At MNA, our Mission is to protect special natural areas and the rare species that live there. The goals of our blog are to cover the latest environmental issues affecting these areas and provide information about the efforts of our volunteers. Our weekly “ENDANGERED!” column serves to inform you about the endangered plant and animal species found in and around these special natural areas, and how you can contribute to conservation efforts before it is too late.

Kirtland’s Warbler
By Brandon Grenier

The Kirtland’s warbler (Dendroica kirtlandii) is in the beginning of a species-recovery success story. Fifteen years ago, it was only known to nest in the northern region of Michigan’s Lower Peninsula. Now, this rare bird is also found in the Upper Peninsula and parts of Canada and Wisconsin. Known to on insects and small fruits, warblers help manage populations of insects such as flies.
Photo by Cindy Mead

Physical Appearance:
The Kirtland’s warbler is approximately six inches in length, and is one of the rarest members of the wood warbler family. It has a bright yellow breast and blue-gray back tail feathers covered in black streaks. The males are songbirds with eyes surrounded by white ringlets. Females are more dull in appearance than their male counterparts, do not sing and do not have ringlet markings. In fall and winter, both sexes have brown plumage, and are much less recognizable.

Preferred Habitat:

This warbler is very particular about where it will nest, nesting only on the ground or in the low hanging branches of jack pine trees. Kirtland’s warblers only nest in trees between the ages of five and twenty; after this the lower branches begin to die and it is no longer suitable. The warbler also requires a large area to sustain populations; each pair typically needs six-to-ten acres for nesting territory. Warblers migrate in the fall to make their voyage to the Bahamas for eight months and return to the Midwest in early May.

Life Cycle:
Once warblers return to Michigan in May, females lay four-to-five eggs, followed by an incubation period of 13-16 days. Both parents help feed the young, which leave the nest within nine days to live on the lowest branches. Parents continue to feed the chicks for five weeks. Most Kirtland’s warblers live for two years.

List Status:
The Kirtland’s warbler is listed as a federal endangered species; however, populations have been improving steadily after a number of programs were enacted to protect its habitat.

Kirtland’s warblers are proof that forest fires are healthy for ecosystems. Jack pine forests were traditionally renewed by forest fires, clearing out old trees and allowing for new growth, and in turn, new nests for warblers. Fires also open the seeds of the pinecones, so when humans prevent natural forest fires to protect their homes and land, the warbler’s habitat is minimized.

The brown-headed cowbird (Molothrus ater) also poses a significant threat to warblers. The cowbird is a nest parasite that lays its eggs in the nests of other birds. The cowbirds’ eggs hatch earlier than other songbirds’, so their young start off stronger and often win fights for food. As the Kirtland’s warbler has no developed defense against this parasitism, cowbirds have ravaged their populations.

Protection Efforts:

The U.S. Fish and Wildlife Service, the USDA Forest Service, the Michigan Department of Natural Resources and the Michigan Audubon Society began working together in 1972 using live traps to catch cowbirds in Kirtland’s warbler breeding areas. Since then, an average of 4,000 cowbirds have been removed per year. The USFWS has also monitored jack pine forests for years, using rotation cuttings, fires and reseeding to maintain breeding areas for warblers. From 167 Kirtland’s warblers in 1974, the number of singing males increased to 1,826 in 2009.

How You Can Help:
You can help ensure the survival of this beautiful bird by:
• Staying out of posted nesting areas
• Camping only in designated campgrounds
• Prohibiting pets from running wild through labeled nesting areas
• Practicing extreme caution with fire
• Tell your friends and family everything you know about this endangered species

MNA volunteers are currently working to protect this and other endangered species, and you can help too. Join our efforts as a volunteer removing invasive plants in the special natural areas where this species lives. Or, become a steward and take responsibility for planning efforts to maintain a specific MNA sanctuary. To find out how to get involved, visit our website.

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