Cooperative Fish and Wildlife Research Units Program: Florida
Education, Research and Technical Assistance for Managing Our Natural Resources

Will, A., H. McFarland, C. Latty, and A. Powell. 2024. Geolocators, stable isotopes, and citizen science identify migratory timing, route, and spring molt of Smith’s Longspurs. Avian Conservation and Ecology 19(1):13. [online] URL:


Climate change is disproportionately impacting the Arctic. For Arctic breeding birds, basic knowledge of their annual cycle, specifically the timing, route, and movement behavior of migration, is needed to understand when and where populations may experience threats. We use a combination of geolocators and stable isotope analysis to identify route and timing of migration in Smith’s Longspurs (Calcarius pictus) that breed in Alaska’s Brooks Range. We trapped males on their breeding grounds in 2011-2014 and collected head feathers for stable isotopes of hydrogen (δ2H). We deployed 22 geolocators on a subset of individuals and retrieved four, which all overwintered in southern Texas. Individual start dates for fall migration based on geolocators were more variable than for the spring, and individuals were highly mobile while on their wintering grounds. Geolocators and stable isotope values were comparable across years and indicated that birds from the Brooks Range undergo their pre-nuptial molt in central Canada. We compared geolocator and stable isotope inferred locations to observations submitted to e-Bird and found that longspurs were distributed farther south during the winter months, but farther north during the spring than most eBird observations. Concurrent deployments of geolocator tags across Smith’s longspur’s breeding range would clarify whether migratory behaviors and routes are population specific or shared widely across breeding locations.