AN ETHOLOGICAL INVESTIGATION OF FEATHER PECKING GEORGINA CUTHBERTSON, B.A.. Thesis presented for the degree of Doctor of Philosophy. University of Edinburgh March 1978. ACKNOWLEDGEMENTS I should like to express my gratitude to Dr. T. C. Carter of. the A. R. C. Poultry Research Centre for the provision of laboratory facilities and the Agricultural Research Council for financial support. My sincere thanks are due to my supervisors, Dr. Aubrey Manning and Dr. David Wood-Gush for their help and encouragement throughout this study. I should also like to thank my colleagues at the Poultry Research Centre, especially Dr. Ian Duncan, for their help and stimulating discussions, Mrs. Gretta Brown for her untiring technical assistance and Mrs. J. Rhodes. who typed this thesi. Finally, I should like to thank my husband and small son for their constant support and interest in my 'Chicken Book". DECLARATION I declare that this thesis has been composed by me and that the work described here is my own. 1 TABLE OF CONTENTS. Page List of Figures iv List of Tables vi Abstract xii CHAPTER 1. General Introduction and 1 Literature Review. 3 CHAPTER 2. Materials and Methods Used in This Thesis. 25 CHAPTER 3. Do All Birds Feather Peck? A pilot study of the phenomenon. 33 Experiment 1. To determine whether 35 2. all birds are equally 43 tt 3. involved in feather pecking. 49 Experiment 4. To determine whether 53 fl 5. pecked birds and peckers 58 ff 6. can be reared as separate 62 types. • General Discussion 67 CHAPTER 4. The Relevance of Stimuli in the Feather Pecking Situation • Experiments 7 and 8. The effect of texture,. 70 • colour and contrast on pecking behaviour. Experiment 9. The effect of response of • 76 10. the stimulus on pecking 84 behaviour. General Discussion 91 CHAPTER 5. Behaviour Following Feather Pecking Incidents. • 94 11 Table of Contents continued. Page. Experiment 11. Various investigations 95 if 12. of behaviour 99 if 13. following pecking 101 I? 14. incidents. 104 General Discus sion. 106 CHAPTER 6. The Effect of the Environment on Feather Pecking. 112 Experiment 15a The effect of cage floor 113 15b composition on feather 118 pecking. 16 The effect of specific. stimuli 120 in the cage environment on feather pecking. 17 An attempt to distinguish 126 ti essen tialU from "non-essential" pecking behaviour. General Discussion 132 CHAPTER 7. The Effect of Exogenous Hormones on Feather Pecking. Introduction 135 Experiment 18 The effect of exogenous 138 gonadal hormones on feather pecking. 19-21 Effect of exogenous 145 22 testosterone on feather 155 pecking. 23 Effect of exogenous oestrogen 159 24 on feather pecking. 166 General Discussion 173 Table of Contents continued 111 Page. CHAPTER 8. The Relationship Between Feather Pecking and the Social Dominance Hierarchy. Introduction 179 Experimental Methods and Results. 182 General Discussion 187 CHAPTER 9. The Influence of Genetic Variation on Feather Pecking. Experimental Methods and Results. 190 Discussion 194 CHAPTER 10. Final Discussion 198 BIBLIOGRAPHY 205 iv LIST OF FIGURES On or Number Title facing page 1.1 Feather pecking and cannibalism in three week old chicks. Feather and tissue damage at the base 2 of the tail. 1.2. Similar damage as in Figure 1. 1. accompanied by 2 feather pecking of the back. 1.3. Feather pecking affecting back, wing and neck. 2 1.4. Feather pecking and cannibalism affecting back 2 and wings. 1.5. Considerable tissue damage and areas denuded by 2 feather pecking. Feather pecking in adult hens. 1.6. Bird with barb pecked tail and wing feathers. 2 1.7. Similar but more severe feather damage. 2 8. Two birds from the same cage showing extreme 2 effects of feather pecking. 1.9. The only damage to the bird was a severe wound 2 on the head. V V 1.10. Damage was again restricted to one region, the 2 base of the tail. 26 2.1. Rearing cage. V 2.2. Some of the stimuli used in this study. 31 3. Model bird with a four week old light hybrid chick. 31 V Experiment 1. Pecking score for the two groups. 36 3.2. Experiment 3. Feather damage scores for the 50 three groupings over a 25 week period. 3.3. Experiment 4. Mean amount of feather damage 54 suffered by peckers and pecked, weeks 1-21. List of Figures continued. 3.4. Experiment 5. Mean feather damage score for 59 the two types of bird. 3. 5. Experiment 5. Pecking behaviour recorded during 60 general observations. 3. 6. Experiment 5. Mean weight of the birds in the 60 two types of group. 3-.7. Experiment 5. Mean comb area. 60 3.8 Experiment 5. Mean number of pecks directed 61 at the stimuli. 9. Experiment 6. Mean feather damage score. 63 4.1. Experiment 7. Number of pecks directed at the 73 seven stimuli by birds of both strains in both environments. 2. Experiment 8. As Figure 4. 1. 73 4. 3. V Experiment 9. Diagram of a bird showing the ten 77 separate areas used for recording pecks directed at the stimuli. 4.4. Stimuli used in Experiments 9 and 10. 77 5.1. Experiment 13. Cardboard and string stimulus. 101 6.1. Experiment 16. The effect of stimuli placed in the 123 cage at an early or later stage on the incidence of feather damage. V 7.1. Experiment 18. Amount of feather damage suffered 140 by the three treatments, weeks 2-6. V 7.2. Experiment 18. Amount of feather damage suffered 141 by the three treatments, weeks 10-25. vi LIST OF TABLES On or Number Title facing page 2.1. Scoring of feather damage. 32 3.1. Experiment 1. Mean number of pecks directed 37 by the feather pecking and non-feather pecking groups at the four bird stimuli. 3.2. Experiment 1. Correlation of allopecking and 38 environment pecking with the response to the modified birds and the novel objects. Days 7-10. 3. 3 Experiment 1. As Table 3. 2, Days 7-24. 3.4. Experiment 1. Number of squares entered and the 40 latency to move in the open field situation correlated with allopecking and environment pecking, days 7-10. 3.5. Experiment 1. As Table 3. 4, days 7-24. 40 3.6. Experiment 2. Pecking behaviour recorded 44 during general observations 3.7. Experiment 2. Response to the bird stimuli. 45 3.8. Experiment 2. Total number of pecks made at 46 the blood stimulus by the two groups. 3. 9. Experiment 2. Score of feather damage at 18 and 47 29 days. 3.10. Experiment 3. Feather damage scores for the 51 three types of group. 3.11. Experiment 4. Mean response to the stimuli, 55 male and female groups combined. 3.12. Experiment 4. Mean response to the stimuli 56 showing different behaviour by male and female groups. 3.13. Experiment 6. Comparison of feather damage over 64 three time periods. 3.14. Experiment 6. Egg production for the first 64 laying week. (week 20). List of tables continued vii 4.1. Experiment 7. Number of pecks made at 73 the stimuli. 4.2. Experiment 8. Number of pecks made at 73 the stimuli. 4.3. , Experiment 7. Number of pecks directed at the 73 models by birds of the two strains and environments. 4.4. Experiment 8. Number of pecks directed at the 73 models by birds of the two strains and environments. 4.5. Experiment 7. Total number of pecks and the 74 number of allopecks observed during six general observation periods. 4. 6. Experiment 8. Total number of pecks and the 75 number of allopecks observed during six general observation periods. 4.7. Experiment 9. Total number of pecks directed 78 at the stimuli over the four tests. 4.8. Experiment 9. A comparison of the response to 78 the six different stimuli, all groups combined. 4.9. Experiment 9. The areas of the bird models 79 ranked according to the number of pecks received. 4.10. Experiment 9. A comparison of the total amount 79 of pecking directed at the models by the six groups. 4.11. Experiment 10. Number of pecks by each group 85 directed at the stimuli. 4.12. Experiment 10. A comparison of the response to 86 the six different stimuli, all groups combined. 4.13. Experiment 10. The areas of the bird models 87 ranked according to the number of pecks received. 4.14. Mean rank of the amount of pecking aimed at 87 different areas of the models in Experiments 9 and 10. 4.15. Experiment 10. Amount of pecking directed at the 87 block stimuli. List of tables continued viii 4.16. Experiment 10. A comparison of the total amount 88 of pecking directed at the models by the four groups. 5.1. Experiment 11. The frequency of giving (A) and 97 receiving (R) pecks for individual chicks housed in groups. 5.2. Experiment 11. Agent and recipient activities 97 following pecking incidents. 5. 3. Experirre nt 11. Agent and recipient activities 97 following pecking incidents in the young and old birds separately. 5. 4. Experiment 11. The amount of agent and recipient 98 activity in the predominant agent in each group. 5. 5. Experiment 12. The frequenôy of giving (A) and 100 receiving (R) pecks for individual chicks housed in groups. 5. 6. Experiment 12. Agent and recipient activities 100 following pecking incidents. 5.7. Experiment 13. The frequency of giving (A) and 102 receiving (R) pecks for individual chicks housed in groups. 5.8. Experiment 13. Agent and recipient activities 102 following pecking incidents.