Alejandro Kacelnik

349 Pages·2013·5.59 MB·English

STUDIES OF FORAGING BEHAVIOUR AND TIME
BUDGETING IN GREAT TITS (Parus major)
by
Alejandro Kacelnik
(Wolfson College)
A thesis submitted for the degree of
Doctor of Philosophy
at the
University of Oxford
Michaelmas Term 1979
a Li» con amor
a Federico,con bronca
a Oliver,con esperanza
Studies of foraging behaviour and time budgeting in Great Tits
(Parus major).
Alejandro Kacelnik, D.Phil.. University of Oxford, 1979.
Part One is an investigation of the dawn chorus in the
Great Tit. The major conclusions are as follows:
Foraging and singing are partly incompatible because of
the temporal and spatial separation of microhabitat conditions
required for each activity. The dawn chorus occurs at
a time of day when: a) foraging efficiency is limited
by low light intensity and possibly by lack of mobility
of the prey due to low temperature; b) acoustic comunication
is more efficient than visual displays because of poor
visibility and an enhanced sound transmission; c) the
rate of territorial intrusion is at its daily peak. Great
Tit's readiness to sing and react agonistically towards
a territorial intruder is enhanced by experimentally lowering
profitability of feeding, but it does not appear to be
affected by time of day. Restricting access to food early
in the morning leads to higher body weight in the evenings
as an anticipatory compensation.
Part Two is a study of sampling strategies based on the
statistical decision paradigm known as the Two-Armed Bandit
problem. I studied transition behaviour in foraging
experiments using concurrent variable ratio schedules.
The birds' foraging behaviour approximated the predictions
of a dynamic programing algorithm that calculates the optimal
balance between exploring and exploiting for finite time
horizons. The birds' response to patch diversity and
time horizon was closer to molar maximization (total
rewards over a certain period) than to molecular maximization
(maximising the instantaneous probability of reward).
When the environment is not totally stable these two
possibilities conflict, and my results supported molar
maximization.
Part Three investigates the trade-off between maximising
foraging efficiency and efficient territorial defence.
Great Tits behaved close to the predictions of the Marginal
Value model when there were no territorial intrusions,
but modified their feeding behaviour in the predicted
way when the probability of intrusion was higher.
ACKNOWLEDGEMENTS
First, I would like to thank my supervisor, John Krebs, for his
constant and enthusiastic encouragement and advice. The many Sundays
spent discussing chapters of this thesis were only the last stage or the
most fruitful professional association that I have enjoyed.
I would also like to thank especially David McFarland who, unwittingly,
was responsible for my approach to quantitative ethology and my coming
to Oxford in 1974. Most of my companeros in the Animal Behaviour Research
Group were a source of inspiration ana learning by osmosis, but the osmotic
x
gradient was specially steep with respect to some of them, who I feel
deserve special mention: Alasdair Houston, Robin McCleery, Richard Sibly,
Marian Dawkins, Shelly Cohen, Roger Tarpy, Mac Hunter, Richard Dawkins,
Jon Erichsen, David Macdonald, Adeline Nunez will always mean Oxford for
me, as will - very especially - Pat Searle.
Alasdair Houston read and criticised the whole of this thesis,
and I benefited enormously from his advice and enjoyed thoroughly all aspects
of working with him. Carlos Bernstein, Robin McCleery and Richard Sibly
also read some chapters and suggested very good ideas. I did my best to
take them into account.
John Roberts introduced me to the world of acoustics. I wish he
enjoyed as much as I did all the rainy dawns we spent x^ith Mac Hunter
in Wytham.
%
Meyer and Elisa, my parents, endured bravely^the worst times of their
lives while I was away. I am most grateful to them for too many things to
list, and feel deeply sad that Meyer did not live to the joy of my return
home.
My research was supported financially by the following sources:
The British Council, The Science Research Council, Wolfson College,
Su and Ed Kleinman, and, last but not least, Lidia Rapaport.
Professor J. W. S. Pringle and Dr. D. J. McFarland provided facilities
in the Department of Zoology and the Animal Behaviour Research Group
respectively.
Nick Styles gave me efficient and enthusiastic technical support and
helped me to train the birds and run some experiments.
Dick Cheney, Dave Palmer and Terry Barker from the different workshops
of the Department built most of my gadgets.
With respect to the pre-history of this thesis, I am grateful to
Enrique Segura for the good neurophysiological years together and his
encouragement to come to Oxford, and to Su Kleinman for teaching me English.
Lidia Rapaport helped me to proof read, by making drawings, typing
references, and correcting my English. Her support has been invaluable.
1.
CONTENTS
(cid:9)Page No.
CHAPTER 1
Procedure and General Methods 1
1.1. Introduction 1
1.2. The Species 1
1.3. The Subject 2
1.4. Acclimitisation to the Laboratory 2
1.5. The holding aviaries 3
1.6. Roosting boxes 3
1.7. Diet 4
1.8. Experimental Aviaries 6
1.9. The feeding discs 7
1.9.1. The perch 7
1.9.2. The logic 8
1.9.3. The discs 10
1.10. Training birds to use the discs 11
1.11. Setting up territorial defense experiments 13
1.12. Data Recording 16
1.13. Data Analysis 16
PART I - Studies on Time Budget
CHAPTER 2
2.1. The Dawn Chorus 18
2.2. Hypotheses about the dawn chorus 18
2.2.1. Proximate explanations 18
2.2.1.1. The fixed threshold 19
2.2.1.2. Internal clock hypothesis 20
2.2.2. Functional explanations 23
2.2.2.1. Ecological constraints 23
2.2.2.1.1. Acoustical factors, especially wind 23
2.2.2.1.2. Non-acoustical effects of temperature 25
2.2.2.1.3. Light intensity 26
2.2.2.1.4. Predation 27
2.2.2.2. Intraspecific factors 27
2.2.2.2.1. The behaviour of receivers 27
2.2.2.2.2. The behaviour of other actors 28
2.3. The dawn chorus in the Great Tit 30
CHAPTER 3
Environmental Factors affecting the Dawn Chorus 34
3.1. Introduction 34
3.2. Light intensity 35
3.2.1. Methods 35
3.2.1.1. Subjects 35
3.2.1.2. Apparatus 35
3.2.1.3. Prey 36
3.2.1.4. Testing 37
3.2.1.5. Units 37
3.2.1.6. Training 38
cont'd
11.
CHAPTER 3 continued
3.2.2. Results 39
3.3. Temperature 41
3.3.1. Method 41
3.3.2. Results 42
3.4. Wind 43
3.4.1. Methods 44
3.4.2. Results 45
3.5. Conclusions 46
CHAPTER 4
Anticipatory control of body weight 49
4.1. Introduction 49
4.2. Method 51
4.3. Results 52
4.4. Discussion 55
CHAPTER 5
On the motivational mechanisms underlying the
dawn chorus 61
5.1. Introduction 61
5.2. Methods . 62
5.2.1. Birds 62
5.2.2. Aviary arrangements 62
5.2.3. Experimental design 63
5.2.4. Deprivation 64
5.2.5. Intrusion 65
5.2.6. Recording 65
5.2.7. Measures of responses 66
5.3. Results 69
5.3.1. Description of responses 69
5.3.2. Supression of feeding by intrusion 70
5.3.3. Return to baseline feeding rate 72
5.3.4. Intensity of the song response 73
5.3.5. Return to baseline singing rate 73
5.3.6. Number of attacks 74
5.3.7. Approach 75
5.3.8. Displays 75
5.4. Discussion 75
5.4.1. Foraging opportunity 75
5.4.2. Circadian clock 78
5.4.3. Intruders pressure 79
5.5. General conclusions 80
PART II - Studies of foraging behaviour:
Optimal sampling
CHAPTER 6
6.1. Optimal foraging and sampling 81
6.2. The Memory Window 82
6.3. Psychological studies of concurrent
schedules 84
cont'd
Ill.
CHAPTER 6 continued
6.4. The Two Armed Bandit 88
6.5. Summary 90
CHAPTER 7
An experiment on optimal sampling 92
7.1. Introduction 92
7.2. Methods 92
7.2.1. Foraging Patches 92
7.2.2. Experimental Sessions 93
7.2.3. Decision criteria 95
7.2.4. Subjects 95
7.2.5. Pilot experiments 95
7.3. The Model 95
7.4. Results 102
CHAPTER 8
v,
Rules of Tumb for the Two Armed Bandit Problem 108
\
8.1. Introduction 108
8.2. Methods 109
8.2.1. Simulation procedures 109
8.2.2. The Rules 110
8.2.2.1. IMMAX 111
8.2.2.2. MATCH ' 112
8.2.2.3. PLWIN 112
8.2.2.4. CULLEN d: Cullen Rules 113
8.2.3. The evaluation of the rules 113
8.3. Results 115
8.3.1. Comparison with real birds 115
8.3.2. Effect of average profitability 116
8.3.3. Effect of patch diversity in a rich
environment 116
8.3.4. Effect of the time horizon 117
8.4. Discussion 118
CHAPTER 9
Optimal Sampling and Time Horizon 120
9.1. Introduction 120
9.2. Methods 123
9.2.1. Subjects 123
9.2.2. Instruments 123
9.2.3. Types of run 123
9.2.3.1. Treatments 123
9.2.3.1. Neutralisations 124
9.2.4- Measures of sampling 125
9.2.4.1. Decision point 125
cont'd
IV.
CHAPTER 9 continued
i
9.2.4.2. Commitment 126
9.2.5. Experimental sequence 126
9.3. Predictions 126
9.3.1. Molar Predictions 126
9.3.2. Molecular Predictions 129
9.4. Results 129
9.4.1. General Behaviour 129
9.4.2. Test of predictions 130
9.4.2.1. Global amount of sampling 130
9.4.2.2. Difference in sampling between
treatments 131
9.4.2.2.1. Graphical analysis 131
9.4.2.2.2. Statistical analysis 133
9.4.2.3. Pattern of switching between patches 133
9.5. Discussion 134
PART III - The trade-off between foraging and
territorial defence
CHAPTER 10
Optimal foraging and territorial defence 136
10.1. Introduction 136
10.2. Methods 139
10.2.1. The birds 139
10.2.1. The experimental set up 140
10.2.3. Foraging schedules 140
10.2.4. Experimental sessions 141
10.3. Predictions 142
10.3.1. The behaviour of control sessions 142
10.3.1. The behaviour in intrusion sessions 143
10.4. Results 143
10.4.1. Do undisturbed birds forage optimally? 143
10.4.2. The effect of intrusions 146
10.4.3. Inverse optimality 147
10.5. Discussion 149
REFERENCES
APPENDICES
1. Algol program to solve the finite horizon
two armed bandit problem with equal sampling
before decision.
2. Kacelnik, A. 1979
The foraging efficiency of great tits (Parus
ma jor L.) in relation to light intensity.
Animal Behaviour, 27, 237-241.
£_ cont'd
V.
3. Roberts, J. , Kacelnik, A. and Hunter, M. 1979
Sound interference patterns in animal acoustic
communication. Technical memorandum 66.
Polytechnic of the South Bank, London.
4. Roberts, J., Kacelnik, A. and Hunter, M. 1979
Acoustic properties of the environment as
determinants of birds' song patterns.
Animal Behaviour(in press).
5. Kacelnik, A. and Tarpy, R. 1979
The effect of hunger and vigilance during prey
handling in the great tit (Parus major) .
Manuscript.
6. Krebs, J.R.> Kacelnik, A. and Taylor, P. 1978
Test of optimal sampling by foraging great tits.
Nature, 275 27-31.
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