Influence of environmental changes on the resource use and abundance of Black Skimmers

QH Natural history;QH301 Biology;QL Zoology

Pinto Vieira, Bianca ; Natural Environment Research Council (NERC) ; Nager, Ruedi

University:University of Glasgow

Department:Institute of Biodiversity Animal Health and Comparative Medicine

关键词: Non-invasive methods, moult, non-breeding season, aquatic bird species, climate change, El Niño Southern Oscillation, Neotropical zone.;   

Others  :  http://theses.gla.ac.uk/8379/1/2017PintoVieiraPhD.pdf

来源: University of Glasgow

【 摘 要 】

Understanding what environmental factors influence species’ responses is crucial for adequate conservation management and prediction of responses to climate change. My study focused on a widespread aquatic migratory bird in Brazil; the Black Skimmer (Rynchops niger). Throughout the thesis I investigated the reliability of using photographs, citizen data, and visual observation to assess biological data such as moult score, occurrence, and identification of sexes. I also used stable isotopes and counts to assess changes in Black Skimmer’s resource use and abundance according to ENSO. I found photographs can be used to score moult in primary feathers, and that sexes in this species can be identified by visual observation from skins and photographs with Black Skimmer males being significantly larger than females. Using citizen photographs from nature enthusiasts web platforms, I found Black Skimmers moult during austral spring to summer in Brazil. Individuals select areas mostly in southern and southeastern Brazil to perform moult. Both sub-species (Amazonian and South American Black Skimmers) and sexes in Brazil selected estuaries while moulting yet coastal built-up areas could also be used. The South American Black Skimmers also selected more dunes and less mudflats than the Amazonian ones. There were differences in timing or duration of moult between sub-species or sexes with males taking more time and starting to moult earlier than females. I found Black Skimmers changed resource and had a higher diet input from estuarine habitats during the El Niño. Not only the foraging use during moult changed but also the abundance. The number of individuals overstaging (staying longer at the non-breeding site during the breeding season) at the study site was higher during the El Niño and lower during the La Niña than in regular years. Abundance was higher during eastern and northern winds but negatively affected by an interaction of temperature and ENSO. This study provided affordable non-invasive methods to studies in ornithology, fulfilled gaps in Black Skimmer’s life-history annual cycle, and was one of the first studies addressing how ENSO affects aquatic species in the South American Atlantic coast. Lessons learned from this study might underpin more effective conservation plans.