This action funds an NSF Postdoctoral Research Fellowship for FY 2010. The fellowship supports a research and training plan entitled "Behavioral drivers of population dynamics for migratory songbirds in a changing climate" for Andrea Townsend. The host institution for this research is the Smithsonian Migratory Bird Center, and the sponsoring scientist is Sillett Scott.
Potential links between behavior, change climate, and population dynamics of declining migratory birds are often invoked but rarely tested, due to the vast amount of data needed to assess these links and sophisticated computational tools necessary to analyze large, complex ecological datasets. By integrating information from the comprehensive behavioral, demographic and climatic database available for Black-throated Blue Warblers from the Hubbard Brook Long-term Ecological Research site, this research uses multimodel inference in a hierarchical Bayesian framework to identify behavioral strategies that optimize fitness in different climatic conditions. Behavioral and environmental drivers of population change are being examined, in order to assess of the capacity of migratory songbirds to respond adaptively to a changing climate.
By the end of this century, models forecast substantial population declines for many migratory birds as a result of climate change. Identifying behavioral drivers of population dynamics in changing climatic conditions is of broad interest to scientists, policy makers and the public. Information gained through this research is broadly transmitted through the Hubbard Brook "Science Links" program, and the Fellow will facilitate data interchangeability with avian census datasets and environmental datasets online. Training goals include SQL programming, database querying, management of large relational databases, metadata documentation, online data dissemination, and mastery of multimodel inference techniques, using computer programs such as MARK, RMark, WinBUGS, and E-SURGE.
Intellectual merit. The work completed during this fellowship contributed to scientific understanding in the field of climate change ecology by documenting the complex relationships between warm springs, lay date, fecundity, and population dynamics in a long-distance migratory bird species. We showed that the black-throated blue warbler, a Nearctic-Neotropical migrant, begins breeding earlier in warm springs, and that early breeders produce more offspring than later breeder. However, we found no direct relationship between spring temperatures and fecundity, suggesting that other factors (e.g., predators, insects, global climate cycles) might be more important drivers of fecundity than spring temperature, and that spring temperature alone will not predict the fecundity and population dynamics of the species. Furthermore, we use a mark-recapture mathematical modeling approach to show that spring temperature has a slight negative impact on adult survival, but an overall neutral effect on recruitment and population dynamics in this species. Broader Impacts. Many previous workers have demonstrated that organisms in a broad range of taxa have advanced their timing of breeding in response to warming temperatures, but relatively few have examined the fitness consequences of this advancement. We have demonstrated that detection of simple links (e.g., the link between warm springs and early breeding, and between early breeding and fecundity) are not enough to infer fitness and population dynamics, either positive or negative, in a species. Our work suggests that the overall effect of warm springs on this species of songbird has been neutral, at least within the range of temperatures observed over the course of this study. Because of the widespread concern about the conservation of declining migratory birds, these results will be of broad interest to scientists and policy makers seeking to understand and mitigate the impacts of climate change.
