The Kirtland's Warbler - An Endangered Bird That Depends on Our Assistance

Image via WikipediaBy Michael Sealy

The Kirtland's Warbler is one of North America's rarest songbirds. These endangered birds are very dependent on human assistance to save them from extinction. Their breeding range is located in Jack Pine tracts in the northern region of Michigan's lower peninsula. Kirtland's Warblers build their nests exclusively on or near the ground under the lower branches of young Jack Pines, where they also utilize the surrounding grasses as camouflage for their nests.

The birds only use Jack Pine trees that are under 20 years old, which is about the time when the branches of the trees become large enough to block out sunlight. Historically, the Jack Pines depended on naturally occurring fires in order for the seeds to be completely released from their cones. Fire suppression practices of recent decades have played a role in the decline of the Kirtland's Warbler. Now controlled burns are performed and seedlings are planted in a rotation that maintains a reliable habitat for the birds.

Another factor that endangers the Kirtland's Warbler is nest parasitism by Brown-headed Cowbirds. The cowbirds lay their eggs in the nests of other bird species in an attempt to trick the parent birds in to raising their young for them. The cowbird chicks are usually larger and more demanding which results in more work for the parent birds and less resources for the true offspring.

The Kirtland's Warbler has failed to develop defenses against the cowbirds like other species have. To offset the damage that would be inflicted upon the Kirtland's Warbler by Brown-headed Cowbird parasitism, a trapping program was initiated in the 1970's and over 150,000 cowbirds have been removed from the region. In order for the Kirtland's Warbler numbers to continue increasing, human assistance will also have to remain in effect.

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