The Michigan Department of Natural Resources completed their annual June survey of Kirtland’s warbler, one of the rarest members of the wood warbler family that nests almost exclusively in Michigan’s northern Lower and Upper peninsulas, with a few locations in Wisconsin and the province of Ontario. They explain:
“We have a great group of DNR, U.S. Forest Service and U.S. Fish and Wildlife Service staff members, as well as volunteers, who are trudging through young, thick jack pine in the early morning hours,” said Department of Natural Resources wildlife supervisor Keith Kintigh. “The reward is getting to hear that singing male Kirtland’s warbler, which is the way we actually census the population.”
The Kirtland’s warbler census is a tool managers use to compare population numbers relative to recovery goals by listening for the male’s song. Kirtland’s warbler numbers had been very low, under 200 nesting pairs, in the mid-1980s. Michigan became the focus for habitat management, since it has been a primary location for the birds’ reproduction.
Kirtland’s warblers spend eight months wintering in the Bahamas. The males arrive back in Michigan between May 3 and May 20, a few days ahead of the females. The males establish and defend territories and then court the females when they arrive. The males’ song is loud, yet low-pitched, ending with an upward inflection – easily recognized to identify the presence of a Kirtland’s warbler.
Additionally, the presence or absence of Kirtland’s warblers determines if protection of that area is needed and allows evaluation of different habitat management techniques. The habitat requirements for Kirtland’s warbler are very specific; they prefer large blocks of young jack pine, usually hundreds of acres in size. The Kirtland’s warbler is a ground-nester, often using the living branches of 5- to 20-foot-tall jack pine trees to conceal their nests, so jack pine trees must be actively managed. Large areas of sandy soils are planted with jack pine and then cut decades later, on specific intervals, to achieve the perfect-aged stands.
Lots more about this rare songbird, including census results that show a steadily increasing population on the DNR’s Kirtland’s Warbler (Dendroica kirtlandii) page.