Where Wayne's Warblers Dwell - The Center for Conservation Biology

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Wayne's Warbler

A Black-throated Green Warbler singing from a branch along Jericho Ditch Trail in the Great Dismal Swamp National Wildlife Refuge, VA. This bird was seen in late March, prior to the arrival of the nominate subspecies. Photo by Kathy Louthan courtesy of eBird and the Cornell Lab of Ornithology.

By: Chance Hines
4/2/24

The Great Dismal Swamp is one of the largest intact wetland ecosystems in the eastern United States and the expansive wilderness creates a sense of isolation and mystery while offering sanctuary to a rich array of flora and fauna.

Looking up at the canopy of an Atlantic white cedar forest. This was once the preferred habitat for Wayne’s Warblers. This tree was almost completely logged out prior to the 20th century but a handful of scattered remnants persist in hard-to-access areas of the Great Dismal Swamp. Photo by Bryan Watts.

Among the avian inhabitants of this vast wilderness is the Wayne’s Black-throated Green Warbler, a genetically distinct subspecies that finds its breeding grounds along a narrow strip of the mid-Atlantic coastal plain. Compared to its nominate cousins, which inhabit the Appalachians and higher latitudes of North America, Wayne’s Warblers are notably smaller and arrive at their breeding grounds much earlier in the season.

A Black-throated Green Warbler singing from a branch along Jericho Ditch Trail in the Great Dismal Swamp National Wildlife Refuge, VA. This bird was seen in late March, prior to the arrival of the nominate subspecies. Photo by Kathy Louthan courtesy of eBird and the Cornell Lab of Ornithology.

Once a common breeding songbird within the Great Dismal Swamp, the current distribution of the Wayne’s Warbler within the swamp remains uncertain. Surveys conducted by the Center for Conservation Biology (CCB) in the early 2000s indicated a decline in population since the mid-20th century, reflecting broader trends across their range. As a response, efforts are underway to petition for the listing of the subspecies under the U.S. Fish and Wildlife Service’s endangered species list, garnering support from state, federal, and non-profit biologists spanning their range from Charleston, South Carolina, to southeastern Virginia.

Currently, CCB and the Virginia Department of Wildlife Resources are collaborating to assess the distribution of Wayne’s Warbler within the swamp and nearby potential habitats. The subspecies’ early breeding onset poses challenges to accurately determining its distribution and occupancy, particularly as it coincides with the migration period of nominate Black-throated Green Warblers. To address this, survey efforts focus on the weeks preceding and following the peak of spring migration.

Riley Strasbaugh, from CCB, surveys for Wayne’s Warblers in the early morning at the Great Dismal Swamp National Wildlife Refuge. A typical survey route includes 10-15 points where all birds that are heard or seen are recorded during the four hours of daylight. Photo by Rylie Strasbaugh.

Plot for the number of detections and expected number of detections (based on the number of surveys) at three National Wildlife Refuges during surveys conducted in the spring and summer of 2001. Birds were more abundant than expected at Alligator River NWR but scarcer at Pocosin Lakes and Great Dismal Swamp NWRs. Plot from Watts and Paxton 2002.

Initial findings from early-season surveys have been promising. Beginning on March 19^th, four Wayne’s Warblers were observed on the first route of the season, with subsequent surveys yielding up to 10 individuals along a single survey route. These observations offer optimism for the subspecies’ population within the swamp, and CCB aims to locate nests and monitor breeding success in the coming weeks.