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Wednesday, July 30, 2014

Kirtland's Warbler and Vesper Sparrow

[Grayling, MI. Late May 2014]

Every serious birder in America is familiar with our rarest (though not our most endangered) warbler -- Kirtland's. The amazing conservation story underlining the comeback of this warbler from near extinction to a healthy and viable population today is good news for all conservationists and birders alike.

It is now possible to easily observe this "Near Threatened" songbird in appropriate habitat in North-Central Michigan where it can be locally common  -- especially in its stronghold of Grayling, MI.

The science behind the conservation efforts that helped the Kirtland's Warbler population increase from just 500 individuals in 1970 to ten-fold that number today, centers around understanding (and expanding) the unique breeding habitat required by the species.

Sadly, had the same principles been applied 50 years earlier to Bachman's Warbler, it might well be around today as well.

As is often the case with the "Law of unintended Consequences", seemingly benign efforts to stop and prevent naturally occurring forest fires resulted in forests with mature Jack Pines. Kirtland's Warbler, however, will not nest unless the trees are short -- between 5 to 10 feet high.

This was a double whammy for the warbler -- not only had most of its original habitat (once stretching from the Canadian Tundra to the Great Lakes region) been wiped out through logging, but the remaining Jack Pines were unsuitably tall for nesting.

There were therefore two critical thrusts to the conservation program -- (1) Prescribed burns to enable young Jack Pines to flourish; and, (2) Eradication of the warbler's brood parasite -- the Brown-headed Cowbird.

Virtually the Planet's entire population of this species breeds in Michigan. However, with the increase in population, some limited breeding has also been reported from Wisconsin and Ontario.

While there is tremendously greater understanding of the warbler's ecology and breeding in Michigan, much remains to be discovered about Kirtland's requirements in its winter habitat in the Bahamas.

The identification of Kirtland's Warbler is straightforward -- the male has a yellow throat and breast while the back and wings are grey (with 2 white wingbars). The flanks are streaked in black (as is the back); the eyes have distinct white eye-crescents and are set in a prominent black mask. The Kirtland's at 6" is relatively large as warblers go.

The most obvious distinction between the male and the female (shown above) is the lack of the black mask, paler grey upper-parts and pronounced black spotting on the breast. The under-parts are also a paler shade of yellow compared to the male's.

In addition to breeding Kirtland's Warbler, Myrtle Warbler was also nesting in the vicinity and Brown Thrasher was observed as well. Another breeder in this area is Vesper Sparrow:

Genetically closest to the Lark Sparrow, Vesper Sparrow is found coast-to-coast across much of the US.

An accomplished songster, it derives its common name from its habit of singing in the evening. This sparrow has a pale pink bill and legs and a striking facial pattern.

While the extinction narratives of the Passenger Pigeon, Eskimo Curlew, Carolina Parakeet, etc., are known only too well, it is heartening to know that extinction is not inevitable and that science can help man coexist with other species by understanding and implementing conservation programs that protect unique ecosystems. And, the Kirtland's Warbler is the perfect "poster child" for showcasing the success of these efforts.

1 comment:

Bob Pelkey said...

The Sony Alpha and the birds served you well for your photo documentation in this article, Hemant. At Church Road in Florida's Hendry County in January 2014 I had my first observation of a Lark Sparrow. Prolific blogger Steven Tucker, AKA Seagull Steve, confirmed another bird seen on that day as Vesper Sparrow that I thought might be Savannah Sparrow. It is interesting to note the relationship of the Lark and Vesper Sparrows in your article. Gotta embrace those prescribed burns down here in Florida and everywhere. I expect to meet up with you again on Church Road.