Finney, Suzanne K. (2002) The dynamics of gull-puffin interactions: implications for management. PhD thesis http://theses.gla.ac.uk/3507/ Copyright and moral rights for this thesis are retained by the author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the Author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the Author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given Glasgow Theses Service http://theses.gla.ac.uk/ [email protected] The dynamics of gull-puffin interactions: implications for management Suzanne K. Finney Presented for the degree of Doctor of Philosophy Division of Environmental and Evolutionary Biology Institute of Biomedical and Life Sciences University of Glasgow February 2002 Acknowledgements I would like to thank Scottish Natural Heritage for granting permission to work on the Isle of May National Nature Reserve and the SNH staff, who went beyond the call of duty to provide help during the fieldwork period, particularly Caroline Gallacher, Darren Hemsley, Jared Wilson, Sue Lewis and Ian Patterson. Thanks also to Jenny Bull, Andy Easton, Juliet James, Mark Newell, Tom Van Pelt, Debbie Russell, Sheila Russell, Jimmy Smith and Linda Wilson for their friendship and assistance during my time on the island. Special thanks to Rebecca Hothersall and Mareike Moeller-Holtkamp, for their early morning starts and commitment to the project and without whom much of the fieldwork would not have been possible. The work was funded by the Natural Environment Research Council, the Centre for Ecology and Hydrology and Scottish Natural Heritage. Most of all I would like to thank my three supervisors, Pat Monaghan, Sarah Wanless and Mike Harris for their unending support and enthusiasm throughout the project. Nozrat Mirzai, Kate Orr, Aileen Adam, Pat McLaughlin, Richard Griffiths and June Freel provided much appreciated technical support. Thanks also to Ruedi Nager, Lukas Keller and David Elston for statistical advice and to my friends at Glasgow who have given me encouragement over the last three years, especially Francis Daunt, Darren Evans, Andrea Fidgett, Kate Greaves, Kat Jones, Ellen Kalmbach, Maggie Hall, Dominic McCafferty, Amanda McLean and Jane Reid. I would like to say a special thank you to Liz Humphreys, for being there through it all, for helping me cope with the ups and the downs, and for simply being a great friend. Thanks also to my family for their support, especially via food parcels during the field season! Finally, I would like to thank Doug, for your kindness, your friendship and for putting up with a fiancee who finds the most awkward places to live. Contents Contents Page List of figures 4 List of tables .. 6 Thesis abstract 7 Chapter 1. General Introduction 9 References 14 C~apter 2. Reducing the density of breeding gulls leads to enhanced recruitment of immature Atlantic puffins to a breeding colony 18 Finney, S.K., Harris, M.P., Keller, L.F., Elston, D.A., Monaghan, P. & Wanless, S. (2002) Submitted. Abstract 19 Introduction 20 Methods 22 Results 24 Discussion 26 References 29 Chapter 3. The impact of gulls on puffin reproductive performance: an experimental test of two management strategies 38 Finney, S.K., Wanless, S., Harris, M.P. & Monaghan, P. (2001) Biological Conservation 98, 159-165. Abstract 39 Introduction 40 Methods 42 Results 46 Discussion 48 References 52 Chapter 4. The impact of kleptoparasitism risk on the foraging behaviour of breeding Atlantic puffins 59 Abstract 60 Introduction 61 Methods 63 Results 64 Discussion 65 References 69 1 Contents Chapter S. The impact of kleptoparasitism risk on body condition in breeding adult Atlantic puffins: implications for gull management.. 74 Abstract 75 Introduction 76 Methods 77 Results 81 Discussion 83 References 87 Chapter 6. Adult body condition and reproductive performance in the Atlantic puffin 96 Abstract 97 Introduction 98 Methods 99 Results 102 Discussion 104 References 108 Chapter 7. Replacement egg laying in herring and lesser black-backed gulls .. 115 Abstract 116 Introduction 117 Methods 118 Results 119 Discussion 121 References 125 Chapter 8. Great black-backed gull predation of adult Atlantic puffins on the Isle of May 130 Abstract 131 Introduction 132 Methods 133 Results 134 Discussion 135 References 138 2 Contents Chapter 9. Behavioural responses of Atlantic puffins to visitor disturbance .. 146 Abstract 147 Introduction 148 Methods 149 Results 151 Discussion 153 References 155 Chapter 10. General Discussion 161 References 166 3 Contents List of figures Figure 1.1 The Isle of May study site 17 Figure 2.1 Population size of herring and lesser black-backed gulls and 33 Atlantic puffins breeding on the Isle of May. Figure 2.2 Isle of May: showing location of study plots. 34 Figure 2.3 Puffin recruitment rate on the Isle of May measured during 35 four time periods between 1975 and 1998 Figure 2.4 Relationship between puffin burrow density and the mean 36 annual recruitment rate of puffins. Figure 2.5 Relationship between puffin recruitment rate and gull-nest 37 density. Figure 3.1 Mean kleptoparasitism risk for puffins breeding in gull- 55 occupied and gull-free areas. Figure 3.2 Mean feeding frequency of puffins breeding in gull-occupied 56 and gull-free areas in the morning and evening. Figure 3.3 Mean kleptoparasitism risk of puffins breeding in areas 57 where gulls were breeding normally and in areas where gull breeding had been experimentally delayed. Figure 4.1 Mean provisioning rate of puffins breeding in gull-occupied 71 and gull-free areas. Figure 4.2 Comparison of food loads carried by puffins breeding in gull- 72 occupied and gull-free areas. Figure 4.3 Mean energy content of food loads brought in by puffins 73 breeding in gull-occupied and gull-free areas. Figure 5.1 Body mass index (mass corrected for structural size) of adult 91 puffins during the breeding season. Figure 5.2 Mean body mass of adult puffins measured during incubation 92 and again during chick-rearing. Figure 5.3 Body mass index (mass corrected for structural size) of adult 93 puffins breeding in gull-occupied and gull-free areas during incubation and chick-rearing. Contents Figure 5.4 Haematocrit and mean corpuscular volume of adult puffins 94 during the breeding season. Figure 5.5 Comparison of haematocrit and mean corpuscular volume 95 of puffins breeding in gull-occupied and gull-free areas during incubation and chick-rearing. Figure 6.1 Mean body mass of male and female adult puffins during 111 incubation and during the chick-rearing period. Figure 6.2 Relationship between body mass index during incubation 112 and the rate of mass loss in male and female breeding Atlantic puffins Figure 6.3 Mean body mass index of male and female breeding Atlantic 113 puffins during incubation in relation to hatching success. Figure 6.4 Mean body mass index of breeding female Atlantic puffins 114 during incubation in relation to chick growth and survival. Figure 7.1 Relationship between the laying date of the first clutch and 128 the probability of laying a replacement clutch for herring gulls and lesser black-backed gulls. Figure 7.2 Mean volume of eggs laid in first and replacement clutches 129 for herring gulls and lesser black-backed gulls. Figure 8.1 Population size of great black-backed gulls breeding on the 140 Isle of May between 1962 and 2001. Figure 8.2 Location of great black-backed gull nests on the Isle of May 141 during the 2001 breeding season. Figure 8.3 Predation rate of adult puffins by great black-backed gulls. 142 Figure 8.4 Frequency distribution showing the number of puffin 143 corpses found at great black-backed gull nests. Figure 8.5 Status of puffins killed by great black-backed gulls on the 144 Isle of May Figure 8.6 Proportion of breeding puffins predated by great black- 145 backed gulls over time. Figure 9.1 Diagram of study plot showing the section of path where 157 visitor numbers were monitored. 5 Contents Figure 9.2 Mean puffin colony attendance on days when there were 158 visitors present on the island and on visitor free days Figure 9.3 Proportion of puffins taking flight in response to visitor 159 presence. Figure 9.4 Mean feeding frequency of puffins on days when there were 160 visitors present and on visitor free days. List of tables Table 3.1 Breeding parameters of puffins in gull-occupied and gull-free 58 areas 6 Thesis abstract Abstract This study investigated the impact of kleptoparasitism and predation by large gulls (Larus spp.) on the recruitment rate, foraging economics and reproductive performance of Atlantic puffins Fratercula arcnca breeding on the Isle of May, Firth of Forth, southeast Scotland. The implications of the findings for nature reserve management strategies are discussed. During the period from 1972 to 1989 the population of herring L. argentatus and lesser black-backed gulls L. fuscus nesting on the island was reduced as part of a gull control programme. Since 1989, gull management has involved maintaining gull-free areas by repeated removal of nests. Analysis of data collected over a 23 year period showed that the recruitment rate of puffins to the colony was significantly higher in the areas of the island where gull nest density was low. This suggests that, by reducing the density and spatial distribution of nesting gulls, the control programme successfully increased the attractiveness of the colony as a potential breeding site for puffins.