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The role of spatial pattern learing in hummingbird foraging Sutherland, Glenn D. 1986

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THE  R O L E OF IN  SPATIAL  PATTERN  HUMMINGBIRD  LEARNING  FORAGING  by GLENN  D.  SUTHERLAND  B.Sc, U n i v e r s i t y Of M a n i t o b a W i n n i p e g , M a n i t o b a 1980 A  THESIS THE  SUBMITTED IN PARTIAL F U L F I L L M E N T REQUIREMENTS FOR .THE D E G R E E OF MASTER OF S C I E N C E in T H E F A C U L T Y OF GRADUATE S T U D I E S (Department of Zoology)  We  accept  THE  this thesis required  as conforming standard  U N I V E R S I T Y OF B R I T I S H O c t o b e r 1986  ©  Glenn  D.  to th  COLUMBIA  S u t h e r l a n d , 1986  In p r e s e n t i n g  t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of  requirements f o r an advanced degree at the  the  University  o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make it  f r e e l y a v a i l a b l e f o r reference  and  study.  I further  agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying of t h i s t h e s i s f o r s c h o l a r l y purposes may  be granted by the head o f  department or by h i s or her  representatives.  my  It i s  understood t h a t copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l gain  s h a l l not be allowed without my  permission.  Department of  ZoO  The U n i v e r s i t y of B r i t i s h 1956 Main Mall Vancouver, Canada V6T 1Y3  Date  IE-6  (3/81)  Columbia  written  i i  ABSTRACT  Foraging behaviour  efficiently  in  relation  distribution  and  hummingbirds  use  their  foraging  arrays  of  spatial  to  are  these  hummingbirds  large  two  information These same  to  groups  learned  feeder had  of  and  and  important  visit  higher  levels  feeders  arrays  quality  was  of  than  of  for  identify were:  "What  of  food  supply  "To  what  extent  those  where  learned  a  larger  even  complex  arrays,  they  performed  feeders  were  Memory  for  location  accounting  the  regularly  for performance  of  of  and  the  a  number to  of  location.  feeders in  arrays  learned  i f the  source  reached  few of  the  spatial  more q u i c k l y and  on  with  only  feeders  spatial  differed  also  but  the  profitable  performance  on  by  hummingbirds  in  memory  profitable  i n which  they  Birds  most  provided  numbers  available;  food.  the  However,  only  in  large  in determining  groups. in  how  with  to  questions  patterning  success?";  food  distributions  l e a r n i n g and  main  of  examines  food  -foraging The  memory  to  equal  of  of  foraging  thesis  laboratory tests  role  spatial  spatial  energy  arrangement somewhat  the  dimensional  arrays total  the  patterns  their  forage?".  Hummingbirds in  used  abilities.  of  and  I  organize  temporal  spatial  hummingbird  hummingbird  learning  about  clarify  in  and  animals  This  behaviour.  characteristics constrain  spatial  information  location on  to  abundance.  feeders  constraints  requires that  large smaller  perform  consistently  well well  distributed.  feeder  in these  groups  was  experiments  more than  important learning  individual  l o c a t i o n s or  simple  in  switched  distribution  which  after a  I  b i r d s had  lag  in  reached  asymptotic  redistributing  little  evidence  faster  after  detailed  the  that  the  the  than  hummingbirds  avoided  their  visits  and  These spatial  results  into and  a  of  reduce  the  of  patterns  birds than  did on  are  rate  persist food. of I  reach  other  in  The  to  small  consistent  with in  set  higher  a  patterns.  new  showed  There  was  distribution  l e a r n i n g phase. array by  model  of  of  A  suggests organizing  of  changes effect  by  of  hummingbird  feeder  expectations  learned  levels  a l l birds  feeders  which  of  spite  be  i t s mirror-image  complex  bad  experiments  patches.  principal  could  to  the  learning distributions used  In  effort.  initial in a  visits  coarse-grained  can  distribution  the  i n the  among  food  re-learned  information-processing  "mapped" stable  within  of  foraging  m o v e m e n t s made  that  rules.  performance,  their  birds  switch  a n a l y s i s of  movement  in  of  that the  performance  is  becomes  underlying  complexity  feeder the  quality  is  to  quality; a l l  birds  although  on  simplest  the  TABLE  OF  CONTENTS  ABSTRACT  i i  LIST  OF T A B L E S  v i  LIST  OF F I G U R E S  v i i  ACKNOWLEDGEMENTS Chapter  1  GENERAL Study Chapter  viii  INTRODUCTION  System  1  and O b j e c t i v e s  4  2  LEARNING SPATIAL  AND MEMORY PATTERNS  Experiment  I N HUMMINGBIRD  FORAGING:  OF FOOD D I S T R I B U T I O N  1: T h e E f f e c t  of P a t t e r n  9  Complexity  11  Methods  12  Training  13  Experimental  Procedures  13  Results  17  Overall  Performance  17  Spatial  P a t t e r n s of Foraging E f f o r t  27  Experiment  2: T h e E f f e c t  of  Expectations  about  Feeder  Quality  36  Methods  37  Results  38  Discussion  43  V  Chapter  3  SPATIAL  PATTERN  IN  LEARNING  COMPLEX P A T T E R N S  OF  BY  HUMMINGBIRDS  PROFITABILITY  49  Methods  51  Training  52  Experimental  Procedures  52  Results  54  Overall  Performance  Behavioural Spatial  54  Components Organization  Discussion Chapter  of Performance of Behavioural  62 Components  ...  75 81  4  GENERAL  DISCUSSION  Concluding LITERATURE  CITED  Remarks  7  88 96 98  vi  LIST  Table  2.1.  early Table  late  good  and  3.2.  3.3.  late  20  within  trials  in  early  pattern  23  the proportion  trials  that  began  of f i r s t  with  visits  a visit  to a 31  of f i r s t  visits  to feeders  before  and 42  in  pattern  Rate  measures  good  before  and within  3.4. F r e q u e n c i e s  and  that  on 57  bad  and a f t e r  patches  on  the  the switch  i n the four  66  components of  patches  of the three  feeders  of performance  patterns  o f improvement  among  o f 4 good  of four  a n d Random  Runlength  performance  runs  feeders  pattern,  Development  Checkerboard  Table  pattern  on e a c h  Checkerboard  Table  on e a c h  and bad f e e d e r s i n  the switch  3.1.  the  t o good  t o good  2.4. D u r a t i o n s  Table  visits  feeder  after  Table  trials  early  of  trials  2.3. F o r e a c h  of  Table  and l a t e  2.2. R e v i s i t s  and Table  Numbers  OF T A B L E S  68  possible  include  patterns  no r e v i s i t s  of 80  vii  LIST  Figure  2.1.  The  presented  four  FIGURES  spatial  patterns  of feeder  quality  to the b i r d s  Figure  2.2. O v e r a l l  Figure  2.3. Mean  taken  OF  at  14  performance  percentage successive  on a l l f o u r  of  patterns  revisiting  intervisit  18  opportunities  intervals  for a l l  patterns Figure  2.4.  25 Spatial  distributions  of v i s i t s  on e a c h  pattern 28  Figure all  2.5. V e c t o r departures  Figure the Figure  switch  last  Figure  each  the Quarters  pattern  in 39  performance  on  the  Checkerboard  and 55  performance  of each on  individual  the  bird  Checkerboard  on and  patterns  59  Changes before  in  four  component  measures  of  the switch  3.4. D i s t r i b u t i o n  total  of 32  on  day of t h e experiment  performance  Figure  distribution  feeder  performance  Overall  3.3.  good  the  patterns  3.2.  Random  expressing  experiment  3.1. O v e r a l l  Figure  Figure  from  2.6. O v e r a l l  Random  the  fields  64  of runlengths  on  first  visits  to  and bad patches 3.5.  Relationship  number  patches,  70  of  f o r 25  between  visits trials  during  before  number  of r e v i s i t s  first  bouts  the switch  in  and good 72  viii  Figure  3.6.  between Figure used  Frequency  good  and d i r e c t i o n  of predominant  moves  patches  4 . 1 . Summary i n the study  of performance  76 on  a l l four  patterns 90  ix  ACKNOWLEDGEMENTS  I the  would  like  e v o l u t i o n of t h i s  ideas,  my  For  collaborator  than  pursue  other  For  many  a l l of that  My each  provided  Gwen  and  Eisler  for  Dianna typed  collection, and  a l l  3.  when time  and branch  Jamie  drafts  t o many and  the  more  of of a  freedom  other  to  projects.  Don W i l k i e  and Lee Gass  critical  times,  thesis.  of Chapter  2.  helped  drafting  with  Rick  Lee  and Miller  Gass,  Dave  figures,  and f a c u l t y  of the  me  stimulating  atmosphere  with  and  source  Dave  of t h i s that  Tamm  Peter  not  programs  of i d e a s ,  Zittin,  analysis.  Sheila  Stefan  and computer  a tireless  techniques  a  Institute and  and a deepened a p p r e c i a t i o n  of ecology.  aspects  Ken L e r t z m a n ,  signs  tables.  Cahoon, with  with  hesitated to  has been me  of t h i s  provided  and p r a c t i s e  helped  there  showed  out into  at  the students  Ecology  Peter  never  he  Smith,  advice  some o f t h e  b u t was a l s o  questions  Chapter  the  construction skills,  intellectually the  either  drafts  intellectual  humour.  Wilkie  writing  Colnett  with  been  throughout  grateful.  and  on e a r l y  the science  contributed  very  criticized  Resource  challenging  always and  of  committee,  Interactions Animal  has  enthusiasm,  questions  help  commented  Bernard  much  He  f o r h i s support  a s u p e r v i s o r , and allowed  I am  research  constructively also  and  t h i n k i n g o r my  ossification.  Lee Gass  study.  encouragement  challenge  of  t o thank  f o r data  criticism,  Don L u d w i g Cahoon  only  a n d Don  contributed  project;  in particular  underly  the  Fitzpatrick,  Tom  to  analyses i n Getty,  Zena  X  Tooze, and  Doug  Rick  My  Armstrong,  Miller  a l l willingly  wonderful  bore  my  job),  but provided  For deeply  neuroses  moral  Research 9876 the  colleagues as a  t o C.L. Gass. analyses  much  provided  by  British  Columbia  assistantship.  ESSA  Lewis,  and  Gayle  friendship.  L t d . not  only  patiently  (and absences  encouragement  Brown  from t h e  to get i t finished.  and s a i n t l y  patience,  I am  Sutherland.  provided  Rick  a n NSERC  at  Kaaren  ideas  encouragement  were  presented  shared  needed  t o Joan  funds  Paton,  student/consultant  support,  grateful  Steve  Miller  in  b y NSERC provided  Chapter  postgraduate  Graduate  3.  operating  grant  additional Personal  support f o r support  scholarship, a University  Fellowship,  and  58-  a  was of  teaching  1  CHAPTER 1 GENERAL  INTRODUCTION  Any global notion of how patterns are detected and stored i s unlikely to be correct i n the present state of knowledge because we simply do not have enough e v i d e n c e , b u t t h a t d o e s n o t make s p e c u l a t i o n worthless. T h e r e i s an obvious dearth of sensible hypotheses to t e s t , but they a r e c e r t a i n l y n e e d e d i f o n e i s g o i n g t o make t h e best of hard-won experimental evidence (Barlow, 1985).  The and  food  availability  1966). is  to gather  Pyke  i n both  F o r most  1984;  gather,  later.  (e.  g . home  Lima  pertinent  animals  1984,  may  also  factors. and  are  sensitive,  information  a r e becoming  analysis  behaviour.  In from  recent  1985).  years  a  behavioural ecology  of f o r a g i n g  This  in quality and  Pianka  effectiveness  also  vary  a l .  food  facing  the a b i l i t y  items)  the  kinds  and  how  of  they  increasingly  among  many  about  important  approach  comparative  use  scales food  detect  potential to  which  and use  topics  combining psychology  to  animals,  i s to  information learn  to  and  of other  an a n i m a l  from  1983;  at several  on t h e b e h a v i o u r  synthetic  et  i n food  information i n order  information  and  (Krebs requires  particular  The problem  about  (MacArthur  information  depend  vary  the p a t t e r n s of v a r i a t i o n  environments  reliable  Questions  of  a component  patches,  animals  and time  a n d remember t h i s  ranges,  availability  sources.  animals,  However,  on o t h e r  space  a n d a c t on t h a t  organize,  it  of a l l mobile  i n f o r m a t i o n about  distribution,  or  resources  in  such the  techniques has  been  2  successfully  applied  approach,  now  learning  (Johnston i n an  learn?",  and  "How  this  about  applications  to  of  (Kamil  Experimental  how  animals  their of  how use  effort  birds  (Smith  can  and  1977). birds  such  Kamil  and  James  and  them.  A  memory  Balda  cached  wide  variety  in  their  found  that  were  located,  were  using  (1986)  1983)  "map"  showed  that  have  forage  ask  require  efficiently, increasingly  has  behaviour  been  used  how  opportunities.  extensive  studies  nutcrackers Sherry  et  that  items  a l .  these weeks  non-hoarding In  accurately  locations bees  and  a  classic  remembered  them  i n ways  with  which  navigate  as  allocate  and  Falls  1980;  Wall  1982;  remember after  also  they  use  study,  Menzel  where that  prey  (Balda  can  to  of  food-hoarding  Vander  months  animals  to  Zach  crows  1982;  or  study  profitable  with  birds  clear  Several species  1974;  and  provide  i n the  Sweatman  honey  to  who  become  foraging  retrieved of  to  Smith  foraging.  and  animals  theorists  decision-makers  of  show  of  chimpanzees  a  of  food  do  foraging  patches  1985;  behaviour  behaviour  remember  tits,  of  as  that  As  of  of  1982).  available  1971;  marsh  of  This  study  "What  information in deciding  recently,  as  ecological  ask  analyses  approach  and  Dawkins  Verbeek  locations  the  learn  More  an  spatial  among  to  approach Yoerg  questions.  descriptions  environments  studies  such  the  uses  animals  their  and  as  these  learned?".  view  this  of  context  behaviour  information  of  1985),  psychological  come  examples  known  ecological  increasingly  widespread  studies  generally  occurring  is  in  (1973)  suggested  i f they  hide  spatial  food  orient.  the  items they Gould  effectively  3  construct  "maps" o f l a n d m a r k s  preferred  feeding  that  locations,  they  and  u s e when  when  foraging  returning  among  t o t h e home  hive.  Thus,  the idea  spatial  location  foraging  i s  foraging  mechanisms spatial and  perhaps  for  constraints  that  and  then  became  interested  patches  animals would study  their  of  in on  use of t h i s  learned  of flowers  in  1985).  suggested  memory  capabilities  those  capabilities)  an  that  integration  i s an  to  the  important  are  and  necessary  to  bases  of foraging  behaviour.  this  thesis  designed  In  be  or use  characteristics  while  that of  study,  at  least  a broader  foraging.  and  to I  foraging  evidence high  analysis  (including  valuable  was  participating in a  territoriality  of hummingbirds would  the  memory  that  of  information-processing  i n hummingbird  the locations  their  studies  sensitivity  component  memory  spatial  the  information-processing  environments  hummingbird  Sutherland  of If  of  to guide  acquire  require  animals'  described  sites  about  theoretical  animals.  of  of s p a t i a l  experiment  hummingbirds  foraging  of the proximate  research  and  the  information  few  analyses  on a n i m a l s '  the role  (Gass  because  component  explore  field  how  individual  understanding  The  quality  specify  characteristics  basic  use  However,  ecology  capabilities,  our  new.  behaviour  foraging  animals  of high  not  information, of  that  of  that  quality spatial  constraints  in understanding  on  their  behaviour.  Here  I define  some  recurrent  terms  used  in this  thesis  that  4  could  be  subject  which  animals  to  perceive,  organization  of  refers  expectations  about  more  two-dimensional  birds  the  by  many  is  few  (Hainsworth  arrangements  1986),  foraging  Sutherland et  a l .  Paton  1985;  energetic  that  The  to  20%  studies  1984). in  in  hummingbird  species  (Selasphorus and  their show  Gass  body  that  ecology  rufus) 1985). weight  migrating  patterns are  temperate  zone  has  two  in  this  high  daily  each rufous  major  and (Gass  a l .  1983;  their  empirical  the  rufous  requirements can  obs.).  hummingbirds  1)  foraging.  study,  (pers.  of  reasons:  2)  hummingbirds  day  Gass  et  and  in  Rufous  1983;  e_t a l .  characteristics  behaviour;  used  Diamond  Hixon  the  important  regulation  territoriality  1978;  for  of  1985;  feeding  studied  is  be  patterns  energy  Gass  Brown  their  can  complex  Hainsworth  hummingbirds  learning  (Tooze of  I  patterns  of  and  and  and  locations  Objectives  and  spatial  hummingbird energy  Tooze  of  prior  quality.  foraging  (Wolf  accountability  evidence  and  spatial  have  groups  experiments,  mechanisms  Kodric-Brown  learning  my  by  distributed  they  whereas  feeder  Tamm j i n p r e s s )  Carpenter  spatial  the  1981;  tactics  1976;  and  of  a l .  of  or  Simple  In  System  including: ejb  if  process  the  Spatially as  descriptors,  descriptors.  known  hummingbirds,  behaving  i s the  remember  events.  array.  Study  Much  and  and  particular locations  over  characterized require  to  S p a t i a l memory  recognize  objects  expectations  distributed  confusion.  for  lose  up  Field  regulate  the  5  numbers their and  flowers  daily  Brown  fat  1978;  pers.  at  comm.  its  their  1979;  ).  I  et  high  therefore  experimental  to  et  provide  a_l.  a l .  1976;  1983)  rates  and  (Carpenter  expected  manipulation  that of  at  least  Kodric-Brown to  accumulate  e_t a l .  these  their  1983;  animals  food  to  supply  distribution.  flowers  which  animals,  the  proportion  generally  i s slowly forager's  of  the  (Zimmerman  individual  flowers  (Gill  and  Wolf  they  have  quickly  do  and  arrays  containing  al.  1982;  Miller visit  territories  expected  to  be  experimentally of  the  most  (Gass able  test  spatial  for  the  can  by  show  and  this  f a c t o r s that  discrimination  and  significant that  several  where  foraging.  can  patches  hours  explicitly  of  1985).  that Birds  feeders  in  (Cole  et  feeders  they  it  revisiting  profitable  Sutherland  use  a  these  remembering  more in  only  profitable  For  avoid  least  unprofitable 1985),  stationary  availability  possibly  visit  and  to  produces  information  mostly a l .  hours.  for at  studies  to  et  several  nectar  1978),  spatial  small  from  often  patches  learn  nectar  Nectarivores  Other  easily  preferentially  in  19B1).  Kamil  use  in  activity  within  1977;  ,on  replenished own  foraged.  hummingbirds  feed  variation  experiences  degree  (Gass  Hixon  sustained  Nectarivores  their  territories  requirements  Gass  s e n s i t i v e to  and  in  energy  reserves  Hixon be  of  also  learn  flowers I  to in  therefore  spatial  ability  influence  the  learning  in  rate  to and  complex  envi ronments.  Within  this  context,  I  defined  the  following  research  6  objectives:  1.  To c l a r i f y in  hummingbirds  with in  2.  the role  identify  patterns  meet  on  these  arrays  i n the  In  to of  2  how  particular,  I wished  and  little  hummingbirds' complex  of  in spatially  experiments heterogeneous  patch  qualities  i s  known a b o u t  how how  between  et  patterns.  quickly  locations  has  used  a l .  1982) and  the importance  or  In  patterns  how  Experimental  work  ( e . g. Gass  of  and  foraging  to  distributed  the complexity  spatial  of t h i s  ( e . g. C o l e  spatially  locations.  learning  most  experiments  profitability  feeder  and  laboratory use  to discover  within  However, arrays  two  influenced  that  both  manipulated  on  foraging  feeder  learned  suggested  simple  variation  I c a r r i e d out a s e r i e s  used  learn  quality  hummingbirds  animals.  spatial  to spatially  hummingbirds  to  important  environments  profitability.  I  information  have  respond  hummingbirds  Chapter  feeder  in  memory  laboratory.  investigate  of  constraints  objectives,  individual  and  q u a l i t y ; and  abilities  To  foraging  ecologically relevant  food  To  of learning  of  well studies  food  bouts  is  i n these  either  small,  unrealistically  Sutherland of s p a t i a l  1985),  memory i n  7  day  to  day  arrays  of  foraging sufficient  of  patterns,  and  low  amounts  food  lacked Thus be  to  of  visible  information  obtained  from  i n more  only  previous  size  to  to  allow  allow each  (Carpenter  environments. me  feeder  1983;  to  the  about  the  energetic  visiting  visits.  The  amount  to  aims  feeder  several  types  realistically  1980).  of  by  used  contain  nectar  value  i t , or major  present  Pyke  cues  by  to  I  of  The they  any  contained.  location  remembering of  these  feeders  its  experiments  could value were  ask i f :  1.  Hummingbirds visit in  2.  large  The  could  higher  and  f u n c t i o n of  Spatial  birds  of  develop  quality  to  preferentially  feeder  and  the  for  l o c a t i o n s even  their  quality;  behave "map"  simple  of rules  of  spatial  and  i s an  learning.  expectations  than  learning is a  complexity  location  this  a  using  of  feeder  constructed  foraging  two  of  memory  component  In  quality  accuracy  organization  3.  learn  arrays;  rate  direct  the  typical  important That  about  as  if  they  the  array,  for directing  is,  do  patch have rather their  movements.  Chapter  3  I carried  complex  patterns  of  out  a  feeder  longer-term  experiment  quality  i n Chapter  used  with 2.  I  8  used  them  complex birds  to  investigate  d i s t r i b u t i o n s of can  learn  the  capacity  spatial  locations  of  of  hummingbirds  information small,  and  to  to  learn  determine  regularly,  if  distributed  patches.  In on  Chapter  spatial  the  I  behaviour  directions of  4  for  of  future  approach  experimental  evaluate  taken  paradigm  spatial  c a p a b i l i t i e s in  studies  of  spatial  my  research  hummingbirds research. in used  this  I  and  study  offers  to  value and  of  point  conclude  hummingbirds  abilities.  i n view  in  with  other  out a  the  possible  reevaluation  determine in  work  if  analysis  the of  cross-disciplinary  9  CHAPTER LEARNING  AND  MEMORY  SPATIAL  Several  locations  or  months  even  1981;  in  of  1982). a  (Balda  other  Roberts  chimpanzees 1982), Some  authors the  important 1984b), 1974;  but  and  believe  that  use  other  locations  have  between  "landmark  bees  is  removed  home h i v e s  several  Samuelson  and  to  learn be  animals  Smith  and  Juno 1981).  could  many  1983),  al.  ability  animals  and very  (Sherry Sweatman  in  return  foraging  their to  foraging  the  Honeycreepers  that  foraging locations  even  1971). sites  from  sources  suggest  routes,  (Jantzen,  feed  food  studies  important  1986).  et  renewing  and  studied  examples).  repeatedly  been  Vander  been  (Menzel  sites of  e_t a l .  1980;  and  the days  Slobin  (Wilkie  (see  for  and  their  (Gould  and  nectarivorous  along  their maps"  few  slowly  nectar)  Euglossine  plants  navigate  1977b  also  marmosets  the  Sherry  (Olton  (Wilkie  behaviour  1977a,  floral  rats  foraging  are  hours,  Tomback  have  remember  for  1986;  general,  good  stationary,  particular plants  those  in  items  can  1985;  doves  studies  and  spatial  behaviour.  and  birds  Balda  including  foraging  Falls  1982,  1978),  1984)  of  food  and  gerbils  FORAGING:  DISTRIBUTION  capabilities  1973,  detailed  (principally  of  1982),  the  conspicuous,  for  Krebs  (Wilkie  Hummingbirds  memory  Kamil  species,  locations  in  Zach  1980;  (Menzel  pigeons  remember  scattered  and  1979,  FOOD  food-hoarding  S p a t i a l memory  few  1976;  of many  Shettleworth  Wall  HUMMINGBIRD  P A T T E R N S OF  species  spatial  IN  2  after  Honeybees as  and  if  they  sunbirds  10  can  avoid  depleted 1977;  and  Kamil  locations without in  revisiting  in  such  coarser  of  flowers  colour  this  a  large  suggests learning  How  of  hummingbirds  spatial  patterns  of  quickly  and  well  distributions  of  distributions  better  than  food,  and  locations  of  distributions kinds  of  spatial focus  information  or  (Gill  to  16  feeders,  Cole  et  a l .  strongly  (Miller  et  also  most  learn  a  On  and  patches use  them  distributed 1985).  This  capability  hummingbirds they How  learn long  quickly  for  or  do  do  some they  spatial kinds  of  remember  the  learn  new  environments  change?  What  to  them  questions they  learn  they  valuable  psychological  1985).  distribution.  do  issues;  and by  and  general  or  influenced  profitable  have  feeder with  which  Sutherland  Wolf  1982)  a l .  and  These  and  individual  (Gass  how  previously  do  as  about not  mechanisms  they  learn  spatial  memory  directly involved  address  in  spatial  problems.  Accordingly, that  memory  small  Do  most  have  are  migrate  are  ecological  physiological memory  they  are  others?  distributions? on  cues  food  food?  if  2  more  patches  others  how  of  hummingbirds  i f those  number  using  1978;  was  colour  they  rapidly learn  (Gass  territories  even  that  by  by  arrays  ability  scale,  their  preferentially among  as  spatial in  this  laboratory  p o s i t i o n than  a  do  Hummingbirds  small  study  spatial  may  1978).  cues  one  they  inflorescences  provided  energetic  a  I  designed range  profitability  of in  a  s e r i e s of  complexity  large  arrays  laboratory of of  geometric visually  experiments patterns  of  identical  11  feeders. than  I  provided  location.  contained  energy  Arrays  little  locations  enough  over  Experiment  a  feeders  series  profitability  a f f e c t e d how learned  unprofitable  complexity  unprofitable  decomposed  into  to  faster  learn  a  other  flowers  must  neutral  of Pattern  how  learn the  or  positive  Complexity  the  a n d t o what  profitable In  of feeder  the  and  the and  studies  problems  animals  (Simon  how t h e  profitable  i f complex  better  avoid  affected  empirical  problems,  perform  of  of  individual  I asked  qualities  and  that  set of simpler  extent  feeders  locations  suggest  distribution  particular,  Theoretical  and  and i n d i v i d u a l  individuals  asked  ones.  problem-solving  quality  trials.  visit  between  feeders.  enough  quickly  of the patterning  discrimination  animal  to  to feeder  to maintain  of  I  cues  that  j _ : The E f f e c t  experiment,  visiting  large  nectar  this  hummingbirds  visible  were  of p r o f i t a b l e  balance  In  no  will  of  c a n be  be  able  1974, 1979; G a s s  1985).  In  this  case,  relationships  among  profitability However,  recognition their  independently of s p a t i a l  discover  to develop  and  use  expectations  better  about  feeder  patterns.  the p r o f i t a b i l i t i e s  o f many  items  without  patterning,  their  i s n o t an  should of  using  on  spatial  simple  patterns  they  distributions  that  perform  can learn  l e a r n i n g , then  spatial  feeders  should  i f they  information  hummingbirds  perform  feeder  important  quality  or i f  component  identically  of  of  on a l l  regardless  of  12  complexity.  I  used  profitable  four feeders,  feeder  quality.  in  size  the  pattern.  In  birds  to  which  I  visit they  of  of  in  the  one  were  number  that  patchy  visible  the  of  differed  irregular  of  of  distribution  there  measures  l o c a t i o n s as  and  patterns  and  arrays  several  the  size  regular  patches,  profitable  learned  same  differed  three  the  used  the  which  were  number none  quality.  of  but  There  and  feeder  to  arrays  cues  to  tendency  i n d i c a t o r s of  the  by  extent  arrays.  Methods  I  used  four  experiment. maintained testing  A l l  al.  1979)  minerals  solution with  weekends.  germ  except  the  feeders syringe  during  performed  was  and  L:  a l l  a  protein  painted on  D).  and  sessions  8.1  x  wooden  one  with  and  6  Their  a  were and  food  (Bolten  et  protein),  acids  (Linatone)  sucrose  solution  available  The (1.07  The and  to  at  on a l l  trials.  m).  panel  then  prior  soya  experimental  2.5  this  maintenance  (95%  35%  in  field,  months  fatty  wall.  epoxy,  the  concentration  Drosophila  x  in  for  (Avitron),  training  hummingbirds  powder  weekdays,  (3.5  plugged  10.5  mass/mass  training  mounted  needles  aviary  adult  chamber,  center,  large  22%  o i l on  rufous  captured  vitamins  Unlimited  experimental in  of  female  were  13.5  added  (Avimin),  wheat  I  in a  (photoperiod  sucrose  times  adult  birds  communally  was  and  naive  sessions  room x  1.24  feeders  mounted  had m)  were on  a  in  an  perch of  64  plastic  removable  13  corks cm  in  apart  a  regular  i n both  arrangement (Hamilton  I  the  array  h o r i z o n t a l and could  No.  removing  orthogonal  refill  PB-600-1)  corks  from  of  vertical  feeders  without  behind  holes  i n the  directions.  with  a  the  11.0  With  repeating  entering  the  panel  this  dispenser  chamber  by  panel.  Training  Each  bird  testing.  On  training  in  64  feeders  of a  each  was  each  trained  day,  the  On  2  days  randomly-generated  food. fact  I  used  that  these  only  experiments,  and  with  the  which  training holding  each  pattern made  2  sucrose  and  random  or  b i r d s may  hours On  solution  only  32  at  the  would  standardize begun  were  first  each  day,  the  a l l  in  contained  birds  contain spatial  to  of  distributed  their  to  the  food  in  biases  experiments.  returned  to  beginning  day),  any  the  prior  trials)  the  accustom  feeders  have  birds  to  (20  feeders,  (different  the  "erase"  the  3  patterns  of  4  immediately  Between communal  cage.  Procedures  Beginning  patterns  to  of  days  procedure.  pattern  50%  sessions  Experimental  days,  ul  three  received  experimental  contained  trial.  i t  for  of  bird  the  was  given  profitable  remained  more  at  time  40  trials  and  constant  complex  same  each  on on  unprofitable during day  as  a l l 40  each  of  one feeders  four of  consecutive  four  spatial  ( F i g . 2.1).  trials  of  a  day,  f o l l o w s : Day  1:  Halves;  but Day  The was 2:  14  Figure  2.1. The f o u r s p a t i a l p a t t e r n s o f f e e d e r quality presented to the birds. Solid c i r c l e s represent "good" f e e d e r l o c a t i o n s ( i . e. f e e d e r s c o n t a i n i n g f o o d a t t h e b e g i n n i n g o f e a c h t r i a l ) ; open c i r c l e s r e p r e s e n t "bad" f e e d e r s ( i . e. f e e d e r s n o t c o n t a i n i n g f o o d ) .  15  Halves o o o o o o o o  • • o o  • • o o • • o o  o o • • o o • •  o o o o o o o o  • • •  o o  • • o o • • o o  • oo o •  • • • • • o o  o  o o  Quarters o o o o o o o o  o o o o o o o o  o o • • o o • •  o o • • o o • •  Checkerboard  o o o o  o o o o  o o o o  o o o o  •• • • •• • • • •• • • •• •  • •• •o o o • •• • o o o • •• •o o o • •• •o o o  o o o o  • • • • •• • •• • • • • ••• • •••••  o •  o o o o • oo o o • o • o o o o o o o o o o o o o o  • o o • • o o  Random  o • • o o • o  16  Quarters;  Day  3:  pattern  from  trial  any  on  sucrose This in  Armstrong -  meal  without  In  of  experimental  day.  from  recorded  each  complete  the  trials  I  blind  over  the  next  Birds flowers  amounts Only  1  removed  i n the  press).  trial  I of of  40  kept  were to  at  through  a  panel,  with a  a  total  ate in  about  the  At  time.  I  640 the  of  birds  could  observed I  recorder,  and  Occasional  the  partial  trials, end  the  each  mirror.  computer.  of  chamber  but  in  field  1986).  start  tape  resulted  from  feeders,  Montgomerie in a  in  feeders  1983;  of  and  each  array,  or I  trial  and  then  do  from  later.  and  this  Carpenter  one-way  replenished  nectar  remaining  visited  a  any  25%  found  experimental  perch  of  volumes  e_t a _ l .  the  each  water.  and  length,  analysis.  9 minutes  (Gass  in  into  of  min  before  orally  15  from  the  1 min the  10  (Diamond  in  records  the  confirmed sucrose  ul  chamber  a l l  field  70  ul  hummingbirds  every  minutes  from  these  began  solution  1980;  ul  of  of  nectar  (Pyke  malfunctions  data  of  experiments,  visit  eliminated a  range  flowers  return  feeder  of  normal  was  equipment loss  pulled  2  pilot  t r a n s c r i b e d these  recording  contained  the  different  beginning  feeders"  Trials  outside  the  "bad  15-20  and  At  (a  2  approximate  for  feeding  pattern).  Random  contained  32  individual  4:  feeders"  sucrose  sizes  food  trials  and  Day  "good  hummingbird  ul  Each  32  is within  1986).  70  normal  later  training  solution,  volume  stop  the  pattern,  typical  60  Checkerboard;  pilot  as  1981;  they  Carpenter  experiment  feeders  after  contained  any  visits  by by  measurable  in  measuring a  bird.  residual  17  solution,  so I assumed  that  a l l revisits  during  trials  were  unprofitable.  Results  Overall  Performance  In  this  section  analyzing  performance.  feeders,  whether  unprofitable consider  of  trials  on e a c h  pattern  trials  (Trials  36-40).  In  general,  pattern. correct  increased  of  good  these  "Early  began  each  made  made  will  energetic 5  trials"  5  they  to  t o the last  trials  at  on  every  approximately visited  50%  increasing  In p a r t i c u l a r ,  they  good  and  feeders,  t o bad feeders  significant  I  or  refers to the f i r s t  (Fig. 2.2). they  t o good  Later  overall  over  day  trials,  of v i s i t s were  trials"  improved  of v i s i t s  changes  the  in  visits  trial.  1-5); " l a t e  feeders  t h e numbers  same  influenced  (Trials  definitions  (profitable)  the  succeeding  t h e number  decreased although  On  following  as,"correct" a l l visits  first  performance  choices.  the  during  bouts.  Individuals  proportions  were  revisits  effectiveness  use  I define  they  revisits  how  I  only  for  (Table  2.1)  Halves  and  Quarters.  The affected  pattern both  performance individuals  of  the  reached  feeder rate  after  exceeded  90%  of  quality within improvement  40 t r i a l s . correct  On  arrays and  dramatically the  the Halves  choices  within  maximum  pattern, a l l 10  trials;  18  Figure  2.2. O v e r a l l p e r f o r m a n c e on a l l f o u r p a t t e r n s . C l o s e d c i r c l e s r e p r e s e n t r e s u l t s f r o m H a l v e s ( t o p ) and C h e c k e r b o a r d (bottom) p a t t e r n s ; open c i r c l e s f r o m Q u a r t e r s ( t o p ) and Random (bottom) p a t t e r n s . Vertical b a r s r e p r e s e n t 95% c o n f i d e n c e i n t e r v a l s f o r e a c h p o i n t . E a c h p o i n t i s an a v e r a g e f o r f o u r b i r d s o v e r f o u r trials. The b r o k e n l i n e i n d i c a t e s c h a n c e p e r f o r m a n c e (50%). T h i s f i g u r e summarizes 38,399 v i s i t s t o f e e d e r s i n 625 t r i a l s .  19  r—  90  O  UJ  cc  cc o o I-  z 111 o cc  80 70  4.  60  LU D.  50 8  12  16  20  24  TRIAL N U M B E R  28  32  36  Table  2.1.  Numbers o f v i s i t s t o good and bad f e e d e r s i n e a r l y and l a t e trials (see t e x t f o r d e f i n i t i o n s ) f o r e a c h p a t t e r n . V a l u e s a r e means p e r t r i a l f o r a l lb i r d s (95% c o n f i d e n c e i n t e r v a l s ) on each pattern. Results of a three factor Kruskal-Wallis analysis of variance are a l s o shown. Means s i g n i f i c a n t l y d i f f e r e n t a t t h e 0.05 l e v e l a r e i n d i c a t e d w i t h a "*"; i n s i g n i f i c a n t d i f f e r e n c e s a r e i n d i c a t e d a s "n.s." (Tukey's t e s t ) . Sample s i z e s (number o f t r i a l s i n e a c h c o m p a r i s o n ) a r e g i v e n b e l o w e a c h mean.  Halves  Pattern  Good Bad  Bad  *  42 . 8  ( 3 7 . 7 - 4 7 . 8) n = 20  *  (13.4 - 2 2 . 5) n = 20  8.8  ( 6.2 - 1 1 . 3) n = 20  *  35 . 1  ( 2 8 . 2 - 4 2 . 0) n = 15  40.9  ( 3 4 . 2 - 4 7 . 7) n = 20  n.s.  32. 8  ( 2 5 . 8 - 3 8 . 3) n = 15  26. 3  ( 2 0 . 3 - 3 2 . 2) n = 20  n.s.  33.0  ( 2 5 . 3 - 4 0 . 8) n = 20  38.2  ( 3 3 . 9 - 4 2 . 4) n = 20  n.s.  28.8  ( 2 2 . 1 - 3 5 . 5) n = 20  24 . 4  ( 2 0 . 4 - 28 . 4 ) n = 20  n.s.  ( 9.0 - 1 6 . 7) n = 18  5.7  35. 5  ( 2 9 . 4 - 4 1 . 5) n = 20  18.0  Feeders Feeders*  Feeders  Checkerboard  Good  7 . 6)  12. 8  Feeders  Feeders  Random  ( 3.7 n = 19  45.9  Good  Bad  *  ( 2 2 . 8 - 4 0 . 7) n = 18  Pattern  Good  ( 3 9 . 5 - 5 2 . 3) n = 19  31. 2  Feeders  Quarters  Bad  Comparison o f Means  Late  Early  Pattern  Pattern Feeders Feeders  21  subsequent  improvement  correlation trials;  p  was  coefficient  =  0.3).  choices  at  least  achieved  less  Rs  Three once  than  of  80%  averaged  correct choices  p  <  on  any  0.001).  65%  trial  after  Quarters 5  similar  significantly  after  Only on  trials  two  was  (Halves:  four  first  the  20  of  the  10,  last  85%;  correct  ten  trials.  Individuals slowly  11-40;  correct  on  120  individual  achieved  different  n=  improved  100%  performance  Quarters:  no  for t r i a l s  achieved  insignificantly  100%  and  then  rank  11-40;  pattern.  individual  Overall  89%;  trials,  0.84  b i r d s ever no  trials  Quarters  =  (Spearmann  b i r d s reached  trial  (Rs  but  for  i n any  by  that  20.  patterns  the  on  Quarters,  trial  0.30  correct  was  but  =  i n the  Performance 82%  insignificant  n=120; choices  less  the  Halves  during  Mann-Whitney  than and  the  U  last  test;  p  >  0.05). Performance and  Random  patterns trials; spite  patterns,  but  R a n d o m : Rs  of  the  =  Birds  the  5  Random);  =  n  =  d i f f e r e n c e i n the  analysis.  performance  Rs  0.79;  performance  last  significantly much more  (Checkerboard:  overall  trial  improved  on  achieved  trials  on  a t t a i n e d on  no  them an  any  individual  slowly  0.75 158;  was  p  <  on  achieved  than  the on  of  Checkerboard  the  trials  0.0001  1-40;  for  these  other n  of  60%  two  correct  less  pattern  than  50%  =  155 In  patterns, by  this  choices  ( F i g . 2.2).  either  two  both).  indistinguishable  patterns  trial  both  for  complexity  average  both  on  was  on  The  best  74%  (on  correct  after  26.  Because "correct"  =  the a  measure  visit  to  a  of  performance  good  feeder  as  defined  regardless  of  above  ( i . e.  whether  i t  22  contains success within  food of  at  the  trials  are  In  trials  (Table  revisits  have  about  birds  good  did  feeders  In  fact,  significant  find  "working  current  ways.  Revisits  the  learn  within  trials  the  of  spatial  those  to  memory  feeders  memory"  trial.  already  for  If  the  birds  can  visited  and  avoid  them,  feeders  visited  relatively  more  recently  expectation  is  information  (Olton used  (Shettleworth  experiments,  and  I  trials  known and as  within-trial  n-1  later  only  one  Krebs  studied for each  opportunity and  a  Krebs  1976;  measure 1982).  the  would  "recency  Samuelson  working  (intervisit  (Shettleworth  as  a  opportunities  visit  of  the  to  late  there  was  the  number  of  To  memory  pattern. for  In  repeat  interval f o r an 1982).  a  of  of  be  in  the  they  expected  that  spatial  1977),  memory  and  capacity  characteristics birds between  sequence  of  intervisit  than This  for  spacing  visits)  more  trial.  e_t a _ l .  the  within  feeders  effect"  the  how  capacity  visited  revisited  v i s i t s to 0  i s the  which  working  of  temporal  be  Olton  examine  determine  have  i t might  ago  are  provide  early  pattern  remember  long  within  feeders  significantly  from  food  l o c a t i o n s they  relatively  of  to  may  containing  visited  be  good they  increase  that  feeders  can  to  and  Quarters  tendency  overestimates  profitability  not  on  i t  time.  birds  their  the  but  component  quickly of  to  2.2).  over  One  in 2  revisits,  unprofitable energetically,  general,  revisits  slight  includes  information  avoid  a  time)  hummingbirds  contradictory location.  the  n  whereas of  these  revisits  visits  feeders  interval  in  to  there be  one  there  is  n-1  visits  23  Table 2.2. R e v i s i t s t o good feeders w i t h i n t r i a l s i n e a r l y and l a t e t r i a l s on each p a t t e r n . Values a r e mean percentage of r e v i s i t s among v i s i t s t o good feeders (SD). R e s u l t s of Mann-Whitney U t e s t s ( t w o - t a i l e d ) are a l s o shown; i n s i g n i f i c a n t d i f f e r e n c e s at the 0.05 l e v e l a r e i n d i c a t e d as "n.s.". Numbers of t r i a l s are shown i n b r a c k e t s below each mean.  Early  Late  p  Halves  37.6 (13.9) n == 19  34.3 (15.0) n = 17  n.s.  Quarters  31 .1 (15.6) n == 20  39.7 (12.0) n = 19  < 0.04  Checkerboard  34.4 (11.2) n == 18  35.5 (13.3) n = 20  n.s.  Random  27.8 (12.6) n =-• 17  27.4 ( 9.9) n = 20  n.s.  24  For  a l l patterns  intervisit  interval  variance; 30-35  p < 0.05  found  intervals  that  locations levels  locations  with they  possible  at  visited  that  this  se.  movement  patterns  Performance trial  was  choices more  I examine  as measured related  (Rs = 0.63;  patterns  energy  (average  by  test;  p < 0.05).  two  simple  test;  H  On  trials;  chance 1977;  visits  than  intake: = 9.1  30  to  visits  memory  for  locations), i t function  10.96;  p  on  intake  of the working  of  their  Halves  =  = 8.9  also  spent  less  Both  on  correct  t h e two  kJ;  simple  Quarters  =  kJ; Kruskal-Wallis  terminated time  t h e two c o m p l e x  < 0.001).  by  each  Birds harvested  10.1  they  for  as measured  p < 0.001).  k J ; Random  average,  than  energy  e n d o f 40 t r i a l s  and t h e r e f o r e  patterns =  to  30  Although in  repeat  working  have  over  a l .  1981).  is a  any  studies  of the c h a r a c t e r i s t i c s  by g r o s s  the  total  kJ; Checkerboard  earlier  after  and not simply  to performance  n = 625  10.2  foraging  their  about  later.  directly  total  et  longer  trials,  some  of  declines  t o make  performance  during  analysis  15, a n d u p t o  i s a p p r o x i m a t e l y 30  high  of  after  memory  et a l .  tended  effect  revisits  Olton  intervals  have  memory  per  1976;  the hypothesis that  o f movements  revisits  before performance  hummingbirds  organization  two-way  spatial  1982; W i l k i e  often  overall  than  at least  Samuelson  and Krebs  more  frequent Other  trials  experiments  also  more  ( F i g . 2.3).  and  significant  pattern) with  within  (consistent  is  visits  a  (Kruskal-Wallis  c a n remember  (Olton  feeders  length  animals  Shettleworth these  was  f o r each  intervening  shorter  there  and energy  ones  factors  bouts  of  on t h e  (Kruskal-Wallis suggest  that  the  25  Figure  2.3. Mean p e r c e n t a g e o f r e v i s i t i n g opportunities taken at successive intervisit intervals fora l l patterns. F o r e a c h b i r d t h e number o f o p p o r t u n i t i e s i t had t o r e v i s i t f e e d e r s f o r e a c h i n t e r v i s i t i n t e r v a l ( s e e text for explanation) was c a l c u l a t e d f r o m t h e t o t a l number o f v i s i t s i n e a c h o f t h e l a s t 10 t r i a l s f o r e a c h pattern. T h e t o t a l number o f r e v i s i t s a n d o p p o r t u n i t i e s t o r e v i s i t w e r e e a c h summed o v e r b l o c k s o f f i v e i n t e r v i s i t i n t e r v a l s and expressed as a percentage.  27  birds two  achieved  simple  The and  over  and  bad  higher  whole  results 40  to  rates  energy  complexity to  forage  Spat i a l  Patterns  carried  that  above:  where  organized of  of  important  effect  in  detailed the  contributed birds  of  to  between  incorrect  the  the  on  of  good  hummingbirds' and  on  their  Increasing  the  decreased  their  pattern,  effort.  every even  correct. less  effort  good  on  feeder  i n an  their  two  components  effort  to  visits, respect  In  general,  the  described  and  to  of  clarify  responses  with  reflected  how  they  the  pattern  the  spatial  Results  made  only  were On to  the  underlying  a l l  4 patterns  more  than  including early  dramatic.  were  of  array.  of  visited  visits  trials,  patterning  quality  overall  feeders  profitability  but  whole  available,  analyses  concentrated  of  pattern  feeder  the  distribution  50%  time  arrays  foraging  near  on  Effort  of  was  bouts  over  foraging.  of  distribution  Halves  the  while  Foraging  in  Distribution  the  indicate that spatial  food  more  movements  bird  on  effectively.  out  profitability  Every  rates  the  patterning  behaviour  factors  an  intake  the  ability  foraging  intake  sessions,  had  locate  of  clearly  trial  feeders  abilities  I  energy  patterns.  above  of  net  any  trials  similar both those  bad  when  for  patterns, feeders  (Fig.  2.4).  feeder  on  performance  the  Quarters  most  of  the  immediately  28  Figure  2.4. S p a t i a l d i s t r i b u t i o n s o f v i s i t s on e a c h p a t t e r n . I n d i v i d u a l f e e d e r s a r e i n d i c a t e d by a h o r i z o n t a l s q u a r e composed of 9 s m a l l e r s q u a r e s ; good f e e d e r s a r e shaded. E a c h d i s t r i b u t i o n i s an a g g r e g a t e d summary o v e r four b i r d s f o r a l l 40 t r i a l s o n t h e g i v e n p a t t e r n . Each f i g u r e i s s c a l e d i n h e i g h t t o t h e maximum f r e q u e n c y at a n y l o c a t i o n on a n y pattern.  30  adjacent  to  (Halves:  88%  difference  Not feeders begin  i n Halves  significant  for  p < 0.001  all  mean  significant  each These  pattern  over  quickly  (Table  a l l birds  Thus  between  while  feeders Random,  was this  on  good  i n c r e a s i n g l y tended  2.3).  This  increase  patterns  to was  (binomial  comparisons;  p >  0.1  comparisons).  vectors.  fields  pooled;  concentrate  and Quarters  I expressed  field  and  and Quarters  direction  as a  bad  10  (Fig. 2.4).  departure  appear  vector  transitions  1  o f Movement.  location  indicating  a n d Random  trial  In c o n t r a s t ,  and  but "birds  feeders  f o r the Halves  good  after  a l l birds  Checkerboard  effort  f o r the Halves  the Checkerboard  feeder  on  for  choices).  among  distinct  good  feeders  choices  and Q u a r t e r s ,  at  only  Patterns  of  less  did overall  trials  test;  different  was much  only  good  1334 i n c o r r e c t  of foraging  clearly  of  incorrect  of  distribution  still  patch(es)  8 7 % o f 673  Quarters: the  the  and  a l l departures a l l trials  and i t s v a r i a n c e  overall  trends  o f 64 v e c t o r s  summarize  of  as a  overall  each  vector  and p l o t t e d movement  ( F i g . 2.5)  significant  l o c a t i o n s and i l l u s t r a t e  from  1  on  .  first-order patterning  movement.  Because statistical comparisons i n v o l v i n g mean v e c t o r s a r e s t r o n g l y i n f l u e n c e d by t h e s a m p l e s i z e , a n d b e c a u s e numbers of m o v e m e n t s f r o m d i f f e r e n t f e e d e r s d i f f e r e d b y a s much a s a n o r d e r o f m a g n i t u d e , a l l mean v e c t o r s a r e s e c o n d - o r d e r m e a n s . That i s , I calculated o n e mean v e c t o r f o r e a c h f e e d e r l o c a t i o n f o r e a c h trial. These t r i a l means constitute the sample values for plotting a n d a n a l y s i s , a n d s a m p l e s i z e s a r e e q u a l t o t h e number of t r i a l s . The r a t i o n a l e f o r u s i n g s e c o n d - o r d e r means i s given in B a t s c h e l e t (1981).  Table 2.3.  For each p a t t e r n , the p r o p o r t i o n of e a r l y and l a t e t r i a l s that begin with a v i s i t t o a good feeder.  Early Halves Quarters Checkerboard Random  0.40 0.25 0.50 0.60  Late 0.90 0.75 0.60 0.65  32  Figure  2.5. V e c t o r f i e l d s e x p r e s s i n g the d i s t r i b u t i o n of a l l departures from each f e e d e r . Each arrow r e p r e s e n t s the mean d e p a r t u r e d i r e c t i o n f r o m t h e l o c a t i o n , a n d i t s l e n g t h r e p r e s e n t s the the v a r i a n c e i n d e p a r t u r e d i r e c t i o n ; greater variance r e s u l t s in shorter arrows. O n l y v e c t o r s s i g n i f i c a n t l y d i f f e r e n t f r o m z e r o (p < 0.05) are p l o t t e d (Rayleigh's test for randomness).  33  HALVES  QUARTERS  34  CHECKERBOARD  \  \\  \  \  ;  1/ /  \  1  /  j *  /  I •  „  *  /  Illllll  4  '  / /  lliilllf  t  t  /  \  / X  RANDOM X  \  ^  • V :  : x : : : : : : : : : : : :'':-:'>:^:-:v: :v: : :  :  :  :  :  :  :  :  :  :  :  :  :  :  :  ^:$S$: : : : >: : ;  :  :  :  :  •X;  \  1-  /  35  Departure patterns clearly birds  ( F i g . 2.5). organized  moved  there. low  directions  The  indicates The  fields (less  Random,  movements rather  than  birds  moved  toward  significant  trends  birds  vectors  in  tended  toward of  vectors  to  indicate  fields  of  profitability  i n the centers  On  t o the  of p r o f i t a b i l i t y  of the array,  and array  within  and there from  of  direction  Checkerboard  respect  direction  remain  general  i n departure  with  were  profitability;  their  in fields  organized  departure  of  and  moved  of movement).  the centre  movements  and  variance  t o the patterns  on a l l  of u n p r o f i t a b i l i t y  direction,  higher  were  itself  to the patterns  insignificant  patterns  orderly  Quarters,  in fields  shorter  indicate  stable  and  that  of  remarkably  of p r o f i t a b i l i t y  departure  the concentration  there  respect  vectors  in  profitability.  these  Halves  fields  longer  orientation  and  with  into  variance  On  were  i t ;  were  most  few  central  feeders.  The shows  good  that  patterned visible In  performance  hummingbirds arrays  the  poor  organization  patterns  suggests  number  of  that  spatial  they  may  organize  their  learning.  the spatial  to  forage  q u a l i t y that overall  locations  on  structure  in  feeders  no  guide and  of kind  with  foraging. the lack and  n o t be a b l e  o f some  patterns  effectively  Checkerboard  independently  structure  That  could  performance  h u m m i n g b i r d s may  require  and Q u a r t e r s  and u n p r o f i t a b l e  o f movement  instead  use  the Halves  learn  of p r o f i t a b l e  effective  large  can  c o r r e l a t e s to feeder  particular,  on  Random  to learn  each  environments,  to help  but  a  other;  i s , hummingbirds can d i s c o v e r  of t h e i r  of  they  them and do  36  this  more  effectively  and  more  quickly  in  simply  structured  environments.  Experiment  2:  The  Experiment successfully distinguish for may  the  On such  as  from  and  the  array they  mechanisms  pattern as  may  a  ( i . e.  or  "map"  have  rules  arrays,  the  kept  them  1983;  and  location  Sutherland  and  them  out  (Krebs Dyck  can  one  does  account  hand,  birds  Wyers  1981).  mechanisms  in patches  of  allowed  of  not  relationships  and  or  forage  could  non-mapping  search),  got  On  Quality  i t  spatial  n e c e s s a r i l y l e a r n i n g the  quality  that  (Menzel  learned  that  Feeder  but  performance.  area-restricted  without  Summers  of  about  hummingbirds  patterned  entire  "errors"  feeder  that  plausible  movement  ( i . e.  Expectations  patterns  hand,  simple  feeders) between  two  i n the  other  feeders recover  large  between  learned  of  demonstrates  from  feeders  the  1  observed  have  among  Effect  good  them  patches  of  to bad  spatial  relationships  et  1983;  1984;  a_l.  Mellgren  Wilkie  and  Roper  1986) .  To  distinguish  "switched" through  the  spatially same  the  resulted  Quarters  these  explanations,  pattern  experiment.  If  to high  u n d i f f e r e n t i a t e d movement  rules  should  between  should  continue from  independently  apply  at  high  learning or  as  a  after  the  its  mirror  rules  within  switch  as  p o s i t i o n s of  pattern,  experimentally  performance  performance. the  I  then  If good  image results  trials,  before, high  midway  and  from the birds  performance  feeders,  performance  whether should  37  deteriorate old  sharply  distribution  after  and  the switch,  learn  t h e new  until  birds  stop  using  the  one.  Methods  I  used  four  hummingbirds birds  and  similar array  in this for  plastic  reservoirs horizontal  and  in  panel  a metal  the  side  marked  with  centers birds;  they 11.0  departure,  an  8 X  were  of a  with  X  11.0 2.4  signals  the  record  to feeders  of  birds'  open  in  both holes  chamber.  positions  punched  in  not v i s i b l e  On were  their to the  red  disks  were  monitored  from  equally by  a  photodarlington  bills  the timing  apart  m  were  with  diameter  feeder  were  feeder  Feeders  cm  2.5  holes  the  long)  mm  X  of p e r f o r a t e d  Visits  by  mm  were  20 mm  2.5  Feeders  recorded  a  3.5  experiment  follows.  X  rufous the  modified  mounted  6.4  tubes.  8 array  triggered providing  diameter  male  maintaining  each  facing the birds,  apart.  which  as  wall  red disks  cm  microcomputer photocells  one  the feeder  saw  collection  adult  for  d i r e c t i o n s behind  the panel  19 mm  for  spaced  vertical  of  I  They  two  to  1.  inside  end.  on  prior  i n Experiment  ( 1 . 6 7 mm  and  Methods  them  of data  a t one  female  experiment.  used  method  tubing  adult  training  t o those and  naive  on  and  arrival  duration  of  and each  visit.  On each  of  After  30  for  the  t h e day 40  following training,  s duration,  trials,  I  remaining  on  the Quarters  "switched" 30  each  the pattern  trials;  a l l good  bird  had  pattern to  trials,  (see F i g . 2.1).  i t s  feeders  60  mirror  suddenly  image became  38  bad, the  and v i c e array  versa.  with  At  clean  the switch,  ones  before  I replaced  adding  a l l  feeders  in  nectar.  Results  Performance results  before  of Experiment  1  at  the  chance  first,  and  then  improved  still  improving  approximately After  the  least 10  F i g . 2.2  30  bird  very  similar  to the  and F i g . 2.6).  Birds  50% c o r r e c t ,  slowly.  trials.  the  was  As  but they  for at least  every  three  after  of  more  80% c o r r e c t  the f i r s t  trials  level  trial  switch,  switch  (compare  began  by  the  before, had been  15 t r i a l s  dropped  below  Performance  switch,  improved  birds  quickly at birds  were  performing  by  at  that  time.  50% c o r r e c t  for at  recovered were  q u i c k l y ; by  averaging  75%  performance.  The the 5  very  switch  trials  beginning  illustrates  before  correct  ( i . e.  20  the  of  feeders). the  Clearly, were the that  good  visits  before  switch.  At  d i d contain  were  even  t h e same food.  shift  the  were  first after  time,  correct,  they  locations no  longer  failed  just  visits  after  the switch, a l l  6 visits 75%  For were  ( i . e. p r e v i o u s l y  of the 5 t r i a l s  these  and  i n performance.  20  incorrect  to v i s i t  though  before  87% of t h e f i r s t  i n each  birds continued  of  just  for 5 trials  the switch  incorrect  profitable  80%  while  trial  dramatic  feeders);  Similarly,  were  this  the switch  first  5 trials  visits  of each  good  i n each  of  of the f i r s t  6  after they  the had  provided  to v i s i t  switch. learned  food  the  after  feeders  39  Figure  2.6. O v e r a l l p e r f o r m a n c e on t h e Q u a r t e r s p a t t e r n i n the switch experiment. T h e p a t t e r n was s w i t c h e d t o i t s m i r r o r i m a g e a f t e r t r i a l 30 ( i n d i c a t e d b y a v e r t i c a l line). The b r o k e n l i n e i n d i c a t e s c h a n c e performance (50%). E a c h p o i n t i s an a v e r a g e f o r 6 b i r d s f o r e a c h trial. T h e f i g u r e s u m m a r i z e s t h e r e s u l t s o f 13,341 v i s i t s t o f e e d e r s i n 360 trials.  40  41  Not  only  previously an  did  good  required  increases minimum and  with time  before  first that  for  a  1981).  switch,  (i.  e.  but  they  they  (i.  e.  no  food  significant  for  the  <  0.03  for  of  n=l04;  0.05),  (Mann-Whitney with due  clean to  U  Persistence the  face  learning  of of  within  test;  feeders,  at  nectar  of  as  had  more  to  feeders  did  (Table  they first  before  This  3  of  effect  was >  the  visit  bad  the  not  I  good  switch,  these  effect U  was  test;  individuals that  after  bad  though  duration;  could  first Rs  the  replaced  result  =  not  (p  trial -0.44;  first a l l  p  trial feeders  have  been  feeders.  profitable of  as  during  Because  switch,  does  birds  detectable  0.2).  formerly  6  after  to  the  (Mann-Whitney  decayed  with  not  in the  arrays  the  on  handling  2.4).  for  trial  visits  time  together  performance  ( i . e.  (Table  taken  (Gass  longer  first  they  some  spend  and the  feeders  nectar  high  a l l  inverted patterns  simple  On  handling  sequence  p  trials  0.001).  long  at  even  The  and  that  no  expected,  birds  visit  ones  residual  then  contain  or  The  although  than  at  each).  <  <  contain,  to  spent  feeders.  feeders  significant  (correlation p  p  also  flowers  process  they  bad  they  to  b i r d s would  feeders  good)  contained  and  as  to  but  returning  good  significantly  previously  0.02),  test;  bad)  spent  <  feeders  in  previously  i f they  switch,  than  spent  previously  even  persist  switch,  nectar  expected  the  nectar) U  of  I  good  Mann-Whitney  the  hummingbird  required  after  the  handling  is  to  contained  2.4;  time  amount  and  visits  long  the  Montgomerie  both  hummingbirds  locations after  unexpectedly  time  the  patterns  opportunity result  of  foraging  demonstrates  entirely  from  in that  learning  42  Table  2.4.  D u r a t i o n s of f i r s t v i s i t s t o f e e d e r s b e f o r e and a f t e r t h e m i r r o r i m a g e s w i t c h . V a l u e s a r e mean s e c o n d s s p e n t h o v e r i n g (SD) f o r a l l b i r d s f o r e a c h t r i a l . T h e s w i t c h o c c u r r e d b e t w e e n t r i a l 30 a n d 3 1 . Sample s i z e s a r e g i v e n below each mean.  Trial  29  Trial  30  Trial  31  Trial  32  Good Feeders  0.47 (0.21) n = 114  0.50 (0.22) n = 120  0.51 ( 0 . 0 9 ) n = 81  0.49 (0.17) n = 74  Bad Feeders  0.29 (0.07) n = 49  0.29 (0.08) n = 57  0.39 (0.31) n = 105  0.29 (0.10) n = 110  43  of  spatially  bad  undifferentiated rules  feeders.  While  rules  particularly  in the early  insufficient  to explain  contrary, they this  within  "know"  quality  a t most, feeder  spite  and i n s p i t e  of  kind  of pattern  the results  30 t r i a l s  i_n  this  stages  profitable  knowledge  of  f o r responding may  to  good  be  involved,  i n d u c t i o n , they  of t h i s  experiment.  hummingbirds  behave  of e n e r g e t i c  experience  shortfalls  that  are  To t h e  l o c a t i o n s and p e r s i s t  immediate  and  as  i f  i n using  of  feeder  contradict i t .  Discussion  Hummingbirds feeders  learned  within  one  feeder Only  quality  poorly many  and  Switching  The c o m p l e x i t y  imposed  of  important patterns  profitable  distributed,  on more  complex  small  or  important  affected component  patterns  pattern  of  depended  performance  discover they  the and  forage,  a n d how  profitable  of the s p a t i a l  feeder  i n which  about they  size  to i t s mirror and was  use t h i s  large,  They  and  image  Because  were  adversely  an  development  of  intake  observations how  animals  in profitability  information  and  that  i t , these  variation  performed  distribution.  energy  about  in and  of feeders  the  questions  spatial  simple,  demonstrated  I measured of  well.  of  capability.  were  few,  groups  in their  quality. as  distribution  of p r o f i t a b i l i t y were  identical locations  c o n s t r a i n t s on t h i s  learning  importance  learn  visit  performance  about  illustrate  of v i s u a l l y  d i d b i r d s perform  expectations on  arrays  feeders  irregular  the Quarters  dramatically  in large  preferentially  i n which  groups  regularly  to  day.  i n cases  which  feeding  later  (Pyke  as et  44  al.  1977; K r e b s  What of  did  properties  organize  et a l .  the birds  of t h e i r  complex  developing  1983; G e t t y  of  action  a n a l y s i s d i d not allow  used  in perception,  study.  However,  conclusions  this  about  these  kind  that  arrays?  to  about  1985).  Examination  clarify  their  afford  how  or storage issues  high  performance.  c o n s t r a i n t s under  mechanisms  of information,  a r e beyond  of a n a l y s i s  they  environments i n  d e s c r i p t i o n of the a c t u a l  processing,  of behaviour;  these  helped  information  This  generation  about  responses  spatial  patterns  learn  and Krebs  did  which  the scope  allow  these  or i n o f my  some  simple  mechanisms  must  function.  Two  important  and  related  properties  learning  observed  here  behaviour  patterns,  and p e r s i s t e n c e  they I  are inappropriate  mean  not  that  just  Several  birds  the  the  regularity  the  vector  (Fig.  2.4)  local  rules  of  behaviour  point  the  for  this  movement  after  of  evidence  i s indirect.  80%  of their  visits the  notion.  i n the arrays  the switch.  wholeness,  q u a l i t y , and independently.  I  argued  patterns  above  account  by  that  f o rthe  clearest  kind  Individuals persisted  i n making  up t o  they  The t h i r d  illustrated  Quarters  cannot  First,  and  to previously switch;  and  Second,  when  t o wholeness.  patterns  Halves  even  By  of feeder  spatial  distributed  patterns  locations  fields  performance  after  individual  o f movement  low  trials  of these  and symmetry  for  of s p a t i a l l y  entire patterns  of t h e i r  supports  the  and e n e r g e t i c a l l y c o s t l y .  learned  quality  aspects  a r e wholeness  of  good  feeders  visited  f o r the f i r s t  mainly  bad  few  feeders  45  (Fig. way  2.6). ( i . e . the  before spite  the of  If on  These  the  switch),  i t were two  not  complex could  pattern  learn  places  that  viewing  whole  on  species  birds  of  preferentially  as  Zach  ovenbirds  (Zach  1974)  opposed  to  Persistence clearly also  visited feeders birds  evident  evident  in  them; in  the  spent  and  appear simply  of  be  nearly  et.  1977b)  able  to  and  they  trial as  after  long  of  treated in  80%  complex  how the  handling  long switch.  of  the  parts  ability I  most  to  suggest  expectations  about  parsimonious  known  that  foraging  several  sites  and  1974;  Smith  and  1984a,  1984b),  and  (Smith  and  titmice  food  of  food  locations.  expectations  feeders those  i t  patterns  learn distributions  structured  lower  its  limited  Sherry  spatially  way  in  ones,  learn  the  a_l.  individual  choices  them  much  of  the  good  1977a;  not  of  i s well  (Krebs  was  conditions.  remembering  particularly first  only  is  It  Falls  to  on  development  Falls  patterned  simple  80%  these  remember  in birds' the  have  under  them  and  did  performance  can to  two  learned  results.  return  1974;  the  locations  the  been  performance  birds  hummingbirds  of  of  Sweatman  poor  l e a r n i n g as  interpretation  both  that  but  particular  intake.  than  independently  patterns  Sweatman  energy  patterns  a l l ,  had  in a  persisted in visiting  that  argued  patterned  feeders  fact  that  the  good  the  But  strongly  were  birds  reduced  be  independently.  the  and  for  at  argues  feeders  i n which  dramatically  plausibly whole  way  bad  to  visit.  feeders they  previously  It  when  spent  Three  was  of  good  was they  handling the  feeders  six as  46  they  had spent  Even  handling  though  this  statistically  those  effect  clear  Because  hovering  component  behaviours  decayed  for at  same  those  (including  influenced  by e x p e c t a t i o n s a b o u t  among  feeders  together.  This  has  been  that  In  this  their  or  study,  respond  they  without showed  locations  after  Thus  of c h o i c e s integrated  i s directed  by  locations.  formerly  profitable  been  changed  a n d Sweatman highest  patches  I  found  little  1974).  degree  tended  most  the  switch  to  them  reason  of  strongly (Smith  independently.  behave  they  as  of their that  cues  limited  i f  environment. of  Miller  in addition ability  to  a  This  to spatial and  This  i s  use  e t a_l.  learn  t o suppose  individual  locations  with  other only  those  prey  the  to resolve spatial  representation agreement  quality  is  has  (Smith  with  c a n d i s c r i m i n a t e between  ability  way;  in titmice  are also  spatial  the environment  individuals  on h i g h  them  to  and  feeders.  of behaviours  returning  after  the wings  sequences  visiting  many  1974).  hummingbirds arrays  of  2.4). of  components of  from  handling  syndrome  demonstrated  flapping  these  i t was  (Table  performance  the quality  spent  continue  even  that  switch.  trial,  individuals  animal,  the u t i l i t y  in visiting  Sweatman  whole  this  study,  persist  and  time  to  specialization to  to  locations  also  In  the  about  tendency  spatial  of  Further,  expectations  suggests  to the  the f i r s t  at least  the  behaviour  3  prior  involves  licking),  the  during  feeders  result  feeders  that  locations suggests  limited  in  in that some  "coarse-grained" conclusion  ( 1 9 8 5 ) who location, remember  is  found  in  that  hummingbirds individual  47  locations  even  The studies work  relatively seem  that  avoid  to  ability Kamil  conclusively  weeks  or months  This  places be  be  1981;  Miller  found  that  by use  capacity  with  information  quality  using as  can  et a l .  spatial  in  at  1980; 1985) o r  and Balda  least  on  having  (Lieblich  size, George  small  their  Several  studies  with  nearby  a n d more  rats  distant  locate objects  (Suzuki  the  sites for  caches radial  that  can This  correlates Montgomerie Wall  (1982)  cached which  seeds they  "landmarks" by  similar  arm mazes  relative  et a l .  by  individual  objects  of these  themselves  marsh  1982).  and  relocate  displacements  as  be  resolved  colour  nearby  missing  conclusions:  cache  Vander  i n the laboratory  to  1985).  1980; G a s s  landmarks.  Wolf  remember  information  or  and  such  and A r b i b  shape  animals  yet  partially  birds  similar  individual  t o d i s t i n g u i s h a n d remember  include  Even  and  field  attributed  has  individual  r e l a t i o n s h i p s between  the  displacements.  Kamil  the places  nutcrackers  many  birds  these  from  (e. g. G i l l  "capability  of  in  nectarivorous  distinguish  dependent  (Laverty  landmarks.  resulted  be  that  Food-hoarding  1984a;  may  strongly  associated  other of  may  that  such  or thousands  (Sherry  observed  c a n remember  locations  can r e a d i l y  paradox  considering  their  demonstrated.  of hundreds  feeders.  i n f l o r e s c e n c e s has been  although  or nutcrackers  locations  animals  visited  of 6  to suggestions  observations  remember  1978),  arrays  responses  in relation  and other  previously to  linear  coarse-grained  F o r example,  can  tits  smaller  paradoxical these  locations.  1977;  i n much  to  yield both  1 9 8 0 ; DeWeer  et  48  al.  1980),  perform  and t h e fewer  (Roberts  1982).  information  available  laboratory  environments  information sources  but  together  discriminations.  to  spatial with  the  landmarks  Hummingbirds them in  in which  location. spatial  the  have  the  less  much  field  richer  than  I intentionally Using  location  well  these  could allow  they  s e t s of  in  simple  removed a l l information much  finer  49  CHAPTER SPATIAL IN  Foraging resources  for  place  at  the  and  of  to  and Pianka  geographic  respond  habitats  spatial  also  individuals  repeatedly  (Wolf  and Hainsworth  influenced plants,  a  territorial  of nectar by  of i t s e l f  Hainsworth  abilities  at  several  variation  e t a_l.  to track  the  in  food  scales,  1981).  regularly forager,  distribution  production  (Zimmerman 1986).  But  fine-grained  to i t  distribution  spatial  this  individual  particular  potentially  different  to  spatial  For a given  nectar  and i t s competitors  of nectarivores  variation  1983).  and  space and  1978).  be e x p o s e d  and temporal  1983; A r m s t r o n g  i n both  at relatively  hummingbird,  dispersion  a n d by t h e s p a t i a l  activities  may  resources  h a b i t a t s , and  a v a i l a b l e t o i t a t any  the  be a t t h e r i g h t  and Montgomerie  occurs  their  et a l .  food  coarse-grained  (Gass  in  effectively  1966; K r e b s  regions,  quality  them  must  Because  animals,  high  1978; K r e b s  and a v a i l a b i l i t y  where  as  to  foragers  times.-  able  variation  relatively  1977; K r e b s  at several  i n those  PROFITABILITY  available  Successful  be  exists  this  abundance  of  et a l .  quality  must  HUMMINGBIRDS  select  scales  such  and  in  whole  ranges  to  BY  OF  choices  nectarivorous  including  spatial  the  (MacArthur  availability  much  PATTERNS  appropriate  vary  For  LEARNING  tend  ( s e e Pyke  animals  variation  home  animals  reviews).  typically time,  COMPLEX  from  environments 1983  PATTERN  3  and  time  i s  rates of  of foraging 1981;  Questions complex  Wolf about  patterns  and temporal  scales  50  are  becoming  1982;  Gass  increasingly  have  locations  and  learn of  shown  to  visible  forage  concluded  behaviour  are  suggested patterns time?  that  to  in  Chapter  than  they  et.  al.  and  memory  coarse-grained  them.  One  approach  and  a then  in  an  1978;  that  they  require of  Could those  whole  their  and  component  of  et  al.  1985;  that  in  patterned  and  not  learn  learn  by  Further,  I  each  location  coarse-grained  numerical  in  just  the  size  I  way  that  fine-grained if I  gave  used.  them  would  learning  relationships  a  set  solutions  of in  size  than  to  among  would  possibly practice  more  require  units  numerical  I  spatial  of  into  can arrays  numbers  of  the  hummingbirds  patterns  problem  pattern  combining  can  experiments  and  spatial  feeders,  structure.  limited  larger  several  the  showed  relatively  the  they  of  spatially differentiated  spatial  actually  this  I  profitability,  patterns,  to  2  variously  using  arrays  of  Miller  quality,  large,  no  foraging,  important  Chapter  and  have  their  correlates  individual  fine-grained  learn  patterns  Cole  remembering  feeder  of  2?  did  Learning  decompose  to  learn  and  In  apparently  hummingbirds  discrimination  to  1978;  visible  guide  (Kamil  1985).  patterns  they  to  is  i t is unlikely  structure  But  flowers  rules  use  flowers,  developing  that  independently;  of  indices  about  movement  cues  e f f e c t i v e l y in  by  expectations  could  learning  patches  Sutherland  of  spatial  that  foraging  feeders  using  landmark  individual  hummingbird  absence  or  of  possibly  Gass  hummingbirds  quality  studies  (Kamil  1985).  Although flower  frequent  be  simpler (Miller  51  1956;  Simon  The two  two  complex  important  ways.  feeders  each  four varied  in  size  discrete not  1974).  and  in  that It  learning  a  so  Random  (see  pattern.  and  i n the The  easily  or  Good  to  but  of  in  pattern  into  a  but  of  the  the  separate four  certain  decompose  were  learning  patches with  of  patches  patches  -decomposable  in  patches  Checkerboard  distributed how  2 differed  pattern,  problem  feeders are  see  i n groups  pattern.  role  of  pattern  I allowed  Random  then  pattern  patterns  they  more  structure  the  I f hummingbirds  patterns  Checkerboard  that  task,  F i g . 2.1).  spatial  Random  is  i n Chapter  and  spacing.  problem  of  pattern.  the  Checkerboard  used  Checkerboard  regularly  to  spatial  the  regularly  easy  clarify  complex  the  are  I  f e e d e r s were  the  learning  the  To  in  pattern  patches  i s not  in  Random  Checkerboard of  Good  spaced  the  problems  patterns  birds than  are  should  quickly  than  i n performance  more  time  I allowed  sensitive  to  be  able  to  the  Random  to  of  learn  in Chapter  2  fine-grained learn  the  pattern.  Methods  I  used  (three  females  caught, to  the  and  and  naive two  maintained  experiment.  commercial each  five  week,  35%  males)  Selasphorus  i n the  in individual Their  hummingbird and  adult  food  experiment. cages  maintenance (Nekton  s u c r o s e on  rufous  U.S.A.,  weekends  f o r two food  A l l were  wild-  months  prior  was  Inc.)  dispensed  hummingbirds  Nektar-Plus for  from  5 a  days  central  52  hanging at  feeder.  a l l  times.  collection, used not  Adult The  feeder  array  2 of Chapter  d u r a t i o n s of v i s i t s  were  2 with to  available  apparatus,  and e x p e r i m e n t a l p r o t o c o l  i n Experiment collect  D r o s o p h i l a s p . were  ad  libitum  method  identical  of  to  data those  the exception that  I did  feeders.  Training  Training 2,  except  hours  that  instead  from  the  35%  o f 4.  bird  of  lived  i t s  training  solution  Between  similar  to those  the three d a i l y  Each  Between  sucrose  feeder.  were  I extended  beginning  experiment. and  procedures  was  training  available birds  training  in  Chapter  sessions  i n the experimental  sessions  experiments  used  to  ad  were  chamber  end  of  array  was  covered,  libitum  from  the  the  to 6  a  each  hanging  returned to their  home  cages.  Experimental  Procedures  Beginning each  bird  on  on  another  Random  pattern.  days  day a f t e r  the Checkerboard  after  opportunities  the f i r s t  three days For each  individual  o f two  which  each  the array  1.  on  t o four  series,  basic  each,  Two  I tested  t o f o r a g e on  sequence  pattern.  training,  of t r a i n i n g ,  i n the following  A  i t s  during  I  weeks  later,  bird  on t h e  each had  several  125  I kept  the  days  o f 40  trials  Checkerboard  to  165  consecutive  design:  o r more  tested  or  53  Random  2.  A  pattern  final  day  "switched" after all  feeders  experimental  days  f o r four  Bird  4 improved  after  25. with  more  with  on  slowly  than  after  visited  the  array  less  termination  trials  o r 5%)  short  choice  on  adding  any b i r d  because  lasted  sequences.  4 days on  than  biases  day  3 3.  i t on t h e  the pattern  on t h e Random  day  4.  of i t s t r i a l s ,  I also  lasted  on  so I kept  I excluded  less  of p o t e n t i a l  25  half  pattern.  visited  25  day and s w i t c h e d  trial than  pattern  trial  the others,  of the s e r i e s ;  o f t h e Random  on w h i c h  replaced  before  after  The s e r i e s  the switch  trials  I  I  image  the Checkerboard  f o r an a d d i t i o n a l  25 o n d a y 4.  analyses  ones  and  which  to i t s mirror  the switch  with  all  on  At the switch,  pattern,  premature  the period;  trials,  clean  series  birds,  pattern  trial  45  over  t o them.  The  constant  of  the pattern  trial  nectar  constant  Bird forcing  i t s data  excluded  8 feeders  3 a  from  individual (66 o f  introduced  by  1325 such  54  Results  Overall  Performance  I  use  "Percent trials  the f o l l o w i n g d e f i n i t i o n s  correct choices"  that  were  (profitable) trial. that  trials" trials"  last  to  last  the  or  of  late  trials,  were  made  with  In  general, on  a l l  both  U  patterns  approximately  constant  through  (Table  3.1;  from before  about  p  <  energy 0.05  50%  the switch  decreased  ( p < 0.05  intake  f o r every  to  over  (p  <  t h e same  of c o r r e c t  choices  same  trial.  "Early  experiment;  and  "last  I  state  that  state  "late  "trials  trials"  unless  time,  but  bird).  0.01  for 2 birds;  for  every  decreased  I  refer and  Comparisons indicated.  their On  per t r i a l  increased  for at least  bird  early  3.1).  number  Correct  a  improved  Table  visits  per t r i a l  on  otherwise  significantly  feeder  80%  measure  just  to the  that  otherwise.  ( F i g . 3.1;  total  gross  by  tests  birds  pattern,  and  first  (e.g. i t s correct choices),  Checkerboard  visits  If  I specifically  Mann-Whitney  were  the switch,  5 trials,  within  during  the  before  i t s performance  unless  the  of  experiment.  "decreased"  a comparison  performance  5 trials  t o the next  of  in  5 trials  they  revisits  i s the percentage revisits  performance.  of a l lv i s i t s  whether  unprofitable  to the f i r s t  the switch" 5 trials  feeders,  revisits"  the  "increased" to  or  unprofitable  refers  i s the percentage  good  visits  "Percent were  after  to  in analyzing  of  remained  profitable  significantly  choices 4 of the  bird)  the  and  increased 10  trials  revisits  insignificantly  for 3  55  Figure  3.1. O v e r a l l p e r f o r m a n c e on t h e C h e c k e r b o a r d a n d Random p a t t e r n s . E a c h p o i n t i s an a v e r a g e f o r a s i n g l e t r i a l : f o r Checkerboard t h i s i s f o r the four birds that c o m p l e t e d t h e e x p e r i m e n t i n 3 d a y s ; f o r Random i t i s f o r the four b i r d s that completed t h e experiment. The asterisk indicates a mirror-image switch i n p r o f i t a b i l i t y of the array. The broken h o r i z o n t a l line i n d i c a t e s c h a n c e p e r f o r m a n c e <50%). Note that the f i n a l day o f e a c h e x p e r i m e n t h a s an a d d i t i o n a l 5 t r i a l s .  DAY  1  DAY 2  DAY 3  DAY  4  1  C H E C K E R B O ARD  .  r  »  1  1.  q  i  1  1  1  i  1  '  •  '  •  *  1  1—i—i—i  i  1  i^  *  •  i  i  RANDOM  ft* 1  0  1  1  L  20  1  1—.  1  1  40  i  i—,  i  i — i  20  i — i — i  1  40  TRIAL  1  1  1  20  1  1  1 -  SLMI  1  40  20  1  J  40  1  Table  3.1.  Development o f f o u r measures o f o v e r a l l p e r f o r m a n c e on C h e c k e r b o a r d and Random.Values a r e means f o r a l l f i r s t v i s i t s t o p a t c h e s by b i r d s over 5 t r i a l s (95% c . i . ) . Results of a three factor Kruskal-Wallis a n a l y s i s o f v a r i a n c e a r e a l s o shown. Means s i g n i f i c a n t l y d i f f e r e n t a t t h e 0.05 l e v e l a r e i n d i c a t e d w i t h a "*"; i n s i g n i f i c a n t d i f f e r e n c e s a r e i n d i c a t e d as " n . s . " (Tukey's t e s t ) . Checkerboard Early  Feeder  Visits  31. 1  Energy Intake (J)  113. 8  Late  ( 2 8 .4 -  Comparison o f Means n.s.  33. 8)  29. 0  ( 2 6 .9  -  ( 1 0 3 . 7 - 122. 9)  171. 1  (155. 6  - 1 8 6 . 6)  *  31. 1)  Percent  Correct  56. 7  ( 5 4 .8 -  5 9 . 5)  81. 4  ( 7 9 .0  -  84. 0)  *  Percent  Revisits  25. 6  ( 2 1 .9  2 9 . 4)  21. 1  (  1 7 .9  -  2 3 . 2)  *  -  Random Early  Late  Comparison o f Means  Visits  27. 9  ( 23. 4 -  31. 7)  25. 1  ( 2 3 .0  -  2 7 . 1)  n.s.  Energy Intake (J)  97. 6  ( 83. 3 - 1 1 1 . 9)  116. 1  (101. 5  - 130. 9)  n.s.  Percent  Correct  52. 0  ( 47. 5 -  56. 6)  66. 2  (  6 0 .0  -  72. 4)  *  Percent  Revisits  22. 5  ( 18. 3 -  26. 7)  22. 8  (  1 8 .7  -  2 6 . 9)  n.s.  Feeder  58  birds).  In  contrast,  Checkerboard increased and  the  trials  were  Table  3.1;  (Table  1  Fig.  p  <  changed  the  I  switched  the  3.2).  This  each  in  bird  late the  switch.  correct  choices  intake +  56.1  0.04  In decreased  for  of  on  to  only  After for  J/trial;  contrast,  on  52.0%  at  more  birds trials  dramatic  13%  switch, 5  after  J/trial  to  on  improved. trials;  choices.  No  good  worse  bird  feeders  in  a l l 5  immediately  image for  dropped  SD)  trials.  declined  (means:  late  (Fig.  before  from  the  birds  83%  first  Similarly,  switch:  98.6  the  birds  +  the (+  below  the  (late 30.0  8%  trial  remained  dramatically  3.1;  Checkerboard,  performance  Checkerboard (+  late  3.1).  mirror  higher  4),  in  200.2  in  revisits  significantly  least  intake  actually  correct  its  trial  significantly  choices  of  on  for Bird  Checkerboard  birds  (Table  to  28% the  4  than  per  0.02  increased  the  Random  was  <  energy  for  correct  achieved  a l l 5  every  of  performed  Random  intake  (p  of  on  (Checkerboard);  percentage  choices  trials  2  only  effect  Correct  rates  choices  pattern  had  bird  than  80%  averaged  birds  energy 163.1  over  general,  after 50%  2  less  well  Energy  one  maximum  only  In  switch. SD)  3.1),  5 averaged  and  only  correct  trials  where  for  less  3.1).  273.0 J / t r i a l  made w i t h i n  after  Fig.  and  Although  significantly they  mean  maxima:  4 and  Birds  3.1;  performed  considerably  (Random)).  Birds  (Table  significantly  both  average  birds  gross trials:  J/trial;  bird).  only  significantly  two in  of  performance  4  after  (Birds the  4 and  switch  5) on  59  Figure  3.2. O v e r a l l p e r f o r m a n c e o f e a c h i n d i v i d u a l b i r d on t h e l a s t day o f t h e e x p e r i m e n t on t h e C h e c k e r b o a r d and Random p a t t e r n s . B i r d 3 d i d not complete the e x p e r i m e n t on Random. E a c h p o i n t i s an a v e r a g e o v e r 5 trials. The a s t e r i s k i n d i c a t e s t h e m i r r o r - i m a g e s w i t c h i n t h e p a t t e r n a f t e r t r i a l 25. The broken horizontal l i n e i n d i c a t e s chance performance (50%).  61  Random  ( F i g . 3.2).  decreased first  from  trial  least  78% + after  4 trials.  decreased  J/trial;  for  both  insignificantly  They  also  energy 83.7  fewer  Checkerboard was  50%  experiment  correct  switch,  and energy  (p <  In  the  t o good  less  (late  trials:  139.5 +  after  switch:  J/trial;  p <  0.05  slightly  in trials  and  but  the  switch  47.5% +  9.3%).  trials  Random,  disrupted well  less  gross  after  switch:  bird  whose  below  no i t  that  every  by t h e s w i t c h  before  the  bird had  i n the last  performance feeders,  variable  Random  intake  on  end  of  either  attained  5 trials  recovered the  pattern  before  the  of the experiment  f o r the 5 t r i a l s  before the  for a l l comparisons).  summary,  visits and  0.03  50% f o r a t  f o r a l l comparisons).  performance  significantly  the  energy  insignificantly  However,  intake  below  made  after  but  choices  ( F i g . 3.2).  t h e maximum  switch  trials  significantly  reached  remained  0.3  2  choices  1 0 5 . 6 + 29.1 p >  15.9% i n  76.8 + 47.3 J / t r i a l ;  and  slightly  individuals  gross  the switch  1  two  t o 16% +  their  switch:  correct  trials:  both  over  after  5 1 . 1 % + 6.8%;  + 40.0 J / t r i a l ;  performance to  and remained  switch,  Birds  harvested  (late  On  the  after  birds).  by t h o s e  trials  Correspondingly,  trials  trials:  choices  12.1% i n l a t e  significantly  48.0  (late  Correct  among  pattern.  higher  levels  High  performance  by  a n d by a v o i d a n c e individuals Birds  of performance on  as measured  both  of r e v i s i t s  intake, was  on t h e C h e c k e r b o a r d  improved on  energy  more q u i c k l y  Checkerboard  patterns  ( a l l 5  than  by  better  than  on  and reached on  Random.  individuals  on  62  Checkerboard; disrupted spatial  2  of  4  individuals  by t h e s w i t c h ,  patterning  indicating  of good  on  Random)  that  learned  f e e d e r s was a n  was  strongly  e x p e c t a t i o n s of  important  component  of  performance.  Behavioural  To on  Components  understand  Checkerboard  analyses  of  of  patches,  perfect among  each  patches  and  focused and  reasons.  this made  First,  distributed  have  on  that  Because  and bad, these f o r each  analysis no  h a s two c a n be For  types further  example,  moving  directly  visiting  any  f e e d e r s i n each  exclusively  direct feeder  quality  groups  patches  on  comparisons  patches.  F i g .2.1). than  p a t c h e s , and  patch. require  on  of  bad those  revisits.  of four  recognizable  on Random  of  good  these  well  of  without  o r g a n i z e a n a l y s e s of behaviour  (see  detailed  selection  would  a l l four  out  better  Performance  two c o m p o n e n t s  easily  pattern  carried  Checkerboard  on t h e a r r a y  as a l t e r n a t i n g  no d i s c r e t e  I  s o much  pattern.  type  performance  because  identify  performed  d i d o n Random,  components:  visiting any  could  patch.  patches  without  pattern  they  and a n a l y z e d  energetic  patches,  birds  two  good  a l l good  I  than  has  within  decomposed  how  Performance  performance  Checkerboard foraging  of  In of  good  Second,  on C h e c k e r b o a r d  with on  and  Random,  within  feeders fewer those  f o r two  Checkerboard  cases  because  Checkerboard  f e e d e r s each,  patterns  most  the  and  I could in  I  could among  clearly  the  birds  was  Random  performed  performed  less  63  well,  there  was  less  behaviour on that  reason  to expect c l e a r o r g a n i z a t i o n of  pattern.  I used four p r i n c i p a l measures to examine how s t r u c t u r e of f o r a g i n g w i t h i n and among patches measures  of  organization  l e n g t h s of sequences  of  foraging  the component  developed.  Two  w i t h i n patches are the  of feeders v i s i t e d on bouts i n good patches  and bad patches (termed " r u n l e n g t h " ) . Runlength on f i r s t in  good  beyond  patches four  during  feeders  trials  as  should i n c r e a s e toward but not  performance  r u n l e n g t h i n any bad patches v i s i t e d feeder.  Birds  costs  of  foraging.  on  each  that  Two  among patches are the visited  improves.  minimize  the  good feeders and time  and  of  the  two  As performance  kinds  of  of the bad patches, to a minimum of 0.  four components of b e h a v i o u r a l o r g a n i z a t i o n good  and  visited  in  bad  energy  patches  improves, b i r d s should  tend to v i s i t more of the good patches, to a maximum of fewer  one  measures of o r g a n i z a t i o n of f o r a g i n g  numbers  trial.  Similarly,  should decrease towards  should a l s o i n c r e a s i n g l y v i s i t  good patches i n sequences  bouts  8,  and  In summary, these are  runlengths  in  patches, and numbers of good and bad patches  i n each t r i a l .  In the a n a l y s e s  below,  I  present  the  r e s u l t s f o r f i r s t bouts i n patches d u r i n g t r i a l s . All above. patches trials p  four  components  Both runlength  in  of performance  improved as p r e d i c t e d  good  and  patches  number  visited  increased  asymptotically  ( F i g . 3.3;  Table 3.2;  r u n l e n g t h : p < 0.05;  < 0.01).  from  of  good  e a r l y to l a t e good  patches:  S i m i l a r l y , both runlength i n bad patches and number  64  Figure  3.3. Changes i n f o u r component measures of performance before the switch. T o p p a n e l s h o w s mean r u n l e n g t h s i n f i r s t v i s i t s t o good and bad p a t c h e s ; b o t t o m p a n e l shows number o f g o o d a n d b a d p a t c h e s v i s i t e d per t r i a l . E a c h p o i n t i s a n a v e r a g e o v e r 15 t r i a l s f o r a l l b i r d s ( t h e average f o r t h e f i r s t and l a s t t r i a l s a r e a l s o shown). C l o s e d c i r c l e s and s o l i d lines i n d i c a t e good p a t c h e s ; open c i r c l e s and b r o k e n lines i n d i c a t e bad p a t c h e s .  65  => 2 . 0 DC  i  1.5 •  ""-cu.  ^  TRIAL  Table 3.2. Runlength i n good and bad patches on the Checkerboard p a t t e r n before and a f t e r the s w i t c h . Values are means f o r a l l f i r s t v i s i t s to patches by a l l b i r d s f o r 5 t r i a l s (SD). Sample s i z e s (number of t r i a l s ) are shown below each mean.  Before Switch Trials 1-5  Trials 101-105  After  Switch  Trials 106-110  Trials 121-125  Good Patches  2.3 (1.2) n = 113  3.1 (1.3) n = 120  1.8 (0.9) n = 114  2.7 (1.4) n = 124  Bad Patches  1.9 (0.9) n = 121  1.2 (0.4) n = 63  2.5 (1.2) n = 147  1.7 (0.9) n = 112  67  of  bad patches v i s i t e d s i g n i f i c a n t l y  period  (runlength:  Performance  p  <  0.05;  improved more q u i c k l y  decreased good  over  patches:  in early t r i a l s ,  the  p  same  <  0.05).  both  within  and among good patches, than the same measures of performance on bad patches ( F i g 3.3). On average, b i r d s took 2.4 times as many trials as  to reach 50% of t h e i r best performance  within  good  patches, and 3.9 times as many t r i a l s  50% of t h e i r best performance ones  (Table  w i t h i n bad patches  3.3).  among bad patches  as  among  still  good  However, birds' reached peak performance on  both measures of o r g a n i z a t i o n among patches before they peak performance  to reach  reached  w i t h i n patches ( F i g . 3.3). In f a c t , b i r d s were  improving w i t h i n both kinds of patches at the time of the  switch.  These  results  performance forage  contributed  effectively  organization  of  spatial scales. respect to  the  in  a l l four  improvement.  the  components  of  C l e a r l y , l e a r n i n g to  Checkerboard  pattern  involved  The hummingbirds o r g a n i z e d t h e i r behaviour with  profitable  good  to  that  behaviour at both w i t h i n patch and among patch  u n p r o f i t a b l e ones. of  establish  patches  faster  than  with  respect  to  T h i s o r g a n i z a t i o n allowed them to v i s i t most  feeders  and a v o i d most of the bad feeders by the  time of the switch.  A provides the  more  detailed  additional  development  frequencies  of  examination  of  these  four  components  i n f o r m a t i o n about the processes u n d e r l y i n g  of o v e r a l l performance. different  runlengths  F i r s t , a n a l y s i s of the in  good and bad patches  .68  Table 3.3. Rates of improvement i n the four components of o v e r a l l performance among and w i t h i n patches. Values are t r i a l s on which b i r d s reached the s p e c i f i e d l e v e l of performance f o r each component, estimated by l i n e a r i n t e r p o l a t i o n of the data used i n c o n s t r u c t i n g F i g u r e 3.3.  Percentage of Best Observed  Performance  Component  Good Patches per t r i a l Bad Patches per t r i a l Runlength  i n Good Patches  Runlength  i n Bad Patches  25  50  75  8  15  21  41  59  66  9  15  35  14  36  59  69  reveals  that  good  and  and  after  bad  runlength visits in in  bad  the  of  more  at  near  zero  be  must  patches  have  birds  only runs  comparison that  about  persisted  after  quality.  I  longer  also  good  to only to  to  were  modal  4  made  runlength  1 visit  bad  modal  trials  visits  the  101-105)  patches,  in early  period,  a l l visits  runlength in  (Trials  a l l correct  r u n l e n g t h s on made had In  four  in  patches  been  visits  fact,  they  late  were  or  in  within  bouts  quality,  were above  differed  developed  no that  i n bad i n the  and  longer modal  feeders  a  that  because  way  this  after  spatially  that that  issue  the  in  switch  structured  these expectations  reinforced  in  revisits  Note  in  runlength  patches  within  demonstrates  examine  that  good  revisits  greater,  r u n l e n g t h s b e f o r e and  birds  than  or  result  I will  fewer  fewer.  five  to  maintained  This  revisits.  of  visits  visiting  visits  feeders.  first  significantly  i n r u n l e n g t h s of  patch  they  showed  threefold  of  of  Third,  reveals  patch  2 visits  of  of  4  below.  runlengths  from  i f they  increase  minimized  expectations  was  same  ( F i g . 3.5).  detail  clearly  the  birds  expected  organized  effectively more  Over  In  of  one.  f o r a l l runs  revisits  per  of  modes  before  121-125).  37%  19.8%  that  random  both  when  examination  reveals  would  them  only  predicted  2 visits  decreased  than  Second,  than  from  4 visits.  when  patches  (Trials  trials,  patches  the  ( F i g . 3.4),  switch  increased  of  trials,  developed  patches  in late  runs  runs  birds  late  same d i r e c t i o n  by  feeder  i n good  patches  trials; ( T a b l e 3.2;  mean p  <  70  Figure  3.4. D i s t r i b u t i o n o f r u n l e n g t h s on f i r s t v i s i t s t o good and bad p a t c h e s . T h e s e a r e summed o v e r a l l b i r d s for the 5 t r i a l i n t e r v a l s i n d i c a t e d . The distributions for bad p a t c h e s a r e shaded.  71  Trials  1-5  80 40 -  Trials101-105 80  > o  40  2  LU =>  o LU CC  Trials106-110 80 40  3  0 Trials 121-125 80 40 0  1  2  3  4  5  RUNLENGTH VISITED  6 IN  PATCHES  7  72  Figure  3.5. R e l a t i o n s h i p b e t w e e n number o f r e v i s i t s a n d t o t a l number o f v i s i t s d u r i n g f i r s t b o u t s i n g o o d patches, f o r 25 t r i a l s b e f o r e t h e s w i t c h . The b r o k e n l i n e i n d i c a t e s e x p e c t e d number o f r e v i s i t s u n d e r c h a n c e expectation. The s h a d e d band i n d i c a t e s t h e 95% confidence r e g i o n a b o u t t h i s e x p e c t a t i o n b a s e d o n 100 Monte C a r l o s i m u l a t i o n s . The v e r t i c a l b a r s i n d i c a t e 95% c o n f i d e n c e l i m i t s a b o u t t h e o b s e r v e d means.  74  0.0001).  This  patches  clear  reversed  recovered reversal  by  the  after last  resulted  patches,  and  Runlength  of  i n bad  good  ( p r e v i o u s l y bad)  runlengths  changes changes  before  switch  the  (p <  although  runlength  about  patches,  i t is also  patch  quality;  birds  the  reversed  Fourth, visited that  and  quality.  bad  patches  more  bad  switch  after  evidence  direct both  patches (p <  shorter The  their  kinds was  fact  i t  0.001).  The  good  bad  and  for of  and  bad  although  the  patches.  longer  0.0001),  than  runlength good  in in  than  in  that  the d i f f e r e n c e i n  after  the  immediate  expectation  patches  switch  i n f l u e n c e d by  i n f l u e n c e d by  than  0.005).  of the  t h e number switch  spatially  Whereas  in late  patches  (p <  (p <  and  shows  expectations  experience with  of  experience  pattern.  b i r d s developed  patch  0.01),  are  is clearly  comparison  before  <  good  i n both  reverse  "correct"  in  in runlength  was  d i d not c o m p l e t e l y  (p  about  0.005).  runs  the experiment  switch  patches  that  of  of  ( p r e v i o u s l y good)  patches  the  switch  expectations  bad  before  the  trials  from  these  development  d i f f e r e n c e between  they  trials good  of  provides  distributed  visited  many  ( F i g . 3.3; patches  good  in  p  bad  additional  patches evidence  expectations  more <  and  good  0.0001),  trials  just  about  patches they  than  visited  after  the  75  Spatial  Organization  Among each  bird  patch,  good  patches  before  began  tended to  different  until  every  trial  to begin  trials  begin  a t t h e same  began  15 o f t h e l a s t  left  feeder  the  began  began  i n one good i n t h e same  good  trials  left  patch  good  in different  developed  with  5 of the last  good  patch,  and  10  bird  I n d i v i d u a l s not only  patch,  patch.  before  the switch,  particular  at least  patch.  in that  25 t r i a l s  of the upper  but  they  tended  F o r example,  the switch  in  Bird  the  ( i . e . the corner  3  upper  feeder  of  array).  Individuals array,  this  also  as measured  during  of  in a  i n one p a r t i c u l a r  feeder  before  canalization  bird  the switch  trials  individuals  This  each  Components  By t h e 25 t r i a l s to begin  ( F i g . 3.6).  experience,  3  patches.  s t r o n g l y tended  although  trials  of Behavioural  the  measure  freedom  25  developed  by t h e s e q u e n c e s  trials  before  o f movement each  between  two g o o d  patches,  could  because  occur  each  arrow  without  considering  occurred  along  more  possible  description  path  in  16  any  patches  good  a  visits  has four  permutations.  path to  of the  between  bad f e e d e r s 16  Note the  a directional  of which  in  two  transition  In  that  each  addition,  good  patches may has  t h e measure  of the o r g a n i z a t i o n of among-patch  that  degrees  feeders,  permutations  Nevertheless,  the  visited  patches  p o s s i b l e permutations.  each  they  (Fig.3.6).  between  represents  each  through  I t under-represents  represents  t h e way,  o f much  o f good  of the b i r d s  Because  "pathways"  the switch  i s coarse-grained.  ways.  path  unique  have even  allows  movement  76  Figure  3.6. Frequency and d i r e c t i o n of predominant moves between good p a t c h e s . The w i d t h of each arrow i s proportional t o t h e t o t a l number o f e v e n t s o b s e r v e d i n t h e l a s t 25 t r i a l s b e f o r e t h e s w i t c h . A l l p a t h s shown a c c o u n t e d f o r a t l e a s t 5% o f a l l m o v e s b e t w e e n g o o d p a t c h e s , w h i c h i s 6.4 t i m e s t h e f r e q u e n c y e x p e c t e d f r o m t h e a s s u m p t i o n o f random movement. Asterisks indicate p a t c h e s i n w h i c h t h e b i r d s most f r e q u e n t l y began trials.  BIRD 1  BIRD 3  H  P  \  OBS/EXP  c H  v \ N  BIRD 4  *  P  mmmt^ »  p  •  11.5-14.0  9.0-11.4  6.5-8.9  LEGEND  78  that  the  birds  are  64  possible  occur  in both  path  is  consider  exhibited. paths  directions, a l l  Since  there are  between  them,  the  expected  0.78%  of  these  additional  null  paths  good  and  between  degrees  8  since  each  of  feeders.  freedom  there  path  frequency  good  of  patches,  can each  I  will  of  movement  following  assertions  separately.  Inspection about  their  also  more  the  than  11.5 be  of  46  dominant  good  patches  fact,  only  3 of  were  patches  the  16  among  movements 12  into  paths  (Fig.  3.6),  type,  and  more  paths  with  than  bad  moment,  one  of  more than  for only  two  or one  than  than  paths  had  Third,  patches.  bad  patch  times  of  more  vertical,  3.8  Second,  paths Only  and  the  8  none  apart.  In  expected  f e e d e r s d u r i n g movements  individuals  They the than  75%  than  more  with 1's  good  5  this.  to  patches.  Bird  adjacent  the  dominance,  frequency.  were  permutations  with more  join  or  8 paths  4 of  that  visits  only  and  horizontal  f o r the  good  least  were  49  possible  at  First,  pathways.  strength,  paths  longer  Disregarding  movement.  expected  to  the  different  the  the  d i a g o n a l and  linked  good  in  frequency,  times  to  frequency  clearly  exhibited  expected  tended the  5  Each  confirms  among-patch  differed  pathways.  times  of  developed  individuals  paths  F i g u r e 3.6  organization  individuals  6.4  of  of  paths  of  the  also 16  were  most  tended  times  movements less  than  only  strongly  to  few  For  of  developed  concentrate  possibilities.  11.5  a l l  exhibited  between  5  their  of  the  expected  frequency  were  only  50%  of of  movements  one of  79  only 18  one  type.  paths  were  average  As  of  bad  number  time  of  to  related  Within  I  this  i n ways  3.4)  possible  table); 2  and  the  bad  per  -0.44;  visiting  and  n  =  5  modal  n  any  during  111  to bad  birds;  pairs  0.05  p  25  <  of  way.  The trials  related  paths;  move  <  the  3.  to  accumulated  feeders  p  was  the  this  observed  between  negatively  =  of  along  movement  was  number  in moving  movement  that  number  feeders  increasingly  earlier that  patterns  in  =  individual  these  the  by  the  0.01).  In  directly  between  along  way  the  for each).  These  the  tendency  to  c a n a l i z e movements  the  tendency  to  perfect  those  (Rs  along  pathways  patches  runs diagonal  (Table  revisits  no  3.4):  adjacent  same  direction  with  1  moves  birds organized  closely,  contained  visited the  that  minimized  more  that  birds  degrees  with  good  organization  (Fig.  f o r no maximum  fewer  of  movements a l o n g  functionally.  suggested  visits  (Rs  that  pathways  276  s t r o n g l y and  (range);  suggest  6,  visited  without  0.77  particular  visited  tended  and  experience  occurrences  birds  the  The  was  was  of  type,  gained  switch  patches  results  is,  of  63%  50%.  feeders  the  addition,  one  path  switch  total  are  any  they  the  0.46  only  individuals  before  good  average,  than  of  patches,  number  =  of  less  permutations  good  On  examined  with  feeders  i n the  move  There  were  three  0 diagonal  moves  (that  table).  in  a l l  examine of  each (Z  To runs  i n the  after  within-patch  ( F i g . 3.5.).  revisits.  runs  diagonal (X  I  their  patch  by  feeder; the  These  turning U  table); patterns  in and  4  90 the  runs  increase  Table 3.4.  Frequencies of the three p o s s i b l e p a t t e r n s among runs of 4 with no r e v i s i t s i n good patches (see t e x t f o r d e f i n i t i o n s ) . Values are pooled f o r a l l 5 b i r d s f o r the 25 t r i a l s before the s w i t c h .  Pattern  Frequency (runs)  U  107  Z  6  X  1  Total  81  from  U  to X  i n both  rules.  Birds  over  other.  any  In clear  switch.  feeders  good  bad  within  of  and p e r s i s t e d  in their  most  later  than  d i d they  developed  movements  that There  the q u a l i t i e s  expectations a t good  they  quickly  i n preference  qualities.  learned  faster  movement  birds  of  feeder  improved  patches,  only  patches,  birds  of  pattern  sequences  that  improved  patches;  complexity  a n d among  patterning  those  they  and  the f i r s t  their  Birds  within  particular,  the  adopted  indications  and bad patches, the  distance  of  the s p a t i a l  several  after  In  both  organization  were  good  clearly  summary,  reflected  good  total  i n terms begin  even  patches,  d i d a t bad  of  and  patches.  of  locating  to avoid  visiting  patches.  Discussion  In  an a r r a y  regular quickly bad  spatial to visit  ones.  array.  did  this  who on  most  less  more  feeders  slowly  half  complex  feeders  hummingbirds  more  than  among  learned  and a v o i d  on a l e s s  most  of  nearly  the simpler  pattern.  As w i t h  t h e two s i m p l e  at high  the d i s t r i b u t i o n  performance  i n the array.  was  This  very  of  similar  correspondence  as  well  of  birds extent,  as  they  patterns  behaviour to the  the  patterned  t o any m e a s u r a b l e  foraged  arrays  of  the  eventually  2,  simple,  relatively  simply  (two o u t o f f i v e )  pattern  in  d i d learn  i n Chapter  energy  distributed  of t h e good  learned  studied  of  food  patterns,  They  Although  learned those  with  in  I  these  distribution  the  animals'  82  behaviour at  and  the  several  both  spatial  within  Every  and  among  switch case,  in  the  the  which  of  reached  behaviour  had  at  them  in  that they  study  was  amount  of  remember,  I  not  designed spatial and  under to  I  did  not  complexity  the  pattern  more them.  other  spatial For  observe  spatial  in  mazes  birds  can  remember  locations and  Krebs  from  this  in  of  both 1982,  body  even  though  of  clear  I  saw  it  among  trials.  strong  spatial  the  ways,  in Chapter  rats over  30  dozens,  by  a  sudden  In  every  locations the  switch  this  was  1986; work  a  at and no  i s that  or  limits  although the  many  arm  or  field 1984b).  animals'  rate is  can  maze  on  showed  can  to  remember  can  perform  Food  hoarding  individual (Shettleworth  possible  capacity  with  offered  of  experiments  that  have  tasks 1979).  the  learning.  i n agreement  thousands  One  This  capacity  of  experiments  to  learn,  the I  animals  (Roberts  hundreds  Sherry  study.  on  me  patterns,  that  limit  capacity  typical  and  of  clear  influences  places  allow  hummingbirds  locations,  to  not  complex  constraints  radial  laboratory  did  learn  that  than  in  2  conditions  studies;  information  well  to  before  limits  memory  example,  and  effort  find  the  many  and  affected  return  explore  remember  to  example,  their  the  to  failure  was  i t s environment.  cannot  hummingbirds  This  in  to  reported  of  of  for  within  food  information  use.  scales;  strongly  hummingbirds  did  environment  do.  experiments  conclude  the  performance  was  similar  of  and  high  concentrated  p r o f i t a b l e to  although  patches  i n d i v i d u a l s continued  behave  The  temporal  d i s t r i b u t i o n of  they  longer  structure  and  i n d i v i d u a l who  structuring  to  spatial  conclusion  remember  the  83  information strongly sense.  they  limited Rather  organize system  sets  have  been  offered  i n an a b s o l u t e  i t may  be  information  of storage  and  (Simon  1974;  may  not  or storage  more  storage,  and r e c a l l  date  anatomical  constrained  for  to  by  capacity  the  way  the resolution Roberts  be  they of the  1982;  Gass  1985).  The  results  behavioural Chapter  of  organization 2  that about  expectations  in  learn  scales. "what,  allow  their  to  do";  conclude  that  spatial  and  Wyers  theories  foraging.  1981; K a m i l embrace  and Yoerg  studies  of  exhibit  to  i s an  location  i s stored  of  foraging  account  for  Animals  make this  choices list  terms.  memory memory in  as a s e t of cues among  f o r a match  several  and  "what  integral  in explicit  model,  at  go",  that  those  they t o do"  i t i s r e s i s t a n t t o change.  b u t no  of s p a t i a l  from  structured  behaviour  1982),  spatial  "list-searching"  searching  they  demonstrates  learning  must  conclusion  spatially  "where  Theories  the issue  models  theoretical a  pattern  my  of t h e i r  learn  t h e components of  capability,  present  foraging  The  which  information  in  list  potential between  and first  about  (Olton  spatial current  Menzel  empirical  organization.  a  of  spatially  (see also  dominate  I  part  in  this  i t s l i m i t a t i o n s and i t s consequences  Two  is  develop  and that  environments  including  to extend  the study  experience,  of  environments;  Hummingbirds  with  structured  me  the organization  develops  hummingbird  analysis  hummingbirds  expectations  spatial  detailed  1978).  locations  perceptions  a  by and  84  sets  of cues  spatial  memory  support  the  collection cuts" That  new  pathways In  surface  my  their  distribution  o f good  variety idea:  variable  birds  patches  directed  Lieblich  memory in their  in  places,  and  and  in  their  which  environment  and  array,  and  model  just  a  "short-  (Gould  1986).  between  places; i t  of p l a c e s , traversing  hummingbirds  and  and them both  with  the  followed  so i s c o n s i s t e n t  movements  between  with  a  this  places in  ways.  (1982)  animals  i s  create  correspondence  the  i n doing  Arbib  before  that  this  not  could  or without  close  work  representation  representations  fact  1973;  study.  i s a  of pathways  in  that  model  with  model  (Menzel  recent  in this  list  the  effort  them  suggest  visited  be a d d e d  review).  1981; S u t h e r l a n d  have  but i n c r e a s i n g l y e f f i c i e n t  Second,  places  a  of d e t a i l e d pathways the  spatial  between  experiment,  distributed  mapping  containing  can e a s i l y  (Morris  l o c a t i o n s , animals  i s not just  little  l o c a t i o n s of places i n  Most  performance  l o c a t i o n s they  lend  1982 f o r a  1982).  model  a spatial  s t u d i e s of  study,  between  a n d two r e s u l t s  of unrelated  entire  first.  1986),  recent  or " c o g n i t i v e mapping"  relationships  relationships  i s , a map an  mapping"  t h e mapping  because  between  is  (see Roberts  f o r hummingbird  spatial  including this  1978; R o b e r t s  with  First, of  and  1984; G o u l d account  model  Most  as l e a r n i n g and remembering  and Nadel  consistent  i n the l i s t .  animals,  "spatial  environment  O'Keefe  may  in  second,  animals  Dyck  stored  f o r the first  The views  already  proposed  not only  spatial  a  model  remember  relationships  of  important between  85  them,  but  those  also  and  store  places  proposed both  they  that  kinds  the  of  behaviour  that  were,  how  then  continued the  to  switch.  Lieblich  about spatial far  with  fully  consideration  that  major  how  locations  in  a  given  than  perceive  that  remember into  a  i f  simpler  (see  issues  well  achieve  places  i f they  to  are  patterning. level  they subsets  can than  remember  of  and  the  i f those  i f they  that  animals  performance  organize  of  with  information cannot,  after  in  do"  the  becomes ideas such  animals  Arbib of  1982),  and  study.  Chapter  learn  as are  this  from  on  they  clear  2,  and  remember  their  spatial  related  levels  of  patches  patches  to  scope  and  two  assuming  Second,  good  by  of  kinds  environment  dependent  higher  the  used  study,  makes  two  same  hummingbirds is  not,  the  Leiblich  this  s e v e r a l kinds  "what  and  they  hummingbird  However,  of  in  of  implication  that  i s beyond  from  how  should  given  the  modified  words  Furthermore,  i n the  with  do  containing  where  i n memory.  environment  of  ways  to  Graph"  these  them.  model  organization  number  patterned  achieve  these  an  animals  in  developed  and  or  forage  representations  conclusion  fast  arrangement First,  of  remember  not  other  provides  learned  constructed,  what  "World  first  go"  or  In  pattern  similar  to  do  observations  do  (1982)  "where  to  is a  My  is consistent  internal  from  to in  Arbib  maps a r e  The  best  This  how  birds  forage  and  associated  c o g n i t i v e map  hummingbirds The  what  together.  Checkerboard  information. and  these  information.  i n the  evidence  remember  predictions.  performance places the  are  simply  animal  should more about  with  be  can  able  places those  f o r example  by  to to  places using  86  cues  such  spatially complex  environment  this  and  done  how  on  potentially  rocks,  they  offer  caches  and t r e e to  birds  e. s t o r i n g  nutcrackers is  caches  (Balda  relationships  Not  with  of  landmarks  that  t o each  other.  locations.  of p r o f i t a b l e  available  this  tested  a l l environments  quality patches  only  (Smith  a  and  sets  t o be  B u t many items  Sweatman  1974;  in  might  tend  i n both  and  Krebs  prediction to  i n simple  are  use  preferences  second  proximate  Zach  when  of p l a c e s )  birds  i f cues  they  landmarks  site  A  as  is  (Shettleworth  found  such  possibility  animals can learn even  Nutcrackers  birds  types  i s whether  could  1980) a n d  of  individual  provide obvious  food  One  to  been  landmarks  different  few  has  objects,  prediction.  tend  a  marsh  that  1984b).  1982).  1980) a n d c h i c k a d e e s  consistent  of  in  of  cues  nearby  t o use s i m i l a r  Observations  work  1980; Tomback in  as  information  little  many  (Sherry  Wall  although  such  use v i s u a l  prominent  (Balda  in  opportunities for  birds,  the  around  (Vander  tend  food  good  but very  among  stumps  has n o t y e t been  classes  sites  displacements  may  sets.  jays  as landmarks  locations,  different  1982)  used  their  these  select  their  sensitive  different  that  may  successfully  of  known.  Food-hoarding  cache  -use the p a t t e r n i n g  to perform  poorly  system  question.  be  logs  recovering  (i.  is still  relocate  to place  that  animals  c h i c k a d e e s , n u t c r a c k e r s and  remember  are  How  information  well-known  exploring  tend  landmarks.  distributed  One  tits,  as  select  geometric  cues  to  the  and  remember  not  readily  and F a l l s  1977;  Gass  87  and  Sutherland  1985);  long  periods  study  demonstrated  an  patterns  that of  that  may  of  usefully  underlie  information.  and  with  how be  high  Roper  the patterning  determinant  attention  processes  cases  ( e . g. M e l l g r e n  important  them,  i n some  1986).  of food  well  and  for  Because  this  distributions  hummingbirds  shifted  recognition  accuracy  and  to  can l e a r n  clarifying  memory  is  of  the  spatial  88  4  CHAPTER GENERAL  The on  research  use  of  capability and  b)  memory for  The  and  distribution other  of  the  future  In  spatial  the  role  this  experiments,  hummingbird  of  resources  animals.  memory  in  I  review  these  point  be  about  hummingbirds  the  in  locations of  and  these  principal  with  out  might  questions  foraging behaviour  chapter,  and  other  the  information;  memory  learning spatial  integrate  behaviour  to  work  i n c l u d e a)  spatial  spatial  point  of  i n the  of  to  earlier  recent  and  results  work  on  possible directions  for  research.  The which  experiments  spatial  i n Chapter  location  was  hummingbirds  quickly  learn  quality  feeders  was  arrays  patterns  in turn  extends  foraging  hummingbird  results  about  thesis  hummingbird  f o r how  characteristics  particular,  of  in  in this  l e a r n i n g complex  suggestions  organized. the  presented  DISCUSSION  of  much more  component  of  coarse-grained feeders;  there  primarily  on  these  arrays.  the  birds  independently  in  The  little  showed  that  in  primary  cue  to  forage  in  about  was the  evidence search  Similarly,  was  learned of  the  other  locations.  of  an  if  the  complex important  development  quality  of  the  birds  clear  to  results  of  groups  of  depended perform  evidence  individual The  in  quality,  learn  that  mechanisms  little  qualities  feeder arrays  the  that  area-restricted  situations  They  indicate  arrays  there  large  patterned.  results  these  expectations was  the  simply  slowly.  learning  to  2  in  that  locations support  89  o b s e r v a t i o n s that hummingbirds have good memory f o r l o c a t i o n s of highly  p r o f i t a b l e feeders or patches of flowers  1985; Gass and Sutherland an  important  results  factor  also  ( M i l l e r et a l .  1985) and that t h i s c a p a b i l i t y may  i n use of a v a i l a b l e resources.  imply  that,  be  However, the  under c o n d i t i o n s of h i g h l y v a r i a b l e  nectar q u a l i t i e s among p l a n t s , b i r d s may not be able to remember l o c a t i o n s of p r e v i o u s bouts or i n d i v i d u a l v i s i t s to f l o w e r s . The experiment i n  Chapter  3  confirms  that  l e a r n l o c a t i o n s of good feeders by developing the  q u a l i t y of feeder l o c a t i o n s .  hummingbirds  e x p e c t a t i o n s about  Even i n complex  distributions  of feeder q u a l i t y , hummingbirds l e a r n to use r e g u l a r i t i e s in the p a t t e r n i n g of feeders in f o r a g i n g .  Given  enough time,  they  can  l e a r n r e l a t i v e l y complex, r e g u l a r patterned a r r a y s , and remember patches  of  good  feeders  variable  improvement on a n o n - r e g u l a r l y d i s t r i b u t e d  feeders  reinforces  the  within  conclusion  d i s t r i b u t i o n s i s an important species.  Analysis  suggested  that  of  the  patterns.  Slow  and  pattern  of  that p a t t e r n i n g of s p a t i a l  factor in s p a t i a l learning in t h i s  movements  birds  r e p r e s e n t a t i o n to guide  those  may  within have  and  been  t h e i r r e t u r n to good  among  using  patches  a  map-like  patches.  To summarize the general r e l a t i o n s h i p between complexity spatial  pattern  performance,  I  and  of  illustrate  experiment i n the study patterning  rate  in  improvement the  primary  F i g . 4.1.  of food d i s t r i b u t i o n  The  and  level  result effect  from of  of of  each  spatial  i n t h i s study can be c o n s i d e r e d  as p r i m a r i l y a r a t e - l i m i t i n g phenomenon.  Performance  began  at  90  Figure  4.1. Summary o f p e r f o r m a n c e o n a l l f o u r p a t t e r n s u s e d in the study. Closed c i r c l e s represent 4-trial a v e r a g e s f r o m H a l v e s (H) a n d C h e c k e r b o a r d ( C ) p a t t e r n s ; o p e n c i r c l e s f r o m Q u a r t e r s (Q) a n d R a n d o m ( R ) p a t t e r n s . V a l u e s f o r H a l v e s a r e from Experiment 1 ( F i g . 2.2); f o r Q u a r t e r s from Experiment 2 ( F i g . 2 . 6 ) . Values f o r C h e c k e r b o a r d a n d Random a r e f r o m E x p e r i m e n t 3 (Fig. 3.1). Only data from b e f o r e the s w i t c h and f o r R a n d o m o n l y t h e t w o b i r d s who i m p r o v e d a r e i l l u s t r a t e d . The s m o o t h c u r v e s a r e f i t t e d by e y e t h r o u g h t h e p o i n t s shown i n t h e f i g u r e .  PERCENT CORRECT  16  92  chance level  levels, on  a l l four  consistent Although the  and  not  Random  I cannot  results  point that  quality  and  information  to  solve  of  processing  If  regularity  rates,  then  becomes  important  spatial  spatial  in  locations of  hummingbirds  food  work  1977;  et  to  to  this  in  learn  human  consistency  Shiffrin  Simon  important  capacity recognize  and  learning  1977;  i s an  an  about  of  factors in  on  learn.  features  and  and  learning  these  patterns  c o n s t r a i n t s on  of  in  which  food, the  and  rate  arose  animal  in  small  1982;  territories  of  (Gass  how  I  memory  a l .  patches and  of  to  1985)  the 16  gap  1985).  in  of  between (Gass  studies or  and  of  study  feeders  and  flowers  Sutherland  learning  this  bridge 2  learn  observations  intended  of  can  organization  spatial field  to  et  the  of  arrays  Miller  use  hummingbirds  from  hummingbirds  done  a l .  to  behaviour.  hummingbirds'  whole  to  Models  patterning  animals  extent  affects  foraging  experimental  analyzing  the  initially  learning  Cole  the  key  types.  of  animals  a  locations.  remember  spatial  as  memory  how  pattern  ability  and  s p e c i f y i n g the  about  hummingbird  spatial  identifying  these  point  showed  patterns  resources.  information  of  of  of  same  i t s performance  that  animal's  (Schneider  Questions  distribution  over  of  between  about  clearly  tasks  determinant  and  questions  the  improvement  improved  capability  distribution  in patterns  of  conclude  an  general  for  to  tested  constrain  complex  1979).  the  rate  approximately  difference  pattern,  beyond  reached  only  repeatable  are  regularity  patterns;  individual  environment the  eventually  every  complexity These  and  done  movements How  do  the  93  results  contribute  learning  to the understanding  i n hummingbird  Nectarivorous avoid  revisiting  (Gill  and  unpubl.  obs.).  evidence animals could  avoid  avoid  1982;  capability  to  study  they  do  remember  small  enough  (see Chapter  grained  (and  finer-grained computer support  two  revisits  efficiency quality locations  up  flowers and of  of  of  within  quickly  giving-up patches  of p r e v i o u s  or  increases bouts.  of  The  hypothesis  those  the their  bouts  are  avoiding coarserand  the  visits.  A  provided  partial  organization.  Model  within  patches  patches  i n patches)  than  to patches. the  the b e n e f i t s Further  for the  bout  in low-quality  increasing  have  patches  of  1986)  of  flowers  to organize  of w i t h i n  type  that  individual  locations  e t al.  revisits  rules  in detail.  hummingbirds  i f  these they  organization:  visits  bouts  avoiding  of  in  as  which  the mechanisms  scale  this  of  that  Thus  (Armstrong  give  numbers  revisits  scale  of  the  by  Gass  taken  memory  explored  l o c a t i o n s and  3).  (and s h o r t - t e r m )  that  remembering  support  suggest  long-term)  organization  to  not  scales  for the benefits  from  been  to reduce  simulation  hummingbirds more  on  not  patch  patches  rely  do  Tamm a n d  mechanisms  to  visited  are usually  detailed spatial  for large  within  may  spatial  a r e known  Sutherland,  I984b),the  have  visits  revisits  of  previously  observations  finely  Sherry  have  1978;  these  u s e memory  revisits;  role  hummingbirds  they  Kamil  Although  in this  hummingbirds to  1977;  revisits  observations  including  inflorescences  for a possibly (Kamil  the  foraging?  birds  Wolf  of  of  empirical  benefit  ( i . e. they  avoid do  Decreasing  by the  variability  in  remembering  the  work  on  the  94  foraging  movements  quantifying bouts,  the  and  on  locations  within  of  flowers  of  variation foraging  the in  the These  alternation  they  that  at  accurate the  sample  size  observations detect my  any  study  profitable those  clear  on  but  on  between  determine  in  the  remembering  found  evidence  no  Gass  by  the  Wolf  a  single  that even  previous  and  and  approximate  can  the  amounts  average  of  remembered 1983).  such of  as  their  locations. a  rule,  In and  locations  (1985) a r g u e d rule  may In  not  any  set  that  operate  day  of  small  to  results  of  locations  of  in  flower  each  reward  per  a  the  (1  The  was  case,  i s too  bouts.  remember  nectar  study  rule  such  data  the  unmanipulated  a  bout  a  by  normal  Hainsworth  individual)  p a t t e r n i n g of  one  birds  Hainsworth.  territorial  when  such  with  of  bout for  quality  open  subsections  Sutherland  Hainsworth  birds  the and  visited  that  leaves  in  c o u l d use  evidence  Wolf  simplest  that  arbitrary  be  high  demonstrated  Results  (Wolf  birds  and  of  environments  quality.  previously  However  patches  locations  1985),  in  for  suggest  patches  and  and  Sutherland  that  memory  the  for  bouts  bouts  measured  of  patches,  t e r r i t o r i a l hummingbirds  c o n c l u s i o n may  scale  that  as  flower  previous  avoid  insignificant.  within  factors  memory  hypothesized  study  concluded  or  by  of  to  concentrate  territories,  and  of  between  territories their  their  r e v e a l e d no  authors  the  memory  (Gass  patch  locations  more  in  role  movements  territories  movements  remembering  good  experiments  question  should  patches.  Hummingbirds'  field  of  identifying  benefits  of  hummingbirds  sequencing  relative  patches  of  several  flower  in in  95  typical  habitats.  capability  This  under  study  information asked in  how  To  normal  birds  other  as  bees  and  1980).  of  in For  species  (Heinrich  colours  with  Only  al.  determining 1985).  feeders. to  of  study spatial  the In  partition  out  the  when  degree  that  presence has  the  patterns birds  relative  visible  characteristics  spatial  location  of  nectar to  valuable  in  interpreting  movements  in  hummingbirds.  the  or  other  size  types  of  shape  food  on  other of  used  rewards  in  (e. the  (such  nearby of  of  flower  g.  George  relative as  colour)  (Miller  cues  approach such  landmarks, flowers  influencing  et  artificial  multi-variable  patches factors  (Goldsmith  located  contribution  other  discriminate  hummingbirds  a  George  with  changes  initially  in  particular  sensitivity  cues  are  items  1980;  "major"  of  Visible  and  determine  flowers,  single  hummingbirds  associate of  that  However,  interspersed  spectral  l o c a t i o n and  study,  and  Hummingbirds  attempted  studies  of  of  location)  information  Laverty  are  of  of  profitability 1976;  source  behaviour.  colour,  they  readily  feeding  Empirical  as  1979).  and the  one  (spatial  foraging  this  clear.  principal  several  (Heinrich  1976,  1979)  use  such  even  high  with  importance in  a  one  efforts.  their  to  not  i n d i v i d u a l bumblebees  flowers,  Goldsmith  appearance  can  cues  example,  on  a c t u a l l y use  p a r t i c u l a r source  foraging  hummingbirds  of  1980).  that  flowers  proximate  is still  hummingbirds  guiding  species  and  use  their  in  characteristics used  to  nectarivores  information  hummingbirds  attention  available  these  extent  conditions  focused  distributing  and  what  would  as and be  foraging  96  Concluding  Remarks  Foraging  in  nature  i n v o l v e s complex  behaviour  and environment  that  temporal  scales  1979; G a s s  psychological of  (Simon  processes  information  unavailable 1982).  observable;  It  difference  each  other  (Simon  in  (Kamil  many  i s  the  learning  between  was  between  ecological  question:  environments?".  an  "How  that  emphasized hummingbirds  the must  question  complexity cope  with.  directly  that  or  might  a  to  a  in different about  interact  with  drive  them  studying  the  perception,  infancy.  t o straddle the  find  I  asked  food  seemed  (spatial  important paradigm  information argue  an  i n complex  mechanisms  experimental spatial  in  whether  as  in their  attempt  memory)  A critic  changes  that  such  component  of  they  psychology.  an  often  not  for  do h u m m i n g b i r d s  using  are  processes,  variables  explicit  I s t u d i e d some  kinds  Mingolla  from  a r e o r how  and  the  theories yet exist  are s t i l l  ecology  The  determine  paradigms  and o r g a n i z a t i o n of that  answering  to  processes,  mechanisms  research  interaction  memory  component  are  inferred  Few  there  1981).  and  o f t h e same p r o c e s s  Experimental  a n d memory  This  be  the environmental  1979).  interactions  (Shaw  1982).  processes  or with  analysis  i s due t o d i f f e r e n t  expression  and  and  manipulate  difficult  and Yoerg,  of these  behaviour,  between  spatial  and Montgomerie  processes  can only  often  different  they  learning  i n behaviour  difference  how  scientific  nature  on  generate  postulate  example,  their  behaviour.  settings  we  to direct  For  that  occur  interactions  that  to  in  that that adopt  97  such  a  and  misleading  remain  cross-disciplinary at  unsatisfied  capability  to  and  thus  claim  the  other  the  believe  this  spatial  terms  some  but  they  However, of  about  future  new  important effects.  data,  he  cannot  and  power.  On  interpret  these to  arguments,  studies  to  depend  analyzing  of  their  systematic  progress  in  changing how  their and  expectations.  upon  of  and  develop,  complex  identification  for  foraging  in  conditions  critically  only  fundamental  foragers  I  complex  about  more  update  of  not  understanding  future  of  and  mechanisms  usefully  Significant  of  information  careful  the  important  predictions  processes.  and  capable  might  because  potential,  illuminating  may  best  offer  predictive  both  good  deeper  current  processes,  that  approach  flexibility a  not  alternative  feel  for  have  for  psychologist  does  no  at  situations.  hypotheses  success  techniques  behavioural  field  does  requires  use  might  a  have  ignored,  behavioural  the  environments  results  inconclusive  hand  between  experimental  also  general  expectations  one  be  approach  justification  general  interpreting  how  of  insights,  behaviour,  the  ecologist  behaviour  generating  possibly  that  might  the  the  inevitably  in  Despite  On  because  an  are  results  worst.  finely discriminate  hand,  variables  approach  development streams  constraints  exploration  of  of on  their  98  LITERATURE  CITED  A r m s t r o n g , D.A. 1986. 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