An evaluation of isotopic (δ2H) methods to provide estimates of avian breeding and natal dispersal

Natal and breeding dispersal represents an important component of animal demography and metapopulation theory. This phenomenon also has implications for conservation and management because understanding movements of individuals potentially allows the identification of key habitats that may be acting as population sources or sinks. Intrinsic markers such as stable isotope abundance in tissues that can be associated with provenance can provide a coarse but pragmatic solution to understanding such movements. Different methodologies have been proposed to quantify natal and breeding dispersal by using stable isotope analyses of keratinous tissues (hair, feathers), each of them with their own advantages and limitations. Here, we compared results provided by four different methods to estimate dispersal (three already published and one novel) in animals using stable isotope measurements. We used a single large dataset of feather δ2H values from golden‐winged warblers (Vermivora chrysoptera) representing five different populations breeding in North America to compare model results. We propose one method as the most adequately supported by data, and we used this method to demonstrate how biological factors explaining dispersal status can be identified and geographical origins of immigrants inferred. Our results point to a generalized methodological approach to using stable isotope data to study immigration and dispersal in birds and other animals. The dispersal of individuals from natal and breeding locations to sites of first or subsequent breeding represents an important component of animal demography and metapopulation theory (Greenwood and Harvey 1982, Walters 2000). This phenomenon is especially relevant to the conservation and management of long‐distance migratory birds because an understanding of the movement of individuals at various scales allows for more informed decisions about the protection of key habitats. By identifying which populations are acting as sources or sinks at local, regional, and continental scales (Donovan et al. 1995a, b), focus can be placed on protecting source populations and those regions acting as ecological traps can be identified (Holmes and Sherry 1992, Hobson et al. 2001, Webster et al. 2001). Despite recognition of the key importance that natal and breeding dispersal have on population demography, little progress has been made since the seminal review paper by Greenwood and Harvey (1982). This contrasts with significant developments in the use of miniaturized tracking devices (Bridge et al. 2011, 2013) that has allowed major