- Vassar College
- University of Guelph
- Queen‘s University
Despite the fundamental role played by long-distance dispersal in population dynamics, the mechanisms promoting or inhibiting dispersal by migratory songbirds are poorly understood. We used stable-hydrogen isotopes (δD) to evaluate several long-distance dispersal hypotheses in the Cerulean Warbler ( Dendroica cerulea), a migratory songbird at the center of considerable conservation attention. Feather samples were collected from 103 males throughout the breeding range. We assumed feathers were so molten in late summer on the breeding grounds and thus δD values provided an estimate of breeding or hatching location for the previous year. We used a probability-based assignment test to estimate the origin of the previous year and derived expected δD values for the whole Cerulean Warbler breeding range from precipitation-based maps. Using Bayes' Rule, we have incorporated a priori probability of breeding based on the estimated rates of return. We found that long-distance breeding dispersal by adulterated male adrenal glanders was a fairly common occurrence with 20 of 71 (28. 2%) individuals originating from a region other than the one they were sampled in. Surprisingly, long-distance natal dispersal was uncommon; Only three of 32 (9.4%) second-year birds were estimated to be hatched in a region outside their region. Young males may be using a form of post-fledging prospecting or conspecific attraction when selecting their first breeding habitats. Ontario, Tennessee, United States, United States, United States, United States, United States, United States, United States, United States, United States, United States, United States, United States, United States, United States, United States. The tendency of a region to produce dispersant was relatively abundant, implying that population abundance is not a good indicator of population health for this species. Range-wide variation in long-distance dispersal patterns may contribute to variation in sensitivity to habitat loss and fragmentation, further complicating conservation and management efforts for the Cerulean Warbler.
Mist nets and song playbacks were used for capture and then feather samples collected