Principal Investigator: David E. Andersen.
Post-doctoral Research Associate: Henry Streby. Students: Sean Peterson (M.S., Natural Resources Science and Management – Wildlife Ecology and Management), Gunnar Kramer (M.S., Natural Resources Science and Management – Wildlife Ecology and Management).
Status: Pilot study conducted at Tamarac National Wildlife Refuge in 2010. Project expanded to Rice Lake National Wildlife Refuge and southeast Manitoba in 2011 and 2012. M.S. student accepted for 2012 (formerly worked on the project as a technician and site leader). Data collection completed in 2012. M.S. thesis defended in October 2013 and final thesis submitted in August 2014.
Golden-winged warbler (Vermivora chrysoptera) populations have been declining across their breeding distribution, especially the Appalachian Mountains portion of their breeding distribution, for at least 40 years. This Nearctic-Neotropical migratory species is listed as “threatened,” “endangered,” or “of management concern” in 10 states, and is described by the U.S. Fish and Wildlife Service as a “species of management concern.” The cause of range-wide declines, and some local extinctions, is a complex combination of habitat loss, blue-winged warbler (V. pinus) hybridization and competition, brood-parasitism by brown-headed cowbirds (Moluthrus ater), and likely global climate change. Although the golden-winged warbler breeding distribution is contracting from the south, it is expanding to a lesser degree to the west and north. However, in areas of recent range expansion, populations have been declining over the past 15 years, and range expansion will soon be limited by lack of suitable habitat to the north and west.
Golden-winged warblers depend on early successional forest stands and open forested wetlands for nesting. The northern hardwood-coniferous forests of northern Minnesota, Wisconsin, Michigan, and south-central Canada host the highest densities of breeding golden-winged warblers. Predicted to be a bioregion among the earliest and most dramatically affected by global climate change, there is currently considerable debate about the desired future composition and juxtaposition of habitats within these forests. Considerations for wildlife, including species associated with early successional forests, are an important part of this conversation. Golden-winged warbler nesting habitat is in decline as abandoned farmlands regenerate to mature forest, timber harvest declines, and wetlands are drained for development. Assessing the demographic response of golden-winged warbler populations to forest management and other habitat alterations is critical for this species to be included in future management planning. Detailed knowledge of habitat-specific demographic parameters is necessary to predict golden-winged warbler population responses to climate change.
Little is known about golden-winged warbler survival and habitat use throughout the nesting period in the western Great Lakes region, and less is known about these parameters during the post-fledging period anywhere in the species’ breeding distribution. To our knowledge, survival and reproductive success have not been compared among breeding habitat types for this species. The objective of this study is to investigate golden-winged warbler adult survival and reproductive success, including nest productivity and juvenile survival between the species’ main breeding habitat types; early successional forests and forested wetlands. We will use resulting demographic data to model golden-winged warbler reproductive success, and better understand factors influencing golden-winged warbler habitat quality. We will conduct this research in the core of golden-winged warbler range, at 3 sites that span a global climate change gradient, and a gradient of blue-winged warbler genetic introgression.