By Annie Perry, MNA Intern
Swamp Lakes Moose Refuge, one of MNA’s sanctuaries in the Upper Peninsula,. experienced a wildfire in May 2012 that affected 40 acres of the 160-acre sanctuary. The fire caused a reappearance of growth and activity among various species in the sanctuary, including young jack pine stands. This could mean good news for the Kirtland’s warbler, one of Michigan’s endangered species.
A Kirtland’s warbler.
Photo: Cindy Mead.
Kirtland’s warblers measure about six inches in length. Their backs and wings are bluish-grey with black streaks, and they have yellow breasts and white rings around their eyes. As with many bird species, the females are not as brightly colored as the males.
The Kirtland’s warbler is one of the most geographically restricted mainland birds in the country. They nest on the ground near lower branches and in large stands of young jack pine, which must be 5-20 feet tall and 6-22 years old, according to the U.S. Fish & Wildlife Service. USFWS adds that the age of these trees is crucial to the Kirtland’s warbler’s habitat, though biologists have not yet learned why.
Jack pine stands are historically created and maintained through natural wildfires. After years of suppressing forest fires, scientists realized certain values of fire in forest ecology: for instance, fire helps jack pine cones release all their seeds. Without forest fires, the Kirtland’s warbler was losing its habitat—and, as a result, its population. Jack pine stands are now being managed through timber harvests, burning, seeding, and replanting to ensure the Kirtland’s warbler has its necessary habitat.
The Kirtland’s warbler reached record lows of only 167 singing males in 1974 and 1987. After 1987, however, the population began a dramatic increase. The primary goal of the current Kirtland’s warbler recovery plan was to re-establish a self-sustaining population at a minimum level of 1,000 pairs—a goal which was reached and surpassed in 2001. In 2012, the Kirtland’s warbler reached a record high of 2,090 singing males, up from 1,828 in 2011.
However, the Kirtland’s warbler is not a true self-sustaining population because it continues to persist through intensive management. In order to maintain the Kirtland’s warbler populations, the DNR, the U.S. Forest Service and the U.S. Fish and Wildlife Service continue to manage the jack pine stands. They also control the cowbird population, a bird which acts as a parasite of Kirtland’s warblers’ nests. According to a five-year review published in August 2012 by the U.S. Fish and Wildlife Service, a true self-sustaining population—one that is free from intensive management—is currently impossible.
The Department of Natural Resources has tips for helping sustain Kirtland’s warbler populations, including staying out of posted nesting areas, camping only in designated campgrounds, staying with tour guides and leaving pets in a safe area. For more information on the Kirtland’s warbler, check out its webpage through the U.S. Fish & Wildlife Service.
If you’re interested in seeing the recovery of MNA’s Swamp Lakes Moose Refuge nearly a year after the wildfire, MNA will host a fire ecology tour at the sanctuary on May 18. See the Calendar of Events or email Adrienne Bozic at firstname.lastname@example.org for details. RSVPs are required.