Big Year for Kirtland's Warbler

This is a record-setting year for Kirtland’s Warbler. The U.S. Fish and Wildlife Service will soon announce officially that the 2011 census of singing males tallied 1,828 birds: 1,805 in Michigan, 21 in Wisconsin, and 2 in Ontario. This total edges past the previous record of 1,826 in 2009.

“We’ve been encouraged by the bird’s response to habitat management, and with the increased numbers, we’ve seen more birds seeking and finding additional habitat outside their core range,” says Chris Mensing a biologist for the USFWS in Michigan. Beyond the core range in lower Michigan, 35 of the singing males were in Michigan’s Upper Peninsula.

Most of us are aware of the success story, which took a significant amount of intensive study, hard work by dedicated biologists, wildlife managers, private conservation organizations, and volunteer census-takers—not to mention serious commitments of funding. Leading government agencies in these immense efforts include the USFWS, the Michigan and Wisconsin Departments of Natural Resources, and Canada’s Department of Defence (correct spelling in Canada). Ontario’s nest site is on an active military training base!

When the formal census of singing males began in 1971, the total was only 201, all in Michigan and none in the Upper Peninsula.

A historical footnote: In 1898, Frank M. Chapman, then the associate curator of ornithology and mammalogy at the American Museum of Natural History, later one of America’s greatest ornithologists, had this to say in concluding a short summary of Kirtland’s Warbler biology in The Auk:

“These brief notes constitute our sole knowledge of the habits of this species, whose nest and eggs, owing to its rarity and the remoteness of its probable breeding range, will doubtless long remain unknown.”

It took five years after Chapman made the pessimistic comment. The first nest was finally discovered in Michigan in 1903.

Graph courtesy of USFWS

More than a century passed until the first nests with eggs outside of Michigan were found in Wisconsin and Ontario—both discovered in 2007. An article about these discoveries and the species’ subsequent nesting history in Wisconsin and Ontario will appear in the November 2011 issue of Birding.