Tuesday, September 30, 2008

Kirtland’s Warbler Population Surges

The 1,791 singing males observed during this year’s census is the highest recorded since monitoring began in 1951, eclipsing the 1,697 singing males recorded in 2007. The lowest number of singing males ever observed was 167, a tally recorded in both 1974 and 1987 (graph).

The 09/28/08 press release from the Michigan Department of Natural Resources follows:
Department of Natural Resources officials today released annual survey information indicating the state's population of the endangered Kirtland's Warbler is the highest number of birds recorded since monitoring began in 1951, with 1,791 singing males observed during this year's census.

The 2008 population exceeds the goal for de-listing that was set in the Kirtland's Warbler Recovery Plan. The number of singing males biologists, researchers and volunteers in Michigan observed 1,791 singing males during the official 2008 survey period, up from 1,697 males observed in 2007. The lowest numbers were recorded in 1974 and 1987, when only 167 singing males were found.

The Kirtland's Warbler survey is conducted each year over a 10-day period during the first two weeks of June, when the birds are establishing their nesting territories. Male warblers are detected by listening for their songs. The songs can be heard at distances up to one-quarter mile, providing an excellent way to detect the birds with minimum disturbance.

The 2008 survey was a joint effort by the DNR, U.S. Forest Service, U.S. Fish and Wildlife Service, Michigan Department of Military Affairs and citizen volunteers. This year, singing males (numbers in parentheses) were found in 12 northern Lower Peninsula counties: Alcona (207), Clare (141), Crawford (288), Grand Traverse (2), Iosco (192), Kalkaska (10), Montmorency (11), Ogemaw (627), Oscoda (209), Otsego (40), Presque Isle (5), and Roscommon (25). Surveyors identified 34 singing males in five Upper Peninsula counties: Chippewa (12), Delta (10), Luce (1), Marquette (6), and Schoolcraft (5). In the U.P., additional effort is made to locate females and several were observed with the males, indicating nesting activity.

For a second consecutive year, singing and mated males were observed outside Michigan. Nine birds were heard in Wisconsin and one male with a female was found in Ontario. Both of these reports are of particular importance as they represent documented breeding of Kirtland’s Warblers outside the known breeding population stronghold.

Although Kirtland's Warblers have begun to expand into new areas, the core of the population remains dependent on northern Michigan's jack pine barrens ecosystem for nesting habitat. The warblers nest on the ground and typically select nesting sites in stands of jack pine between four and 20 years old. Historically, these stands of young jack pine were created by natural wildfires that frequently swept through northern Michigan. Modern fire suppression programs altered this natural process, reducing Kirtland's Warbler habitat. The result was that the population of Kirtland's Warblers declined to the point that they were listed as endangered.

To mimic the effects of wildfire and ensure the future of this species, the DNR and its partners at the state and federal level manage the forests through a combination of clearcutting, burning, seeding and replanting to promote warbler habitat. Approximately 3,000 acres of jack pine trees are planted or seeded annually on state and federal lands, primarily for the purpose of providing habitat for Kirtland's Warblers.

"New habitats are continually developed to replace those that become too old for Kirtland's Warbler nesting," said acting DNR Endangered Species Coordinator Sherry MacKinnon. "Through continuing management, we expect there to be sufficient habitat to support the warbler population through the foreseeable future."

Elaine Carlson, DNR wildlife biologist, emphasized how the habitat management program has produced benefits that extend well beyond the recovery of a single species.

"In addition to generating habitat for the Kirtland's Warbler, the jack pine management program provides valuable forest products as well as habitat for a variety of plants, songbirds, game animals and other wildlife," Carlson said.

For more information on the Kirtland's Warbler, contact the DNR Wildlife Division, Natural Heritage Program, Box 30180, Lansing, MI 48909, or visit the DNR Web site. Contacts: Sherry MacKinnon 517-373-1263 or Mary Dettloff 517-353-3014.


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