Principal Investigator: David E. Andersen.
M.S. Student: Gunnar Kramer (M.S., Natural Resources Science and Management – Wildlife Ecology and Management)
Most Neotropical migrant birds spend only 4 or 5 months on their breeding grounds, with the rest of the year spent on wintering grounds and migration routes. Recent demographic models suggest that songbird population growth is more sensitive to annual survival than to reproductive parameters. As a result, tracking songbirds during migration and linking breeding populations to their wintering grounds is a critical research need in songbird conservation and population dynamics. Furthermore, identifying population-specific wintering grounds is critical to allow state and regional North American stakeholders to justify targeted spending on wintering ground conservation efforts.
It is particularly important to identify population-specific wintering grounds for species experiencing dramatic population declines and breeding distribution shifts despite apparently high reproductive success. Golden-winged warblers (Vermivora chrysoptera; hereafter GWWA) are one such species, and the GWWA Working Group has identified the non-breeding season as a primary research need for the conservation of this species. Despite apparently high reproductive success across much of the breeding range and availability of abundant breeding habitat in many areas, populations are approximately stable in a few areas, declining precipitously in most others, and expanding their range to the north and west in Canada. Nest success estimates from GWWA populations in Michigan, New York, North Carolina, and Tennessee suggest that those populations are highly productive, but are all declining at concerning rates. An intensive study of nest productivity and fledgling survival in Minnesota found that those apparently stable populations are reproducing at levels that should support very strong population growth. Results from the first year of that same study suggest that populations in Manitoba may be reproducing at levels far too low to explain the observed population growth and breeding distribution expansion in that province. This apparent mismatch between productivity and population growth may be associated with differential survival on population-specific wintering grounds.
Using a combination of methods, including stable isotope analysis and attaching geolocators to GWWA on their breeding grounds, we propose to address the following research objectives:
- Identify wintering grounds used by GWWA populations across their breeding distribution,
- Combine geolocation and stable isotope analysis (if necessary) to compare methodology to identify wintering ground affiliations,
- Identify anthropogenic land-use patterns on specific GWWA winter grounds,
- Identify possible relationships between climate change and GWWA population declines, and
- Inform political jurisdictions (e.g., states) about wintering distribution of relevant breeding populations.