Thursday, August 11, 2011

Curlew Update

Text by Flat Ranch Manager Sarah Grigg and Volunteer Host Nancy Elkins

The Nature Conservancy’s Flat Ranch’s Ranch Preserve provide a key breeding ground for the rare and imperiled long-billed curlew, the largest North American shorebird.

In an effort to better understand the specific habitat features required by this species, Idaho Department of Fish & Game biologists visit the property several times throughout the summer to monitor curlew population numbers.

An initial survey in June turned up 100 individual birds, most of which were displaying breeding behavior. “This is the largest concentration of long-billed curlew that we know of in the Upper Snake Region and is a very significant population for Idaho," noted IDFG Regional Biologist Rob Cavallaro.

About 40 curlews were spotted during the second survey on July 11. These lower numbers do not necessarily reflect a loss of birds, but rather indicate changes in behavior.

Once curlews have laid their eggs, the female sits on the nest, remaining low and flush to the ground to avoid predation.

When broods hatch, the birds move to cover, sticking to tall grasses, and shrubs. We noticed during our July survey that many of the birds were located in tall Wyethia (mule's ear).

On occasion, birds with broods will mob a perceived threat, and dive bomb the trespasser. Though we did not experience this mobbing behavior, we did witness one perturbed curlew fearlessly chase two adult bald eagles.

Thanks to Rob Cavallaro and his crew for leading the charge on these intensive surveys, and for teaching Flat Ranch staff so much about this rare and imperiled species.

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