t s i n e r r o r and,  p r o p o r t i o n s p r e d i c t e d f o r Ambystorna were a mean o f 19.5 p e r centage  points i n error.  discussed  The.reasons  and p r e d a t i o n s t r a t e g i e s  s a l a m a n d e r a r e compared.  f o rthis discrepancy are  o f t h e t r o u t , m a n t i d and  vi. TABLE OP CONTENTS Page L I S T OF TABLES L I S T OP  viii.  FIGURES  x.  ACKNOWLEDGEMENTS  xiio  INTRODUCTION  1 .  SECTION I . A COMPARISON OP THE S I Z E , STRUCTURE AND DISTRIBUTIONAL PATTERNS OP THE SALAMANDER POPULATIONS OP MARION LAKE.  6.  MATERIALS The  AND  study  Trapping  6.  METHODS  6.  area and  observation  7.  Marking  8.  Population  estimates  9.  RESUL-TS  U.  Ambystorna g r a c i l e  population  14.  Taricha granulosa  population  16.  Trappability  19.  P o p u l a t i o n d i s t r i b u t i o n and  movements  Mortality  26  SECTION I I . A COMPARISON OP THE FEEDING BEHAVIOUR OF THE SALAMANDERS OF MARION LAKE. MATERIALS  Deprivation  28.  curves  Stimulus-response  30.  on f e e d i n g  30.  experiments  32.  experiments  34.  RESULTS Feeding  34.  periodicity  Echogram o f f e e d i n g Retention  eliciting  35.  behaviour  o f f e e d i n g h a b i t s by A.  Stomach c o n t e n t s Stimuli  28. 28.  Temperature e f f e c t s density  0  28.  AND METHODS  Observation  Prey  20.  gracile  38 o  analysis feeding  38.  behaviour  43.  vii.  Page  SECTION  Hunger c u r v e s  46.  Effect  o f t e m p e r a t u r e on d i g e s t i v e r a t e  47.  Effect  o f h u n g e r on f e e d i n g b e h a v i o u r  49.  Effect  of prey  58.  d e n s i t y on f e e d i n g  I I I : A COMPUTER SIMULATION MODEL OP  SALAMANDER 60.  FEEDING- BEHAVIOUR. MATERIALS AND  60.  METHODS  60.  The computer  60.  RESULTS  60.  B a s i c a t t a c k r a t e model Temporal p a t t e r n i n g o f h u n t i n g  bouts  Calculation of reactive distance  68.  Handling  69.  t i m e and p r e d a t o r  Calculation of vulnerable  velocity prey  density  II.  70.  Calculation of digestive rate  71•  Number o f p r e d a t o r s  72.  Number o f p r e y  72.  Simulations  72.  by t h e model  79.  DISCUSSION I.  67o  POPULATION S I Z E , STRUCTURE AND FEEDING  MOVEMENTS  79. 84.  BEHAVIOUR  Reactive  field  84.  Effector  organs  86.  S e a r c h r a t e and p o s i t i o n  87.  Attack  88.  thresholds  P r e d a t o r d i s t r i b u t i o n and t h e f u n c t i o n a l response of predators to prey d e n s i t y Trout  and s a l a m a n d e r e f f e c t s  on  91.  prey  populations  96.  A c c u r a c y o f t h e model p r e d i c t i o n s  97. 99.  SUMMARY LITERATURE  CITED  105.  viii.  L I S T OP  TABLES  TABLE 1.  Ambystoma g r a c i l e p o p u l a t i o n s i z e d a t a t e n o u s a d u l t s and  2.  Areas of capture eight  3.  Page  1  young o f t h e  Occurance o f f i x e d  neo-  second y e a r .  f o r Taricha granulosa  22.  action patterns i n Taricha.  f e e d i n g Ambystoma and  w a t e r column 39.  f e e d i n g Ambystoma. 4.  S a l a m a n d e r stomach c o n t e n t s  5.  Pood i n t a k e and  7.  Table  densities.  model.  Predator  a t t a c k parameters used i n the  Prey  Marion 65.  model.  p a r a m e t e r s u s e d i n t h e M a r i o n Lake 66.  model.  Comparison of observed and  57,  62.  predator  predator 9o  fed at f i v e prey  o f symbols u s e d i n t h e M a r i o n Lake  Lake p r e d a t o r 8.  40.  data.  time between i n g e s t i o n s o f  Taricha granulosa 6.  12.  caught  d u r i n g 1970.  o r more t i m e s  benthic  for  and  proportions of tadpoles  eaten  p r e d i c t e d numbers and  horse  heart  i n T a r i c h a predation experiments.  76  0  ix.  TABLE 10o  Page Comparison o f observed  and p r e d i c t e d  t i o n s o f p r e y e a t e n by M a r i o n Lake  propor-  Taricha  and Ambystoma. 11.  Predicted  numbers o f p r e y e a t e n by  Lake s a l a m a n d e r s August.  77,  during  May,  June,  Marion J u l y and 78.  X  L I S T OP FIGURES  FIGURE IA.  Page Map o f M a r i o n  L a k e showing t h e p o s i t i o n  o f the 11  trapping grid.  11.  IB.  Map o f s u b s t r a t u m  types i n Marion  Lake  2.  Ambystorna g r a c i l e  sise  distributions  plotted ferent 3.  through  time  substratum  frequency  0  and between a r e a s o f d i f 13.  type.  Taricha granulosa adult  size  frequency d i s ~ 17.  tributions. 4.  Weekly c a t c h e s in  (1969)  o f T a r i c h a granulosa,  a r e a s o f Marion Lake h a v i n g d i f f e r e n t  sub-  s t r a t u m t y p e s and i n t h e l a k e a s a whole. 5.  A plot  0  showing t h e r e l a t i o n s h i p  18„  between t h e  t i m e d u r i n g w h i c h T a r i c h a g r a n u l o s a were marked and t h e mean number o f t i m e s  that 24°  t h e y were r e c a p t u r e d , 6.  Schematic  diagram  o f the apparatus  used i n 33.  prey d e n s i t y experiments. 7.  Hunger c u r v e s o f male T. g r a n u l o s a v e n t l e n g t h 5.9 (5.2 -  (6.1  5.6  -  6 » 3 cm.) f e m a l e  cm.) andA, g r a c i l e  - 7 . 7 cm.).  (snoutT.granulosa  o f both  sexes  45o  FIGURE 8.  Page The e f f e c t  o f t e m p e r a t u r e on T a r i c h a  granulosa  digestive rate. 9.  48.  " R e f r a c t o r y p e r i o d " i n seconds a g a i n s t volume o f f o o d  plotted  t o be e a t e n  before  satiation.  53.  10.  The p r o b a b i l i t y  of T a r i c h a nosing a prey.  11.  The mean time  12.  The p r o b a b i l i t y o f T a r i c h a p e r f o r m i n g  spent  by T a r i c h a i n n o s i n g  54. food.  an i n -  complete f e e d i n g sequence. 1 3 .  56o  F l o w d i a g r a m t o show t h e f l o w o f computations  14.  i n t h e M a r i o n Lake p r e d a t o r model.  61.  P r o p o r t i o n s o f f o o d e a t e n a s p r e d i c t e d by t h e model p l o t t e d  against proportions  observed  i n a c t u a l stomach c o n t e n t s . 15.  55»  75.  R e l a t i o n o f a t t a c k t h r e s h o l d s t o each shown i n t h e f o r m a t 3 4 ) .  of Holling  other  (l966 F i g . p  89.  xii.  ACKNOWLEDGEMENTS  The work d e s c r i b e d i n t h i s support  o f an I n t e r n a t i o n a l B i o l o g i c a l P r o g r a m g r a n t t o D r .  I.E. E f f o r d W.S.  t h e s i s was done w i t h t h e  and a g r a n t  i n a i d of research presented  Hoar by t h e N a t i o n a l R e s e a r c h  course  of this  study  s c h o l a r s h i p from  I was  Council.  supported  During the  by a b\a.rsary and a  the N a t i o n a l Research  I am v e r y g r a t e f u l f o r t h i s s u p p o r t .  t o Dr.  C o u n c i l o f Canada. I am  indebted  t o Mr.  P. P r i n c e and Mr. B. H e n d e r s o n f o r a s s i s t a n c e w i t h t h e work, t o Mr. B. P a i r b a i r n and Mr. R. D e l u r y  field  f o r assistance  w i t h some o f t h e l a b o r a t o r y work and t o Mrs. D. L a u r i e n t e f o r a s s i s t a n c e w i t h t h e computer p r o c e s s i n g o f d a t a . due t o D r s . W.S. Holling this  Hoar, I . E . E f f o r d ,  P.A.  Thanks a r e  L a r k i n and  C.S.  f o r a d v i c e and a s s i s t a n c e w i t h v a r i o u s a s p e c t s o f  study.  D u r i n g my  work w i t h t h e M a r i o n  Lake  study  f r u i t f u l d i s c u s s i o n s were h e l d w i t h many w o r k e r s on t h e project.  Special  Mr. Dan Ware, my thesis.  thanks  a r e due t o Mr. George C a l e f and  c o - w o r k e r on t h e m o d e l l i n g p o r t i o n o f t h i s  INTRODUCTION  Animal f e e d i n g behaviour has been s t u d i e d by a number of d i s c i p l i n e s .  scientifically  In r e a d i n g the s c i e n t i f i c  liter-  ature one f i n d s that a t l e a s t f o u r approaches have been used. They may  be c a l l e d the p h y s i o l o g i c a l psychology, e t h o l o g i c a l ,  e c o l o g i c a l , and n a t u r a l h i s t o r y approaches which may  be  d e s c r i b e d as f o l l o w s : a)  P h y s i o l o g i c a l psychology approach -  Physiologists  and p s y c h o l o g i s t s have g e n e r a l l y concerned themselves with the endogenous aspects of the m o t i v a t i o n and c o n t r o l of f e e d i n g . Mammals such assthe dog, cat,monkey, white r a t and white mouse have been the favoured t e s t animals and l i t t l e  emphasis has  been placed on the comparative study of f e e d i n g behaviour (Beach, 1 9 5 0 ) .  Almost a l l p h y s i o l o g i c a l psychology has been  done i n the l a b o r a t o r y with l i t t l e  a t t e n t i o n to the  sig-  n i f i c a n c e of feeding behaviour to the animal's p o s i t i o n i n an ecosystem.  The experimental methods have u s u a l l y i n v o l v e d  s u r g i c a l , hormonal or mechanical manipulation of the t e s t animal's sense or e f f e c t o r organs. ing  The " i n t e n s i t y " of f e e d -  behaviour has been measured e i t h e r i n terms of the  animal's a b i l i t y to perform c l e a r l y d e f i n e d t a s k s i n the l a b o r a t o r y (eg. a b i l i t y to run a maze, amount o f food eaten, number of button pushes) or i n terms of p h y s i o l o g i c a l and anatomical measurements (eg. o b e s i t y , l i v e r glycogen  level  9  s p i k e p a t t e r n s on an b)  E t h o l o g i c a l approach -  been t y p i f i e d animals  electroencephalogram).  by a c o n c e r n w i t h t h e c o m p a r a t i v e  i n nature.  behaviour  The e t h o l o g i c a l a p p r o a c h h a s study  of intact  E t h o l o g i s t s have u s u a l l y a n a l y s e d  a f t e r observing animals  Many e t h o l o g i c a l e x p e r i m e n t s  i n nature  feeding  or i n enclosures.  i n v o l v e the manipulation o f  o b j e c t s i n the environment r a t h e r than m a n i p u l a t i o n o f the animal's  e f f e c t o r o r sense  organs but the t e s t  animal  itself  is  sometimes t r e a t e d w i t h hormones and o t h e r c h e m i c a l s ,  or  mechanical c)  has  devices.  E c o l o g i c a l approach -  studied feeding behaviour  flow through  an ecosystem.  Traditionally  as a process  P r e d a t i o n has been regarded  I n the e c o l o g i c a l l i t e r a t u r e  been r e p r e s e n t e d as a simple mathematical for to  d) orted any  treatment  attempt  behaviour.  Many a u t h o r s have without  to assess the processes u n d e r l y i n g t h e i r  rep-  making, findings.  i n t h e b u i l d u p o f l a r g e numbers o f m i s -  cellaneous o b s e r v a t i o n s , anecdotes, analyses.  T h i s has u s u a l l y l e d  o b s e r v a t i o n s on f e e d i n g b e h a v i o u r  T h i s has r e s u l t e d  f o r the  ( s e e H o l l i n g , 1966  of feeding  N a t u r a l h i s t o r y approach -  field  o f energy  component i n a c a l c u l u s - b a s e d  o f p r e d a t i o n models).  a rather simplistic  as a  f e e d i n g h a s commonly  model o f p o p u l a t i o n p r o c e s s e s  a b r i e f review  the e c o l o g i s t  i n v o l v e d i n energy  source o f m o r t a l i t y f o r the prey andsa source predator.  surgery  and stomach  I n the salamander l i t e r a t u r e  alone,  contents stomach  contents  3.  analyses have been p u b l i s h e d by Anderson (1968), (1918), Earner  (1947), Martof  Chandler  (1957), Morgan (1932), Schonberger  (1944) and S l a t e r (1962), t o name j u s t a few.  Scientific  j o u r n a l s such as Copeia and H e r p e t o l o g i c a c o n t a i n notes and observations o f t h i s s o r t i n almost every i s s u e . The f o u r approaches o u t l i n e d above are not n e c e s s a r i l y represented by d i s c r e t e bodies o f knowledge though i n the past there has been a r e s t r i c t e d flow o f i n f o r m a t i o n between people employing them.  In the past decade, however, there has been  some tendency f o r researchers t o study f e e d i n g u s i n g elements o f a l l approaches.  behaviour  This hsabeen true o f the  work done i n De R u i t e r ' s group i n Holland  (Redingius,  pers.  comm.) and R o l l i n g ' s group i n Canada and i t i s true o f the study described here. H o l l i n g ' s technique  o f "experimental  components a n a l y s i s "  (1963, 1966) has been used i n t h i s study to t i e i n f o r m a t i o n together and t o i n t e g r a t e i t i n t o the present body of knowledge regarding the subject o f f e e d i n g behaviour.  The predator  model constructed here was based on H o l l i n g ' s mantid model (1966).  When the present model was constructed by D. Ware  and the author i t was designed  f o r s i m p l i c i t y o f use.  Our  i n t e n t was t o use few enough parameters t h a t simple measurements would provide the i n f o r m a t i o n necessary f o r use with any predator.  to adapt the model  I t was hoped that the p r e c i s i o n  l o s t by t h i s approach would be o f f s e t by the ease with which the model could be used.  4.  The work d e s c r i b e d i n t h i s t h e s i s was  done as p a r t of an  e c o l o g i c a l study of Marion Lake, B r i t i s h Columbia.  Predation  i s one of many processes which are being s t u d i e d so that a r e a l i s t i c a n a l y s i s o f energy flow i n t h i s a q u a t i c ecosystem can be made.  Marion Lake c o n t a i n s f o u r predatory a q u a t i c  vertebrates.  Two  Richardson (Kokanee).  of these are the salmonid  f i s h Salmo g a i r d n e r i  (Rainbow t r o u t ) and Onoorhynchus nerka Walbaum The other two are salamanders.  One  i s the P a c i f i c  coast newt, T a r i c h a granulosa S k i l t o n and the other i s a neotenous form of the Northwestern salamander Ambystoma g r a c i l e Baird.  The f i r s t two  s e c t i o n s of t h i s t h e s i s r e f e r to work done  by the author on salamanders.  The l a s t s e c t i o n , the computer  s i m u l a t i o n modelling, i s : p a r t of a paper done i n c o - o p e r a t i o n with Mr. Dan Ware, who  has worked on Salmo g a i r d n e r i .  The  model could not have been constructed i n i t s present form without  the combined i n f o r m a t i o n and e f f o r t s of Mr. Ware and,  myself. In the present i n v e s t i g a t i o n salamanders have been s t u d i e d as predators r a t h e r than as salamanders.  They were s e l e c t e d  as a subject f o r t h i s study because they were p l e n t i f u l , to keep i n the l a b o r a t o r y , they were of a convenient  easy  size,  t h e i r n a t u r a l h i s t o r y and morphology had been s t u d i e d , they fed r e a d i l y i n the l a b o r a t o r y and they were present i n Marion Lake, where a l a r g e body of data was  being c o l l e c t e d on the  h a b i t a t i n which the salamanders were found.  5.  The present i n v e s t i g a t i o n was  intended as a  comparative  a n a l y s i s of p r e d a t i o n by e n t i r e p o p u l a t i o n s of animals. aims of t h i s study were as f o l l o w s : 1.  To determine the s i z e and s t r u c t u r e of the  a d u l t p o p u l a t i o n s of the T a r i c h a and Ambystoma i n Marion Lake and to determine the s i z e of salamander l a r v a p o p u l a t i o n s i f t h i s proved be 2.  to  feasible. To determine the s p a t i a l d i s t r i b u t i o n of  both salamander p o p u l a t i o n s d u r i n g d i f f e r e n t times of the year. 3.  To f i n d out what prey the Marion Lake  salamanders were e a t i n g . 4.  To c o n s t r u c t an ethogram of salamander  feeding 5.  behaviour.  To c o n s t r u c t a computer s i m u l a t i o n model  of salamander p r e d a t i o n u s i n g expe r i m e n t a l components a n a l y s i s .  This model was  intended to  d e s c r i b e the behaviour of the salamander once i t had found an area where prey were present. was  It  not intended to d e s c r i b e the l o c a t i o n of  hunting areas by salamanders.  The  6.  SECTION I A COMPARISON OP THE S I Z E , STRUCTURE AND D I S TRIBUTIONAL PATTERNS OP THE SALAMANDER POPULATIONS OF MARION I A K E .  MATERIALS AND METHODS The  study area -  lake situated about  M a r i o n L a k e i s a s m a l l mud  10 km. n o r t h o f Haney, B r i t i s h  coniferous forest.  of the l a k e see E f f o r d A substratum (Pig. 1).  Por a d e t a i l e d  when  wooded  description  (1967).  map o f t h e l a k e was made d u r i n g a d i v i n g Seven substratum  o f w a t e r d e p t h and v e g e t a t i o n t y p e . substratum  It is  The l a k e i s s i t u a t e d a t  300 m. e l e v a t i o n i n a n o r t h - s o u t h v a l l e y h e a v i l y  with secondary  survey  Columbia.  10 h e c t a r e s i n a r e a d u r i n g t h e d r y summer s e a s o n  most o f t h e p r e s e n t work was done. about  bottomed  o f sediment  t y p e s were d e f i n e d i n t e r m s "Open mud" a r e a s had a  c o n t a i n i n g s t i c k s and l e a v e s .  During  t h e summer a s p a r s e c o v e r o f f i l a m e n t o u s a l g a e o c c u r r e d i n open mud a r e a s d e e p e r  t h a n 1m.  w i t h a t h i c k mat o f a l g a e . as  S h a l l o w e r a r e a s were  The s u b s t r a t u m  covered  type r e f e r r e d t o  "submerged v e g e t a t i o n " i n c l u d e d a r e a s h a v i n g a g r o w t h o f  Potamogeton e p i h y d r u s Isotes occidentalis on t h e l a k e b o t t o m .  ( R a f . ) , Chara  (Henders.).  g l o b u l a r ! s ( T h u i l l ) and  These p l a n t s formed a mat  Potamogeton n a t a n s  ( L . ) and E q u i s e t u m  ep.  a r e s p e c i e s o f emergent p l a n t s w h i c h o f t e n o c c u r r e d t o g e t h e r so a r e a s c o n t a i n i n g t h e s e s p e c i e s were c o n s i d e r e d a s one sub—  7  stratum was  type.  the l i l y  The pad  grew i n w i d e l y some c a s e s  P.  l a r g e s t emergent m a c r o p h y t e i n M a r i o n L a k e  Nuphar p o l y s e p a l a  (Bngelm.).  s p a c e d clumps w i t h open mud n a t a n s grew among N.  These  between them.  polysepala.  The  s h a p e s o f weed b e d s i n M a r i o n Lake change f r o m y e a r T h i s c a n be  clearly  October 1 9 6 8  and  and  1966  observation  April  - During  the  (Davies,  T.  mounted on  seen i n water hot  the  to escape the d i p n e t  e x c e p t when the  t h a n 10°C.  T h i s s p e c i e s was  with  a b o u t 1m.  the 1 9 6 9  study  according  a  species  a dipnet.  Ambystoma  w a t e r was  colder gun"  a spring  period that p o r t i o n of surveyed  from a boat  week. During  J u l y , A u g u s t and  f u n n e l t r a p s were d i s t r i b u t e d two  stern of  i n length with  t h e l a k e l e s s t h a n 3 m e t e r s i n d e p t h was  every  A.  u s u a l l y caught u s i n g a " s l u r p  which i s a s y r i n g e - l i k e d e v i c e During  to  deeper than 3 meters.  were a b l e  b)  1969  and  calm both  captured  once p e r  year.  1970).  granulosa  Prom t h e b o a t T a r i c h a c o u l d be  plunger.  to  and  t h e months o f J u l y  A t n i g h t when t h e l a k e s u r f a c e was  o f s a l a m a n d e r c o u l d be  loaded  sizes  f o l l o w i n g methods:  A s e t o f f l o o d l i g h t s was  rowboat.  data  to October, 1 9 6 9 ,  g r a c i l e were o b s e r v e d by a)  In  seen i f P i g . 1 i n t h i s paper (showing  d a t a ) i s compared w i t h D a v i e s ' Trapping  plants  days.  In 1969  to a g r i d  September 1 9 6 8 ,  a r o u n d t h e l a k e and  f u n n e l t r a p s were p l a c e d  pattern  (Pig. 1).  The  grid  75 wire  mesh  were c h e c k e d i n the  consisted  lake of  2 114  traps placed  a t the  corners  o f 1000  m  quadrats.  Auxiliary  8.  t r a p s were p l a c e d a l o n g t h e s h o r e l i n e , traps.  These were a l l c h e c k e d  five  giving a total  o f 132  t i m e s p e r week d u r i n g t h e  p e r i o d May 1 t o September 15 and t w i c e p e r week u n t i l m i d October.  The t r a p p i n g p r o g r a m was d i s c o n t i n u e d a t t h i s  b e c a u s e v e r y few Ambystorna and no T a r i c h a were b e i n g c)  Once p e r week f r o m  e n t i r e l a k e was s u r v e y e d gear.  Marking  -  w i t h t h e u s e o f s k i n and SCUBA d i v i n g  A l l T a r i c h a c a p t u r e d by t h e above methods were Immediately a f t e r  measurement o f e a c h a n i m a l  s e x was d e t e r m i n e d time  c a p t u r e d by a d i v e r b u t  by h a n d .  marked w i t h i n d i v i d u a l t o e c l i p s . the snout-vent  caught.  May 1 t o September 1 5 , 1969, t h e  Ambystorna c o u l d n o t be e a s i l y  many T a r i c h a were c a u g h t  time  capture  was r e c o r d e d ; i t s  and i f t h e a n i m a l was;caught f o r t h e f i r s t  i t was marked.  The a n i m a l  was t h e n r e l e a s e d a t t h e s i t e  o f c a p t u r e , u s u a l l y w i t h i n a few m i n u t e s o f b e i n g removed the  from  water. I n d i v i d u a l m a r k i n g o f A, g r a c i l e was done o n l y d u r i n g t h e  summer o f 1968.  The r e g e n e r a t i v e powers o f l a r v a l  Ambystorna were s u c h therefore decided rakers. animals  that toe c l i p s  c o u l d n o t be u s e d .  T h i s was done t o 5Q4 a n i m a l s  i n the l a k e .  marked i n t h i s way d i d n o t l o s e  captured  Laboratory  t h e i r marks b u t t h e  consuming a n d t h e r e t u r n s were so l o w (16  recaptures) that this gracile  I t was  t o l o o p c o l o r coded t h r e a d s a r o u n d t h e g i l l  method was so t i m e  A.  and n e o t e n o u s  program was n o t c o n t i n u e d  i n grid  i n 1969. A l l  t r a p s were measured and t h e  9.  Ambystoma c a t c h r e c o r d t e n o u s A. g r a c i l e Population  c o u l d n o t be a c c u r a t e l y estimates  was d e t e r m i n e d u s i n g estimate the  o f e a c h t r a p was k e p t .  -  The s i z e  The s e x o f n e o -  determined.  of the Taricha  the mark-recapture r e s u l t s  population  o f 1969.  The  was c a l c u l a t e d u s i n g t h e Schumacher m o d i f i c a t i o n o f  Schnabel estimator  (equation  I n view o f the d i f f i c u l t y was d e c i d e d  to estimate  18, p . 101 i n R i c k e r , 1 9 5 8 ) .  e n c o u n t e r e d i n m a r k i n g Ambystoma. i t  the size  o f t h e A. g r a c i l e  population  u s i n g t h e f o l l o w i n g method: a)  A l l A. g r a c i l e  caught i n t h e Marion Lake t r a p  were c o u n t e d and ( a f t e r June 16) t h e i r  grid  snout-vent lengths  were  measured. 2 b)  A l l A. g r a c i l e  were removed by t r a p p i n g f r o m t h r e e  plywood pens s i t u a t e d i n M a r i o n L a k e . were t h e n p l a c e d  i n these  9m  Known numbers o f a n i m a l s  pens and were a l l o w e d  to settle  down  f o r a b o u t two weeks. c)  On 10 n i g h t s d u r i n g J u l y andAAugust 1969 a g l a s s  bottomed b o a t was rowed a l o n g  grid  t r a n s e c t s i n t h e 1-2m.  open mud p o r t i o n o f t h e l a k e , w h i c h o c c u p i e d bottom.  deep  21 $ o f t h e l a k e  The t r a n s e c t s were 1 m e t e r wide and had a mean l e n g t h  o f 275 m e t e r s .  The t o t a l number o f A. g r a c i l e  s e c t was r e c o r d e d . recordings  On t h e n i g h t s when t r a n s e c t s were r u n  were made o f t h e number o f a n i m a l s w h i c h c o u l d be  s e e n i n t h e plywood e n c l o s u r e s . the percent  seen p e r t r a n -  A. g r a c i l e  This allowed  a calculation of  exposed a t t h e time o f s a m p l i n g .  10  d)  The number o f A. g r a c i l e / m  on the t r a n s e c t s was c a l -  c u l a t e d as f o l l o w s : D = Nx1OO/P A  (1)  where D = density N = number o f animals seen on t r a n s e c t P = percentage o f animals observed i n enclosure A = area of t r a n s e c t C o r r e c t i n g f a c t o r s were employed to determine the d e n s i t y of A. g r a c i l e i n subhabitats f a c t o r s were obtained  other than 1-2m. open mud.  These  ae f o l l o w s : C = Ni Nm  (2)  where C ss the c o r r e c t i n g f a c t o r Ni = the mean number o f animals p e r t r a p i n subhabitat " i f ( T a b l e 1 ) . Nm ss the mean number o f animals p e r trap i n the 1-2m. open mud p a r t of the l a k e . I t was assumed that the c a t c h a b i l i t y o f A. g r a c i l e d i d not vary between subhabitats. The  number of animals i n each subhabitat  determined by the f o l l o w i n g  could be  expression:  Nj = DxCxAj  (3)  where Nj = the estimated number of A. g r a c i l e i n subhabitat "j". D as estimated d e n s i t y o f animals i n 1-2m. mud C = correcting factor Aj 0 area o f subhabitat "j".  11.  Pig.  1.  M ps o f Marion Lake.  A.  The g r i d s y s t e m shown was marked i n t h e l a k e  a  by  means o f numbered f l o a t s a t t h e i n t e r s e c t i o n o f t r a n sects.  The a r e a s e n c l o s e d i i n h e a v y l i n e s a r e r e f e r r e d  t o i n F i g . 34 B.  A map  and i n t h e t e x t .  o f s u b s t r a t u m t y p e s , w h i c h were  i n terms o f v e g e t a t i o n  and w a t e r d e p t h .  defined  O p e n mud; 0-1 m. I ];1-2m. i « * l ; 2 - 3 m . ^ i " ^ ^ ^ Nuphar polysepala ; P o t a m o g e t o n natans & Equisetum sp.E^M Submerged v e g e t a t i o n ; Dry a r e a s i H I I I I .  •  <*$ CD  Tl  cd  ft  ft  CO  a fl  •rl  0)  CD  CD  • o  a  #  caught  CM  1  3 o  CO  No 9 animals  Tt  ta a  cd +> •H ' o• •= u CD cd CD  fl•rl  H  t> ft  — '  ta > ft CD  Tl  CD  Tl  CD  ta u a CD  a + 7* CO  CM * —  a  a  T—  1  o  Tl  a  to  *—  CM  i  C A  Tl  Tl  T J  a  a  aa  A  A  CD  . g  a  A  a  CM  CD  CD  CD  ft  ft  ft  o  o  O  A  ft  O  618  216  201  64  203  239  106  116  1762  23  10  10  8  12  25  13  13  114  26.9  21 .6  20.1  7.9  16.9  9.6  8.2  6.4  15.5  10.8  7.4  6.1  4.5  8.0  6.3  4.2  3.7  Correcting factor  2.79  2.25  2.09  0.82  1 .76 1.00  0.85  0.67  Area o f substratum(m )  5481  9795  7020  5290 17190 30245 15015 19800 109836  A. g r a c i l e / m  t.19  0.96  0.89  0.35  0.43  0.36  0.29  0.56  6500  9364  6234  1846 12858 12854  5420  5643  60719  6,5  7.1  6.7  6.7  6.1  6.6  7.2  7.2  6.7  biomass/m (gm) 7.7 T o t a l biomass(kgm) 42.3  6.8  6.0  2.4  4.6  2.8  2.6  2.1  3.7  67.0  42.1  12.5  12.5  79.0  85.6  38.9  408.5  5.0  8.9  6.4  4.8  15.7  27.5  13.7  18.0  10.3  16.4  10.3  1.2  19.3  21 .0  9.5  10.1  No. t r a p s Mean no. / t r a p i  1 S.E.  2  T o t a l no. A. g r a c i l e Mean wt. A. gracile(gm) Estimated  2  Percent o f lake area Percent o f biomass TABLE 1,  0.75  1 .61  Ambystorna g r a c i l e p o p u l a t i o n s i z e data f o r neotenous a d u l t s and young  o f the second year.  The data were c o l l e c t e d over 79 t r a p p i n g days between June  3 and September 19, 1969.  The mean percentage  n i g h t was 35.8$ (range of 21.0$ - 52.4$).  o f animals hunting on a g i v e n  The mean number of animals seen on  a t r a n s e c t through 1-2m open mud was 0.425/m . 2  13.  Fig.  2  Ambystoma g r a c i l e  through  time  and  size  frequency d i s t r i b u t i o n s  between a r e a s w i t h d i f f e r e n t  plotted  substrata.  June N = 385 x = 4.53  25-  Julyl-16 N = 349 _ x = 5.16  July?7-31 N = 354 J x =5.25  Nx=4.= 1 602 9 5  POOLED DATA September N=201 J x=4.46  August N=314 xs5.17  2015-  c 3  D"  5-  J . c 25-  mud 0-lm. N = 147 x=4.53 '  Jl  J  II  mud 1-2 m. Nuphar polysepala N = 202 N = 503 x= 4.87 x = 4.80 -  0)  Jll  I*.  submerged P.natans &Equ»setum vegetation N= 345 N = 216 x = 5.28 " x = 4.99  °-2015105ro  Llil  T  5  , • • • • • • •5• f i i i i i i i i iuo 5 ro 5 ro 5 Body l e n g t h (cm.) T  •I'O n  ....I  To  N--189 Ii  mud 2+/J)" x=5.30  14.  The t o t a l oftheee  f igureBgives an i n d i c a t i o n of the  total  l a k e p o p u l a t i o n , e x c l u d i n g young o f the year which were not caught i n f u n n e l t r a p s and were not seen on the t r a n s e c t . only animals i n c l u d e d i n the estimate  The  are l a r v a e i n t h e i r  second summer and neotenous a d u l t s . e)  Over the 1969  g r a c i l e per trap was  t r a p p i n g p e r i o d the mean number of A.  c a l c u l a t e d f o r each substratum  type.  RESULTS Ambystorna g r a c i l e p o p u l a t i o n -  The  estimated  A.  gracile  p o p u l a t i o n approximated about 14,500 a d u l t s and 45,000 young of the second year (Table 1 and P i g . 2 ) . t o t a l mid-summer biomass of 408  T h i s represents  a  kgm.  Size class d i s t r i b u t i o n s -  The  t i o n s of A. g r a c i l e through time and  s i z e frequency  distribu-  through space r e v e a l e d  three main s i z e c l a s s e s w i t h i n the p o p u l a t i o n ( P i g . 2 ) . a)  Young of the year -  These animals were about 0.9  l o n g when they hatched from t h e i r eggs d u r i n g May  and  cm.  June.  Larvae were not r e c r u i t e d i n t o the trapped p o p u l a t i o n u n t i l September probably  because of t h e i r 6mall s i z e and  their  tendency not to move around u n t i l t h e i r l e g s are f u l l y d e v e l oped at 2.5 In May  to 3.5 1970  cm.  d u r i n g a Rana aurora egg count an attempt  made to count A . g r a c i l e eggs.  Although Ambystorna eggs were  o f t e n d i f f i c u l t to see about 750 and  egg masses were d i s c o v e r e d  these were d i s t r i b u t e d i n a l l quadrats of the l a k e .  was  15.  Lindsey  (1966) f o u n d  t h a t t h e mean number o f egg6 f o u n d  egg masses was 47.4.  Reckoned on t h i s b a s i s a t l e a s t  l a r v a e o f Ambystorna e n t e r e d t h e p o p u l a t i o n i n 1970. be a n u n d e r e s t i m a t e  i n 22  35.000 T h i s may  s i n c e many egg masses were p r o b a b l y n o t  found. b) of  Young o f t h e p r e v i o u s y e a r -  I n J u n e 1969 a b o u t  t h e t r a p p e d a n i m a l s were one y e a r o l d .  78$  A t t h i s time the  l a r v a e e n t e r i n g t h e i r s e c o n d y e a r were 1.5 t o 5.5 cm. i n body l e n g t h , w i t h t h e h i g h e s t p r o p o r t i o n o f them b e i n g between 4.0 and  4.5 cm. l o n g ( F i g . 2 ) .  By A u g u s t  most o f t h e s e  animals  were 4*5 "to 5.0 cm. l o n g and much o f t h e i n c r e a s e i n mean population size growth. of  d u r i n g t h e summer was no doubt  I n l a t e August  and e a r l y  September a l a r g e p r o p o r t i o n  t h e s e c o n d y e a r a n i m a l s metamorphosed.  formed  i n the s i z e  y e a r formed  due t o t h e i r  The peak w h i c h t h e y  d i s t r i b u t i o n d i s a p p e a r e d and young o f t h e  a peak i n t h e l o w e r s i z e  ranges  as they e n t e r e d  the trapped p o p u l a t i o n . Second y e a r a n i m a l s formed  almost  the e n t i r e  A.  p o p u l a t i o n i n 1m. deep a r e a s w i t h a n open mud b o t t o m . s u b h a b i t a t s i n t h e l a k e t h i s age c l a s s  gracile In a l l  was i n t h e m a j o r i t y  a l t h o u g h t h e y were i n r e l a t i v e l y low p r o p o r t i o n i n deep a r e a s and  beds o f Potamogeton n a t a n s c)  Adults -  Efford  M a r i o n Lake A. g r a c i l e  less  andEquisetum  and M a t h i a s  sp.  (1969) have f o u n d  that  t h a n 5.0 cm, l o n g d i d n o t p o s s e s s  16.  gonads but i t appeared that most animals matured a t about 5 . 5 to  6.0 cm. body l e n g t h .  morphosis may  occur.  were of a d u l t  size.  T h i s i s a l s o the s i z e at which meta-  In June about 22$ o f the animals trapped  About 35$ of the neotenoueadult A . g r a c i l e caught were i n open mud  areas deeper than 2m.  about 40$ of the p o p u l a t i o n .  In these areas a d u l t s formed Very few a d u l t s were caught i n  shallow open mud a r e a s . I t was found that not a l l o f the A . g r a c i l e a d u l t s breeding i n Marion Lake were neotenous.  In A p r i l 1969 on nine n i g h t s o f  o b s e r v a t i o n 106 metamorphosed and 117 neotenous a d u l t s were seen. These numbers were not s i g n i f i c a n t l y d i f f e r e n t from a 50:50 r a t i o CX ,p = » 0 1 ) . of  Only three breeding p a i r s were seen, a l l  which c o n s i s t e d of a metamorphosed male and a neotenous  female.  I t was not known what p r o p o r t i o n o f the a d u l t popula-  t i o n bred during the year. to have l e f t  A l l metamorphosed a d u l t s appeared  the l a k e by the f i r s t week i n May.  T a r i c h a granulosa p o p u l a t i o n -  The T. g r a n u l o s a popula-  t i o n was estimated at 2450 with the 95$ confidence l i m i t s ranging from 2363 to 2542.  The mean weight of a d u l t T a r i c h a  was 7.5 gni. so the t o t a l l a k e biomass of t h i s animal was 18 kgm.  about  L i t t l e was discovered about the eggs and l a r v a e of T.  granulosa. small clumps  This animal i s known to l a y i t s eggs s i n g l y or i n (Chandler, 1918) and females were seen l a y i n g  eggs i n t h i s way i n Marion Lake.  The eggs were very s m a l l ,  however, and could not be found i n the l a k e , d u r i n g d i v i n g  17.  Fig.  3.  Taricha  granulosa adult  size  frequency  distributions.  MALES  15-  n=805 x = 5.82±.01(s.E.)  10-  g5D  Offi  •  $1  cr c  FEMALES n=945 X = 5.48±.00(S.E.  QQ  10-  5-  5.0  6.0  Body length ( cm.)  7.0  18.  Fig.  4.  Weekly c a t c h e s  having d i f f e r e n t a whole.  (l96°) o f T a r i c h a g r a n u l o s a i n a r e a s  types o f substratum  The c a t c h e s a r e t h e t o t a l r e s u l t  d i v i n g and n e t t i n g f r o m b o a t s . i n g was done. ated from The  and i n t h e l a k e a s of trapping,  D u r i n g week 14 no  The p r o b a b l e d i v i n g c a t c h was  t h e numbers o f a n i m a l s  caught  div-  extrapol-  by o t h e r methods  a r e a numbers shown r e f e r t o t h e a r e a s shown i n F i g .  1 A.  19.  excursions.  Very few T a r i c h a l a r v a e were found i n the l a k e .  These animals were too s m a l l t o be caught i n f u n n e l  traps  f r e q u e n t l y and i t i s probable t h a t many o f those l a r v a e were erroneously  trapped,  i d e n t i f i e d as A. g r a c i l e l a r v a e .  In e a r l y August 1969 the f i r s t T a r i c h a l a r v a e o f i t h e year were found i n the l a k e .  Pour o f the f i v e l a r v a e caught had a  body l e n g t h o f 2.5 - 2.7 cm. and were undergoing metamorphosis to the t e r r e s t r i a l stage when they were caught.  One specimen  caught on August 20 was 0.9 cm. i n l e n g t h and had reached the stage o f development where i t had two toes on each hind f o o t . The  s i z e frequency d i s t r i b u t i o n s o f male and female  a d u l t T a r i c h a approximated a b e l l shaped curve ( F i g . 3 ) . No . seasonal changes i n s i z e c l a s s d i s t r i b u t i o n could be recorded i n e i t h e r sex s i n c e T a r i c h a i s a very slow growing animal. The mean growth r a t e o f males i s 0.93 mm/yr and that o f females i s 0.59 mm/yr ( E f f c r d and Mathias, 1969).  The s i z e frequency  d i s t r i b u t i o n o f T a r i c h a appeared t o be constant  through space  as w e l l as through time during the study p e r i o d . Trappability funnel traps.  T a r i c h a granulosa  were a t t r a c t e d t o  In the l a b o r a t o r y and i n Marion Lake i t was  found that newts would enter and leave t r a p s i n much the same was as they would enter and leave clumps o f v e g e t a t i o n o r f i s h net.  Ambystorna g r a c i l e d i d not appear t o be a t t r a c t e d t o t r a p s  andthere were i n d i c a t i o n s t h a t some degree o f trap avoidance l e a r n i n g took place with these animals.  Many  trapped  Ambystorna were i n j u r e d a f t e r being removed from t r a p s and a l l  20.  trapped animals showed " f r i g h t " r e a c t i o n s such as v i o l e n t swimming.  T h i s was not observed among trapped T a r i c h a .  P o p u l a t i o n d i s t r i b u t i o n and movements g r a c i l e observed from a boat a t n i g h t appeared dispersed.  Ambystoma to be widely  Animals seen to approach each other c l o s e l y d i d not  show any n o t i c e a b l e a g o n i s t i c behaviour.  When two animals were  seen to touch, both animals would u s u a l l y swim r a p i d l y a p a r t . Although 504 A. g r a c i l e were i n d i v i d u a l l y marked only 16 were recaptured.  Since only f i v e of these were caught more  than one day a f t e r f i r s t to  capture the r e t u r n s were^too scanty  allow any r i g o r o u s statement about how  A. g r a c i l e movements a r e .  extensive i n d i v i d u a l  In a l l cases, however, recaptured  animals were found i n the subhabitat type that they were marked in.  Furthermore,  since the s i z e compositions and trapped  numbers of Ambystoma i n i n d i v i d u a l subhabitat types d i d not change from e a r l y June to l a t e August,  i t appeared  that there  were no l a r g e s h i f t s i n the Ambystoma p o p u l a t i o n d i s t r i b u t i o n except d u r i n g the e a r l y s p r i n g when metamorphosed a d u l t s e n t e r ed the l a k e f o r a few weeks andduring e a r l y September when metamorphosed young of the second year l e f t  the l a k e .  The t o t a l weekly c a t c h r e s u l t i n g from a l l methods of capture i n d i c a t e d that i n 1969  the f i r s t  T a r i c h a entered  Marion Lake around m i d - A p r i l and the l a s t animals l e f t l a k e i n l a t e September or e a r l y October ( F i g . 4 ) .  the  There were  two peaks i n the c a t c h per u n i t e f f o r t - t i m e curve, s i n c e the  L e a f 21 omitted i n page numbering.  22.  TABLE 2 . or  Areas  o f c a p t u r e f o r T a r i c h a g r a n u l o s a caught  during 1 9 6 9 .  more t i m e s  chronological order.  The  The dates  eight  a r e a s o f c a p t u r e a r e shown i n of f i r s t  and  last  capture  are  shown i n p a r e n t h e s e s .  An.  Capture  Number  Capture  Data  No.  1  2  3  4  5  6  7  8  1  7  7  7  5  5  5  5  5  (14/5-1/9)  2  7  12  7  12  5  5  5  5  (21/5-19/8)  3  12  12  4a  4a  12  12  5  5  (21/5-26/8)  4  12  12  7  t2;  12  1b  5  5  (21/5-26/8)  5  4b  6  7  6  4b  5  5  (21/5-26/8)  6  12  11  12  7  12  12  12  8  6  6  6  6  4c  6  6  9  1b  8  8  2  1b  3  5  10  12  10  10  11  4b  12  6  12  12  12 8  12 9  5  8  5  6  4c  5  5  5  5 12  6  10  9  10  10  4a  9  12  10  11  12  (first  & la  (22/5-11/8)  5  (22/5-1/9)  10  (23/5-18/7)  5  (26/5-12/8)  10  . (28/5-18/8)  5  5  (2/6-1/9)  6  5  5  (4/6-1/9)  3  (12/6-17/8)  13  1b  2  11  12  7  5  8  14  12  10  9  12  5  5  11  15  2  3  3  3  3  3  3  3  16  7  7  7  6  5  5  5  5  5  ( H / 5 - 1 6/8)  17  7  4b  4b  5  9  6  7  5  5  (14/5-26/8)  18  7  4c  5  5  5  5  5  (21/5-26/8)  19  4b  4b  6  5  5  5  (21/5-1/9)  20  12  12  5  5  (21/5-1/9)  5  5  (22/5-5/9)  9  (23/5-18/7)  21  3  22  9  3 10  12 3 9  6  4a  4a  5  12  5  5  5  5  8  4a  10  5  12  (14/6-21/8) (18/6-21/7)  12  11  12  11  10  10  10  10  10  .11  10  10  10  23  12  12  12  12  11  24  12  1b  10  10  10  (23/5-24/7) (23/5-18/8)  23  Table 2. (cont'd.)  An. No.  Capture Number  Capture Data  1  2  3  4  5  6  7  8  9  25  12  12  11  10  12  10  10  5  9  (26/5-22/7)  26  12  12  10  5  10  5  8  9  5  (10/6-1/9)  27  5  9  5  9  3  9  8  9  9  9  28  8  1b  12  7  12  10  10  11  10  10  29  7  5  2  3  5  9  5  5  5  5  (15/5-19/5)  30  9  9  12  12  12  11  1 2 12  5  8  (20/5-15/8)  12  12  12  7  1b  10  (21/5-18/8)  32  7  7  12  12  5 ' 55  (21/5-19/8)  33  6  6  (22/5-26/8)  34  11  35  12  311  1 1 12  12  3  10  11  12  (first & l a  (7/5-23/6), (14/5-6/8)  10  10  5  10  6  1 2 12  6  7  5  5  8  7  7  12  7  12  7  7  6  8  5  (12/4-10/6)  12  10  12  9  12  10  5  10  5  5  (23/5-5/8)  24.  P i g . 5.  A p l o t showing the r e l a t i o n s h i p between the time  during which T a r i c h a granulosa were marked and the mean number of times that they were r e c a p t u r e d . v e r t i c a l bars show standard e r r o r s .  The  6  9  Time from initial  12  15  c a p t u r e (weeks)  18  25  areas  o f t h e l a k e i n w h i c h i t was  animals animal  a l l shifted was  their  captured  "home r a n g e " a t l e a s t  caught i n 7 o f the  12 a r e a s  p a t t e r n h e l d true f o r animalsacaught T h i s and that  the  stability  t o and  f r o m the The  season, r e f l e c t  One The  l e s s e r numbers o f  a)  times.  ( F i g . 5) i n d i c a t e s  t h e movements o f i n f l u x and  Spatial  9 and  roots.  individuals  egress  of  animals  complexity  10 c o n t a i n e d  i n the l a k e .  The  —  I t was  built  i n the  complex.  A r e a s 2»  i n clumps o f f i s h n e t  to a doubled  summer o f 1 9 6 7 o  placed  placed  caught i n a r e a l a y e r of f i s h Similarly  w a t e r a t t e m p e r a t u r e s above 2 0 ° C  net  week,  centre.  c h a r a c t e r i s t i c s and 0  12  after  In the l a b o r a t o r y T a r i c h a tended  t h e i r a q u a t i c secondary sex  4»  tree  i n a r e a 10 d u r i n g c a p t u r e  r a p i d l y became a c o n c e n t r a t i o n Temperature -  t h a t a l l major  t h i c k clumps o f v e g e t a t i o n o r  clinging  a p i e c e o f n e t t i n g was  t h a t as t h e  found  l a r g e numbers o f a n i m a l s  were a l m o s t a l l f o u n d on a l a r g e pen  be  following factors:  T a r i c h a were a l s o f o u n d  b)  observed  p o s i t i o n s of c o n c e n t r a t i o n c e n t r e s appeared to  c e n t r e s o f c o n c e n t r a t i o n were s p a t i a l l y 7,  same  lake.  c o r r e l a t e d w i t h the  lose  once.  i n the l a k e .  o f the p o p u l a t i o n  w i t h i n the p o p u l a t i o n sBodnnt the  it  These  s h i f t s i n the p o s i t i o n s of c o n c e n t r a t i o n c e n t r e s  d u r i n g t h e 1969  6,  (Table 2 ) .  leave  I n t h e l a k e i t was  s u r f a c e w a t e r n e a r e d 20°C d u r i n g l a t e  water c o n c e n t r a t i o n c e n t r e s disappeared  and  June  to the  observed shallow  l a r g e numbers  of  26.  animals were found i n deeper areas where the temperature about  was  15°C, c)  Social interaction -  The presenoe o f T a r i c h a at a  c o n c e n t r a t i o n centre may have a t t r a c t e d other T a r i c h a .  During  capture week 15, 30 newts were p l a c e d i n a c y l i n d r i c a l cage of hardware c l o t h . t h i s cage.  A clump of 3/4  i n c h f i s h net was draped  around  Although no animals e s t a b l i s h e d themselves on the  n e t t i n g , a number of animals e s t a b l i s h e d themselves i n a P. natans bed immediately adjacent to i t and when the cage removed t h i s c o n c e n t r a t i o n centre ceased to e x i s t .  was  Twitty  (1966) has shown that T a r i c h a t o r o s a males are a t t r a c t e d to females through the use of pheromones.  In Marion Lake i t was  found that T a r i c h a granulosa males are a t t r a c t e d tooother males as w e l l , at l e a s t to the p o i n t where homosexual amplexed p a i r s were o c c a s i o n a l l y seen.  In clumps of T a r i c h a seen i n concentra-  t i o n c e n t r e s , very few animals were i n amplexus, so these aggregations may d)  not have been simply breeding aggregations.  Prey - During the f o u r t h week of t r a p p i n g l a r g e  numbers of Rana aurora tadpoles hatched i n areas 9 and At t h i s time T a r i c h a appeared to be e a t i n g t a d p o l e s .  10.  i n these areas and were found  As the tadpoles d i s p e r s e d there was  decrease i n the number of T a r i c h a  caught.  M o r t a l i t y - Although the present study was  concerned  with an i n v e s t i g a t i o n of salamandersMJs p r e d a t o r s , c e r t a i n observations were made on t h e i r r o l e as p r e y  0  I t has been  found that T. granulosa was not eaten by the f i s h i n Marion  a  27.  Lake although A. g r a c i l e were found i n the stomachs of rainbow trout  ( E f f o r d and Mathias, 1969)» and one specimen was  the process of being eaten by a icanus ( L e i d y ) ) . (Brodie, 1968)  d i v i n g bug  seen i n  (Lethocerus amer-  The potent p o i s o n possessed by T a r i c h a  makes i t u n l i k e l y t h a t newts were eaten by the  mink, heron and mergansers which p e r i o d i c a l l y frequented the lake although some Ambystoma may animals.  have been eaten by these  Ambystoma g r a c i l e i n the process of r e g e n e r a t i n g  limbs and t a i l s were f r e q u e n t l y captured i n the l a k e but t h i s was  never found to be the case with To granulosa.  No dead  T a r i c h a were found i n the l a k e although dead Ambystoma were occasionally  found.  These specimens were r a p i d l y consumed by  c a r r i o n feeders (such as tadpoles andcamphipods) and decomposers.  28.  SECTION I I  A COMPARISON OP THE FEEDING BEHAVIOUR OP SALAMANDERS OF MARION LAKE.  MATERIALS AND  In  METHODS  Marion  Lake o b s e r v a t i o n s o f s a l a m a n d e r f e e d i n g were  made e i t h e r a t n i g h t , f r o m t h e day  by  appeared boat.  a boat  equipped  s k i n o r SCUBA d i v i n g .  t o be d i s t u r b e d by  So  THE  with l i g h t s ,  At n i g h t , f e e d i n g  the presence  o f the  that uninterrupted feeding behaviour  or i n  animals  observation c o u l d be  ob-  2  s e r v e d , a 15 m galvanized mud  and  animals  wire n e t t i n g .  lily  a r e a and  pads.  Red  were l e f t  used  The flood  observable  A.M.,  M.D.T.  lights  this  were mounted o v e r  Under t h e s e c o n d i t i o n s  from  e i t h e r s i d e of the  8  T a r i c h a were hand c a p t u r e d by a with a  pen. captured  u s u a l l y between 3s00  " s l u r p gun",  device with a s p r i n g loaded plunger.  a  syringe-like  Captured  Ambystorna  A l l T a r i c h a and  Ambystorna were a n a e s t h e t i z e d w i t h M S - 2 2 2 and stomachs pumped. stomachs removed.  S m a l l Ambystorna were k i l l e d  had and  measured u s i n g l i q u i d  the  their their  t h e t o t a l volume o f e a c h sample displacement.  on  large  Stomach samples were examined w h i l e  f r e s h and  and  diver.  a c c o r d i n g t o w h e t h e r t h e y were h u n t i n g  l a k e b o t t o m o r i n t h e w a t e r column.  were s t i l l  i n c h mesh  f o r s t o m a c h c o n t e n t s a n a l y s e s were  Ambystorna were c a p t u r e d  were c l a s s i f i e d  in  open  the e a r l y hours o f the morning  8:00  enclosed  enclosure contained both  on a t a l l t i m e s .  were e a s i l y  Animals in  a r e a o f t h e l a k e was  Samples o f e a c h  they  was prey  29  species were s e t aside so t h a t the mean volume o f each prey type could be determined. In the l a b o r a t o r y , salamander p r e d a t i o n was observed i n wading pools and a q u a r i a c o n t a i n i n g l a k e mud.  Experimental  animals were held i n l a r g e tanks and were f e d f r o z e n b r i n e shrimp o r horse heart.  During the determination  o f hunger  curves salamanders were h e l d i n white p l a s t i c dishpans o r buckets.  The animals were f e d with 0.06 « 002 cc p i e c e s o f 0  horse heart cut to the d e s i r e d s i z e u s i n g a mitre board. T a r i c h a were f e d from f o r c e p s . Hunger curves were determined u s i n g the method o f H o l l i n g (1966),  Twelve standard a d u l t female T a r i c h a between 5°2 and  5.6 cm.in l e n g t h were used d u r i n g the determination f i r s t T. granulosa hunger curve. animals'  s t r i k e d i s t a n c e (about  o f the  Prey were h e l d w i t h i n the <>5 cm.) and a r e c o r d was made  of the temporal p a t t e r n i n g o f the f i x e d a c t i o n p a t t e r n s o f predation.  An animal was considered; to have reached  when twenty minutes passed without  any f e e d i n g  satiation  behaviour.  The d e p r i v a t i o n p e r i o d s were from one to e i g h t days. A l l animals were f e d at a l l d e p r i v a t i o n l e v e l s with the order of d e p r i v a t i o n p e r i o d being randomly assigned t o each  animal.  A second hunger curve was c a r r i e d out u s i n g male T a r i c h a 5,9 to 6.3 cm. i n l e n g t h but only f i v e hunger l e v e l s were used and no recordings were made o f t h e i r behaviour d u r i n g f e e di ng s e s s i o n s .  During  curves the experimental  the determination  o f both hunger  o o animals were h e l d a t 17 + 1 C  0  30.  Ambystorna r e a c t e d  t o the presence o f f o r c e p s .  a n i m a l s were g i v e n a l a r g e e x c e s s o f f o o d  and were a l l o w e d  to  I t was f o u n d t h a t o n l y 20-25$ o f Ambystorna  f e e d ad l i b i t u m .  would f e e d i n t h e l a b o r a t o r y . ed u s i n g 22  These  The h u n g e r c u r v e  n e o t e n o u s a d u l t A. g r a c i l e  a n i m a l s were between 6.1  cm. and 7.7  was  determin-  o f both sexes.  The  cm. body l e n g t h and were  known t o f e e d . The  effect  o f a c c l i m a t i o n t e m p e r a t u r e on f e e d i n g by  Taricha granulosa 5.8  was d e t e r m i n e d u s i n g f e m a l e a n i m a l s 5o4  cm. i n l e n g t h c a p t u r e d  from M a r i o n Lake i n the s p r i n g o f  1970.  Sixty l i t r e  of 3 ° ,  5 ° , 7 ° , 1 0 ° , 1 3 ° , 1 5 ° . 1 8 ° , 2 0 ° , 2 3 ° , 2 5 ° , 2 8 ° , and  30°C.  Ten a n i m a l s were p l a c e d  a q u a r i a were s e t a t c o n s t a n t  a n i m a l s were a l l o w e d were f e d .025 periods  temperatures  i n e a c h a q u a r i u m and t h e  one month t o a c c l i m a t e .  gm p i e c e s o f h o r s e h e a r t .  the weight o f horse h e a r t  a n i m a l s was r e c o r d e d .  The v a l u e s  The a n i m a l s  During  two  feeding  e a t e n by e a c h group o f were c o n v e r t e d  t o mean r a t e  o f f o o d p a s s a g e p e r h o u r by d i v i d i n g t h e w e i g h t o f f o o d by  -  eaten  24. During  O c t o b e r , 1968  some e x p e r i m e n t s were done i n an  a t t e m p t t o o b t a i n some i d e a o f t h e s i g n s t i m u l i w h i c h manders r e s p o n d e d t o d u r i n g f e e d i n g .  Ten T  0  granulosa  A. g r a c i l e were s e l e c t e d a t random f r o m ! l a b o r a t o r y were p l a c e d  in;60 l i t r e  aquaria.  salaand  10  s t o c k s and  These a n i m a l s had been f e d  f r o z e n b r i n e shrimp ad l i b i t u m , o n t h e day b e f o r e  testing,  31.  A f t e r a two h o u r s e t t l i n g p e r i o d t h e a n i m a l s with  the f o l l o w i n g s i t u a t i o n s , A 1 cm. by -J- cm. f l a t  a)  s u s p e n d e d on a t h r e a d b)  c) about  i n a randomized  orders was  and s p u n i n f r o n t o f t h e a n i m a l . was p r e s e n t e d  inside  a  tube. Pieces  of s u r g i c a l rubber  tubing having  .05 c c . were suspended on t h r e a d d)  presented  p i e c e o f aluminum f o i l  A similar piece of f o i l  plexiglas  were  and p r e s e n t e d  A j e t o f water from a p i e c e o f f i n e  tubing attached  a volume o f as above.  polyethylene  t o a s y r i n g e was d i r e c t e d a t t h e a n i m a l s '  heads. e)  Clear, f i l t e r e d  b r i n e shrimp o r horse test  w a t e r c o n t a i n i n g j u i c e washed  heart  was p l a c e d  containing  animals. f)  A 1.3 a . d i a m e t e r f i b r e g l a s s t t a n k was c o n s t r u c t e d .  A 10 gauge h y p o d e r m i c n e e d l e of  i n aquaria  from  was i n s e r t e d t h r o u g h t h e c e n t r e  the tank, f l u s h w i t h the tank bottom.  Using  a perfusion  pump pumping a t a r a t e o f 90 m l . / n r . s o l u t i o n s c o u l d be i n t r o duced i n t o t h e tank.  During  each o f the nine  s p e c i m e n o f e a c h s p e c i e s was p l a c e d to  s e t t l e down.  the animals  t r i a l s one  i n t h e t a n k and a l l o w e d  The edge o f t h e t a n k was p a i n t e d  always s e t t l e d  n e a r t h e t a n k edge.  b r i n e s h r i m p were i n t r o d u c e d  and t h e b e h a v i o u r  animals  was r e c o r d e d .  rinsing  350 gm. o f f r o z e n b r i n e s h r i m p w i t h  b l a c k and  Extracts of. of the t e s t  The c o l o u r l e s s e x t r a c t s were made by 1 litre  o f water.  32.  From June 7 to J u l y 30, 1970 done to determine rates.  was  the e f f e c t of prey d e n s i t y of T a r i c h a f e e d i n g  The T a r i c h a were presented with prey a t d e n s i t i e s of 8,  2 30, 60, 100 and 100 per m , of  a s e r i e s of experiments  from 5.4  to 5«6 cm.  Ten females with snout-vent 2  were placed i n a 2 m  d i v i d e d i n h a l f by a c l e a r p l a s t i c w a l l . placed on each s i d e of the w a l l .  tank which  Each animal was marked with The bottom of the  constructed o f c l e a r p l a s t i c .  r o l l e r s were placed on the tank bottom ( F i g . 6 ) . c l e a r p l a s t i c was  was  F i v e animals were  toe c l i p s or with threads t i e d to the t a i l . experimental tank was  lengths  placed on the r o l l e r s and was  Solid glass  A layer of connected  to a  motor d i r v e n l e v e r which moved the p l a s t i c back and f o r t h with an amplitude minutes.  Two  of .5 cm. at a frequency of about 60 c y c l e s per .4 cm.  t h i c k sheets of white, l i g h t  p l a s t i c were mounted above the moving l a y e r . had 200 evenly spaced h o l e s , 1.5 lower sheet was  cm.  diffusing  The upper sheet  i n diameter, per m  The  0  glued to the upper sheet and s l i t s were cut  down the centre of each h o l e . p l a s t i c sheet i n such a way  Pins were set i n the moving  that they extended  the s l i t at the bottom of each h o l e .  s l i g h t l y above  A p i e c e of food could be  placed on the moving p i n i n such a way  that i t could not  seen by a f e e d i n g salamander u n t i l the animal was to  look over the edge of the h o l e .  to  search f o r t h e i r food.  of  horse heart 0.042 cc. i n volume served as food.  in  be  iposition  T h i s f o r c e d the salamanders  In the present experiments  pieces  33.  P i g . 6.  Two  schematic diagrams of the experimental apparatus  used i n prey d e n s i t y experiments. A.  Shown i s a c r o s s - s e c t i o n through the centre o f the  experimental tank, which was the m i r r o r was  1 m. wide.  1 m. above the tank and the camera was  2 m. from the centre of the m i r r o r . the tank was  The centre of  15 cm.  The water depth i n  The lamps used were 46*watt  incan-  descent tubes which were connected to a r h e o s t a t so that l i g h t i n t e n s i t y could be a d j u s t e d .  Room l i g h t s gave  l i g h t i n g from above. B.  A diagramatic cross s e c t i o n of one of the h o l e s i n  the tank bottom.  Layers 4 and 5 were mounted on p o s t s  which were attached to the tank bottom  (layer  9)«  Holes d r i l l e d through l a y e r 7 allowed the posts to pass through.  Layer 7 r e s t e d on g l a s s r o l l e r s and was a t -  tached to a motor which moved i t back and f o r t h hence moving the p i n s which were s e t i n i t (see t e x t ) .  camera  •mirror  .-tank  I  A&5  -10 -lamp  B  / I  1 hole horse heart 3 slit  light  /payers of diffusing  6  7 \sJ8 ,9 10  plastic  pin  clear plastic glass rod clear plastic tank bottom diffusing layer  34.  O b s e r v a t i o n s o f f e e d i n g a n i m a l s were r e c o r d e d on f i l m . Dim l i g h t s u n d e r t h e t a n k p r o v i d e d back l i g h t i n g shadows.  and e l i m i n a t e d  The camera u s e d was a h a l f frame 35 mm.  "Photo e y e " camera w i t h a 33 m. magazine Audio V i s u a l E l e c t r o n i c s , Vancouver, I l f o r d FF4 w h i c h was d e v e l o p e d  F s t o p s e t t i n g o f 8.0. allowed photographs  (made b y W e s t e r n  B.C.).  a t ASA 320.  p o s u r e s were made a t a n i n t e r v a l  Olympus  The f i l m u s e d Automatic  was  tine ex-  o f once e v e r y 15 s e c . a t a n  A m i r r o r s e t a t an a n g l e o v e r t h e t a n k  t o be t a k e n f r o m a t r i p o d  on t h e l a b o r a t o r y  floor. The  two g r o u p s  days a t e a c h d e n s i t y . order.  o f a n i m a l s were f e d f o r s i x c o n s e c u t i v e The d e n s i t i e s were p r e s e n t e d i n random  The d e n s i t y o f f o o d was m a i n t a i n e d  o f f o o d a s i t was e a t e n .  T r i a l s were s t a r t e d  r e c o r d i n g was c o n t i n u e d f o r s i x h o u r s . temperature  by t h e r e p l a c e m e n t a t s u n s e t and  The t a n k was h e l d a t a  o f 16° - 2°C.  ,  F i l m n e g a t i v e s were examined i n a v i e w e r w h i c h had a frame c o u n t e r .  P i e c e s o f h o r s e h e a r t were e a s i l y  markings on t h e s a l a m a n d e r s  allowed i d e n t i f i c a t i o n  s e e n and of individuals.  RESULTS  Feeding p e r i o d i c i t y many h o u r s  -  I n o v e r 100 h o u r s  o f o b s e r v a t i o n o f a n i m a l s intjbhe l a k e and i n t h e  o b s e r v a t i o n pen, no. A. g r a c i l e light  o f d i v i n g and  were s e e n d u r i n g h o u r s  u n l e s s weeds o r mud were d i s t u r b e d .  a n i m a l s were i n p l a i n v i e w  o f day-  /At n i g h t the  and were v e r y a b u n d a n t .  In the  35.  lake enclosure A. g r a c i l e emerged from cover about one hour a f t e r sunset  and by dawn no animals could be seen.  the lake as a whole.  T h i s was true of  At no time during the n i g h t could a l l  animals i n the enclosure  be seen and even during the warmest  part o f the year ( J u l y and August) when A. g r a c i l e were most r e a d i l y found, only a b o u t 3 6 ^ o f the animals could be seen i n s  pens c o n t a i n i n g known numbers o f animals.  Although f e e d i n g  T a r i c h a were very o c c a s i o n a l l y seen during d a y l i g h t hours i t appeared that almost a l l f e e d i n g occurred  during the n i g h t .  This was a l s o the case with T a r i c h a f e d continuously  i n the  laboratory. Ethogram of feeding behaviour s e r v a t i o n i n the l a k e enclosure,  During 1 6 hours o f ob-  248 f u l l sequences o f p r e d a t i o n  by A . g r a c i l e were observed and recorded.  In the l a k e  about f i f t y acts o f p r e d a t i o n were observed.  itself  A s i m i l a r number  of T a r i c h a p r e d a t i o n sequences were observed i n the l a k e but most q u a n t i t a t i v e data on T a r i c h a p r e d a t i o n were c o l l e c t e d i n the l a b o r a t o r y . Both T a r i c h a and Ambystoma were seen hunting  on the l a k e  bottom and i n the water column around v e g e t a t i o n and d e b r i s . In general the f i x e d a c t i o n p a t t e r n s o f p r e d a t i o n were s i m i l a r i n the two s p e c i e s .  However there were c e r t a i n d i f f e r e n c e s not  only between T a r i c h a and Ambystoma. but a l s o between Ambystoma feeding on benthos and i n the water column. patterns observed were as f o l l o w s :  The f i x e d a c t i o n  36.  a)  Emerge:  The animal dug i t s way out o f bottom mud,  clumps of d e b r i s or v e g e t a t i o n . b)  A i r gulp;  took i n a i r .  The animal swam t o the water s u r f a c e and  F o l l o w i n g t h i s T a r i c h a and benthic  feeding  Ambystoma u s u a l l y swam q u i c k l y toward the l a k e bottom.  Water  column f ee ding Ambystoma showed t h i s behaviour very f r e q u e n t l y and a f t e r i n h a l i n g a i r they d i d not swim toward the bottom but showed "hovering" c)  Swim:  behaviour (see below). A sustained movement through the water i n -  v o l v i n g the passage o f S-shaped waves down the e n t i r e body i n A. g r a c i l e but only down-the t a i l i n T. granulosa. Ambystoma g r a c i l e were able to swim much f a s t e r than T„ granulosa. d)  Darting:  A r a p i d forward  s i n g l e f l i c k o f the t a i l .  motion r e s u l t i n g from a  This type o f locomotion  mostly d u r i n g c r u i s i n g or prowling  was seen  i n A. g r a c i l e and was not  seen i n T. granulosa. e) support  Hovering:  Suspension i n the water column with no  from a f i x e d o b j e c t .  This type o f behaviour was seen  only i n water column feeding A. g r a c i l e . f)  Propping s  This type o f behaviour was s i m i l a r to  hovering but i n v o l v e d contact with a f i x e d o b j e c t i n the environment. g)  Cruising:  C r u i s i n g occurred only among water  column f e e d i n g A. g r a c i l e .  I t i n v o l v e d movement through  the water with p r o p u l s i o n r e s u l t i n g frammovement o f l e g s only.  37.  h)  Prowling;  Prowling was seen among benthic f e e d i n g  i n d i v i d u a l s o f both s p e c i e s .  T h i s behaviour p a t t e r n con-  s i s t e d of a very slow walking movement d u r i n g which the head was slowly moved from s i d e to s i d e .  An i r r e g u l a r path  was f o l l o w e d . i)  Sitting:  At i n t e r v a l s d u r i n g hunting the animals  were seen to remain motionless on the lake bottom oroon veget a t i o n and  sticks.  While s i t t i n g some animals were seen to  snap. j)  Nose down:  Benthic feeders were o f t e n seen s t a n d i n g  s t i l l during prowling and t i l t i n g  t h e i r heads downward while  moving the head slowly from s i d e t o s i d e .  T h i s behaviour was  u s u a l l y followed by a snap. k) the  Snap:  This behaviour c o n s i s t e d o f the opening o f  mouth, r a p i d expansion o f the g u l a r r e g i o n and r a p i d  c l o s i n g o f the mouth.  Both A. g r a c i l e and T. granulosa ap-  peared t o suck i n t h e i r prey r a t h e r than grasping i t u n l e s s the  prey was l a r g e i n r e l a t i o n t o the salamander's mouth.  Among benthic f e e d i n g A. g r a c i l e about 40$ o f the snaps observed were preceded by the nose down p o s t u r e . l)  Swallow{  About 21$ o f A. g r a c i l e "snaps" were f o l -  lowed by c o n v u l s i v e swallowing movements i n v o l v i n g r a p i d opening and c l o s i n g o f the mouth, and movement o f the head both up and down and from s i d e to s i d e .  Swallowing behaviour  was always shown by T. granulosa when a snap r e s u l t e d i n a s u c c e s s f u l prey capture.  38.  m) toward  Dive:  A l l members o f both spa c i e s q u i c k l y swam  the l a k e bottom o r toward  d e b r i s when they were s t a r t l e d . by an attempt  clumps o f v e g e t a t i o n and A d i v e was u s u a l l y f o l l o w e d  at b u r y i n g under the mud  or among weeds and  debris. n)  Bury:  A f t e r they had ceased showing f e e d i n g be-  haviour A . g r a c i l e u s u a l l y b u r i e d themselves under l a k e u s i n g t h e i r l e g s to move the sediment. d i d not u s u a l l y do  mud  Taricha granulosa  this.  As has been i n d i c a t e d a l l o f these types o f behaviour were not shown by a l l three types of p r e d a t o r (Table  3).  Although T. granulosa i&i&ef&fe^L on water column animals they d i d t h i s by c r a w l i n g up an o b j e c t i n the environment a l i l y pad)  and s i t t i n g on t h i s while c a p t u r i n g prey.  (such as They d i d  not show the "hovering" behaviour seen i n water column f e e d i n g A.  gracile. R e t e n t i o n of f e e d i n g h a b i t s by A. g r a c i l e -  1968  In J u l y ,  s i x t e e n of the A. g r a c i l e i n the l a k e enclosure were  marked with coloured beads and were watched over a p e r i o d of about s i x days ( a f t e r which time they l o s t t h e i r beads). was  It  found that known water column f e e d e r s tended to hunt i n  the water column every n i g h t although sometimes they f e d on the bottom as w e l l . Stomach contents a n a l y s i s (Table 4) was  The stomach contents a n a l y s i s  done u s i n g combined d a t a i n c l u d i n g samples c o l -  39.  TABLE 3 . the l e f t  A "+" indicates was o b s e r v e d  that  the a c t i o n pattern  listed  by t h e t y p e o f a n i m a l r e f e r r e d  the t o p o f the t a b l e .  Ambystorna Oolumn  Taricha Benthic  Emerge  +  +  Air  +  +  gulp  Swim  +  Dart  +  Hover  +  Rare  Rare +  Prop Cruise  +  Prowl  +  +  Sit  +  +  +  Nose down  +  +  +  Snap  +  +  +  Swallow  +  +  +  Dive  +  Bury  +  Rare  on  to at  to  si o  • o  a5  H0 aB)  e 0  > +»o  +>  fl to^•->ca aj o 0• ©flo S -rl — Taricha  MAY JUNE JULY AUG. TOTAL  567  .149  104  1244  .059  32 57  .113 288 .109  28  JUNE  .118  49  60  1  I 1  31  2  1  • HI  0) a) o to o S rl c- -H O 0) 0) r- Tl -<4,fl -F O T l O  ftOft )'c« — '•Oa—  W  12  13  12  I  1  1  1  1  9 2  1 60  16 1  5 1  2 1  11 1  1  9  2  2  2  2  31  1  •  is  4  1  42  1  22  1  1  1  2  336  45 £2  1  8  14  7  6  695  68  3861  253  AUG.  .145  41  481  .089  16  94  OCT.  .160  16  214  TOTAL  .122 172  2073 8602  12 12 11  1  i  1  1  3  4  9  2  2  1  5  2  3  1  *  II  1 11  53  1  35 62  1  46  2  1  1  18  4 5  4 1  1  2  12 11 23  2  1  42  20  8  2 60  71  21  39  1 21  25  8  63  12  1 22  S a l a m a n d e r stomach c o n t e n t s d a t a .  italics  CO  1  (Water column) TABLE 4.  39  12  301  22  29  22 58  .108  .176  9  749  JULY  TOTAL  a ) ri  0  95  .098  to  n  40.  •  ftrO t^v •rl O o VO 0 O H o •P co •rl ai T) O flo a) >> 6 A O B o 0. CM -Op a > to ftO o o• •rl • Tl U -rl § • Hai o « - EH — ' EH ft  H  .146  MAY  SEPT.  Ambystoma  i • aj o bo fl h  1  1  4  1 1  4  1  1 5 1  1  1  2  2  1  1  2  1  2  1  The numbers i n  show p e r c e n t by number and t h e u n d e r l i n e d numbers  are percentages theses next  by volume.  The numbers shown i n p a r e n -  t o t h e names o f p r e y  t h e i r mean volumes i n c c .  organisms r e f e r to  Tl •rl  CO  MAY JUNE  1  6  3  1  1  1  1  JULY AUG.  Gi-—  9  5  o  •rl  EH  6  1 9 2  3 1  2 1  o o  CO  too do .  1  A  1  1  1  2  6  5  6  i  2  8  6  6  2  2  11  3  3  3  5  2  2  1  1  5.  1  1  2  2  6  8  12  3  2  12  1  4  2  2  1  22 1  4* <D  •ift. 1  1 1  1  1 1  1 1  20 1  6  35  4  1  1  3 2  1 1 1  2  1 2  9 1  o  (A O •H  1  1 1  2 3  1  11  to co* O •H £  t -  00-— o 1 9 1 1  1  16  4 2  o  CD  I +> O CD  •A • H o  2  1  1_  o5  1  7  5  •H  9 2  1  1  m o H in  2  1  1  4  4  o o o  1  1  1  12  1  OCT.  3  1  1  2  7  H O 2  1  hi 'v •  ts  co  1 18  5  SEPT.  TOTAL  ct) •  05  1  1  TOTAL  HO OO ft Tl O  s oo a o to  1 1_  1 JUNE  <D —  2 1 i  AUG.  MAY  2  1  JULY  TOTAL  •  Insect  rail) o ^ o o to cu o  CO  co  Tl  CQ/->  o C DO o + > CM 03 •H O  u  +» CO  o 1  1  1  1  1 1  SO •  41 .  lected  by t h e p r e s e n t a u t h o r i n 1968  lected  by B. H e n d e r s o n  I . E. E f f o r d MS.).  The  and  Mr.  caught  K.  Tsumura i n 1963  (Efford  on t h e l a k e b o t t o m and  were t a k e n o n l y between May  pads.  and A u g u s t  and  so b e n t h i c A.  gracile  Tsumura,  f o r Ambystorna Taricha  because  samples  these  i n h i g h numbers o n l y d u r i n g t h i s p a r t  Ambystorna were v e r y d i f f i c u l t were low  col-  separately f o r Taricha.  i n the w a t e r column n e a r l i l y  were c a u g h t  samples  (1970) and samples c o l l e c t e d by Dr.  r e s u l t s were c a l c u l a t e d  f o r Ambystorna c a u g h t  and 1969,  t o f i n d when w a t e r  animals  of the y e a r . temperatures  were sampled o n l y f r o m May  to  October. T h e r e a r e few  s t r i k i n g d i f f e r e n c e s between t h e  c o n t e n t s o f T a r i c h a and  t h o s e o f b e n t h i c Ambystorna.  abundances o f p r e y were r e f l e c t e d  d u r i n g May.  p o l e s t h a n Ambystorna concentrated  and  w h i c h were most  T a r i c h a appeared t h e r e was  that  Taricha  T a r i c h a s k i n and  wider v a r i e t y  C e r t a i n items such  of  as  c e r t a i n types of aquatic b e e t l e  o n l y i n T a r i c h a stomachs.  I n b o t h s p e c i e s about  o f stomachs c o n t a i n e d d e t r i t u s f r o m  mean volumes o f f o o d  heavily  Girard).  p r e y i t e m s t h a n Ambystorna s t o m a c h s .  39%  t o e a t more t a d -  some e v i d e n c e  T a r i c h a stomachs c o n t a i n e d a s l i g h t l y  were f o u n d  case  available  i n t a d p o l e h a t c h i n g a r e a s where t h e y p r e y e d  on Rana a u r o r a ( B a i r d and  T a r i c h a eggs,  Seasonal  i n t h e samples as i n the  o f E p h e m e r o p t e r a nymphs a n d - t a d p o l e s , to salamanders  stomach  the l a k e bottom.  ( i n c l u d i n g d e t r i t u s ) i n t h e stomachs  The was  4 2 .  similar  between  t h e two s p e c i e s w i t h  cc.  and t h e range  The  volumes  being  from  s h o w n may h a v e  maximum a m o u n t  o f food  w h i c h was  s i n c e , some d i g e s t i o n  probably  sampling  cases  a n d i n some  slight  took  animals  they  had f i n i s h e d  hunting.  were  found.  o f the samples  in  volume  Most  but occasional  umes  of food  with  the occurance  May, 1970 of  i n their  The  animals  plus  captured  other food  .426 c c . w i t h  all  stomachs  and In  dipteran  Taricha larvae  sampled  have  were  close  found  t o have  large  t o be  was r e m o v e d  five  During an  cc.  hatched.  stomach  Less  than  prey  azteca  numbers.  (Saussure)  Harrison). taken  from  each contents 3$ o f  empty.  a n d b e n t h i c f e e d i n g Ambystorna  accounted  (Baird) accounted  late  area  to ten tadpoles  t o .570  vol-  associated  from  their  prey  t o t h e mean  tadpoles had r e c e n t l y  o f .330  before  stomach samples l i v e  The mean v o l u m e i s o f  were  been  f o r 64$ o f t h e f o o d  amphipods  by  volume.  w a t e r c o l u m n f e e d i n g Ambystorna t h e c l a d o c e r a n S i d a  lina the  both  aurora  a range  examined  may  T h i s appeared  contained from  items.  was  In  Rana  s a t i a t i o n and  were  Taricha  of the  during a given day  i n very high densities.  o f seven  4)  p l a c e between  taken  stomachs.  o f food  a sample  t h e l a k e where  I n some  animals  underestimates  i n stomachs  .123  mean b e i n g  c c . t o .176 c c . ( T a b l e  .059  been  the overall  f o r 63$ o f t h e f o o d  The amphipods o r Crangonyx  were  richmondensis  B. T . H a r g r a v e ( p e r s . salamander stomachs  eaten  volume  a n d 99$ o f  a l le i t h e r  Hyalella  ( H u b r i c h t and  comm.) e x a m i n e d  and found  crystal-  no s i z e  the  amphipods  selection.  43.  Most o f t h e d i p t e r a n l l a r v a i : f o u n d were t i p u l i d s .  I n c a s e s where  a number o f g e n e r a w i t h i n a f a m i l y were p r e s e n t i n t h e l a k e , t h e s p e c i e s t a k e n were s u r f a c e d w e l l i n g f o r m s . almost  a l l o f the c a d d i s l a r v a e found i n salamander  were l a t e pers.  F o r example  instar Banksiola crotchi  (Martynov)  stomachs  (M. W i n t e r b o u m ,  comm.). Stimuli e l i c i t i n g  feeding behaviour -  A l l the t e s t  s i t u a t i o n s d u r i n g t h e p r e s e n t s t u d y were s u c h t h a t some o f t h e fixed of and to few  a c t i o n p a t t e r n s o f p r e d a t i o n were s e e n .  moving aluminum f o i l  and r u b b e r models r e s u l t e d  s n a p p i n g by a l l a n i m a l s t e s t e d . still  i n nosing  The a n i m a l s d i d n o t r e s p o n d  models and d i d n o t a p p r o a c h  c e n t i m e t e r s away.  The p r e s e n t a t i o n  t h e models e x c e p t  from a  S i m i l a r r e s p o n s e s were o b s e r v e d  models were p r e s e n t e d i n p l e x i g l a s s t u b e s .  when  A l l animals  tested  snapped when a j e t o f w a t e r was d i r e c t e d a t t h e i r mouth o r nasal region.  They d i d n o t snap when t h e s e j e t s were aimed a t  t h e body and t h e y d i d n o t snap a t t h e t u b e i t s e l f h e l d about  5 cm. f r o m t h e t e s t a n i m a l ) .  ( w h i c h was  When T a r i c h a were  t e m p o r a r i l y b l i n d e d by c l o s u r e o f t h e i r e y e l i d s w i t h s u t u r e s , t h e y were a b l e t o h u n t ,  l o c a t e and e a t b o t h l i v e  as T u b i f e x s p . ) and dead p r e y and  frozen brine  prey  (such  ( s u c h as p i e c e s o f h o r s e h e a r t  shrimp).  When T. g r a n u l o s a and. A. g r a c i l e w a t e r w h i c h had been u s e d  to rinse  were esrposed t o f i l t e r e d  frozen brine  shrimp  they  were s e e n t o c a r r y o u t s e a r c h i n g b e h a v i o u r and r e a c t e d t o many  44  o b j e c t s i n the environment juice  by s n a p p i n g a t them.  o r h o r s e b l o o d were p u t i n a n a q u a r i u m  I f brine  containing  manders, t h e a n i m a l s commenced p r e d a t i o n b e h a v i o u r and at  e a c h o t h e r , o r a t p l a n t s and  bottom. of  When b r i n e  a round  shrimp  t a n k i t was  b o t h Ambystorna and  debris s t i r r e d  e x t r a c t was  T a r i c h a showed t h e f u l l  were begun a f t e r t h e two the t a n k .  test  They r e m a i n e d  val  ( r a n g e : 15-45  b e h a v i o u r was  range  min.)  trials  of benthic  settled  A l l trials a t the r i m shrimp  A f t e r a mean t i m e  inter-  t h e commencement o f h u n t i n g  marked by t h e o b s e r v a t i o n o f a "nose down" p o s t u r e  on t h e p a r t o f one  or both t e s t  n o s e down p o s t u r e f i r s t 2 trials  aquarium  the c e n t r e  a t the tank r i m as b r i n e  from the tank c e n t r e .  min.  from  swallowing.  a n i m a l s had  extract diffused o f 30.5  snapped  found t h a t i n a l l n i n e e x p e r i m e n t a l  f e e d i n g b e h a v i o u r e x c e p t i n g e s t i o n and  of  sala-  from the  diffused  shrimp  animals.  in 5 trials,  Ambystorna showed t h e  Taricha i n 2 t r i a l s  and i n ,  t h e 2 a n i m a l s commenced h u n t i n g s i m u l t a n e o u s l y .  The  mean time i n t e r v a l between t h e commencement o f h u n t i n g by  the  2 a n i m a l s was  1.2  Ambystorna h u n t e d  min.  ( r a n g e ; 0.0  i n t h e immediate  - 3.0  min.).  vicinity  In a l l t r i a l s  o f t h e s p o t where  h u n t i n g b e h a v i o u r commenced, w h i l e T a r i c h a a l w a y s c e n t r e o f t h e t a n k w i t h i n 2 min. h u n t i n g b e h a v i o u r w i t h i n a 20 cm. the  s o u r c e o f shrimp  extract.  a concentration gradient. head the  from s i d e t o s i d e , tank.  and p e r f o r m e d  always  a l l of  diameter c i r c l e  T a r i c h a appeared  They walked  reached  their  surrounding  t o be  s l o w l y , moving  t u r n i n g toward  the  following their  the c e n t r e o f  45.  Pig.  7.  Shown a r e t h e h u n g e r c u r v e s  (snout-vent  o f male T a r i c h a g r a n u l o s a  l e n g t h 5.9 - 6,3 cm.), f e m a l e  (5.2  - 5.6 cm.) and Ambystoma g r a c i l e  (6.2  - 7.7 cm.).  limits.  limits  cluttering  o f the  o f both  sexes  The v e r t i c a l b a r s a r e 9 5 $ c o n f i d e n c e  The c o n f i d e n c e l i m i t s  Confidence  T. g r a n u l o s a  shown were  typical.  a r e n o t shown f o r a l l p o i n t s t o a v o i d figure.  46.  Hunger c u r v e s -  When volume o f f o o d r e q u i r e d  T a r i c h a and Ambystoma was it  was  found  that  i n female  t h e s e two  used  The maximum was T a r i c h a and  were 6.1  v a r i a b l e s were l i n e a r l y  1.62  1.06  - .2 cm.  The male  T a r i c h a were 5.4  - .8 cm.  T h i s was  present determination.  t o be  cm.  the stomach  the case d u r i n g the  A l l t h r e e h u n g e r c u r v e s c o u l d be  d e s c r i b e d t o t h e p o i n t were t h e maximum was e q u a t i o n o f the  .2  from  t o t h e amount o f f o o d i n t h e not found  Taricha  commencement  o f t h e p r e s e n t s t u d y showed a r a t e o f f o o d p a s s a g e  ( H o l l i n g , 1966).  -  cc.  long.  A l l hunger curves determinedpjprevious t o the  related  up  s t o m a c h volume  c c . i n Ambystoma.  l o n g and Ambystoma were 6.9  time  related  c c . i n male T a r i c h a . 1.16  l o n g , female  stomach w h i c h was  satiate  p l o t t e d against food d e p r i v a t i o n  t o a maximum, w h i c h r e p r e s e n t e d t h e t o t a l (Pig. 7).  to  reached  by  an  form H = R + AD(TP)  (4)  where H = amount o f f o o d e a t e n R sa d e v i a t i o n f r o m i n t e r s e c t i o n a t the o r i g i n AD = r a t e o f movement o f f o o d f r o m t h e stomach TP = d e p r i v a t i o n t i m e The  d a t a f r o m Ambystoma  d e s c r i b e d by t h e same l i n e  and  female  T a r i c h a c o u l d be  s i n c e a t t h e 17° - 1°C.  of these determinations both animals c l e a r e d stomach a t a r a t e o f 0.22 v a l u e o f 0.27  ml/day.  ml/day.  R was  0.02  temperature'  food from  Male T a r i c h a had  an  the AD  i n t h e c a s e o f Ambystoma  47  and  female It  T a r i c h a and  s h o u l d be  0.04  Calef  of  ( i n p r e p . ) has times  found  live  v a r y with the type o f food that Hyla r e g i l l a  f a s t e r than horse heart.  i n advance o f t h a t r e a c h e d  by  amphipods were removed f r o m  tadpoles.  from  the  so i t was  i n m o d e l l i n g i t ;was  decided  l i n e s were f i t t e d detailed  t o use  of  I n some  digestion cases  i n Section III  by e y e .  The  decided  For  dif-  t h e sake o f  t h e s i m p l e s t p o s s i b l e means as shown. were n o t  hoped t h a t u n t i l  t h e s e l i n e s would a d e q u a t e l y  o f salamander d i g e s t i v e  rate at  t h a t t h e d a t a shown  data presented  i t was  The  stomach o f T a r i c h a a t  three s t r a i g h t l i n e s  a n a l y s i s but  were c o l l e c t e d ,  analysis  stomachs w i t h w e l l d i g e s t e d  i s shown i n F i g . 8.  i n F i g . 8 s h o u l d be d e s c r i b e d by  response  other prey.  o f tempe r a t u r e on f e e d i n g r a t e s -  temperatures  simplicity  for  During  heart.  which horse h e a r t passed ferent  eaten.  t a d p o l e s were c o n s i d e r e d t o be d i g e s t e d a t  t h e same r a t e as h o r s e Effect  pas-  tadpoleswwere  F o r t h e sake o f t h e model p r e s e n t e d  prey but the  increasing  which i s the r a t e of food  stomach c o n t e n t s t a d p o l e s were a l w a y s i n a s t a t e  far  all  (AD)  t h e stomach, may  d i g e s t e d 4.7  o f male T a r i c h a .  emphasized t h a t the s l o p e o f the  phase of the hunger curve sage f r o m  i n the case  These adequate  better data  d e s c r i b e the  r a t e to temperature  of  ac-  climation. The experiment  5*4  - 5*8  cm.  l o n g female  T a r i c h a used  i n the  d i g e s t e d h o r s e h e a r t a t a maximum r a t e (Mdr)  present of  48.  P i g . 8.  The  effect  o f t e m p e r a t u r e on t h e d i g e s t i v e r a t e o f  Taricha granulosa. two  Each p o i n t r e p r e s e n t s  f e e d i n g s each f o r t e n animals.  symbols i s shown i n T a b l e  6.  The  t h e mean o f  meaning o f  the  49  7.5 mg/hr.  T h i s r a t e o f d i g e s t i o n was c o n s i d e r e d  f r o m 1 3 ° C ( T 1 ) t o 20°G. ( T 2 ) . used t o d e s c r i b e  the data  t o be  constant  Prom 0 ° C . t o 1 3 ° C . t h e l i n e  increased with a slope  (M1) o f 0.58  mg/hr. / ° C . and f r o m 20°C. t o 3 2 ° C . t h e s l o p e  o f the l i n e  had  were  a value  o f -0.63 m g / h r . / ° C .  t o be mean v a l u e s the  f o r the M a r i o n Lake p o p u l a t i o n  a n i m a l s u s e d were c l o s e t o t h e mean s i z e  lake. size  F o r a d e s c r i p t i o n o f animals with t h a n t h e above a n i m a l s  t h a t T1 and T2 were c o n s t a n t and  These v a l u e s  Effect  o f animals i n the  a different  f o ra l l sizes.  d u r i n g hunger curve  tremely  high prey  b a s i s o f a changed  determinations  density situation.  handling  that the e f f e c t  (refractory period) during  (M1  maximum  The p r e s e n t a t i o n  m i m i c k e d a n ex-  No s e a r c h  i n v o l v e d s o t h e t i m e between a c t s o f p r e d a t i o n  So  stomach  New s l o p e s  o f h u n g e r on f e e d i n g b e h a v i o u r -  time spent  ( T a b l e 7) s i n c e  (Mdr).  of food  the  considered  ( a s i n S e c t i o n I I I ) i t was assumed  M2) c o u l d be d e t e r m i n e d o n t t h e  digestive rate  prey  and t h e t i m e s p e n t  b e h a v i o u r was involved  only  eating  prey.  o f hunger c u r v e s .  were  collected;  D a t a were  proces-  + sed  f o r i n s t a n c e s where a n i m a l s were s a t i a t e d  and  28 i 2 p i e c e s o f 0.06 c c . h o r s e h e a r t .  considered  15, 10 and 16 i n d i v i d u a l p r e d a t i o n i n the three  ;  o f h u n g e r o n time between e n g u l f m e n t s  c o u l d be d e t e r m i n e d , d a t a  the determination  pectively  (M2)  at 5 - 2 ,  + 1 8 - 2  T h e r e were r e s sequences  groups o f d a t a .  Under t h e c o n d i t i o n s o f t h i s e x p e r i m e n t a c o m p l e t e  50  p r e d a t i o n sequence c o n s i s t e d more snaps I t was  which r e s u l t e d  found  finally  s a t i a t i o n t h e r e was  t i m e between p r e y i n g e s t i o n s  i n t e r v a l s when p l o t t e d  or  i n the i n g e s t i o n of food.  t h a t as a n i m a l s a p p r o a c h e d  i n c r e a s e i n the t o t a l time  o f a n o s e down f o l l o w e d by one  a g a i n s t number o f  (TR).  an  These  ingestions  n e c e s s a r y b e f o r e s a t i a t i o n c o u l d be d e s c r i b e d by t h e  function  (Pig. 9 ) . TR  = 20.0  + 150e  "^  HI  = t h e volume o f f o o d t o be eaten before s a t i a t i o n .  1 3 3  H I  )  (5)  where  This negatively exponential function f i t t e d when o n l y one  o r two  prey remained  t o be  eaten before  However, t h e a n i m a l s i n t h e s e e x p e r i m e n t s unnaturally high l e v e l present  TR  prey  so f o r t h e p u r p o s e  i s e q u i v a l e n t t o a summation o f what H o l l i n g  time s p e n t h a n d l i n g p r e y (TE).  Not  o n l y does t h i s  i n c l u d e s the t i m e  (TH)  I t was  an  of the  an  s p e n t i n what H o l l i n g  during this  observed  time  spent  the time  ( 1 9 6 6 )  eating  spent  a c t i o n p a t t e r n s o f f e e d i n g but i t a l s o  time  s w a l l o w i n g movements and  b e h a v i o u r was  and  include  p a u s e " when t h e a n i m a l i s r e f r a c t o r y  al  satiation.  d e s c r i p t i o n of the data.  c a r r y i n g out t h e f i x e d  prey.  except  were b e i n g f e d t o  i n v e s t i g a t i o n e q u a t i o n (5) c a n be a c c e p t e d as  adequate  calls  of s a t i a t i o n ,  the d a t a w e l l  that  calls  the  to s t i m u l i received  from  t h e a n i m a l s made o c c a s i o n -  as TR became l o n g e r  between  "digestive  engulfments.  locomotory  51.  Most s a l a m a n d e r f e e d i n g i n M a r i o n L a k e o c c u r r e d hunger l e v e l s  and p r o c e d e d o n l y u n t i l  c o u l d be d i g e s t e d  a t high,  t h e amount o f f o o d  i n one d a y had b e e n i n g e s t e d .  which  They were  t h e r e f o r e f e e d i n g a t a h u n g e r l e v e l where t h e i r r e f r a c t o r y p e r i o d remained e s s e n t i a l l y  constant  throughout the f e e d i n g bout. constant As  value  a t about  30 s e c .  I n t h e model ( S e c t i o n I I I )  was c a l l e d h a n d l i n g  this  time ( H t ) .  s a t i a t i o n was a p p r o a c h e d much o f t h e i n c r e a s e i n r e f -  r a c t o r y p e r i o d was due t o a n i n c r e a s e i n t h e p r o b a b i l i t y o f nosing, and  an i n c r e a s e i n t i m e s p e n t  an i n c r e a s e  i n the p r o b a b i l i t y  sequence t a k i n g p l a c e . lowing  nosing  when n o s i n g  o f an incomplete  These q u a n t i t i e s i n c r e a s e d  occurred, feeding  i n the f o l -  ways: 1)  P r o b a b i l i t y of nosing:  As a n a n i m a l a p p r o a c h e d  a t i o n i t was found t h a t t h e p r o b a b i l i t y o f p r e y preceded by n o s i n g function  (PH) c o u l d be a d e q u a t e l y  sati-  i n g e s t i o n being  described  by t h e .  ( F i g . 10). PN = 90.0 ( 1 . 0 - " " ( ° '  2 4  e  H  )  (6)  where H = volume o f f o o d of feeding A t low h u n g e r l e v e l s of a l o g transformation data) d i d not give  s i n c e the onset  t h i s f u n c t i o n (determined  on t h e b a s i s  and r e g r e s s i o n a n a l y s i s o f h i g h  a very  T h i s was t r u e i n g e n e r a l  eaten  accurate  hunger  d e s c r i p t i o n o f the r e s u l t s .  s i n c e t h a a n i m a l s o f t h e low h u n g e r  group were v e r y v a r i a b l e i n t h e i r r e s p o n s e s .  Visual inspection  52.  i n d i c a t e d t h a t the i n c r e a s e i n the p r o b a b i l i t y o f nosing was s l i g h t l y g r e a t e r than exponential but the e x p o n e n t i a l  curve  gave a f a i r l y good f i t to the data. 2)  Time spent nosing;  I t was found t h a t a t medium and  h i g h hunger l e v e l s as an animal approached s a t i a t i o n not only d i d the p r o b a b i l i t y of nosing i n c r e a s e but so d i d the d u r a t i o n of nosing  (TN).  T h i s i n c r e a s e could be d e s c r i b e d by the  f u n c t i o n ( F i g . 11 ). TN = 3.549 + 0.1779 H 3)  (7)  P r o b a b i l i t y o f a p a r t i a l sequence o c c u r r i n g ; At  medium and h i g h s t a r t i n g hunger l e v e l s , i t was found that as the animal reached s a t i a t i o n the p r o b a b i l i t y o f an  incomplete  f e e di ng sequence o c c u r r i n g ( P i ) i n c r e a s e d a c c o r d i n g t o the f u n c t i o n ( F i g . 12). PI = 0.6825 + 3.684 H An "incomplete  (8)  sequence" was d e f i n e d as a temporal a s s o c i a t i o n  of the f i x e d a c t i o n p a t t e r n s o f p r e d a t i o n not r e s u l t i n g i n prey i n g e s t i o n .  Because o f the v a r i a b i l i t y seen among animals  of low hunger l e v e l i t was found t h a t the above f u n c t i o n d i d not d e s c r i b e the r e s u l t s w e l l a t t h i s  level.  I t was found t h a t r e g a r d l e s s o f s t a r t i n g hunger l e v e l or degree o f s a t i a t i o n d u r i n g a f e e d i n g sequence, the p r o b a b i l i t y of prey i n g e s t i o n being preceded by a snap and miss was 0.6. This value f o r capture  success was used i n the model (Table 7 ) .  53.  Pig.  9.  " R e f r a c t o r y p e r i o d " i n e e c o n i s i e shown p l o t t e d  volume o f f o o d w h i c h t h e a n i m a l feeding session. equation  w i l l e a t before ending  The smooth l i n e s  were c a l c u l a t e d  5 i n t h e t e x t and t h e v e r t i c a l  bars  data. "A" shows d a t a f r o m t h e h i g h h u n g e r "B" shows medium h u n g e r d a t a and "C"  shows l o w h u n g e r  data.  against  level,  a  using  are a c t u a l  54.  Pig.  10.  The p r o b a b i l i t y  plotted  of a T a r i c h a nosing i t s prey  a g a i n s t cc o f food eaten s i n c e the onset  feeding session.  The smooth l i n e  equation 6 i n the text,  was d e t e r m i n e d  of a using  w h i c h was c a l c u l a t e d u s i n g a  r e g r e s s i o n a n a l y s i s on h i g h hunger d a t a . from t h e h i g h hunger l e v e l , and "C" shows l o w h u n g e r  i s shown  M  B  M  data.  "A"  shows  shows medium h u n g e r  data data  1.00  A  c c . of f o o d  eaten  55.  P i g . 11. is  The mean t i m e s p e n t  by .. T a r i c h a i n n o s i n g  shown p l o t t e d a g a i n s t c c o f f o o d e a t e n  onset  of a feeding session.  food  s i n c e the  The s t r a i g h t l i n e s  were  d e t e r m i n e d u s i n g e q u a t i o n 7 i n t h e t e x t and t h e v e r t i c a l bars are a c t u a l data.  56.  Fig.  12.  The  p r o b a b i l i t y o f T a r i c h a p e r f o r m i n g an  incomplete  f e e d i n g s e q u e n c e i s s h o w n i p l o t t e d a g a i n s t volume o f f o o d eaten s i n c e the onset o f a f e e d i n g s e s s i o n . l i n e s were d e t e r m i n e d  The  straight  u s i n g e q u a t i o n 8 i n the t e x t  the v e r t i c a l b a r s a r e a c t u a l  data.  and  57.  TABLE 5•  Pood i n t a k e and time between i n g e s t i o n s f o r T a r i c h a  granulosa f e d a t f i v e prey d e n s i t i e s .  The prey were 0.042 cc  p i e c e s o f horse heart mounted on moving p i n s .  Prey density (No./m ) 2  Mean d a i l y food i n t a k e (cc) shown with 99% confidence limits  N  Mean time between prey ingestions (min) shown with 99% confidence limits  N  Mean no. prey eaten per animal  8  .191 (.148-.233) 12  34.3(20.9-47.7) 127 4.55  30  .171 (.062-.279) 14  16.5(0.2-32.9)  60  .177 (.587-.296) 10  100 200  Mean time spent feeding (min)  156  55 4.07  67  30.9(13.0-48.9)  100 4.22  130  .191 (.047-.336) 10  14.4(2.1-26.0)  116 4.55  143  .197 (.11 3*»282) 13  25.5  62 4.69  68  460 4.42  109  O v e r a l l .185  59  58.  Effect of  o f p r e y d e n s i t y on f e e d i n g -  I n the present s e r i e s  e x p e r i m e n t s and o v e r t h e r a n g e o f f o o d d e n s i t i e s u s e d t h e r e  was no m e a s u r a b l e behaviour  effect  (Table 5 ) .  nificantly different densities.  o f f o o d d e n s i t y on T a r i c h a  Mean d a i l y (t-test,  f o o d consumption  was n o t s i g -  P = .01) between any two f o o d  The same was t r u e f o r t i m e between p r e y  T h e r e was some s u g g e s t i o n t h a t  feeding  salamanders  ingestions.  f e e d i n g a t 200  2 " p r e y " /m  ate their f i r s t  salamanders nificant  few p r e y i n a s h o r t e r t i m e t h a n d i d  f e e d i n g a t 8 " p r e y " /m  b u t no s t a t i s t i c a l l y  sig-  d i f f e r e n c e was f o u n d .  The mean amount o f f o o d e a t e n p e r d a y (.185 c c . ) was slightly less  t h a n t h e 0.220 c c . w h i c h f e m a l e T a r i c h a o f t h e  s i z e used c o u l d d i g e s t of cc. of  the experiment.  i n one day a t t h e 1 6 ° - 2 ° C . t e m p e r a t u r e s  T h i s v a l u e was s l i g h t l y  above t h e 0.113  w h i c h was t h e mean volume o f f o o d r e c o r d e d i n t h e s t o m a c h s M a r i o n Lake  Taricha.  I n t h e p r e s e n t experiments,, a s i n  the  l a k e , t h e salamanders  but  were e a t i n g s l i g h t l y l e s s t h a n t h e amount w h i c h  digested  were n o t m a i n t a i n i n g a f u l l  stomach  c o u l d be  i n one day, t h e n r e s u m i n g f e e d i n g on a n empty o r  n e a r l y empty  stomach.  T h e r e seemed t o be a t e n d e n c y  f o r animals to eat large  amounts o f f o o d on t h e f i r s t n i g h t a f t e r t h e y had s w i t c h e d 2 2 f r o m a low (8/m ) t o a h i g h (l00/m ) f o o d d e n s i t y . One group of  5 a n i m a l s a t e a mean o f .412 c c . o f f o o d a p i s c e u n d e r  conditions.  T h i s heavy  such  e a t i n g was f o l l o w e d by a day o r two  59.  of l i g h t feeding. I t was f o u n d periment  t h a t a l l o f t h e 1 0 animals used  d i d n o t f e e d every day.  The d a i l y  intake o f individual  a n i m a l s v a r i e d f r o m 0.000 c c . (minimum o b s e r v e d ) (maximum o b s e r v e d ) limits  i n the ex-  t o 0.504 c c .  b u t a n e x a m i n a t i o n o f t h e 99% c o n f i d e n c e  ( T a b l e 5) i n d i c a t e d  d a i l y f o o d i n t a k e was l o w .  that the variance i n i n d i v i d u a l  60.  SECTION I I I  A COMPUTER SIMULATION MODEL OP SALAMANDER FEEDING BEHAVIOUR MATERIALS AND  METHODS  The model described here was I.B.M. model 1130  computer.  i n programming the model. obtained  designed f o r use  F o r t r a n IV was  i n the  the language used  Prey data used i n the model were  from v a r i o u s workers on the Marion Lake P r o j e c t .  A l l salamander data were obtained i n Sections I and  i n experiments described  II.  RESULTS Basic attack r a t e models  The  g e n e r a l i z e d a t t a c k model  presented here bears a c l o s e resemblance to H o l l i n g ' s tebrate"  (1965) and  " i n v e r t e b r a t e " (1966) models,both of which  are e l a b o r a t i o n s of the " d i s c e q u a t i o n " ( H o l l i n g , :(  present  model was  "ver-  designed f o r s i m p l i c i t y of use.  1959).  The  It i s  simpler than H o l l i n g ' s l a t e r models but i t contains many of the same components.  L i k e H o l l i n g ' s model the present  was  intendent  had  reached the s i t e where i t d i d i t s hunting.  intended predator.  to d e s c r i b e  the predator's  model  a c t i v i t i e s once i t I t was  to i n c l u d e the l o c a t i o n of hunting areas by  not the  61.  F i g . T3»  Flow diagram t o show the flow o f computations i n the  Marion Lake,predator model.  I n the complex v e r s i o n o f the  model Ware's d i g e s t i v e r a t e submodel enters the computations a t "A" and a r e a c t i v e d i s t a n c e submodel enters the computations at "B" (Ware, i n p r e p . ) .  X  s.Fr,Ht J,K1,:K2,k3,K4,Lv,M1,M2 M3, 'M4J l  l  Mdr.Np,Nps,T.tl.T2.Vy.  \iviii.•Mdj.Wj.Wii *5vi/  _  f | D r = M d r - ( ( K 4 + M l ( l o g , T ) ) f |Q0)| c  • Ves  „ i — '  I  T  "  Calculation  of  prey density  *|P = Dr-24J  vulnerable  j  |Dr=Mdr-(M2-T)l L  CalcuJation  o f w t . food eatejT7jjnrt_jjrne .  C a l c u l a t i o n of r e a c t i v e  |  distance  fXr.= 2-Vy R d - V n - C s l  Wc  =L [ 2 <Ar''..-W.ol-rSar ' J N  p  1  s  1  BE} JNch = ( S a r . Spd)^-[l + ( S a r • H t S p d ) ] | |  Tnc= £ Nch n  | W=Tnc • W c  no yes | N o , = T p • T n c -Ar--Np"| ;  C a l c u l a t i o n o f attack  n°—^^>y  e s  >(STOP)  rates  62  TABLE 6.  Table  o f symbols u s e d i n t h e s i m p l e  M a r i o n Lake p r e d a t o r  v e r s i o n o f the  model.  th Rate a t which the " i " s p e c i e s i s a t t a c k e d .  Ar^  -  Cs  -  Capture success success).  D  -  Amount o f f o o d d i g e s t e d d a i l y  Dr  -  Digestive rate  Pr  -  Reactive constant  f i e l d radius i freactive distance i s (cm.).  Ht  -  Handling  time/prey  J  -  Number o f two week t i m e  -  Constants  K5  -  Trout d i g e s t i v e r a t e  Lv  -  L i m i t o f v i s i o n w h i c h c a n n o t be e x c e e d e d by Rd. (cm.).  K*1 f K3»  £2 9 K4  M1  (strike  success  + recognition  (gm.).  (gm/hr.).  capture  (hr.).  periods being  s e r v i n g as switches  simulated.  i n t h e model.  constant.  Slope o f g o s i t i v e (gm./hr./ C . ) .  sloping line  i n T-Dr p l o t  sloping line  i n T-Dr p l o t  M2  -  Slope  o f negative  M3  -  Slope  o f T-Va^plot.  M4  -  Slope  of Ml -Rd  Md^  -  Mean d e n s i t y / m  Mdr  -  L e v e l o f t h e p l a t e a u o f t h e T-Dr p l o t j maximum r a t e o f d i g e s t i o n ( g m . / h r . ) .  Ml  -  Mean l e n g t h o f p r e y  Np  -  Size of the predator population during the two week i n t e r v a l .  Nps  -  Number o f p r e y  Sar  -  O v e r a l l a t t a c k r a t e on t h e "mean  (gm./hr./oc.).  i  i  plot.  2  i  o f prey  " i " .  :  "i™ c a p t u r e d  also  i n Tp.  types. 'prey".  63. Spd  -  O v e r a l l d e n s i t y o f t h e "mean p r e y "  Svi^  -  Seasonal v u l n e r a b i l i t y o f prey  T  -  Mean t e m p e r a t u r e d u r i n g (°C).  T1  -  Temperature a t which t h e p l a t e a u T-Dr p l o t ( ° C . ) .  T2  -  T e m p e r a t u r e a t w h i c h t h e p l a t e a u ends on t h e T-Dr p l o t ( ° C . ) .  Tnc  -  T o t a l number o f "mean p r e y " c a p t u r e d / i t e r a t i o n .  Tp  -  Time p e r i o d t o be i n c l u d e d i n one i t e r a t i o n (days).  Tw  -  T o t a l wt. o f f o o d (gms.) d i g e s t e d by p o p l n . d u r i n g Tp.  Vi^  -  Prey v u l n e r a b i l i t y  Vn^  -  Vulnerable  Vp_^  —  P r o p o r t i o n o f prey  Vy  -  Search v e l o c i t y  -  Mean w e i g h t o f p r e y  W  -  Weight o f f o o d  Wc  -  Weight i n g e s t e d / c a p t u r e  starts  on t h e  predator  ((0 o r 1 ) .  d e n s i t y o f prey  " i " .  vulnerable.  of predator "i"  "i".  t h e two week p e r i o d  index  "i"  (no./m ) .  (m/min.).  (gm.).  i n g e s t e d by a p r e d a t o r (gm.).  (gm.).  64  Holling processes ing. His  (1966,  P i g . 1) h a s d i s c u s s e d a number o f component  w h i c h s h o u l d be c o n s i d e r e d  i n any s t u d y  H o l l i n g ' s model i s b a s i c a l l y a t i m e  o f animal  apportionment  feed-  model.  " b a s i c " t h r e e components a r e r a t e o f s u c c e s s f u l s e a r c h ,  time  prey  i s exposed t o p r e d a t o r a n d h a n d l i n g t i m e .  i n g sequences these  three time  In a l l feed-  components must be p r e s e n t . A l l  o f H o l l i n g ' s s u b s i d i a r y components m o d i f y t h e r a t e s o f t h o s e processes  which a r e c a r r i e d  make up t h e p r i m a r y The basic  "disc  equation"  o f prey  f e e d i n g and t h e r e f o r e  components.  components p l u s p r e y  the e f f e c t  out d u r i n g animal  ( H o l l i n g , 1959) contains only the three d e n s i t y and i s a s i m p l e  expression of  d e n s i t y on a t t a c k r a t e s : N  a  = aT, N / ( 1 t o  + aT, N ) h o  where N  = number o f p r e y a t t a c k e d / p r e d a t o r / u n i t time a = rate of successful search T^_ = t i m e p r e y exposed t o p r e d a t o r N = prey d e n s i t y T^ = t i m e s p e n t h a n d l i n g (pursuing,, capturing, k i l l i n g , eating) prey I n t h i s model t h e d i s c expanded  equation  appears i n the f o l l o w i n g  form: Nch  i=i = ( ^ ( 2 . Nps  Vy.Rd..Vn . C s ) ) .  1  (1 + ( j r j ( 2 . V y . R d . V n . C s ) ) . Nps i  (See  i=i ( Vp. .Md . ) ) Nps  (9)  X  V p ^ M d ^ ) .Ht)  i  Nps  Table 6 f o r i d e n t i f i c a t i o n o f symbols.)  65  TABLE 7.  Predator  a t t a c k parameters used i n the  o f the M a r i o n Lake p r e d a t o r  version  model.  M a r i o n Lk. benthic feedi n g A. g r a c i l e (1 y r . o l d o r older.)  Predator Parameter  simple  M a r i o n Lk. a d u l t T. granulosa.  A d u l t male T.granulosa Calef's experiment.)  T f r o m  Cs  .60  .60  .60  Pr(cm.)  .5  .5  .5  Ht(hr.)  0.005  0.005  0.005  K1 , K2  1  1  1  -  -  K5  -  M1(gm./hr./°C.)  0.00048  0.00058  0.00102  -0.00051  -0.00063  -0.00094  K3,  K4  M2(gm./hr./°C.) M4  -  Mdr(gm./hr.)  -  -  -  .0062  .0075  .0113  Np  60,000  2.450  T1(°C.)  13.0  13.0  13.0  T2(°C.)  20.0  20.0  20.0  Tp(days)  14.0  14.0  6.0  5.0  5.0  5.0  Vy(m./min.)  T h i s i s a maximum v a l u e . according  8  1  T a r i c h a d e n s i t y i n the l a k e v a r i e d  t o t h e p a t t e r n shown i n S e c t i o n  I.  66.  TABLE 8.  A.  Mean l e n g t h s o f p r e y  for a description  o f prey  period  a  A  B  20.0  y  2  4 5  J  u  l  y  6 7  . Aug.  8  4.3  20.0  4.5  E  3.7  10.0  4 . 0  8.0  10.0  8.0  10.0  2 . 5  11.0  8.0  10.0  G  12.0  8.0  1 0 . 0  4.8  F  8.0  10.0  4.7  4.1  20.0  D  4.5  3.9  20.0  June  T  C  3.7  20.0  3  Mean w e i g h t s  Prey Jype  k  M  B.  types.  1°; f  1  i n mm.;  10.0 9.5  8.0  20.0  5.2  2.8  10.0  8.0  9.0  20.0  5.7  3.1  10.0  8.0  8.5  20.0  6.0  3.4  10.0  8.0  8.0  .2  . 0 0 5  .008  . 0 4  . 0 1 7  . 0 2 4  .009  .2  . 0 0 5  .009  . 0 4  . 0 1 7  . 0 2 2  . 0 1 7  A. M l . i  • May  1  2 3  ___  .2  June  T  4  .006  .2  5  , July  6 7  .  Aug.  8  .04  . 0 0 9  . 0 0 7  .2  T  _  . 0 0 2  .008••;  . 0 1 7  .04  . 0 0 5  _«__________-  . 0 2  .017  . 0 4  .017  .043  . 0 2  . 0 1 9  .2  . 0 1 4  o 0 0 2  . 0 4 ; '  .017  o 2  .016  .003  .04  . 0 1 7  . 0 1 7  .2  . 0 2  .003  .04  . 0 1 7  .016  .018  B. W. X_  i  1  M  a  ;  y  2 3  June T  4  5  July  1  6 7  .  Aug.  8  3 .  71.  6 2 6 .  7 .  2 5 .  4 .  1 0 0 .  3 .  71.  5 1 5 .  7.  15.  4 .  5 2 .  4 .  5 .  2 .  1 2 5 .  615.  5 .  6 .  2 .  1 6 2 .  530.  5 .  6 .  *  Md  ±  2  3  5  °  1 .  2 6 3 .  1 . 1  C.  ;  ;  .  6  3  0  °  2  *  2  *  4 .  4  *  7 5 0 .  2 .  2 .  4 .  291.  1 1 5 0 .  1 .  2.  4 .  284.  1 4 5 0 .  1 .  2 .  4 .  67.  The cerned  other equations  and  submodels i n t h e model were c o n -  w i t h the i n t e r n a l d e r i v a t i o n o f a t t a c k parameters,  conversion of values ( e g , number o f p r e y  from one eaten  patterning of hunting  type  o f measurement t o  sequences.  I I o f t h i s t h e s i s and  shown i n T a b l e s 7 and  The  to run i t e r a t i o n s  A s i m u l a t e d day  values  f o r the  parameters  experimentally i n Sections  i n Ware ( i n prep.}1970) and  of h u n t i n g bouts:» s i m u l a t i n g one  are  The  model  was  hour of p r e d a t i o n .  t h e r e f o r e c o n s i s t e d o f 24  iterations.  The  a t o r s s t a r t e d f e e d i n g a t a g i v e n p o i n t i n time,  fed u n t i l  stomach was  time  beginning hunting and  full  and  temporal  8.  Temporal m t t e r n i n g designed  another  to weight o f prey eaten) or the  o f t h e a t t a c k model were d e t e r m i n e d I and  the  digested food u n t i l  o f the next  hunting period.  s t a r t e d were d e t e r m i n e d  i t was  The  times  predtheir  f o r the  at which  by o b s e r v a t i o n s i n M a r i o n Lake ,  i n the l a b o r a t o r y . C a l c u l a t i o n o f r e a c t i v e d i s t a n c e - For  the  salamander,  reactive distance  ( o r r a d i u s o f t h e r e a c t i v e f i e l d ) was  a t a b o u t 0.5  S i n c e T a r i c h a a p p e a r e d t o be a b l e t o l o c a t e  areas why  cm.  of h i g h prey  these  T h i s was  animals  d e n s i t y f r o m l o n g d i s t a n c e s one  were a s s i g n e d a s t i k e d i s t a n c e o f 0.5  done b e c a u s e t h e p r e s e n t model was  t o h u n t i n g by p r e d a t o r s w h i c h had present  ( e g , a weed b e d ) .  cm.,  intended  to  wonder cm. apply  l o c a t e d a r e a s where p r e y  Once s u c h an a r e a had  s a l a m a n d e r s d i d have an e f f e c t i v e 0.5  may  constant  were  been l o c a t e d  r e a c t i v e d i s t a n c e o f about  which i s a l s o t h e i r s t r i k e d i s t a n c e .  68.  S i n c e t h i s model was a l s o meant t o d e s c r i b e p r e d a t o r s t h a n s a l a m a n d e r s r e a c t i v e d i s t a n c e c a n be c a l c u l a t e d linear  other  a l s o by t h e  equation* Rd.  x  In r e a l i t y predator,  = M4.M1.  (10)  x  t  the r e a c t i v e distance of trout  depends on a number o f f a c t o r s  r a t e o f movement o f p r e y , of illumination.  complexity  such  a s c o n t r a s t and  o f t h e s u b s t r a t e and l e v e l  Ware ( i n p r e p . ) h a s p r e s e n t e d  model w h i c h s i m u l a t e s t h e r e s p o n s e  which i s a v i s u a l  of a trout  a complex  t o these  sub-  factors.  H i s submodel c a n e n t e r t h e f l o w o f c o m p u t a t i o n s i n t h e model presented  here  ( F i g . 13).  E s t i m a t i o n o f h a n d l i n g time prey d e n s i t y experiments made o f h a n d l i n g time Search  ( S e c t i o n I I ) crude  at after  a t a b o u t 5m/min.  of predator This  (Vy).  estimate  the t i m i n g o f s e a r c h i n g T a r i c h a as they  moved o v e r known d i s t a n c e s . e q u a l t o 30 s e c .  - During  measurements were  ( H t ) and s e a r c h v e l o c i t y  v e l o c i t y was e s t i m a t e d  was a r r i v e d  and s e a r c h v e l o c i t y  Handling  (0.005 h r . ) .  time  was c o n s i d e r e d  t o be  T h i s i s t h e mean l e n g t h o f t h e  r e f r a c t o r y p e r i o d when a n a n i m a l  f e d a t a h i g h hunger  level  (Pig. 8 ) . C a l c u l a t i o n o f v u l n e r a b l e prey d e n s i t y - P o r each t y p e u s e d d u r i n g a s e r i e s o f s i m u l a t i o n s by t h e model m a t i o n had t o be p r o v i d e d d e s c r i b i n g mean p r e y mean p r e y w e i g h t To  prey  infor-  length (Ml^),  (W^) and mean p r e y d e n s i t y (Md^),  (Table 8 ) .  i n f o r m a t i o n on o v e r a l l p r e y d e n s i t y i s added a n  index  o f the p r o p o r t i o n o f prey  i n question  (Svi.).  a v a i l a b l e t o the predator  With salamanders b e i n g  the predator  69.  s t u d i e d a n i m a l s a t o r n e a r t h e mud be v u l n e r a b l e t o p r e d a t i o n . amphipod a c t i v i t y prep.)  was  The  effect  of temperature  known as a r e s u l t  so amphipod v u l n e r a b i l i t y  temperature.  s u r f a c e were c o n s i d e r e d t o  was  oh  o f Ware's work ( i n  adjusted according to  A c o m b i n a t i o n o f a l l o f t h e s e f a c t o r s gave  an  e s t i m a t e o f t h e mean d e n s i t y o f a g i v e n p r e y s p e c i e s v u l n e r a b l e t o p r e d a t i o n by t h e p r e d a t o r . The  a c c u r a c y o f any p r e d i c t i o n s made by t h i s model must  by n e c e s s i t y be l a r g e l y d e p e n d e n t on t h e a c c u r a c y o f mation  about  prey.  I n t h e p r e s e n t model a l a c k o f a c c u r a c y  i n s u c h i n f o r m a t i o n may  be  the g r e a t e s t source o f e r r o r .  the s i m u l a t i o n o f p r e d a t i o n i n Marion Lake seven were u s e d used  infor-  f o r T a r i c h a and  were n o t n e c e s s a r i l y  s i x f o r Ambystorna.  The  In  "prey types" prey  types  s p e c i e s b u t c a n be d e s c r i b e d as  fol-  lows: Prey type A - Large d i p t e r a n grubs, u s u a l l y No  i n f o r m a t i o n was  available  tipulid  on t h e s e a n i m a l s , e x c e p t  larvae.  that  which  c o u l d be o b t a i n e d by c u r s o r y o b s e r v a t i b n . P r e y t y p e s B and  C - These two  s p e c i e s Crangonyx r i c h m o n d e n s i s H y a l e l l a azteca (Saussure). fully  s t u d i e d by M a t h i a s  ( i n prep.)  and  f o r m a t i o n has  prey types are the  ( H u b r i c h t and  These two  amphipod  H a r r i s o n ) and  s p e c i e s have b e e n c a r e -  (1967), Hargrave  ( i n prep.)  i t i s from these s o u r c e s t h a t  and  Ware  the p r e s e n t i n -  been d e r i v e d .  Prey type D - T h i s prey type i s the l a r v a of the caddis fly  Banksiola crotchi  to salamander  (Martynov).  T h i s l a r v a becomes  predation only i n i t s l a s t  available  i n s t a r when i t becomes  70.  carnivorous and l i v e s on the mud of v e g e t a t i o n .  M. Winterbourn  s u r f a c e or climbs up the stems  ( i n prep.) provided i n f o r m a t i o n on  t h i s prey type. Prey type E - Within the past few years Ephemeroptera (mayflies) have begun o c c u r r i n g i n Marion Lake. i n s t a r s of the l a r g e s p e c i e s appeared salamanders  Only l a t e  to be eaten by t r o u t and  so these made up prey of the type "P" .  Data  on  mayfly abundance were obtained from an a n a l y s i s of benthic samples from Marion Lake. Prey type P - Late i n s t a r damsel f l y nymphs (Neuroptera) ' formed t h i s prey type.  Density data were obtained from  Hamilton  (1965) and s i z e data from P. P e a r l s t o n e ( i n p r e p . ) . Prey type G aurora.  T h i s prey type i s the tadpole of Rana  During t h e f i r s t f o u r weeks of l i f e  s m a l l enough to be eaten by salamanders.  these animals are  A f t e r t h i s age the  tadpoles are too l a r g e to be eaten by salamanders not considered.  so they are  The tadpole d e n s i t i e s shown are very h i g h and  do not represent mean lake d e n s i t i e s but represent d e n s i t i e s i n the weed beds where they hatched and where they were eaten by T a r i c h a . which invaded areas of h i g h tadpole d e n s i t y d u r i n g the hatch.  C a l e f ( i n prep.) has d e a l t i n d e t a i l with salamander  p r e d a t i o n on tadpoles. C a l c u l a t i o n of d i g e s t i v e r a t e -  The r a t e at which a g i v e n  volume of prey w i l l leave the stomach can depend on a number of factors.  Those which have been considered here are the f o l l o w i n g :  71 .  a)  Temperature: the  r a t e at which food  stomach o f T a r i c h a a t d i f f e r e n t 8,  Section I I .  T2  and  Mdr,  values  effect  d e s c r i b e d u s i n g the  the v a l u e s  the  t e m p e r a t u r e s i s shown i n F i g .  I n t h e model t h e  d i g e s t i o n r a t e was  passed from  of which are  of temperature q u a n t i t i e s M1,  shown i n T a b l e  on M2,  7.  T1,  These  were c a l c u l a t e d t a k i n g i n t o a c c o u n t d i f f e r e n c e s i n  maximum d i g e s t i v e r a t e  (Mdr)  f o r the  three  types  of  animal  used i n s i m u l a t i o n . b)  Ration  size:  i t has  b e e n shown t h a t t h e d i g e s t i v e  r a t e of salamanders i s independent o f r a t i o n s i z e . model d i g e s t i v e r a t e i s h a n d l e d as a c o n s t a n t  In  a t any  the  given  temperature. c) types  Prey type:  Calef  are d i g e s t e d a t the  ( i n prep.) found t h a t not same r a t e .  regilla  tadpoles  heart.  I n t h e model t h i s was  4o7  into live  by  the present  were p r o b a b l y  4.7  were d i g e s t e d  tadpole  He  a c c o u n t e d f o r by  volume.  Observations  author suggested t h a t food digested  a t about the  were assumed t o be  d i g e s t e d a t the  regardless of t h e i r a predator felt  size.  o f mean s i z e was  o f stomach  other  contents  tohhave t h e  tadpoles heart. of  same r a t e o f d i g e s t i o n  strictly  justified.  heart  model p r e d a t o r s  used i n the present  t h a t s u c h an a s s u m p t i o n was  than  same r a t e as h o r s e  T h i s i s not  of  items i n M a r i o n Lake  i n the p r e s e n t  a g i v e n s p e c i e s were c o n s i d e r e d  the d i v i s i o n  same? r a t e as h o r s e  I n t h e model a l l p r e y  Size of predator:  Hyla  times f a s t e r than horse  (see S e c t i o n I I ) .  d)  found that  a l l prey  t r u e but model i t  I n the  since was  complex ;  72.  v e r s i o n o f t h e model a number o f t r o u t s i z e Ware (Ware and  Neish,  t r o u t body s i z e has  i n prep.).  an e f f e c t  Ware h a s  c l a s s e s were u s e d found  t h a t among  on d i g e s t i v e r a t e and  t e d a submodel d e s c r i b i n g t h e r e l a t i o n s h i p .  he  construc-  H i s submodel  can  e n t e r t h e f l o w o f c o m p u t a t i o n s i n t h e p r e s e n t model ( f f i g . Number o f p r e d a t o r s  -  by  13).  I n t h i s model a "mean" p r e d a t o r  h u n t s an a r e a o f mean p r e y d e n s i t y c o n t a i n i n g a "mean" p r e y , w h i c h combines t h e was  c h a r a c t e r i s t i c s of a l l a v a i l a b l e prey.  done so t h a t thasonodal;,  i n t h e M a r i o n Lake model.  t i o n o f the number o f p r e d a t o r s  constant but time  f o r use  weeks) t h e  times  the  the  total  multiplica-  effect  of  the  F o r Ambystoma t h e number o f p r e d a t o r s was  f o r T a r i c h a "Np"  was  changed f o r e a c h two  held  week  p e r i o d u s i n g p o p u l a t i o n s i z e d a t a from S e c t i o n I ( F i g . 4 ) , Number o f p r e y  -  I n t h e M a r i o n L a k e model ( M a r i o n  R e s e a r c h Group, i n p r e p . ) p r e y culated  internally.  d u r i n g the present were u s e d for  two  c a l c u l a t e d by  (Np)  size  p e r i o d d u r i n g which a l l  ( i n t h i s case  o f p r e d a t o r p o p u l a t i o n s was  mean p r e d a t o r .  of s u i t a b l e  F o r each time  parameters are h e l d constant effect  would be  This  investigation direct  time  Simulations-by u s i n g the a)  s i z e data are  S i n c e t h e M a r i o n Lake model was  ( T a b l e 8)  succeeding  abundance and  t o r e - e s t a b l i s h new periods  (Tp)  Lake cal-  incomplete  inputs of prey  data !  p r e y d e n s i t i e s and  sizes  0  t h e m o d e l , - F o u r s i m u l a t i o n s were done  model: During  t h e summer o f 1970  G.  C a l e f ( i n prep.) d i d 2  s e r i e s of p r e d a t i o n experiments i n f i v e  2m  plastic  pools.  a  73  Each p o o l contained 8 l a r g e male T a r i c h a . 0.051  gm.  The prey used were  p i e c e s of horse heart and 0.058 gm.  Hyla  tadpoles, which were p l a c e d i n the pools i n f i v e  different  combinations of p r o p o r t i o n and d e n s i t y (Table 9 ) . fed on prey at  regilla  The  Taricha  set p r o p o r t i o n s and d e n s i t i e s f o r s i x conse-  c u t i v e days during which the number o f each prey type eaten were recorded.  The mean temperature d u r i n g the experiments  was  18°C. C a l e f ' s experiments were simulated by the model and  ob-  served values were compared to p r e d i c t i o n s by the model (Table 9,  The predator parameters used (Table 7 ) were der-  P i g . 14).  i v e d from experiments d e s c r i b e d i n S e c t i o n I I ( P i g . 6 ) . found  that observed  and p r e d i c t e d p r o p o r t i o n s of  heart eaten d i f f e r e d by a mean of 0.9 one prey was there was  I . t was  tadpoles:horse  percentage p o i n t s .  Where  present i n h i g h d e n s i t y and i n v e r y h i g h p r o p o r t i o n  some tendency f o r the model to underestimate  the  numbers o f the more abundant prey eaten and overestimate  the  numbers of the l e s s ahundant prey eaten.  very  s l i g h t ( F i g . 14).  When observed  This e r r o r was  p r o p o r t i o n s were p l o t t e d a g a i n s t  p r o p o r t i o n s p r e d i c t e d hy the model a l l p o i n t s f e l l on or very near the l i n e of p e r f e c t c o r r e l a t i o n between observed  and  p r e d i c t e d values. b)  P r e d a t i o n by T a r i c h a and benthic f e e d i n g Ambystorna  populations i n Marion Lake was months of May,  June,July  simulated B|t -monthly f o r the  and August ( T b l e s 10 and a  11, F i g . 14).  74  Prey types  A-F were u s e d i n s i m u l a t i o n s  s p e c i e s o f s a l a m a n d e r and p r e y  types  of predation  both  A-G were u s e d i n a s i m u -  l a t i o n o f p r e d a t i o n by T a r i c h a d u r i n g May and t h e f i r s t weeks o f J u n e . eaten  A f t e r this/!;time t a d p o l e s  by T a r i c h a .  ^Prey types  o f t h e weight o f food Ambystoma The  eaten  two  were t o o l a r g e t o be  A-P a c c o u n t e d f o r a mean o f 7 9 $  by T a r i c h a and 7 5 $ o f f o o d  eaten  by  (Table 4 ) . predator  parameters used  experiments d e s c r i b e d  (Table  animals.  I t was f o u n d t h a t t h e p r o p o r t i o n s from observed p r o p o r t i o n s  o f prey  p r e d i c t e d by t h e  by a mean o f 5 . 3 p e r -  c e n t a g e p o i n t s i n t h e c a s e o f T a r i c h a and 1 9 . 5 p e r c e n t a g e i n t h e c a s e o f Ambystoma each s p e c i e s eaten f o r Ambystoma  during  (Table  from  i n S e c t i o n I I , most o f w h i c h were done  u s i n g T a r i c h a as the experimental  model d i f f e r e d  were d e r i v e d  (Table  10).  The e s t i m a t e d  points  number o f  t h e summer months was much l a r g e r  11 ) t h a n f o r T a r i c h a b e c a u s e o f t h e g r e a t  d i f f e r e n c e s ihnpdpulation  size.  75.  Pig.  14.  I n e a c h o f t h e t h r e e g r a p h s shown p r o p o r t i o n s o f p r e y  a c t u a l l y eaten are plotted by t h e model. exact  agreement  diagonal lines  against proportions predicted  I f t h e model and o b s e r v a t i o n s h a d shown a l l p o i n t s s h o u l d have f a l l e n  on the  shown w h i c h have a s l o p e o f 1.0.  A.  Data from T a r i c h a i n C a l e f ' s experiments  B.  D a t a f r o m T a r i c h a i n M a r i o n Lake  C.  D a t a f r o m Ambystorna  (Table 9 ) .  (Table 10).  i n Marion Lake  (Table 10).  Proportion predicted by model  76  TABLE 9.  T o t a l numbers and p r o p o r t i o n s o f h o r s e h e a r t and  Hyla r e g i l l a  t a d p o l e s e a t e n by g r o u p s  of eith large  male  T a r i c h a d u r i n g s i x day p e r i o d s .  The r e s u l t s  were o b s e r v e d d u r i n g e x p e r i m e n t s  done by G. C a l e f and t h o s e  i n columns "E" a r e r e s u l t s t i o n s by t h e m o d e l . mean l i v e of  expected  on t h e b a s i s o f p r e d i c -  The p i e c e s o f h o r s e h e a r t u s e d h a d a  volume o f 0*058 c c . b u t a n i n g e s t e d volume 1/4.7  t h i s s i z e s o t h e y were c o n s i d e r e d  c c . (seei  i n columns "0"  to  have a volume o f 0.012  text).  Horse Heart  Hyla reeilla  (#/m2)  (#/m2)  No. H o r s e Heart • eaten 0  E  No. H y l a P r o p o r t i o n eaten Horse Heart eaten  Proportion Hyla eaten  0  0  E .  75  1  314  378  1  75  5  324  360  75  25  280  5  75  15  300  0  E  E  0-E  99.6  98,6  0.4 1.3  0.9  15  24 92.4  93.7  7.6 6.9  0.7  288  91  96 75.4  75.0 24.6 25.0  0.4  79  60  1170  900  6.9  6.3 93.1 93.7  0.7  37  45  1477  914  1  4.7 97.3 95.2  2.1  5  .7  mean=0» 9  77.  TABLE 10. Shown a r e t h e p r o p o r t i o n s by w e i g h t o f e a c h t y p e o f p r e y e a t e n by s a l a m a n d e r s . The r e s u l t s shown i n columns E a r e t h o s e e x p e c t e d on t h e b a s i 6 o f p r e d i c t i o n s by t h e m o d e l . Those i n columns "©"are r e a l v a l u e s d e t e r m i n e d f r o m stomach a n a l y s i s o f M a r i o n Lake s a l a m a n d e r s . The f i g u r e s i n columns "D" a r e t h e a b s o l u t e v a l u e s o f 0-E. Results predicted f o r T a r i c h a a r e a mean o f 5.3 p e r c e n t a g e p o i n t s i n e r r o r and r e s u l t s p r e d i c t e d f o r Ambystorna a r e a mean o f 19.5 p e r c e n t a g e p o i n t s i n erf or. The :lao.t column i n t h e t a b l e shows t h e p r o p o r t i o n o f t o t a l p r e y w h i c h t h e p r e y c o n s i d e r e d h e r e composed i n a c t u a l stomach s a m p l e s . S e c t i o n s "A" and B b o t h show T a r i c h a d a t a b u t i n s e c t i o n "B" t a d p o l e s were i n c l u d e d i n t h e s i m u l a t i o n o f the f i r s t t h r e e time p e r i o d s . S e c t i o n "C" shows Ambystorna data. H  W  No. o f 2 wk. time period  A  B  A  3 D  0  0  E  M  D  B+C D  0  E  P E  D  27 18 18  0  6 6  2  4  12  9 10  1  9  7 8  5  3  16  84  1  6 5  2  13 3 10  5  5  16 17  92  0  3 3  3  0  7 5  3  2  18 .19  75  18 20 19  1  13  J  3 4  35 39 37  31 2 22  18 46 24 20 10 10  5 6  34 33 27 17 10 48  63  15  A 7 8  21 16 12  80  8  M 1 2  24 24  5 8  1  30  26  11 15  M 1 2  39 42 11  10 14  18 20 63 49  8 12  27 18  9  9  6 6 19  J  3 4  35 39  31 5 35 22  83 61  18 20  4 16  9 10  2  8  8  J  5 6  34 27  33 0 27 48  89 41  11  7  3  5  3  2 10  31  4 3  1  2  3 3  0  3  J  A 7 8  65 4 72  31  21 65 16 53 37 72  4 3  3  17  11  14 41  acct. for" *  0  0  10 4 14  14 11 12  Temp,  D  D  39 42 46  J  G  E  E  M 1 2  1  W  0  E  °C.  9  4 4  40 42  9 12  8  6  15  15  13  6  7 5  66  15  10  %  1  13  9 12  72  2  15 16  82  0 10  16 17  59  0  18 19  86  6  5  78  TABLE 1 1 ,  Shown a r e t h e t o t a l numbers o f e a c h p r e y t y p e w h i c h t h e  model p r e d i c t s would be e a t e n u n d e r t h e c o n d i t i o n s Sections  No. o f 2 wk. time period  "A",  M  B"  o f the s i m u l a t i o n .  and "C" h a v e t h e same meanings a s i n T a b l e 1 0 ,  Prey  Type  gms. f o o d eaten Wt. (gm  A  B+C  D  2  7040 98850  45681 75945  16427 23065  58666 49425  9387 131 80  2149 gm. 3706 n  J  3 4  97380 13728  198390 294908  23426 34321  28111 41185  18741 27457  6092 11 6092 i«  J  5 6  5470 6638  293769 467950  10941 13276  10941 13276  21881 26551  3046 11 4686 ti  A 7 8  5698 1719  640420 260317  5698 1719  11395 3435  22790 6877  5076 *• 2030 n  M  2597 4940  16859 37990  11520  6060  21645 12468  12955  269094  32388  38865  172406 387331  1118711 2975797  402281 903773  1436717 1936657  229875  M  1  1 2  J  3  Mil 2  E  P  3463 86580 2149 6600 85710 3706  51644V  3 4  229577 336205  4765595 7222258  573943 840513  688732 1008615  459154 672410  J  5 6  214340 169065  11510947 11918417  428679 338131  428279 338131  857358 676261  A 7 8  139531 105257  15683761 15957952  139531  279061  558123 421016  2 1 0 5 1 3  •1 11  25910 32387 6092 ti  J  1 0 5 2 5 6  G  87091 116122  11  124992  II  !l  II M H  II 1  II II  II  II  II  •1  79.  DISCUSSION  I.  POPULATION S I Z E . The  T. g r a n u l o s a a d u l t p o p u l a t i o n s i z e  during the present (1969)  Mathias'  STRUCTURE AND MOVEMENTS e s t i m a t e made  s t u d y compares f a v o u r a b l y w i t h E f f o r d and  e s t i m a t e o f 3965 i n d i v i d u a l s .  A very l a r g e  ( a b o u t 8 3 $ ) o f t h e p o p u l a t i o n was marked s o t h e  proportion  e s t i m a t e o f 2449 i n d i v i d u a l s  c a n p r o b a b l y be r e g a r d e d  w i t h some  confidence. The  A. g r a c i l e p o p u l a t i o n e s t i m a t e  differed radically  tracted  o f s u c h a method depended on t h e a s s u m p t i o n  was n o t t e n a b l e s i n c e T a r i c h a a p p e a r e d  Avoidance  punctatum Mathias  that that  this  t o be a t -  them t o some  l e a r n i n g h a s b e e n d e m o n s t r a t e d i n A.  (Schneider, 1968J  and t h e f a i l u r e  o f E f f o r d and  to obtain c o n s i s t e n t trapping records i n areas  repeatedly trapped phenomenon a s t h e y  t o s a t u r a t i o n may have b e e n due t o t h i s suggested.  According to the present g r a c i l e per hectare  year.  I t was f o u n d  t o t r a p s and Ambystoma may have a v o i d e d  extent.  on t h e  captures i n funnel traps.  t h e two s p e c i e s were e q u a l l y t r a p p a b l e . assumption  Mathias  the estimate obtained d u r i n g the present  o f T. g r a n u l o s a t o A. g r a c i l e  Acceptance  A.  and  T h e i r e s t i m a t e o f 2 3 0 0 i n d i v i d u a l s was based  study. ratio  from  of Efford  estimate  t h e r e were a b o u t  6000  i n Marion Lake, e x c l u d i n g young o f the  T h i s i s h i g h when compared t o t h e d e n s i t i e s  o f 41 t o  3 2 3 8 p e r h e c t a r e r e c o r d e d among t e r r e s t r i a l a d u l t s a l a m a n d e r s  80*  ( A n d e r s o n , I960; H e n d r i c k s o n , 1954;  S t e b b i n s , 1954)  but i t  must be remembered t h a t t h e p r e s e n t c e n s u s i n c l u d e d s e c o n d y e a r larvae.  T h e r e were a b o u t 1450  neotenous  a d u l t A. g r a c i l e  per  hectare i n the l a k e . The l a r g e e s t i m a t e o f A . g r a c i l e numbers was on t h e b a s i s o f t r a p p i n g r e s u l t s and d a y t i m e  not expected  observations.  The n o c t u r n a l f e e d i n g h a b i t s o f t h e s e a n i m a l s and t h e s h o r t ; time d u r i n g w h i c h t h e y a r e e x p o s e d a s t h e y h u n t make Ambystoma v e r y i n c o n s p i c u o u s except d u r i n g the e a r l y hours o f darkness, when most o f t h e p r e d a t i o n o c c u r r e d .  Personal  communications  from r e s e a r c h e r s working i n l a k e s i n B r i t i s h Columbia n o r t h e r n M a n i t o b a s u g g e s t t h a t n e o t e n o u s A. g r a c i l e t i g r i n u m may  be v e r y abundant  i n many l a k e s .  b e n t h i c p r e d a t i o n by s a l a m a n d e r s T h i s means t h a t predator. salamanders  A.  ( i n press) o f the  i n Marion Lake. significant  I t i s probable t h a t such i s the case w i t h  neotenous  i n many o t h e r l a k e s .  Ambystoma young  i n t h i s study d i d not  o f the year.  c o u n t i n g specimens  The  c a u g h t i n mud  s i n c e v a s t amounts o f mud  i n M a r i o n Lake  reveal  c e n s u s o f t h e s e a n i m a l s by samples  was  deemed  imprac-  would have t o be sampled  o r d e r t o get even a minimal e s t i m a t e .  consistent  55$  i n M a r i o n Lake Ambystoma i s a v e r y  The methods employed  tical  and f i s h  and  Efford  has e s t i m a t e d t h a t A. g r a c i l e a c c o u n t s f o r a b o u t  and  I t was  estimated that  t h e r e were a b o u t 14,500 a n i m a l s o f a  w i t h t h e p o s s e s s i o n o f gonads,  in  size  y e t o n l y about  750  81  egg  masses were c o u n t e d .  The  between t h e number o f egg n o t be  adequately  breeding  season the animals gregations.  masses and  explained  b i o l o g y o f A.  reasons  f o r the l a r g e  t h e number o f a d u l t s c o u l d  s i n c e not  gracile.  were w i d e l y  enough was  During  the  neotenous-metamorphosed A.  gracile populations  nation of this discrepancy  awaits  ratio.  a v e r y l l o w number o f egg  Anderson  discovered  d e n s i t y and The  so an  mass/adult  t h a t t h i s was  and  associated with high  r e s o r p t i o n o f eggs by  w i t h the l a t t e r h a v i n g  d i s t r i b u t i o n w h i c h underwent d r a s t i c  t h r o u g h o u t t h e s p r i n g and i n t h e l a k e d i d A.  masses s i m i l a r t o t h o s e  summer.  t h a t A.  Neither  commonly f o u n d  d e n c y t o snap a t e a c h o t h e r . found  t h e f o r m e r had  among T.  have b e e n r e l a t e d I n t h e l a k e and  g r a c i l e had  A.  gracile  dispersed, a highly  changes  i n the l a b o r a t o r y  g r a c i l e appear to gather  o f Ambystoma may  populations  a widely  contagious  was  population  and  stable d i s t r i b u t i o n while  it  aurora  females.  s p a t i a l d i s t r i b u t i o n s of T.granulosa  out  Calef  Aneides l u g u b r i a  apparently  spacing  expla-  (i960) f o u n d a s i m i l a r d i s p a r i t y i n p o p u l a t i o n s  were v e r y d i f f e r e n t  nor  o f mixed  c h o r u s o f Rana  of the salamanders Batrachoseps a t t e n u a t u s and  ag-  Little  further research.  ( p e r s . comm.) i n w o r k i n g on t h e b r e e d i n g a l s o found  i n breeding  behaviour  the  breeding  p a i r s were s e e n .  a p p e a r s t o be known a b o u t t h e b r e e d i n g  has  known o f  spring  d i s p e r s e d , not  Only three breeding  discrepancy  i n closely  knit  granulosa.  The  to t h e i r  ten-  i n the l a b o r a t o r y  a t e n d e n c y t o snap a t  each  82  o t h e r s ' l i m b s and in  t h e two  gills.  I n the l a k e t h i s appeared  to  result  a n i m a l s i n v o l v e d swimming away f r o m e a c h o t h e r .  t h e l a b o r a t o r y t h e l o s s o f l i m b s and  g i l l s was  Such s n a p p i n g a p p e a r e d  to feeding behaviour  than to a g o n i s t i c difficult  to  t o be r e l a t e d  t h i s never r e s u l t e d  i n injury  s e p a r a t e d , t h e two  swim away f r o m e a c h  of  each o t h e r .  to e i t h e r  animal  animals u s u a l l y d i d not  ejb a l . (1970) have d e s c r i b e d a l a r g e c o n c e n t r a t i o n  t h e a g g r e g a t i o n w h i c h t h e y o b s e r v e d was  land.  of  other.  phenomenon r e f l e c t i n g  the tendency  concluded  a post-reproductive  o f T a r i c h a to aggregate  on  C o n c e n t r a t i o n s o f a n i m a l s i n M a r i o n L a k e were s e e n d u r i n g  the e n t i r e pe r i o d  o f o b s e r v a t i o n so t h e y c a n n o t  s i m p l y as a p o s t - r e p r o d u c t i v e phenomenon. and  the limbs  T. g r a n u l o s a i n C l e a r L a k e , O r e g o n . These a u t h o r s  that  was  Although i n  of food scent these animals grasped  a f t e r t h e y had  Coates  rather  determine.  other Taricha. and  common.  behaviour although such a d i s t i n c t i o n  T a r i c h a d i d not tend to i n j u r e the presence  fairly  In  egg l a y i n g f e m a l e s  concentration.  I t was  pairs  near centres of  f o u n d , however, t h a t t h e l a r g e s t  c e a s e d t o be  a r e a o f the l a k e  conjust  caught.  An o u t s t a n d i n g c h a r a c t e r i s t i c granulosa i s that  regarded  Amplectic  were f o u n d b o t h i n and  c e n t r a t i o n o f a n i m a l s o c c u r r e d i n one before Taricha  be  o f t h e d i s t r i b u t i o n o f 81.  c o n s i d e r a b l e changes were o b s e r v e d b o t h i n  t h e numbers o f a n i m a l s i n t h e l a k e and  i n the p o s i t i o n s  c o n c n e t r a t i o n c e n t r e s as t h e y e a r p r o g r e s s e d .  No  of  Taricha could  ,  83.  be  found  i n t h e l a k e b e f o r e m i d - A p r i l and  T h e r e was late  a decrease  June and  early July.  " w a n d e r i n g " i n and Pimentel panied  i n the  (l96l).  out The  observed tivity  by  abundance. gradient  The  (1970) and  by D a v i e s  related  as  complex a r e a s  such as  tangled  of Tarioha to follow a  (above 2 0 ° C . ) .  vegetation  may  Loon Lake, B r i t i s h  prey  have b e e n r e l a t e d t o the;  with a heavy tadpole  hatch.  i n v o l v e d the avoidance Shallow water  a t d e p t h s up  of  concentrations spring  t h e d i s t r i b u t i o n o f T.  L a r g e c o n c e n t r a t i o n s were f o u n d  centres  concentration  formed i n c o o l e r , d e e p e r a r e a s .  appear to r e s t r i c t  coin-  centres  e f f e c t s o f t e m p e r a t u r e and  source  accom-  contents  A l l concentration  temperatures rose d u r i n g the l a t e  concentrations  and  Depth  alone  granulosa.  t o 40  feet  in  Columbia.  c o n s i d e r a b l e movements o f i n d i v i d u a l T a r i c h a  an a p p r a i s a l o f what i s meant by connection  stomach  by  a drop i n macrophyte produc-  (1970).  tothe  ability  h i g h temperatures  The  have b e e n  p a i r s i n t h e l a k e and  of temperature probably  disappeared  may  during  i n t h e T a r i c h a c a t c h was  e n t r y o f newts i n t o a r e a s  d i d not  time animals  i n t h e volume o f f i s h  to l o c a t e a food  effect  of effort  Changes i n t h e p o s i t i o n s o f c o n c e n t r a t i o n  a p p e a r e d t o be  new  this  decrease  i n spatially  or f i s h net.  The  At  September.  o f t h e l a k e i m t h e manner d e s c r i b e d  Sandercock  observed  were f o u n d  rapid  catch per u n i t  by an a b s e n c e o f a m p l e c t i c  cided with a decrease  after late  with these  animals.  suggest  t h e t e r m "home r a n g e " i n The  displacement  experiments  84.  of E f f o r d and Mathias as w e l l as those done i n the present study suggest that T. g r a n u l o s a r a p i d l y returned to the p o i n t from which they were removed.  I t was  the homing was through water.  evident i n both s t u d i e s that  The home range t o which the  animals returned can a t best be d e s c r i b e d as temporary,  however,  s i n c e some animals were caught i n up to seven d i f f e r e n t areas of  the l a k e d u r i n g the 21 weeks of o b s e r v a t i o n and almost a l l  of  the animals caught f i v e or more times were captured i n more  than one area.  II.  FEEDING BEHAVIOUR. Using the r e s u l t s of H o l l i n g ' s (2.966) work with the mantid  H e i r o d u l a c r a s s a G i g l i o - T o s , Ware's work with t r o u t ( i n prep.) and the present author's work with salamanders  one can compare  the s p e c i f i c hunting s t r a t e g i e s used by these animals. Reactive f i e l d  -  The mantid and t r o u t are both v i s u a l  predators which do most of t h e i r f e e d i n g d u r i n g d a y l i g h t hours. Both animals show s i z e s e l e c t i v e p r e d a t i o n and appear to have the a b i l i t y to d i s t i n g u i s h between animals of d i f f e r e n t The r e a c t i v e f i e l d  sizes.  of the mantid changes i n s i z e as hunger  changes but t h i s i s not the case with the t r o u t and  salamander.  I t has been found that c e r t a i n of the f i x e d a c t i o n patterns of urodele f e e d i n g can be e l i c i t e d by chemical, mechan i c a l and v i s u a l s t i m u l i a c t i n g e i t h e r together or i n combin a t i o n (Burr, 1916;  Copeland, 1913;  D i j k g r a a f , 1963;  Goldstein,  85.  1960;  Martof, 1962; Mathias, 1964; N i c h o l a s , 1922; Reese, 1912;  Sayle, 1916).  Various i n v e s t i g a t o r s have found that  urodeles  can feed i n a l a b o r a t o r y s i t u a t i o n as l o n g as a t l e a s t one sense organ i s l e f t i n t a c t .  The r e s u l t s o f the present  study  suggested that a normal animal used a combination o f s t i m u l i i n l o c a t i n g and c a p t u r i n g prey.  I n both T a r i c h a and Ambystorna  the a c t i o n p a t t e r n s o f searching were e l i c i t e d by o l f a c t o r y s t i m u l a t i o n , T a r i c h a appeared to f o l l o w a c o n c e n t r a t i o n gradient to l o c a t e centres o f strong s t i m u l a t i o n though t h i s was not seen among Ambystorna.  T h i s o b s e r v a t i o n i s c o n s i s t e n t with the sug-  g e s t i o n that Ambystorna tend t o remain i n a given area i n the l a k e which they search e x t e n s i v e l y while T a r i c h a tend to concentrate t h e i r p r e d a t i o n i n areas o f h i g h prey d e n s i t y . The s i z e and.shape of the salamander's r e a c t i v e f i e l d appeared to vary depending on the sense being  considered.  Chemical cues could be responded to a t v a r y i n g d i s t a n c e s depending on the c o n c e n t r a t i o n and d i s t r i b u t i o n the substances being responded t o . on hunger.  The responsiveness  to chemical  s t i m u l i depended  The v i s u a l and t a c t i l e r e a c t i v e f i e l d s o f the  salamander appeared to be roughly equal to the s i z e o f the s t i k e d i s t a n c e (about 0.5 - 1.0 cm.).  This i s much l e s s than  the maximum r e a c t i v e d i s t a n c e s o f the mantid (35 cm.) and the t r o u t (about  100 cm.).  In Marion Lake salamanders  probably  eould not use v i s i o n d u r i n g many f e e d i n g bouts because they hunted a t n i g h t i n a mud bottomed l a k e i n an area which o f t e n had heavy cloud cover.  T a r i c h a used chemical s t i m u l i to locate,  86.  a r e a s o f h i g h p r e y d e n s i t y b u t Ambystoma d i d n o t .  Both  manders were s t i m u l a t e d t o s e e k p r e y i n t h e p r e s e n c e odors  but the v i s u a l l o c a t i o n  their  stike  behaviour.  strike distance.  Water column  have r e a c t e d t o p r e y f u r t h e r away  d i s t a n c e but  t h i s was  not r e f l e c t e d  than  in their  When f e e d i n g on c l a d o c e r a Ambystoma a p p r o a c h e d  h e a v y c o n c e n t r a t i o n o f p r e y and Effector and  of food  o f f o o d o c c u r r e d o n l y when t h e  prey i s w i t h i n the salamanders' f e e d i n g Ambystoma may  sala-  limbs used  organs  -  The  t o h o l d and  sucked  size  ingest  and  them i n . structure  of the  f o o d e x e r t s some  on t h e s i z e a n i t y p e o f f o o d w h i c h an a n i m a l may  organs  limitations  eat.  Both  u p p e r and l o w e r p r e y s i z e l i m i t s o f s a l a m a n d e r p r e y were s o l e l y determined  i n t h i s manner.  a n y t h i n g l a r g e enough t o see and attempted large  a  Salamanders appeared  almost to attack  s m a l l enough t o i n g e s t .  t o swallow prey too l a r g e  earthworms) b u t d i s e n g o r g e d  They  to get i n the stomach  such prey  the  (eg,  i f they f a i l e d to  s w a l l o w them. Trout, l i k e salamanders, selection  by t h e t r o u t  tual level.  Trout tend  appears  t h e i r p r e y whole.  to occur mainly  to s e l e c t  u p p e r s i z e l i m i t o f p r e y may to  ingest  be  on t h e  Size  percep-  l a r g e p r e y , however, and  the  s e t by t h e a n i m a l ' s c a p a c i t y  ingest. The  nite  geometry o f t h e m a n t i d ' s g r a s p i n g arm  r e s t r i c t i o n s on t h e s i z e  places d e f i -  o f p r e y which a mantid  may  capture  87.  even though t h i s  a n i m a l does n o t i n g e s t  i t s prey whole.  Size  s e l e c t i o n i s f o r a n optimum p r e y s i z e r a t h e r t h a n f o r l a r g e o r small prey.  S e l e c t i o n may be b a s e d  as t h e m e c h a n i c a l  a t the p e r c e p t u a l as w e l l  level.  S e a r c h r a t e and p o s i t i o n - D u r i n g s e a r c h i n g t h e t r o u t moves q u i c k l y and w i t h i t s l a r g e " r e a c t i v e f i e l d of  habitat/unit  o f time.  can search l a r g e  I t i s capable o f c a t c h i n g q u i c k l y  moving p r e y s u c h a s o t h e r f i s h and c a n move f r e e l y d i m e n s i o n a l space. rapid  strike,  The m a n t i d ,  i s also  by v i r t u e  capable o f c a p t u r i n g f a s t  moving  i s , however, a n ambush p r e d a t o r w h i c h p u r s u e s ,  at  p r e y t h a t move w i t h i n i t s r e a c t i v e f i e l d effective  the r e a c t i v e The and ing. time  searching area i s ^ t h e r e f o r e field  and t h e m o t i l i t y  prey.  then  or strike  strikes field.  a f f e c t e d by s i z e o f  o f the prey.  s a l a m a n d e r moved v e r y s l o w l y when s e a r c h i n g f o r p r e y  approached  p o t e n t i a l food items v e r y c l o s e l y b e f o r e  S a l a m a n d e r s had a f a i r l y  slow  strike  "nosing," f o o d b e f o r e i n g e s t i n g i t .  a s p e c t s o f the salamander's p r e y w i t h no r a p i d by  i n three  o f i t s extaremejfcy  It  The  areas  escape  and t h e y s p e n t  As a r e s u l t  feeding behaviour  response  striksome  o f these  o n l y slow  moving  c o u l d be c a p t u r e d f r e q u e n t l y  salamanders. When t r o u t  s e a r c h a l a k e bottom they c r u i s e w i t h  nose a n g l e d down a t a n a n g l e a p o s i t i o n about  o f about  1 0 ° - 2 0 ° and assume ;  15 cm. above t h e s u b s t r a t u m .  predator observing prey a t a distance trout a n i m a l s above t h e mud s u r f a c e .  their  As a v i s u a l  could detect only  I n M a r i o n L a k e t h e t r o u t and  s a l a m a n d e r a t e many o f t h e same p r e y  s p e c i e s b u t a much h i g h e r  88  p r o p o r t i o n o f t h e s e s p e c i e s c o u l d be d e t e c t e d by which searched substratum.  the  salamander,  on t h e l a k e b o t t o m w i t h i t s n o s e a t o r n e a r  By  the salamanders  a s s u m i n g s u c h a p o s i t i o n on a r o u g h l a k e b o t t o m therefore greatly restricted  their ability  d e t e c t p r e y a t a d i s t a n c e b u t t h e y have a s h o r t r e a c t i v e t a n c e i n any n i c a l and substratum  the  case.  Since the salamander can respond  c h e m i c a l cues,  dis-  t o mecha-  p r e y s l i g h t l y below, above o r on  c a n be d e t e c t e d .  With t h e i r  small reactive  and  slow movements s a l a m a n d e r s  u s u a l l y encountered  few  prey a t a time u n l e s s the p r e y organisms  to  the  field  one  or a .  are very small.:  They t h e r e f o r e d i d n o t have t o choose between a number o f s i m u l t a n e o u s l y p r e s e n t e d a l t e r n a t i v e s as a t r o u t Salamanders appeared s e a r c h i n g and  or mantid  t o e a t p r e y as t h e y were e n c o u n t e r e d  exercized l i t t l e  selection.  There  may,  to underestimate  Attack thresholds cussed  the importance  The<error Rolling  was  very s l i g h t ,  (1963, 1965,  1966)  that  tended  t h e a c t u a l number o f p r e y e a t e n i f t h e  were i n h i g h p r o p o r t i o n .  prey  however. has  paper  depicting  f o u r a r r a n g e m e n t s o f a t t a c k t h r e s h o l d s w h i c h one  i n nature.  dis-  o f t h r e s h o l d s i n b i o l o g i c a l systems.  t h i s 1966  find  during  however,  have b e e n some s e l e c t i o n s i n c e t h e model, w h i c h assumed t h e y would be e a t e n i n p r o p o r t i o n t o t h e i r abundance,  may.  ( F i g . 34) R o l l i n g  F i g . 15  In  showed a s e r i e s o f p a r a d i g m s  shows p a r a d i g m s o f t h i s  may  type f o r the  three animals being d i s c u s s e d here. The  ordering of attack thresholds r e f l e c t s  s t r a t e g i e s o f the mantid,  t r o u t and  salamander.  theuhunting The  trout  89.  Fig.  15» in  Relation  o f a t t a c k t h r e s h o l d s to each o t h e r  the format o f H o l l i n g  (1966, F i g . 34).  figure  i s drawn a f t e r H o l l i n g  figure  i s s i m i l a r to H o l l i n g ' s  (1966) and  The the  stickleback  shown  mantid  trout  figure.  90.  p r o b a b l y depends t o a g r e a t e x t e n t on l e a r n i n g a s i t d i s c o v e r s and  remembers a r e a s s a t i s f a c t o r y  will  search f o r , pursue,  strike  f o r hunting.  and c a p t u r e p r e y e v e n when i t  w i l l not e a t i t i s m o t i v a t i o h a l l y equipped of  t i m e r e a c t i n g t o and l e a r n i n g a b o u t  of  the mantid  and s a l a m a n d e r  Since the trout  t o spend a g r e a t d e a l  prey.  This i s not true  ( F i g . 15) b o t h o f w h i c h p r o b a b l y  do n o t r e l y  o n l e a r n i n g a s much a s t r o u t do i n t h e i r p r e d a t i o n  behaviour.  When t h e y a r e n o t h u n g r y enough t o e a t , t h e m a n t i d  and  salamander w i l l n o t s e a r c h f o r , o r pursue  availability  i s such that  t h e y have t o p u r s u e  they w i l l n o t e a t but i f p r e y  prey. prey  I f prey to get i t ,  come c l o s e enough t o be c a p t u r e d  t h e y w i l l be e a t e n . For the mantid is  "search" i s not the a c t i v e p r o c e s s which i t  w i t h t r o u t and ( t o a l e s s e r e x t e n t ) s a l a m a n d e r s .  uses  a g r e a t d e a l o f energy  i n i t s search f o r food but the  s a l a m a n d e r p r o b a b l y does n o t . of  t h e day a c t i v e l y  the salamanders hours  Although  t h e t r o u t spends much  swimming i n M a r i o n Lake  ( H y a t t , p e r s . comm.)  were u s u a l l y i n a c t i v e and o n l y s p e n t  a t most i n h u n t i n g .  30 min. mean t i m e w i t h a p r e y o f .042 c c ) . time  a few  A f t e r e a c h p r e y was t a k e n t h e s a l a -  mander was below i t s s e a r c h t h r e s h o l d f o r some t i m e  of  The t r o u t  (about  -Since t h e amount  s p e n t a c t u a l l y h u n t i n g was a s m a l l p o r t i o n o f t h i s  t i m e t h e s a l a m a n d e r was below i t s s e a r c h t h r e s h o l d i t s p e n t  about 2  t h e same t o t a l l e n g t h o f t i m e r e a c h i n g s a t i a t i o n a t 8 prey/m as i t d i d a t 200 p r e y / m . 2  The t r o u t , however, w i l l  commence  91 .  searching a few seconds a f t e r a prey capture. Predator d i s t r i b u t i o n andtthe f u n c t i o n a l response of predators to prey d e n s i t y - H o l l i n g (1966) has p o i n t e d out that predators appear to respond to prey d e n s i t y i n one of three ways. In the type 1 response the r e l a t i v e p r o p o r t i o n of a prey eaten r i s e s l i n e a r l y with r e s p e c t to prey d e n s i t y up to a p l a t e a u . U n t i l the p l a t e a u i s reached type 1 p r e d a t i o n i s d e n s i t y  independ-  ent and a f t e r the p l a t e a u i s reached such p r e d a t i o n i s depensatory ( n e g a t i v e l y d e n s i t y dependent) ( H o l l i n g ,  1965).  Among animals showing the type 2 f u n c t i o n a l response the r e l a t i v e p r o p o r t i o n of a prey eaten r i s e s i n a n e g a t i v e l y a c c e l e r a t e d f a s h i o n to a p l a t e a u as the p r o p o r t i o n of the s p e c i f i c prey i n quest i o n changes. At a l l d e n s i t i e s , type 2 p r e d a t i o n i s depensatory (Holling,1965). The type 1 and 2 responses have been c a l l e d responses by H o l l i n g (1965, 1966). response the " v e r t e b r a t e " response  "invertebrate"  H o l l i n g c a l l s the type 3 (although i t i s not i m p l i e d  that these c a t e g o r i e s are p h y l e t i c a l l y r i g o r o u s ) . The type i m p l i e s l e a r n i n g on the p a r t of the p r e d a t o r .  3,response  I t c o n s i s t s of &•  sigmoid response of the predator to prey d e n s i t y .  Significant  d e n s i t i y dependent e f f e c t s can t h e r e f o r e occur s i n c e type 3 preda t o r s have p o s i t i v e l y d e n s i t y dependent e f f e c t s on prey m o r t a l i t y when prey are at low d e n s i t y and depensatory e f f e c t s at h i g h e r d e n s i t y ( H o l l i n g , 1965).  The evidence a v a i l a b l e suggests that  the t r o u t (Ware, i n prep.) shows the type 3 response.  Holling .  (1966) has shown that the mantid shows a type 2 response. the present model the salamander  In  was assumed to have a type 2  92. response to prey d e n s i t y .  The s l i g h t d i f f e r e n c e between observed  and p r e d i c t e d values suggest, however, that these animals a c t u a l l y have a s l i g h t type 3 response. The f u n c t i o n a l response of the p r e d a t o r to prey d e n s i t y i n a s m a l l area i s only one way  i n which a p r e d a t o r may  cause  d i s p r o p o r t i o n a t e m o r t a l i t y on one prey s p e c i e s , such as when: tadpoles were eaten i n t h e i r hatohing areas by T a r i c h a .  Walters  (pers. comm.) has found that i n the Marion Lake energy flow , model the coincidence of l o c a l i z e d h i g h p r e d a t o r and prey d e n s i t i e s can r e s u l t i n prey m o r t a l i t i e s which can have profound population-effects.  Although there are only about 2450 T a r i c h a  i n Marion Lake these animals can have a s i g n i f i c a n t e f f e c t tadpolesnumbers able to  on  before the tadpoles grow too l a r g e to be a v a i l -  salamanders.  The d i s p r o p o r t i o n a t e e f f e c t s of p r e d a t i o n by one p r e d a t o r s p e c i e s on a s p e c i f i c prey may  be p a r t i c u l a r l y marked i f one.  deals with mean d e n s i t i e s of predators and prey i n a l a r g e system such as Marion Lake. s p e c i e s may  High p r e d a t i o n on i n d i v i d u a l  be enhanced by the f o l l o w i n g e f f e c t s , which were  not' i n c l u d e d i n the model: a)  Predators may  have means of l o c a t i n g h i g h concen-  t r a t i o n s of c e r t a i n prey and l i l l t h e r e f o r e take l a r g e numbers; of t h i s prey. i)  This may  occur i n a number of ways:  Predators may move i n a manner such that they  are not o r i e n t i n g toward prey c o n c e n t r a t i o n s but i f they l o c a t e such c o n c e n t r a t i o n s may feed there.  stop and  The l o c a t i o n of areas of h i g h prey  93.  d e n s i t y may  be  from v a r y i n g d i s t a n c e s .  Taricha.  f o r example, r e s p o n d e d t o p r e y a t a g r e a t  distance  because they used o l f a c t o r y cues t o d e t e c t l o c a t e p r e y but  a t r o u t or mantid, which r e l i e s  v i s u a l cues, can ii)  only l o c a t e prey  H a v i n g once l o o a t e d  an a n i m a l s u c h as  number o f w i d e l y Once one  separated  o r a few  o f h i g h p r e y d e n s i t y and p r e s e n c e may species ferent  attract  it  occur  exhibited  on  the  populations.  a n i m a l s have f o u n d an have r e m a i n e d t h e r e  other  predators  area their  dif-  evident  haviour  exploit a  (as i n T a r i c h a ) . o r perhaps even o f H o l l i n g has  called  complex a r e a  pheno-  s u c h a s a weed  that differences i n feeding  even w i t h i n a s p e c i e s .  two  this  facilitation".  In a s p a t i a l l y  could  prey  quickly  same  species.  was  therefore  to  density  o f the  menon " s o c i a l iv)  prey  l e a r n how  They c a n  on  visually.  areas of high  a t r o u t may  r e l o c a t e such areas.  iii)  and  benthos o r i n the  behaviour  Ambystorna  d i f f e r e n t .types o f f e e d i n g  w h i c h were a p p r o p r i a t e  bed  be-  to predation  either  w a t e r column a r o u n d weeds.  T h e r e were some i n d i c a t i o n s t h a t t h e s e d i f f e r e n c e s i n b e h a v i o u r were r e t a i n e d by H e n d e r s o n (1970) p l a c e d l a r v a e and H a l f o f the the  one  i n d i v i d u a l animals.  newly h a t c h e d  Ambystorna  year old larvae i n small  aquaria.  a n i m a l s were g i v e n S i d a c r y s t a l l i n a  o t h e r h a l f w e i a g i v e n l a k e mud  containing  and  9 4 .  benthic prey.  A f t e r 30 days the animals were p l a c e d  i n tanks c o n t a i n i n g both types o f prey  organisms.  Even a f t e r 3 0 days i t was found that animals r e a r e d on benthic prey a t e s i g n i f i c a n t l y fewer S i d a than did  animals reared on S i d a ( t - t e s t , P - 0 . 0 5 ) .  b)  When prey are l o c a t e d and f e d on a t h i g h d e n s i t y the  predator may feed a t a h i g h r a t e . or  The t r o u t ( l i k e many f i s h )  mantid d i g e s t food f a s t e r and probably l e s s  efficiently  when the stomach i s f u l l than they do when the stomach i s l e s s than f u l l .  At h i g h prey d e n s i t y when the stomach can be kept  f u l l the prey turnover r a t e may t h e r e f o r e be enhanced. Rolling ( 1 9 6 5 ,  1966)  considered the f u n c t i o n r e l a t i n g  d e p r i v a t i o n time t o food consumption  to be v i t a l i n the cons-  t r u c t i o n o f an experimental components a n a l y s i s o f p r e d a t i o n . Salamander curves d i f f e r e d i n two ways from the curves o f a l l animals p r e v i o u s l y examined.  The salamander  curves were l i n e a r  r a t h e r than n e g a t i v e l y a c c e l e r a t e d and they reached t h e i r maximum a t a d e p r i v a t i o n time o f f i v e to 6 i x days r a t h e r than one to two days t h e r e f o r e the salamanders'  daily ration f e l l far  short of t h e i r maximum stomach c a p a c i t y .  Among animals  i n Marion Lake and animals UBed i n prey d e n s i t y  caught  experiments  food r a t i o n volumes were l e s s than the mean amount o f horse heart which could be d i g e s t e d i n a day so i t appeared salamanders  were not m a i n t a i n i n g a completely f u l l  that the  stomach  but were e a t i n g approximately what they could d i g e s t i n 2 4 hours.  T h i s means that most hunting was done at a h i g h hunger  95.  l e v e l when t h e p r o b a b i l i t y o f n o s i n g , mean t i m e o f n o s i n g , p r o bability  o f an i n c o m p l e t e  f e e d i n g s e q u e n c e and l e n g t h o f  t o r y p e r i o d were a l l a t t h e i r l o w e s t , t h e r e f o r e t h e were m a x i m a l l y  responsive to t h e i r prey.  d e a l t w i t h i n the experiments  "low"  if  one  salamanders  hunger  level  d e s c r i b e d here.  A l l p r e y a r e n o t d i g e s t e d a t t h e same r a t e , d e n s i t y two  salamanders  In nature  p r o b a b l y n e v e r e a t p r e y whenthey a r e a t t h e  refrac-  At h i g h  p r e y o f e q u a l s i z e w i l l be e a t e n i n d i f f e r e n t  p r e y i s d i g e s t e d much more q u i c k l y  than the other.  p o l e s f o r example were d i g e s t e d by s a l a m a n d e r s  about  f a s t e r t h a n h o r s e h e a r t o r amphipods t h e r e f o r e 4.7 t a d p o l e s c o u l d be  eaten per u n i t  of time.  numbers  4.7  Tadtimes  t i m e s more  I n t h e p r e s e n t model  d a t a on d i f f e r e n t i a l d i g e s t i o n r a t e s were i n c o m p l e t e and  i t was  assumed t h a t p r e y o t h e r t h a n t a d p o l e s were d i g e s t e d a t t h e same r a t e as h o r s e h e a r t so some e r r o r was this  p r o b a b l y i n t r o d u c e d from  source. I n some i n s t a n c e s t h e volume o f stomach c o n t e n t s i n a n i m a l s  captured  i n M a r i o n Lake exceeded  e s t e d i n one  day.  t h e amount w h i c h c o u l d be  I n many c a s e s t h i s may  have b e e n due  type of i n d i v i d u a l v a r i a b i l i t y  observed d u r i n g d e n s i t y  ments o r i t may  the i n g e s t i o n o f a l a r g e  have r e f l e c t e d  p r e y i t e m s u c h as an earthworm. been another f a c t o r  involved  of food during a s i n g l e  H i g h p r e y d e n s i t y may  dig-  to the experisingle have  i n t h e i n g e s t i o n o f a h i g h volume  f e e d i n g bout.  A l t h o u g h p r e y d e n s i t y d i d n o t have a l o n g t e r m  effect  on  t h e amount o f f o o d i n g e s t e d by T a r i c h a t h e r e were i n d i c a t i o n s  that  96.  short term e f f e c t s occurred.  During hunger curve  determinations  and d u r i n g food d e n s i t y experiments when animals were moved from low to h i g h d e n s i t y i t was  found that T a r i c h a ate more food  could be d i g e s t e d i n one day.  than  By n e c e s s i t y the mean d a i l y food  intake of an animal i s l i m i t e d by the r a t e a t which food can be moved through the stomach but i t i s p o s s i b l e that the p o s s e s s i o n of a l a r g e "reserve" stomach volume p l u s an immediate i n c r e a s e i n the volume of food eaten as food i s encountered  i n high  d e n s i t y could be of f u n c t i o n a l s i g n i f i c a n c e i n a s i t u a t i o n where the predator meets short term, h i g h prey d e n s i t y s i t u a t i o n s . T h i s c o n d i t i o n i s t y p i c a l of the pond and l a k e h a b i t a t of salamanders where sudden emergences of i n s e c t s and tadpoles commonly occur. Trout and salamander e f f e c t s on prey p o p u l a t i o n s -  The  p r e d a t i o n behaviour of the t r o u t and salamander are a s s o c i a t e d with d i f f e r e n t types of e f f e c t on prey p o p u l a t i o n s .  The  i s an a c t i v e predator,with a f a s t food turnover r a t e a n d tendency to s e l e c t l a r g e prey.  trout 1  a  Where a l l s i z e c l a s s e s of a prey  species f a l l i n the range which a t r o u t w i l l i n g e s t (as i n the case of amphipods) t h i s means that reproducing animals w i l l  be  selected. The salamander does not p e l e c t f o r prey s i z e to the same extent as the t r o u t .  For example, Hargrave (pers. comm.) found  that a l l amphipod s i z e c l a s s e s were eaten i n p r o p o r t i o n to t h e i r abundance by the salamanders i n Ma±?ion Lake.  Salamanders eat a  low p r o p o r t i o n of t h e i r body weight i n food every day  (about  2.7$)  97  and the average  salamander i s much s m a l l e r than the average  trout.  As a r e s u l t o f these two aspects o f salamander p r e d a t i o n the numerical and demographic e f f e c t s o f p r e d a t i o n by an i n d i v i d u a l average  salamander may be l e s s marked than the e f f e c t s o f pred-  a t i o n by an average  t r o u t espe c i a l l y when a prey such as the  amphipod i s being considered.  T h i s d i f f e r e n c e i s magnified when  p r e d a t i o n by t r o u t and: salamanders i s viewed on a year around basis.  The newt T a r i c h a i s present i n Marion Lake o n l y d u r i n g  about f o u r months o f the year while the t r o u t i s i n the l a k e . d u r i n g the whole year. Accuracy o f the model p r e d i c t i o n s — The model gave a r e a s onably accurate p r e d i c t i o n o f the r e s u l t s o f C a l e f ' s experiments. The p r e d i c t i o n of p r o p o r t i o n s o f food eaten by T a r i c h a were a l s o considered t o be f a i r l y a c c u r a t e .  Most o f the e r r o r i n the  p r e d i c t i o n s was due to poor data d e s c r i b i n g some o f the prey eaten although some e r r o r was probably due to the s i m p l i c i t y o f the model as w e l l .  Ware ( i n prep.) has found that p r e d i c t i o n s  by -this model were improved f o r the t r o u t when subroutines were added to c a l c u l a t e r e a c t i v e d i s t a n c e and e f f e c t o f body s i z e on ration size. for  These p a r t i c u l a r submodels were not necessary  a s i m u l a t i o n o f salamander p r e d a t i o n however. P r e d i c t i o n s of Ambystorna stomach contents were l e s s ac-  curate than p r e d i c t i o n s o f T a r i c h a stomach contents. probably due p a r t l y to the reasons mentioned above.  T h i s was I t may  a l s o have been due to the f a c t that most of the a t t a c k parameters  98.  in  the model were d e t e r m i n e d i n e x p e r i m e n t s done u s i n g  Finally  i t should  was  sampled as t h o r o u g h l y as-the  not  be p o i n t e d  possible  t h a t the  were n o t  r e p r e s e n t a t i v e o f the  the  field  data  out  stomachs o f M a r i o n Lake  t h a t t h e Ambystoma  Taricha.  population  Taricha population.  It i s  compared t o t h e model p r e d i c t i o n s actual proportions  animals.  of prey  in  SUMMARY  1.  I t was  estimated that i n 1969  there were 2449 a d u l t T a r i c h a  granulosa. 14,500 a d u l t neotenous Ambystoma g r a c i l e and45,500 l a r v a l A. g r a c i l e i n Marion Lake, biomasses  of 18 kgm  This represents t o t a l lake  of T a r i c h a and 409 kgm  of Ambystoma.  It  was a l s o found that about h a l f the Ambystoma breeding populat i o n was metamorphosed.  The number of Ambystoma egg masses  found (750) was much l e s s than expected on the b a s i s of adult p o p u l a t i o n s i z e estimates.  I t was  concluded that a l l a d u l t s  d i d not breed i n a g i v e n year. 2.  The A. g r a c i l e p o p u l a t i o n was d i s p e r s e d and constant  through the s p r i n g and summer.  Density and s i z e composition  v a r i e d between areas with d i f f e r e n t v e g e t a t i o n and  substratum.  The T. granulosa d i s t r i b u t i o n i n Marion Lake was h i g h l y contagious and changed through time.  I t was  suggested  that  T a r i c h a p o p u l a t i o n d i s t r i b u t i o n was r e l a t e d to a combination of e f f e c t s r e s u l t i n g from food abundance, s o c i a l substratum type and temperature.  facilitation,  Although d i s p l a c e d  animals  returned to the areas where they were o r i g i n a l l y caught the p o s i t i o n of t h e i r home ranges changed through time. concluded that T a r i c h a was  I t was  capable of l o c a t i n g s p e c i f i c areas  i n the l a k e but d i d not have a permanent home range. 3«  T a r i c h a granulosa entered the l a k e i n A p r i l and  showed evidence of wandering  May,  i n and out of the l a k e i n mid-  1 oo; summer a n d morphosed the  lake  adults all  left  portion  and  were  found  and  4.  of  Ambystoma values  first  concluded  the  seen  end  of  year  an  to  be  adult  October.  remained year  they  about  five  span  of  from  lake in larvae  metamorphosed  The  years  Neotenous  Taricha  summer o f  granulosa.  entered  i n the  few  also  second  meta-  metamorphosed  r a p i d l y i n the  life  The  breeding.  Although  that  grew  after  second  their  i n Taricha  appeared  suggest  left  the  and  Ambystoma p o p u l a t i o n  e a r l y September.  Ambystoma g r a c i l e  g r o w t h was  and  i n their  i t was  autumn a t  adult  May  Some l a r v a e  August  i n September  the  and  larvae  year.  lake  of  in April  late  the  the  life.  lake life  but  no  span  of  maximum. 16  in  to  Literature  20  years  for  Taricha. 5.  No  source  Marion Lake and  dead  but  of  T.  A.,  gracile  specimens  were  6.  Taricha  ators  i n Marion Lake.  stayed  under  masses  of  7.  and  the  were  found  Ambystoma  or  Ambystoma  of  the  lake  found  fish  to  lake  and  found  diving  in bugs  bottom. be  bottom  nocturnal  pred-  the  salamanders  and  in  tangled  debris. feeding  were p r i m a r i l y b e n t h i c high  by  the  Taricha  locate  eaten  daylight hours  Ambystoma had  to  m o r t a l i t y was  were  feeding  scent  adult  on  During  sediment  vegetation  Taricha.  granulosa  different  on  benthos  types  of  feeders,  d e n s i t i e s of  prey  and  feeding capable  such  as  water  column  behaviour. of  utilizing  hatching  1QT*.  tadpoles.  T h e r e was  E v i d e n c e was benthic  and  retained 8.  no  evidence  w a t e r column f e e d i n g Ambystorna may  f o r at l e a s t  Amphipods and  cladoceran  one  benthic  feeding  stomach c o n t e n t s  9.  The  by 10.  have b e e n  t h e i r numbers i n  s a l a m a n d e r s r e a c t e d w i t h f e e d i n g b e h a v i o u r when t a c t i l e or chemical  that a combination of these  animals feeding  i n the  independent of the  Male T a r i c h a o f 5.9 a r a t e o f 0.27  - 6 . 3 cm  cc/day.  stimuli.  stimuli  It  was  were r e s p o n d e d  to  lake.  B o t h s p e c i e s o f s a l a m a n d e r had  w h i c h was  at  T h i s may  were  density.  stimulated with v i s u a l , concluded  an  tadpoles,  o f b o t h s p e c i e s but  to the tendency of T a r i c h a to concentrate of high prey  a  S e a s o n a l abundances  i n t h e l a k e , s u c h as m a y f l i e s and  areas  food  t h a n Ambystorna b o t h on  more marked i n T a r i c h a stomach c o n t e n t s . due  Ambystorna.  Taricha ate  on a p o p u l a t i o n wide l e v e l .  i n the  and  the  S i d a c r y s t a l l i n a accounted f o r 6 3 $ of the  of c e r t a i n prey were r e f l e c t e d  learned  t i p u l i d l a r v a e accounted f o r 6 4 $ of  s l i g h t l y more d i v e r s e r a n g e o f p r e y and  be  month.  volume o f w a t e r column f e e d i n g Ambystorna.  individual  this.  c i t e d w h i c h s u g g e s t e d t h a t the d i f f e r e n c e s between  t o t a l f o o d volume o f T a r i c h a and The  t h a t Ambystorna c o u l d do  a constant  amount o f f o o d  rate of d i g e s t i o n  tbn t h e  stomach.  body l e n g t h d i g e s t e d h o r s e  Eemale T a r i c h a 5o2  - 5.6  cm  heart long  102.  and  Ambystorna  (both  s e x e s ) 6.1 - 7.7 cm. l o n g had a d i g e s t i o n  r a t e o f 0.22 c c / d a y .  T a r i c h a were c a p a b l e o f e a t i n g s i x t i m e s  t h e volume o f h o r s e h e a r t and  Ambystorna c o u l d  they could  that  eat f i v e  t i m e s t h e amount o f h o r s e h e a r t  d i g e s t i n one d a y .  f o r a l l t y p e s o f p r e y however. volume o f t a d p o l e s constant  11.  which  D i g e s t i v e r a t e was n o t t h e same Taricha could  e a t 4.7 t i m e s t h e  than the T a r i c h a eat o f horse heart.  d i g e s t i v e r a t e o b s e r v e d h e r e was o f i n t e r e s t  salamanders a r e the only hunger  t h e y c o u l d d i g e s t i n one d a y  The  since  a n i m a l s known w h i c h have had a l i n e a r  curve.  The mean volume o f stomach c o n t e n t s  animals feeding  i n t h e l a b o r a t o r y was e q u a l  t h a n t h e amount w h i c h c o u l d were t h e r e f o r e h u n t i n g responsive  from lake  be d i g e s t e d  a n i m a l s and  to or s l i g h t l y  i n one d a y .  less  The a n i m a l s  a t a h i g h h u n g e r when t h e y were m a x i m a l l y  t o p r e y and had a s h o r t  refractory period  between  ingestions. 12.  T a r i c h a were p r e s e n t e d  w i t h 0.042 c c . p i e c e s  a t d e n s i t i e s o f 8, 30, 60, 100 and 200 p i e c e s / m  o f horse  ,  heart  The mean  d a i l y r a t i o n and t h e time between i n g e s t i o n s were n o t s i g nificantly  different  when s a l a m a n d e r s were f e d a t a  density f o r s i x consecutive  days.  When T a r i c h a were  given switched  2 to a high prey d e n s i t y density on  the  ) a f t e r feeding  a t a low p r e y  (8/m ) t h e y r e s p o n d e d by e a t i n g a l a r g e volume o f f o o d 2  the f i r s t  effect  (l00/m  day.  I t was c o n c l u d e d  that  the l a c k o f a d e n s i t y  on o v e r a l l f e e d i n g r a t e s may have b e e n p a r t l y due t o  large size  o f thefood  items used.  103.  13.  The  results  o f t h e p r e s e n t s t u d y were combined w i t h Ware's  i n f o r m a t i o n on f e e d i n g by ( i n p r e p . ) , and produced. (1959),  The  gairdneri  a computer s i m u l a t i o n model o f p r e d a t i o n model was  w h i c h was  based  on H o l l i n g ' s  "disc  and  P r e d i c t i o n s by  o f hunger,,  temperature.  the model were compared t o t h e r e s u l t s  expe r i m e n t s i n w h i c h T a r i c h a f e d on t a d p o l e s and  horse heart.  The  was  equation"  expanded t o i n c l u d e some e f f e c t s  prey v u l n e r a b i l i t y  five  t h e r a i n b o w t r o u t Salmo  observed  and  pieces of  p r e d i c t e d proportions eaten  f e r e d by a mean v a l u e o f 0 © 9 $ .  When a p r e y t y p e was  a t a h i g h d e n s i t y t h e model t e n d e d  s l i g h t l y underestimate  numbers o f t h e more numerous p r e y  t h e model t e n d e d  p r e s e n t i n low  to s l i g h t l y  numerous p r e y e a t e n . fact  type  3 response.  degree  T h i s d i s c r e p a n c y may  low d e n s i t y less  have b e e n due  t o p r e y d e n s i t y when i n f a c t that  ;  eaten.  to  were assumed t o have a  T h i s would s u g g e s t  o f l e a r n i n g and  to  o v e r e s t i m a t e numbers o f t h e  t h a t i n t h e model s a l a m a n d e r s  2 f u n c t i o n a l response  p r o p o r t i o n and  dif-  present  i n h i g h p r o p o r t i o n and  When a p r e y t y p e was  of  the  type  t h e y have a  salamanders  show some  are capable of e x p l o i t i n g prey  present  in high proportion. 14.  P r e d a t i o n by T a r i c h a and Ambystoma i n M a r i o n Lake  simulated  f o r t h e months o f May,  June, J u l y  and  was  August.  d e s c r i b i n g s e v e n p r e y t y p e s were u s e d  i n the model.  Lake t h e s e p r e y a c c o t t n t e d f o r a t o t a l  o f 79$ o f thervolume  T a r i c h a stomach c o n t e n t s and stomach c o n t e n t s .  In  Data M rion a  of  7 5 $ o f b e n t h i c f e e d i n g Ambystoma  P r e d i c t e d proportions of prey types  eaten  104.  by T a r i c h a were a mean o f 5.3 p e r c e n t a g e  p o i n t s i n e r r o r and  p r o p o r t i o n s p r e d i c t e d f o r Ambystorna were 19.5 p e r c e n t a g e in error.  I t was  concluded  that the r e l a t i v e l y  p a n c i e s between r e a l and o b s e r v e d  and  may  Secondly  The f i r s t  o f Ambystorna stomach c o n t e n t s was  was  that  field  not v e r y comprehensive  n o t have b e e n r e p r e s e n t a t i v e o f t h e whole p o p u l a t i o n . i t was p o i n t e d o u t t h a t t h e model was  d a t a w h i c h was m o s t l y was  large discre-  v a l u e s i n t h e c a s e o f Ambystorna  was p r o b a b l y due t o one o f two c a u s e s . sampling  points  the-experimental  determined animal  i n experiments  so t h e model may  T a r i c h a more t h a n i t r e p r e s e n t e d Ambystorna.  constructed using were T a r i c h a  have  represented  1 0 5 .  LITERATURE  CITED  A n d e r s o n , J.D. 1968. A c o m p a r i s o n o f t h e f o o d h a b i t s o f Ambystoma m a c r o d a c t y l u m s i n g i l l a t u m . Ambystoma macrodact.vlum croceum and Ambystoma t i g r i n u m c a l i f o r n i e n s e . H e r p e t o l o g i c a , 2±i 273-284. ". A n d e r s o n , P.K. I960. E c o l o g y and e v o l u t i o n i n i s l a n d p o p u l a t i o n s o f s a l a m a n d e r s i n t h e San F r a n c i s c o Bay R e g i o n . E c o l . Monogr. 50; 359-385. Beach, P.A. 1950. Psychologist.  The S n a r k was a Boojum. £ : 115-124.  The  American  Brodie, E.D.,Jr. 1968, I n v e s t i g a t i o n s on t h e s k i n t o x i n o f t h e a d u l t r o u g h - s k i n n e d newt T a r i c h a g r a n u l o s a . C o p e i a #2: 307-515. B u r r , H.S. pits  1916. The e f f e c t s o f t h e r e m o v a l o f t h e n a s a l i n Amblystoma embryos. J . E x p . Z o o l . 20s 27-57.  C h a n d l e r , A.C. 1918. The w e s t e r n newt o r w a t e r dog, ( N o t o p h t h a l a m u s t o r o s u s ) a n a t u r a l enemy o f m o s q u i t o e s . O r e . A g r i c . C o l l . E x p . S t a . B u l l . 152; 1. C o a t e s , M., B e n e d i c t , E . & C.L. S t e p h e n s . 1970. a g g r e g a t i o n o f t h e newt T a r i c h a g r a n u l o s a . 1970 ( I ) ; 170-178.  An u n u s u a l Copeia  C o p e l a n d , M. 1915. The o l f a c t o r y r e a c t i o n s o f t h e s p o t t e d newt D i e m y c t y l u s v i r i d e s c e n s . J . Animal Behaviour 2 260-273. s  Davies,G.S. 1970. P r o d u c t i v i t y o f macrophytes i n M a r i o n Lake, B r i t i s h Columbia* J . P i s h . R e s . Bd.Can. 27s 71-81. D i j k g r a a f , S. 1963. The f u n c t i o n i n g the l a t e r a l - l i n e organs. B i o l .  and s i g n i f i c a n c e o f Rev. ,3J3; 51-105.  E f f o r d , I . E . 1967. T e m p o r a l and s p a t i a l d i f f e r e n c e s i n p h y t o p l a n k t o n p r o d u c t i v i t y i n Marion Lake, B r i t i s h Columbia. J . P i s h . R e s . Bd. Can. 2&i 2 2 8 3 - 5 2 0 7 . E f f o r d , I . E . 1970. An i n t e r i m r e v i e w o f t h e M a r i o n L a k e Project. P r o c . UNESC0-IBP Symposium on p r o d u c t i v i t y problems o f f r e s h w a t e r s , P o l a n d .  106.  E f f o r d , I.E. and J . Mathias. 1969. A comparison o f two salamander populations i n Marion Lake, B r i t i s h Columbia. Copeia 1969 ( 4 ) : 723-736. E f f o r d , I.E. and K. Tsumura (M.S.) A comparison o f the food o f I f i s h i n Marion Lake, B r i t i s h Columbia. Earner, D.S. 1947. Notes on the food h a b i t s o f the s a l a manders o f C r a t e r Lake, Oregon. Copeia 1947 (4)s 259261. Parner, D.S. and J . Kezer. 1953. Notes on the amphibians and r e p t i l e s o f C r a t e r Lake N a t i o n a l Park. An. M i l d . Nat. __): 448-462. G o l d s t e i n , A.C. I960. S t a r v a t i o n and f o o d - r e l a t e d behaviour i n a p o i k i l o t h e r m , the salamander T r i t u r u s v i n i d e s c e n s . J . Comp. P h y s i o l . P s y c h o l . _T_,s 144-150. Hamilton, A.L. 1966. An a n a l y s i s o f a freshwater benthic community with s p e c i a l reference t o the chironomidae. Ph.D. t h e s i s , U.B.C. 1-216. Hargrave, B.T. ( i n press) The d i s t r i b u t i o n , growth and seasonal abundance o f H y a l e l l a a z t e c a (amphipoda) i n r e l a t i o n t o sediment m i c r o f l o r a . J . P i s h . Res. Bd. Can. Henderson, B.A. 1970. Some b i o l o g y and the f e e d i n g behaviour of Ambystorna g r a c i l e i n Marion Lake, B.Sc. t h e s i s , U.B.C.  1-37.  Hendrickson, J.R. 1954. Ecology and systematics o f s a l a manders o f the genus Batrachoseps. Univ. C a l i f . Pub. Zool. 1-46. Ho31ing, C.S. 1959. Some c h a r a c t e r i s t i c s o f simple types of p r e d a t i o n and p a r a s i t i s m . Can. Ent. <_1: 385-398. H o l l i n g , C.S. 1963• An experimental component a n a l y s i s o f p o p u l a t i o n processes. Mem. Ent. Soc. Can. _ _ _ J 22-32. H o l l i n g , C.S. 1965. The f u n c t i o n a l response o f predators to prey d e n s i t y and i t s r o l e i n mimicry and p o p u l a t i o n r e g u l a t i o n . Mem. Ent. Soc. Can, 4J5_: 1-60.  107.  H o l l i n g , C.S. 1966, The f u n c t i o n a l response of i n v e r t e b r a t e predators to prey d e n s i t y . Mem. Bnt. Soc. Can. No. 48: 1-86. Lindsey, C.C. 1966. Temperature-controlled meristio v a r i a t i o n i n the salamander Ambystoma g r a c i l e . Nature 209: 1152-1153. Martof, B.S. 1962. Some observations t i o n among s a l i e n a t i c n a m p h i b i a . 270-277.  on the r o l e of o l f a c P h y s i o l . Z o o l . 55 *  Martof, B.S. & D.C. S c o t t . 1957. The food of the salamander Leurognathus E c o l . 28: 494-501. Mathias, J.A. 1964. Some aspects o f the b i o l o g y of T a r i c h a granulosa: B.Sc. t h e s i s , U.B.C. A p r i l 1964. 1-59. Mathias, J.A. 1967. P o p u l a t i o n e n e r g e t i c s o f two amphipod species i n Marion -Lake. M.Sc. t h e s i s , U.B.C. 1-74. Morgan, A.H. & M.C. G r i e r s o n . 1952. Pood end-winter h a b i t a t s of spotted newts. E c o l . 13_s 54-62. Pimentel, R.A. 1961. I n t e r and i n t r a h a b i t a t movements of the rough-skinned newt, T a r i c h a t o r o s a granulosa. ( S k i l t o n ) Am. Midland. N a t u r a l i s t . 6j|8 470-496. Reese, A.M. 1912. Pood endlohemical r e a c t i o n s of the spotted newt Diemyctylus v i r i d e s o e n s . J . Animal Behaviour 2: 190-208. Ricker, W.E. 1958. Handbook of computations f o r b i o l o g i c a l s t a t i s t i c s of f i s h p o p u l a t i o n s . P i s h . Bd. Can. B u l l . #119. 1-500. Sandercock, K. 1969. B i o e n e r g e t i c s of the Rainbow t r o u t (Salmo g a i r d n e r i ) and the Kokanee (Oncorhynchus nerka) populations ofMarion Lake, B r i t i s h Columbia. Ph.D. t h e s i s , U.B.C. I - I 6 5 . Sayle, M.H. 1916. The r e a c t i o n of Neo-turus to s t i m u l i r e c e i v e d through the s k i n . J . Animal Behaviour 6_s 81-101. ™ Schneider, C.Wv 1968. Avoidance l e a r n i n g and the response tendencies of the l a r v a l salamander, Ambystoma punctatum to p h o t i c s t i m u l a t i o n . Animal Behav. 16: 492495.  108.  Schonberger, C P . 1944. Pood o f salamanders i n the n o r t h west United S t a t e s . Copeia 1944 (4):257. S l a t e r , J.R. 1962. Some food o f some Ambystorna macrodactylum B a i r d . Occ. Pub. Univ. Puget Sound. #1£: 203. Stebbins, R.C. 1954. N a t u r a l h i s t o r y o f the salamanders o f the p l e t h o d o n t i d genus E n s a t i n a . Univ. C a l i f . Pub. Zool. 47-124. Twitty, V.C. 1966. Of S c i e n t i s t s and Salamanders. Freeman & Co., San F r a n c i s c o & London. 1-178.  W.H.  

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:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0102232/manifest

Comment

Related Items