|9/28/2011 3:38:00 PM|
Blue-gray Gnatcatcher -
by Don ReimerDue to its minuscule size and treetop-dwelling habits, this week's featured species may be unfamiliar to readers. And even for birders who are actively seeking it, this fidgety little bird can be quite challenging to locate. We are talking about a Gnatcatcher.
The tiny Blue-gray Gnatcatcher is smaller than a chickadee, but it has a feisty, energetic manner worthy of a much larger bird. It is the most widespread member of its genus in North America and the only one found in cold temperate regions. It is also the only truly migratory gnatcatcher, spending its winters in the southern U.S. and Central America.
Some have described this gnatcatcher's appearance as resembling a miniature mockingbird. Much of the bird's four-and-a-half-inch body length is taken up by its relatively long tail. The tail is often cocked at an angle and constantly whipped from side to side and up and down, the white outer tail feathers helping to flush flying insects out of hiding.
Up until recent decades, Gnatcatchers were seldom found as far north as Maine. The Atlas of Breeding Birds in Maine project (1978-83) first confirmed Gnatcatcher breeding in Maine in 1979. Prior to the 1950s, New Jersey was the northern extent of the breeding range, but small numbers now nest into southeastern Canada.
Male Gnatcatchers are bluish above, darkest on the head and nape, with white underparts. A black line that extends above the bill and around the sides of the head creates a rather angry-looking expression. The bill is small and thin, a perfect feeding tool for grasping insects and spiders. Females are paler, with a gray face, and both sexes feature a prominent white eye ring.
Nesting in a variety of open, deciduous woods settings, these Gnatcatchers seem to prefer moist areas with broad-leaved trees bordering habitat edges such as power lines or parks. Gnatcatchers are occasional victims of Brown-headed Cowbirds that lay eggs in their nests. Can you picture the diminutive Gnatcatcher parents scurrying about to provision a squawking baby cowbird?
Although they are extremely vocal, the birds' high-pitched, wheezy song is often hard to hear. Surprisingly harsh-sounding scold notes are interspersed with thin nasal call notes. Despite their vocal habits, however, the Gnatcatchers are rather easy to miss.
An exquisitely compact nest of catkins, plant fibers and bark is placed on a high horizontal limb up to 50 feet above the ground. Built by both mates, the exterior nest is bound together with spider webbing and decorated by lichens. Gnatcatchers have a well-documented habit of tearing apart half-built or even completed nests and reusing the old materials in their next nest. The camouflaged nests may appear as a small lump or gall on a branch. Probably the best chance of spotting a nest would be through careful observation of a parent bird carrying food to its young.
This year I was fortunate to find Gnatcatcher pairs on Pen Bay Medical Center's nature trail and at Cramer Park in Rockport.
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