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by Tom Thomson
A Success Story
"My interest in the Kirtland's warbler ," Harold Mayfield once wrote, grew out of my friendship with the late Josselyn Van Tyne who started a study of this species in 1932."
Although Van Tyne looked forward to the time when he would write a full account of the elusive warbler of the jack pines, the day-to-day demands of teaching, editing, and curatorship kept him from the task. After his untimely death, his widow, Helen Bates Van Tyne, gave all the notes and other material pertaining to the warbler to Mayfield.
"I had assisted Van Tyne in his work beginning early in the 1940s," Mayfield said, "and after his death, I took over the project and completed it." All in all, his field work stretched over a period of eighteen years. His book, The Kirtland's Warbler, was published in 1960 by the Cranbrook Institute of Science.
The work is a paradigm of excellence and covers a detailed analysis of the breeding grounds, mating and territorial behavior, nest building, the laying of eggs and incubation, data on the fledglings, descriptions of the normal songs and variations, the influence of cowbird paraszitism, and an extensive bibliography.
Between 1961 and 1971, the numbers of Kirtland's warblers declined precipitously, crashing to 40% of their previous population. Emergency measures were instituted through the cooperation of federal, state, and private agencies.
After cowbird control was initiated in 1972, parasitism decreased to only about 3% of the nests. Controlled cutting and burning of selected sites was also undertaken, along with the planting of sapling jack pines. All of these efforts paid off.
The incredibly good news is that from a low population of 167 singing males in 1974, the Kirtland's Warbler has shown a remarkable year-by-year comeback until the numbers today might come close to matching those at the turn of the century. Here are the numbers for the last few years from censuses of singing male warblers as supplied by the Wildlife Division of the Michigan Department of Natural Resources:1987 . . . . . . . . . . 167 pairs 1988 . . . . . . . . . . 207 " 1989 . . . . . . . . . . 212 " 1990 . . . . . . . . . . 265 " 1991 . . . . . . . . . . 347 " 1992 . . . . . . . . . . 397 " 1993 . . . . . . . . . . 485 " 1994 . . . . . . . . . . 633 " 1995 . . . . . . . . . . 765 " 1996 . . . . . . . . . . 692 "
Chcuk-chuck, wer-o-wee, see see see. Chuck-chuck, wee-o-see-see-see. Chip-chip, wer-o-wee-o-lee dee dee
Those were my impressions of a Kirtland's Warbler song many years ago near Mio, Michigan. It was the first time I had ever seen the species. The morning was sunny, the bird was perched in a scrubby pin oak amidst a stand of Jack pines, was singing fairly steaddily even though it was July 22nd-and I was incredibly happy.
Thank you, Spenser F. Baird and Dr. Kirtland. Thank you, Nathan Leopold. Thank you, Josselyn Van Tyne and Harold Mayfield. Thank you, Larry Walkinshaw (he wrote another splendid book on the Kirtland's Warbler). Thank you, Tom Weise of the Michigan DNR for keeping me up to date on the numbers, and thank you to all the other folks who have cared.
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