KW habitat management benefits far more than one little songbird

 
By ROBERT HESS

Kirtland’s Warblers are picky about where they call home. They will nest only in thick, young jack pine forests that grow on a special sandy soil that is found only in a few counties in Northern Michigan – and nowhere else on earth.

And coincidentally, about three-fourth of the world’s population of the little bird currently nests in the four-county area that includes Crawford, Ogemaw, Oscoda and Roscommon counties – precisely the district served by Kirtland Community College, host and sponsor of the annual festival to celebrate the remarkable comeback of the bird from which the college took its name.

This energetic, yellow-breasted bird once was much more abundant because there used to be much more of their thick, young jack pine forest type. Modern forest fire control has been very successful in controlling wildfires, which – before Smokey Bear arrived – created vast areas perfect for Kirtland’s warbler nesting habitat.

Fire control has allowed jack pine forests to mature, preventing the natural creation of new young jack-pine areas. This big reduction in nesting habitat brought about a big reduction in the jack-pine warbler. Nest parasitism by the non-native brown-headed cowbird is the other main reason for he warbler’s rapid decline.

After Congress passed the federal Endangered Species Act in 1973, the Kirtland’s Warbler was the first bird species designated an endangered species.

Since then, the Michigan DNR, U.S. Forest Service and the U.S. Fish and Wildlife Service have worked closely together to insure the survival of the warbler.

The three agencies set aside roughly 150,000 acres of publicly owned forestland to save this endangered warbler. Clear-cutting and replanting to jack pine has been the main tool used to re-create their thick nesting and breeding habitat. Prescribed burning is also used, but to a much lesser degree

Now 150,000 acres might seem like an awful lot of land to set aside for one little bird, for just one single wildlife species. But the warbler is hardly the only species the benefits from this special management. And it is not the only species that the natural resource agencies target when managing jack pine on the 50-year rotation, or cycle, used to assure the survival of the warbler.

Dozens, probably hundreds, of other species benefit the managing of the jack-pine forests for the endangered Kirtland’s warbler, wildlife biologists believe. Throughout the 50-year management cycle, the habitat goes through significant changes. This creates different forest stages – creating ever-chancing habitat conditions brought on by an ever-changing array of plant and animal species.

Early in the cycle, following clear-cutting and re-planting, habitat is open. It looks and functions more like a prairie or grassland than a forest. Birds like the upland sandpiper, Lincoln’s sparrow, clay-colored sparrow and Brewer’s blackbird – all grassland species – move in when the habitat is open.

Dead snags are left standing during the clear-cutting, and downed logs are also left for wildlife. This attracts cavity nesters like kestrels, bluebirds and chickadees. The dead wood also provides habitat for snakes, salamanders, meadow voles and field mice. This increased prey base attracts northern harriers, red-tailed hawks and, during the winter, rough-legged hawks and even bald eagles. Badgers and coyotes are often found in this more open habitat stage.

As the planted jack pine grows and as the oaks, cherries and other deciduous trees that were also clear-cut sprout back up, woody habitat returns, creating a thicker, brush-like stage. More browse and cover is available for white-tailed deer and their numbers increase. Black bears feel more secure and are attracted by blueberries and ants that are also more abundant in this stage.

Brush-land birds such as brown thrashers, chipping sparrows, ovenbirds and house wrens move in. Ruffed grouse, spruce grouse and wild turkeys also begin using brushy, dense jack-pine habitat. It is during this stage when the Kirtland’s Warblers begin using these treated areas, usually when the planted jack pine reach about 8 years of age or four to five feet tall.

The Kirtland’s Warbler nests on the ground under the thick pine boughs. They will use this jack pine habitat for only another eight to 10 years, and stop using these areas when the lower branches of the jack pine begin dying back due to shading.

As the jack-pine trees become taller and fill out, the habitat becomes more forest-like. Grasses and sedges that were more dominant in earlier, more open stages begin receding, also due to shading, and blueberries and June berries become dominant. The more mature forest habitat attracts Nashville warblers, hermit thrushers, rose-breasted grosbeaks, robins, and white - throated sparrows – the forestland species. Some jack pine trees die from the deeper shade and the dead snags provide more habitat for woodpeckers, squirrels and bats.

Therefore, it goes, the forest succession progresses, changing the forest structure – the food, cover and shelter conditions – bringing about a complementary succession of plant and animal (especially bird) species that are best adapted to these changing conditions.

Therefore, while all this land is being set aside for one endangered bird, it also benefits much, much more.

Bob Hess is a retired wildlife biologist with the Michigan Department of Natural Resources and a former journalism student at Kirtland.