By Lee Franks
Birds pay a price for the advantages of flight. They must commit their forelimbs almost entirely to that enterprise. As a result the bill (or “beak”) often must assume responsibility for diverse functions for which many mammals use their forelimbs—grasping, carrying, scratching, fighting, and digging.
The bill consists of the upper and lower jaws (mandibles), ensheathed in a layer of toughened skin. As tools, bills are not used just for eating food, but also for catching it. Have you ever watched a perched bird launch itself, and after a few quick flaps of its wings, seize an insect in mid-air, and then, holding its catch firmly in its bill, loop back to the same or another close-by perch? This is the “art of flycatching.”
Flycatchers have ligaments connecting the upper and lower jaws that act as springs to snap the gaped jaw shut when an insect is snared.
The Ash-throated Flycatcher (a summer migrant), is frequently observed in the Park and hangs out in the open grasslands on the west end of the Park.
The Ash-throated Flycatcher is a medium to large flycatcher (8”) with a moderately long tail and relatively large head with a short, bushy crest. Its bill is black and moderately long. The upperparts of adult birds are grayish-brown. The throat and breast are pale gray, and the belly has a pale yellow wash.
The Ash-throated Flycatcher prefers to forage in open habitats by moving from perch to perch, pausing to scan for prey (wasps, bees, leafhoppers, moths, etc.) and then moving on rather than returning to a preferred perch. Insects are captured in flight, on the ground, and in foliage while hovering, and swallowed whole. They sometimes take small fruits.
The Ash-throated Flycatcher is opportunistic, using almost any natural or artificial cavity, size permitting and at least 4 feet above ground. As a late arriving (mid-May to mid-June) migrant, they are at a disadvantage in competing for nest sites with other cavity nesting species, and at times must occupy less desirable cavities. Occasionally, they will evict other species from a cavity. They readily adapt to a wide variety of artificial nest sites, including hollow horizontal, diagonal, or vertical metal pipes and wooden or tin-can nest boxes.
Ash-throated Flycatcher flight is generally rapid and direct with continuous flapping and without undulations. They engage in acrobatic aerial maneuvering and hovering in pursuit of prey, during courtship chases, and in territorial disputes. They typically aggressively defend breeding territories used for mating, nesting, and foraging. After egg-laying, pairs are less aggressive, with males wandering considerable distances beyond the territory, and females often quietly forage alone.
The Birds of North America No 268,1997; Wolf, Blair O.
The Birds of North America No 664, 2002; Cardiff, Steven W.; Dittmann, Donna L.