William Rapai discusses The Kirtland’s Warbler on Interlochen Public Radio

by Phillip Witteveen on March 29, 2013

William Rapai, author of The Kirtland’s Warbler, appeared on Interlochen Public Radio’s Points North with Peter Payette recently to discuss the ornithological history of the rare Kirtland’s warbler. “Our understanding of the Kirtland’s warbler developed just in time to save it from extinction, and today, the population is estimated at more than 2000 birds,” Rapai said. This bird, soon to come off the endangered species list, nests primarily in stretches of jack pine forest that grow in the sandy soil of Northern Michigan.

The first Kirtland’s warblers baffled the natural scientists of the mid 1800’s, and from its early elusive sightings,  they have continued to fascinate birdwatchers and ornithologists, including the notorious intellectual and murderer Nathan Leopold. It was Leopold, who, a year before he and an accomplice would kidnap and kill a millionaire’s son, traveled to Northern Michigan to study the Kirtland’s warbler. “He was a brilliant young man from Chicago, who went to school at the University of Michigan. He was an ornithologist, and an outstanding birdwatcher from a very young age. He was the first person to recognize the connection between the Brown-Headed Cowbird and the Kirtland’s warbler,” Rapai said on “Points North.”

Nathan Leopold

The nesting strategy of the nefarious Brown-Headed Cowbird was developed to keep up with the nomadic bison of the great plains, with whom they enjoyed a symbiotic relationship. In order to reproduce while moving with the great clouds of insects kicked up by bison hooves, and teeming in bison hide, the Cowbird lays its eggs in the nests of other birds. In doing so, they remove one of the native bird’s eggs, to avoid unwanted attention. While other birds developed defenses against the parasitic bird, the isolated Kirtland’s warbler, unable to distinguish between similar looking eggs, was very strongly affected. In a clutch of eggs with a Brown Headed Cowbird, one or two Kirtland’s warblers might survive. With two Cowbird eggs – none. “There have been two points in the last 50 years when the numbers of Kirtland’s warblers was estimated to be less than 400, [the bird] simply could not sustain its population.” explained Rapai.

In response to this, biologists, bird enthusiasts, and residents of Kirtland’s warbler territory have set up traps for Brown-Headed Cowbirds in the area. The traps contain food, water, and mock Cowbirds to attract their fellows. Then, the Cowbirds are destroyed, and buried. The traps have been enormously successful, and thousands of Cowbirds have been caught already. The Kirtland’s warbler, while increasing in population, will continue to need this intervention in order to grow.

Brown-Headed Cowbird Chick

As Rapai explains, “There’s no other species like the Kirtland’s Warbler that has come off the endangered species list so far. All the other species are not conservation reliant. Kirtland’s warbler is going to require a lot of help moving forwards.”

You can listen to the full interview here, and read more about The Kirtlands Warbler here.

Photo credits: biography.combiologydude.com


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