Individual variation is increasingly recognized as a central component of ecological processes, but its role in structuring environmental niche associations remains largely unknown. Species’ responses to environmental conditions are ultimately determined by the niches of single individuals, yet environmental associations are typically captured only at the level of species. Here, we develop scenarios for how individual variation may combine to define the compound environmental niche of populations, use extensive movement data to document individual environmental niche variation, test associated hypotheses of niche configuration, and examine the consistency of individual niches over time. For 45 individual white storks (Ciconia ciconia; 116 individual-year combinations), we uncover high variability in individual environmental associations, consistency of individual niches over time, and moderate to strong niche specialization. Within populations, environmental niches follow a nested pattern, with individuals arranged along a specialist-to-generalist gradient. These results reject common assumptions of individual niche equivalency among conspecifics, as well as the separation of individual niches into disparate parts of environmental space. These findings underscore the need for a more thorough consideration of individualistic environmental responses in global change research.
Bibliographical noteFunding Information:
This research was funded by National Aeronautics and Space Administration (NASA) grant 80NSSC18K1404 to W.J. and B.C. and by the Max Planck Institute of Animal Behavior. We acknowledge funding of DIP grants (DFG) NA 846/1-1 and WI 3576/1-1 to R.N. and M.W. yielding the stork movement data. R.N. also acknowledges support from the Minerva Center for Movement Ecology and the Adelina and Massimo Della Pergola Chair of Life Sciences. We also acknowledge funding by the Deutsche For-schungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy—EXC 2117—422037984. We thank the Max Planck-Yale Center for Biodiversity Movement and Global Change for additional support.
© 2021, The Author(s).