This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Numerous species are expected to modify their geographical range in response to climate change. Predicting the extent and speed with which such range changes will occur is difficult because we currently have a poor understanding of the mechanisms that enable species to invade and spread into new areas. The proposed research will capitalize on the recently discovered large scale range expansion of western bluebirds (Sialia mexicana) to gain insight into the mechanisms underlying this process. In this species, during the colonization of new populations at the edge of the range, breeding females influence the colonizing behavior of male offspring in response to changes in local resource abundance. When resources are limited, they produce males that disperse and spread into new areas; whereas, when resources are abundant, they produce males that remain in their natal population to breed. However, the proximate mechanisms by which breeding females influence offspring dispersal are not known. The proposed research combines a detailed knowledge of the history of western bluebird's range expansion and long-term tracking of marked individuals with field experiments on maternal physiology to test alternative hypotheses of how mothers influence offspring behavior during range expansion. Not only will this work provide insight into the mechanisms underlying range expansion, but it also provides a unique opportunity for dissemination of information about species coexistence and biodiversity in relation to climate change through existing bluebird monitoring programs which involve collaborations between local ranchers, Native American tribes and members of the general public.
