The Kirtland's Warbler Annual Cycle
This project is part of my current research program as a postdoctoral researcher at the Smithsonian Migratory Bird Center and is funded by the US Fish and Wildlife Service. The Kirtland's Warbler (Setophaga kirtlandii) is North America's rarest migratory songbird. Although past research has succesfully informed breeding-season recovery plans, both state and regional agencies have identified several other periods of the annual cycle that are in critical need of research. More specifiically, key information is needed regarding: 1) post-breeding survival and habitat use, 2) migration routes, and 3) wintering distributions.
Post-breeding Mortality and Habitat Use
During the post-breeding period fledlging birds are particullarly vulnerable to both predation and starvation. Survival rates during this period range from as low as 22% to as high as 70%. Recent research has shown that fledglings of some species use different habitat types during the post-fledgling period. By attaching radio transmitters to fledglings just before they leave the nest and tracking their survival and movements for ~35 days, I will be able to quantify Kirtland's Warbler's basic survival rates and habitat use for the first time in this species. This past spring (2014), I attached radio-transmitters to 70 fledglings. Analysis of these data is ongoing so check back soon for an update.
Migration Routes, Stopover Sites, and Wintering Locations
Migration routes, and stopover and wintering locations for Kirtland's Warblers are poorly understood. Most annual mortality of adults occurs during migration, but previous research has shown that conditions on the wintering grounds can influece migratory performance. Understanding where and when Kirtland's Warblers migrate represents the necessary first step towards not only better understanding migration and the wintering period, but also conserving habitats crucial for their success.
I will be studying Kirtland's Warbler migration and wintering distribution using small (~0.5 g) light-level geolocators. These small devices infer latitude and longitude based on ambient light levels. In May and June of 2014, I attached 60 geolocators to male Kirtland's Warblers throughout their breeding habitat in Michigan. Once recovered next spring, these devices will provide me with invaluable information about migration routes and the timing and routes for both fall and spring migration. Check back next year for these exciting results.
In 2015, Joe Wunderle (USFS), Dave Ewert (TNC), and I will be working on Great Abaco and Cat Island in the Bahamas. We will be conducting island-wide point counts in the hopes of finding new wintering locations. Additionally, we will be testing some ideas about habitat preferences in winter. In 2016, we are hoping to also travel to Cuba and possibly Hispaniola for more searches.