July 23, 2014
Update on VCU’s long-term studies of the Prothonotary Warbler along the lower James River 2014: Geolocators
Between June 16 and June 26 , 25 geolocators were deployed by Team Warbler members from VCU and J. Sargeant Reynolds Community College at two study sites along the upper James River (Presquile National Wildlife Refuge and Deep Bottom Park). The units were deployed on 19 females and six male Prothonotary Warblers, at least two years of age, and with active nests. These birds that are two years old or older that have nested a second year at a specific site have the highest return rates in subsequent years. All individuals fitted with geolocators continued to be monitored by Team Warbler to ensure the units remain in place and do not interfering with normal nesting activities.
Prothonotary Warblers provide an ideal research model for Neotropical migratory species because they readily utilize artificial nest boxes and have a high tolerance for handling, making them easy to capture and monitor over long periods. In addition to the James River population in Virginia, Prothonotary Warblers currently are being monitored by researchers across their breeding range including research initiatives in Illinois, Arkansas, South Carolina, and Louisiana. However, data gaps still exist regarding migratory pathways and geographic (migratory and genetic) connectivity among populations occupying breeding and wintering habitats. Understanding the connections between breeding and wintering ranges is essential to informing conservation strategies going forward.
To that end, a group of conservation partners comprised of several federal, state, non-government organizations (NGOs), and universities including Virginia Commonwealth University and its Audubon partners, are working to better understand the full life-cycle of the Prothonotary Warbler. The research partners are utilizing cutting-edge technologies, including stable isotope analysis, population genetics, and deployment of geolocators (miniaturized solar light-logging devices) to track Prothonotary Warbler migratory routes in order to understand the ecology and conservation needs of migrant birds throughout the entire annual cycle.
The first year of the project is a trial study involving deployment of 50 geolocators on Prothonotary Warblers at two sites (Virginia and Louisiana). The geolocators being deployed are smaller than used previously on Prothonotary Warblers, and have specially designed light stalks. The small size and angled aspect of the light stalks are designed to decrease weight and drag, maximizing return rates of individual birds carrying the units. The birds have to be recaptured upon return to the breeding grounds in 2015 in order to download the data from the geolocators. The data should provide information on the species’ migration routes, timing, duration and location of tropical wintering grounds.
Funds toward purchasing geolocators and conducting stable isotope analysis have been generously provided by the VCU Center for Environmental Studies, the U.S. Fish and Wildlife Refuge System and the Norcross Wildlife Foundation through a grant to the Virginia Audubon Council.