Using human-imprinted pheasant ( Phasianus colchicus ) chicks to investigate farmland foraging potential Gwendolen Elizabeth Hitchcock A thesis submitted for the degree of Doctor of Philosophy of Imperial College London , Department of Life Sciences, Division of Biology March 2010 ABSTRACT Pheasant chicks, like many other farmland birds, require a large proportion of invertebrates in their diet for successful growth and development during their first few weeks. This study used human-imprinted pheasant chicks as a novel sampling tool to investigate which arable habitats provided the best foraging. Using human-imprinted chicks decreased sampling bias and allowed a biologically relevant method of assessing invertebrate availability within each habitat. Faecal analysis was used to identify which invertebrates were eaten and correction factors established to take into account the differing digestion rates of different fragments. The validity of using commercially farmed chicks for this study was confirmed by the comparison of wild and farmed strain chicks. The value of non-cropped areas, both long-term set-aside and crops planted for game cover, in terms of diet and cover is confirmed. Greater proportions of preferred prey groups were consumed in both types of set-aside than in the commercial crop fields. Interestingly, no difference was found between spring and winter sown cereals and non-cereal crops. The long-term set-aside areas were found to be particularly beneficial to foraging birds as their vegetation structure allowed easy access to potential prey items. As farming has intensified, many farmland birds, which also require invertebrates during their early stages, have declined. If the diet of imprinted pheasant chicks is comparable to those of other farmland birds this method could be used to accurately assess benefits to avian conservation on a wider scale. Human-imprinted grey partridge foraging with pheasant chicks showed similar behaviour and ate similar insects indicating that habitats benefiting one are likely to benefit the other. Faecal samples collected from wild broods of other farmland birds - the skylark, yellow wagtail and lapwing - showed certain similarities in dietary preference implying that careful comparisons may be made. 2 DECLARATION I confirm that this thesis is my own work with the exception of Chapter 7 where the research was conducted together with two MSc students, Claire Whittington and Zoe Pittaway, under my supervision. Signed: ..........................................G Hitchcock .............................. Date: ............................................10/03/2010 ................................ 3 ACKNOWLEDGEMENTS To begin with I would like to thank Imperial College London, the Game and Wildlife Conservation Trust (GWCT), Graf. Hardegg and the BBSRC for funding my research; also my supervisors, Dr Simon Leather, Dr Rufus Sage and Professor Jim Hardie, for their help and support throughout. Especial thanks goes to Graf. Maximilian Hardegg for inviting me to use his estate for my fieldwork and for providing accommodation, transport and equipment. To all the staff at the Seefeld estate my eternal gratitude for welcoming me and helping me settle in a new country. In particular thanks to Karl Pock, without whom this project would have been impossible, thank you for being my first port of call in any incident – from finding bamboo canes field markers to explaining my work to the border police! My thanks to Roger Draycott and Dave Butler for their help in setting up this project, their combined knowledge of the Seefeld estate and imprinting was irreplaceable. Thanks to Steve Moreby and the entomology laboratory at the GWCT for teaching me the basics of faecal fragment identification and bearing with me until I could tell the differences between insect legs! Also thanks to Donald Quicke (Imperial College) and Jon Flanders (University of Bristol) for further assistance with the identification of faecal fragments. To Nicholas Aebischer (GWCT) and Tilly Collins (Imperial College) thank you for your patience whilst helping me to understand the complexities of statistics whilst struggling my way through my results. To Claire Whittington and Zoe Pittaway, I cannot thank you enough for your assistance in the field and, more importantly, your friendship. My thanks to Andrew Hoodless and Richard Dale for their many patient hours in the field helping us to find wild nests and broods. Also thanks to Fransisca Sconce, Mimi Sun and Laurence Livermore for assisting with laboratory work and to Sam Jervis for his support and assistance in the field. Last but by no means least my thanks to Diane Hitchcock and Vicky Levett for proof- reading this thesis and patiently correcting my spelling and grammar – I owe you one! Thank you to all my family and friends for their love and support, especially my parents, Keith and Diane, and my partner Mark. 4 CONTENTS Abstract 2 Declaration 3 Acknowledgements 4 Contents 5 Tables and figures 7 1 Introduction and background information 11 1.1 Farmland as a natural resource 13 1.1.1 Detrimental effects of the intensification of agriculture 14 1.1 .2 Can agri -environment schemes benefit farmland birds? 16 1.2 Natural history of the Pheasant ( Phasianus colchicus ) 20 1.2.1 Taxonomy and distribution 20 1.2.2 Ecology and habitat use 22 1.2.3 Why are pheasants important? 24 1.3 Study aims 25 2 Study site and general methods 27 2.1 Study site 27 2.2 Chick foraging trials 33 2.2.1 Imprinting 34 2.2.2 Field trials 36 2.2.3 Faecal collection and analysis 37 2.3 Invertebrate sampling 38 2.4 Vegetation survey 40 3 Differential recovery of invertebrate fragments 42 3.1 Introduction 42 3.2 Methods 44 3.2.1 Correction factors 46 3.3 Results 46 3.3.1 Correction factors 59 3.4 Discussion 52 4 The diet and foraging behaviour of farmed and wild strain human- imprinted pheasant chicks 54 4.1 Introduction 54 4.2 Methods 56 4.2.1 Diet 57 4.2.2 Behaviour 58 4.3 Results 58 4.3.1 Diet 58 4.3.2 Behaviour 62 4.4 Discussion 65 5 The diet of pheasant chicks foraging in different arable habitats 68 5.1 Introduction 68 5.2 Methods 71 5.2.1 Diet 72 5.2.2 Vegetation 73 5.3 Results 74 5.3.1 Invertebrate sampling and chick preference 75 5.3.2 Foraging in different commercial crops 77 5 5.3.3 The benefits of non-crop areas to pheasant chicks foraging in arable farmland 83 5.3.4 Comparison of long-term set-aside and game crop schemes 92 5.4 Discussion 99 5.4.1 Insect sampling methods 99 5.4.2 Preferred prey items 100 5.4.3 Beneficial farmland habitats 101 6 Dietary and behavioural comparison of human-imprinted grey partridge and pheasant chicks 105 6.1 Introduction 105 6.2 Methods 107 6.2.1 Diet 108 6.2.2 Behaviour 109 6.3 Results 109 6.3.1 Diet 109 6.3.2 Behaviour 111 6.4 Discussion 11 3 7 The habitat use and diets of skylark and lapwing chicks sharing arable farmland with breeding pheasants 116 7.1 Introduction 116 7.1.2 Skylarks on arable land 119 7.1.3 Lapwings on arable land 121 7.2 Methods 122 7.2.1 Breeding skylark territories 122 7.3.2 Diet of wild farmland birds 124 7.3 Results 12 8 7.3.1 Skylark territories 12 8 7.3.2 Diets of wild birds 130 7.4 Discussion 13 8 7.4.1 Skylarks breeding on arable farmland 139 7.4.2 The diets of wild chicks compared with human-imprinted pheasant chicks 140 8 General discussions 143 8.1 The methodology of using human-imprinted pheasant chicks 143 8.2 Arable habitats beneficial to foraging pheasant broods 145 8.3 Potential application for other species 14 6 8.4 Management suggestions 149 8.5 Further research 150 8. 6 Conclusions 151 9 References 152 Appendix I. Flora of the Seefeld estate 168 Appendix II. Birds of Seefeld estate 170 6 TABLES AND FIGURES List of tables 3.1 Quantities of invertebrates used during feeding trials and the diagnostic fragments that can be obtained from each with the number of fragments per individual. 45 3.2 Number of fragments recovered at 18 hours compared with 24 hours. 47 3.3 Correction factors (f) to be used in dietary reconstruction. 51 4.1 Ranking matrix of the relative differences between the diets of imprinted (2007 – 2008) and wild (2001 – 2002) pheasant chicks. 61 4.2 Summary of the GLM investigating factors affecting the distance of imprinted pheasant chicks from their human handler. 63 4.3 Summary of the GLMs investigating factors affecting the distance of imprinted pheasant chicks from their human handler at different time intervals. 64 5.1 Seed mixes sown as potential brood rearing cover providing food and shelter for chicks. 71 5.2 Number of field trials in different farmland habitats over 2007, 2008 and 2009. 72 5.3 Data used to assess vegetation structure. 74 5.4 Comparing the proportions of different taxa collected in sweep net and vacuum samples. 75 5.5 Comparing the proportions of different taxa found in the diet of pheasant chicks with those collected in sweep net samples. 77 5.6 Comparing the proportions of different taxa found in the diet of pheasant chicks with those collected in vacuum samples. 77 5.7 Ranking matrices of the relative differences in the larval component of the diet of pheasant chicks foraging in different cereals. 81 5.8 Ranking matrix of the relative differences between the diets of human- imprinted pheasant chicks foraging in crop and non-crop areas. 86 5.9 Compositional analysis results comparing the larval component of the diet of pheasant chicks foraging in crop and non-crop areas.