Monday, August 11, 2008

Great Crested Flycatcher Nest

There’s a great-crested flycatcher that has been hanging around our neighborhood for several years. Its “wheeeeep” call can be heard constantly throughout the summer.
I had been out working in the yard and began hearing it so I grabbed my binoculars to search for it. Its call was coming from a tallow tree in my son’s backyard, and about 10 foot up the trunk of the tree I spotted an old bird box that had been mounted years ago. On a nearby limb, perched, was the flycatcher. The entrance hole of the box appeared to have been enlarged by the gnawing of a squirrel. Could the flycatcher be nesting there? They’re secondary cavity nesters, meaning they prefer natural cavities or those made by others birds such as woodpeckers. They are also known to use bird boxes.

I raised my extension ladder and poked a mirror into the entrance hole of the cavernous box and discovered a nest consisting of grasses, a few brown leaves, a feather, what looked like to be hair of some sort, and a single piece of cellophane. All of the contents fell right into the description of a nest produced by this bird. It must be noted that this particular flycatcher has been known to include snakeskin in its nests’ contents, as do wrens, indigo buntings, titmice, blue grosbeaks and even roadrunners. Though questioned, it has been suggested that the reason for this behavior is that it may help prevent predation of the nest by invaders such as squirrels, mice, etc. Kinda like a scarecrow, due to possible “snake odors” given off by the skin or just by sight which would offend predators keeping them away from the nest.

Could the introduction of the single piece of cellophane be due to the fact that it was unable to find a snakeskin so instead it used something that closely resembled it? One theory, as noted by John S. Strecker in his article “On the Use by Birds, of Snakes’ Sloughs as Nesting Material” in a 1926 issue of AUK, is that it may be due to birds being attracted to shiny objects. Snakeskin as well as cellophane being somewhat reflective, may be the cause of its fascination. Or maybe they use it just like any other conspicuous object, such as twigs, grasses, hair, and feathers. I guess we’ll never know for sure. A week later I revisited the nest box and discovered 3 cream-colored eggs streaked and scrawled with brown and red markings. Eventually the clutch was completed and placed in orderly fashion for incubation to begin.


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