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

Abstract

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.

Host dispersal and landscape conversion are associated with the composition of haemosporidian parasites of the golden-winged warbler

“…Consistent with historic and natal dispersal trends from the southeast to the northwest: golden-winged warblers in Ontario and Manitoba share a common Leucocytozoon lineage that is also present but much less common in Wisconsin, and Golden-winged warblers in Wisconsin and Manitoba share a complex of very similar Leucocytozoon parasites that are not found in other study areas. Manitoba also has at least one unique and distinct parasite lineage from each parasite genus, consistent with the Novel Enemies hypothesis, as golden-winged warblers appear to rarely migrate south from Manitoba, which could limit movement of unique parasites (Lopez-Calderon et al ., 2019). Further, differences in parasite communities between the two Ontario study sites are also consistent with the Novel Enemies hypothesis.…”

“…1). While adult golden-winged warblers tend to have strong site philopatry, natal dispersal is high, and second-year individuals also tend to disperse to the north-northwest (López-Calderón et al ., 2019, Fig. 1).…”

“…(2016), natal dispersal data is from López-Calderón et al . (2019). Map data is from openstreetmap.org.…”

Multi-isotopic (δ2H, δ13C, δ15N) tracing of molt origin for European starlings associated with U.S. dairies and feedlots

“…There have been several approaches previously used to derive an estimate of local vs. non-local origins of birds using feather δ 2 H measurements and comparing those to values expected for a given location based on the long-term Global Network of Isotopes in Precipitation (GNIP; https://www.iaea.org/services/networks/gnip ). Most recently, López Calderón et al [ 25 ] recommended an approach which applied the normal probability density function to ascertain the probability of a feather being molted at a particular site given the expected distribution of feather δ 2 H values for that site. However, in our case, we did not have a starling-specific δ 2 H f vs. δ 2 H p calibration curve for known-origin starlings and we recognize that this relationship can differ between juvenile and adult birds during their post-natal and post breeding molt [ 26 ].…”

Empirical tests of habitat selection theory reveal that conspecific density and patch quality, but not habitat amount, drive long‐distance immigration in a wild bird

“…The random, ideal free, ideal dominance, and social cues hypotheses make alternative predictions about the relationships between immigration and patch characteristics, but empirical tests of these hypotheses are rare due to the inherent challenges of tracking dispersing individuals over large spatial scales and distinguishing immigrants from local recruits (reviewed by Diffendorfer 1998; Furrer & Pasinelli 2016). Intrinsic markers, including stable isotopes and genetic markers, provide an emerging method for studying long‐distance immigration that can overcome these challenges (López‐Calderón et al, 2019). In particular, because the geographic origin of individuals can be inferred from intrinsic markers without having to track individuals as they disperse, these markers allow researchers to obtain large sample sizes that are not biased towards short‐distance dispersal events and allow inferences to be made about most or all individuals in a study population.…”