Conservation Ecology of the European Roller

Conservation ecology of the European Roller Thomas M. Finch A thesis submitted for the degree of Doctor of Philosophy School of Biological Sciences University of East Anglia, UK November 2016 © This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with the author and that use of any information derived there from must be in accordance with current UK Copyright Law. In addition, any quotation or extract must include full attribution. Abstract Among temperate birds, two traits in particular are associated with current population declines; an association with farmed habitats, and the strategy of long-distance migration. The European Roller Coracias garrulus enjoys both of these characteristics, and has declined substantially over the last few decades. Here, I investigate intra- specific variation in Roller breeding ecology and migration in an attempt to work towards conservation solutions. I first compare the breeding ecology of Rollers from two populations; one in Latvia at the northern range limit, and one in France in the core Mediterranean range. I show that the French population is limited principally by nest-site availability, whilst foraging habitat is more important in Latvia. I also highlight the lower productivity of Latvian birds, which also varies substantially from year to year. Comparison of insect and chick feather δ13C and δ15N in France provides little support for specific foraging habitat preferences, providing further evidence that foraging habitat is not limiting for the French population. Next, I provide the most comprehensive analysis of Roller migration to date, showing that Rollers from seven European countries generally occupy overlapping winter quarters. I also show that Rollers from Latvia migrate up to twice as far as their southern European counterparts. Ring recoveries provide the first chance to study the migration of juvenile Rollers, as well as non-breeding season mortality. In particular, I highlight the shooting of Rollers from eastern populations in Arabia during spring migration. Finally, I describe patterns of connectivity among 98 populations of 45 migrant land-bird species from two trans-continental flyways. As with the Roller, connectivity is generally weak, such that any non-breeding season drivers of population decline will have widespread but diffuse impacts on breeding populations. My research highlights the utility (at least in the short-term) of nest-boxes for Roller conservation, but also demonstrates that, in more marginal parts of the range, the provisioning of nest-boxes alone is probably insufficient. 2 Contents Abstract ............................................................................................................................ 2 Contents ........................................................................................................................... 3 Acknowledgements .......................................................................................................... 7 Author contributions .................................................................................................... 10 Chapter 1: The loss of avian abundance and the need for evidence-based conservation ................................................................................................................... 12 1.1 Defaunation in the Anthropocene ..................................................................... 12 1.2 The decline of European farmland birds .......................................................... 13 1.3 The decline of sub-Saharan migrant birds ........................................................ 15 1.4 Thesis outline ................................................................................................... 17 1.5 References ........................................................................................................ 18 Chapter 2: Description of the study system ............................................................... 22 2.1 The European Roller ........................................................................................ 22 2.2 Study sites ......................................................................................................... 28 2.3 References ........................................................................................................ 33 Chapter 3: Intra-specific variation in the breeding ecology of the European Roller... ........................................................................................................................... 37 3.1 Abstract ............................................................................................................ 37 3.2 Introduction ...................................................................................................... 37 3.3 Methods ............................................................................................................ 39 3.4 Results and Discussion ..................................................................................... 45 3.5 References ........................................................................................................ 61 Appendix 1: Supporting information for Chapter 3 .................................................. 66 Supplementary figures ................................................................................................ 66 3 Supplementary tables .................................................................................................. 67 Chapter 4: Insights into the foraging ecology of the European Roller from chick feather stable isotopes ................................................................................................... 79 4.1 Abstract ............................................................................................................ 79 4.2 Introduction ...................................................................................................... 80 4.3 Methods ............................................................................................................ 81 4.4 Results .............................................................................................................. 87 4.5 Discussion ........................................................................................................ 90 4.6 References ........................................................................................................ 95 Appendix 2: Supporting information for Chapter 4 .................................................. 98 Supplementary tables .................................................................................................. 98 Supplementary figures ................................................................................................ 99 Chapter 5: A pan-European, multi-population assessment of migratory connectivity in a near-threatened migrant bird ....................................................... 100 5.1 Abstract .......................................................................................................... 100 5.2 Introduction .................................................................................................... 101 5.3 Methods .......................................................................................................... 102 5.4 Results ............................................................................................................ 106 5.5 Discussion ...................................................................................................... 112 5.6 References ...................................................................................................... 117 Appendix 3: Supporting information for Chapter 5 ................................................ 122 Supplementary tables ................................................................................................ 123 Supplementary figures ............................................................................................. 124 Results of randomised iterative procedure exploring the sensitivity of our analyses to geolocator imprecision. ............................................................................................. 129 4 Results of resampling experiments exploring the influence of sample size on the precision of our results .............................................................................................. 131 Chapter 6: Insights into the migration of the European Roller from ring recoveries ..................................................................................................................... 133 6.1 Abstract .......................................................................................................... 133 6.2 Introduction .................................................................................................... 134 6.3 Methods .......................................................................................................... 135 6.4 Results ............................................................................................................ 136 6.5 Discussion ...................................................................................................... 139 6.6 References ...................................................................................................... 142 Chapter 7: Long-distance migrants have low connectivity: good

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