Posted On: 09/18/2017 - 11:55am, Posted By: Other
This post is guest-authored by Stanley Hedeen, professor emeritus at Xavier University and long-time volunteer at the Geier Collections & Research Center.
A male Kirtland’s Warbler is one of the rarest specimens in the bird collection of Cincinnati Museum Center. When it killed itself by smashing into a patio window in Westwood during late September, 1975, only about 300 members of its species remained on earth. All of them nested in Lower Michigan and wintered in the Bahamas and nearby islands.
Kirtland’s Warbler male found on a Westwood patio in September, 1975.
In 1975, the breeding range of the Kirtland’s Warbler was restricted to a 240-square-mile area where it nested in young Jack Pine (Pinus banksiana) groves growing on burned areas. When the maturing trees reached a height of about 15 feet, the warblers moved their breeding activities to younger groves in more recently burned areas. But because humans were increasingly suppressing forest fires during the twentieth century, the species was losing its nesting sites and its numbers were declining.
The Kirtland’s Warbler that struck the Westwood window in 1975 had been caught in Michigan as a 10- to 12-day-old nestling on July 2, 1971, and fitted with a numbered metal band. Field observations of the banded male warbler during his summers in Michigan determined that during his lifetime he sired at least 14 offspring. The male was over four years old when he died, a relatively advanced age for a small migratory bird.
Since 1975, the Kirtland’s Warbler population has grown due to the controlled burning of Jack Pine stands, rotation cutting of Jack Pine forests, and removal of the Brown-headed Cowbird (Molothrus ater), a nest parasite and competitor that had colonized Lower Michigan as land was cleared for crops and pastures. The Kirtland’s Warbler today has a population of about 4000 individuals and has increased its breeding range to include Upper Michigan, Wisconsin, and Ontario. Even though its population has expanded over the decades, the Kirtland’s Warbler currently remains a federally-designated endangered species.