On a lovely morning in late June, I watched a pair of great crested flycatchers calling back and forth. One was in our side yard and the other in our front yard.
Then both of them landed on a black walnut tree beside our driveway and appeared to be interested in a deserted woodpecker hole. Still, it seemed a bit late for them to be seeking a nest hole unless their first nesting attempt was foiled by a predator. Eventually, they flew away, still calling their raucous “wheep, wheep.”
Flycatchers are not true songbirds but belong to a closely related line that have brains unable to imitate songs. They are born with genetically predetermined calls and voice boxes simpler than those of songbirds. Thus most of us hear only their “wheeps,” “rasps,” and a rapid series of “whits,” the latter reminiscent of a policeman’s whistle. A two-minute YouTube video shows a great crested flycatcher calling.
But W. John Smith and Anne Marie Smith studied the vocalizations of great crested flycatchers in southeastern Pennsylvania and discovered at least 12 different calls which related to their behavior during breeding and even on their wintering grounds in southern Mexico, Central America and northwestern South America. They found that the flycatchers were particularly adept at using their vocalizations to manage their social behavior. Mated pairs duetted and males defended their territories by vocalizing as they approached their shared territorial borders
Donald Kroodsma, who is an expert in birdsong, describes the dawn song of one great crested flycatcher male as “an emphatic ‘wheeee-up,’ followed by another, then a faint low, buzzy note, barely audible, the pattern repeating. I can hear how successive ‘wheeee-up’ songs are different, as he plays with duration, frequency, emphasis, tone quality, and more—like snowflakes, no two ever quite alike,” he writes in his book Listening to a Continent Sing.
One of nine breeding flycatchers in Pennsylvania, most, such as the eastern phoebe, eastern wood pewee, Acadian and least flycatchers, are variations on gray and white, and some are most easily identified by their distinctive calls. However, great crested flycatchers are not only noisier than the others but showier with lemon-yellow bellies, gray heads, throats and upper breasts, and long, reddish-brown tails that glow in the sunlight. When excited they erect their crown feathers to form crests, hence their common name.
Unlike other tyrant flycatchers, so-called because they pursue and capture prey in flight, great crested flycatchers also glean insects from vegetation. In addition, they are the only cavity-nesting flycatchers in eastern North America.
Those cavities include natural openings in trees, abandoned woodpecker holes, hollow posts, and even nesting boxes, as well as more bizarre choices such as a cannon at Gettysburg National Park, an old wooden pump, stove pipe or open gutter pipe, old boxes or tin cans. But a recent study of great crested flycatchers’ nests in Florida found that the higher off the ground the nests were, the more likely they were to fledge young.
That study also reported that those flycatchers preferred to nest in abandoned woodpecker nests, particularly those of red-bellied woodpeckers. Of the 44 nests the Florida researchers surveyed, 20 were in old red-bellied woodpecker holes. Furthermore, contrary to earlier studies, those great crested flycatchers had less interest in nesting in naturally occurring hollows in live trees.
Great crested flycatchers are summer residents throughout eastern North America east of the Great Plains, from southern Canada to the Gulf States. They like to nest in mixed deciduous forests, but will make do in human-constructed places such as orchards, gardens, or golf courses.
Here on our mountain the males return from their wintering grounds in late April or early May, a week or more ahead of the females. Most of them return to the same area year after year and occasionally have the same mates. The males establish their territories by clashing with their competitors. Dr. Samuel Dicky, writing from the backwoods of West Virginia where he watched great crested flycatchers for more than 30 years, observed (as quoted by Arthur Cleveland Bent, Life Histories of North American Flycatchers, Larks, Swallows, and Their Allies, p.107) that “males were seen to clash…where the natural habitats of pairs overlapped. They then would draw up close to one another…expand their wings, spread their tails, and dart rapidly at each other. Then they tore some feathers from breasts, held fast with their claws, and tossed and tumbled on the ground.”
Once the females arrive, the males spend their time chasing and copulating with them. They also follow their mates closely during nest-building and egg-laying to make sure they are not cuckolded. Nests in Pennsylvania are built in May and early June. After pairs choose their nesting cavity, the female fills it with a wide variety of materials from leaves, seed pods, and grass to the hair of domestic and wild animals, feathers of native birds and poultry, and bits of bark, cloth, and paper, making them packrats of the avian world.
Almost every great crested flycatcher nest has a shed snakeskin, often left hanging outside the cavity, and lacking that, items of similar texture—cellophane, plastic wrappers, onion skins, or thin paper. Why they do this has been debated for years. Since not all nests have snakeskin, many researchers think the birds don’t recognize what they have and like the texture. Others believe that they are used to deter nest predators, but surely not snakes because they are major predators on their eggs and nestlings especially black rat snakes.
Recently, researchers in Arkansas found that the presence of snakeskin in nest boxes deterred mammalian predators, particularly southern flying squirrels. And nest boxes without snakeskin were preyed on by those squirrels. That seems to settle the question, at least in Arkansas.
Once the nest is built, both parents defend it and the surrounding area, attacking small mammals and most birds, which may be why I observed one May day a great crested flycatcher attack a singing, flying yellow-throated vireo in our yard, only my second sighting ever of that vireo species on our mountain. They tumbled earthward before the flycatcher flew one direction and the vireo the other.
Great crested flycatchers are feisty birds. Florida ornithologists watched them attack most birds near their nests from Carolina wrens to European starlings and even woodpeckers, including northern flickers. Once one even went after a black rat snake that had eaten its nestlings, yelling so loud that it attracted a northern mockingbird, blue jay, and northern cardinals that added their cries to those of the flycatcher.
The female great crested flycatcher incubates her four to eight, heavily splotched, yellowish or pinkish-white eggs while her mate continues to guard her and the nest. After 13 to 15 days, their eggs hatch and the young spend another two weeks in the nest. Both parents feed them, although the female is the primary breadwinner.
The nestlings eat the same variety of insects the adults do, namely butterflies, moths, beetles, grasshoppers, crickets, stinkbugs, flies, bees, wasps and dragonflies. But the parents will crush the larger insects in their mandibles before feeding them to their nestlings. They also give them spiders and small wild fruits.
When they fledge, at 13 to 15 days old, the family stays together for three more weeks. The parents continue to feed them with diminishing frequency. They also defend their fledglings.
By midsummer I no longer hear the strident calls of the great crested flycatchers. And in September they are heading south.
Because they are edge species and able to adapt to nest boxes, they are still common throughout their breeding range. Here they increased in southeastern Pennsylvania from the first breeding bird atlas, when they were detected in 73% of the atlasing blocks, to the second atlas when they were found in 89% of the blocks. Roy A. Ickes, writing in the Second Atlas of Breeding Birds in Pennsylvania, theorizes that the birds “may benefit from the increased number of dead trees and canopy gaps associated with adelgid infestation” that has killed most of the hemlocks.
But great crested flycatchers remain most abundant in the ridge and valley, lower Susquehanna Valley, and north western corner of the state. They also live in forested residential areas around lakes. But even though they are still widespread here with about 192,000 birds during the season, their population declined an estimated 32% in the two decades between the first (1983-1988) and second (2004-2009) breeding atlases.
We can only hope that this loudest and showiest member of the flycatcher family will continue to adapt in the future to the human-caused changes in their increasingly fragmented habitat.
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