FRIENDS OF EDGEWOOD NATURAL PRESERVE
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FRIENDS OF EDGEWOOD NATURAL PRESERVE
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FLYCATCHERS 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), and the Black Phoebe (resident) are frequently observed in the Park. The Phoebe is most often found in and around the Cordilleras Creek area, and the Ash-throated hangs out in the open grasslands on the west end of the Park. Appearance
Ash-throated—medium to large flycatcher (8”) with moderately long tail and relatively large head with a short, bushy crest. Bill is black and moderately long. Upperparts of adult birds are grayish-brown. Throat and breast are pale gray, and the belly has a pale yellow wash. Black Phoebe—medium sized flycatcher (6.5”) that is the only black flycatcher in North America. The upper back, breast, and head are a sooty black, while the lower back, wings, and tail are brownish slate. The belly is entirely white, along with the undertail feathers. Food Habits Ash-throated—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. Sometimes take small fruits. Black Phoebe—visually locates prey (flies, bees, beetles, butterflies, grasshoppers, etc.) from a low perch or by hovering, and pursues it until capture. Typically, only one prey item is captured on each flight, which take place in open areas. Small prey is eaten in flight and larger prey is taken to a perch where it is beaten then swallowed whole. Nesting Ash-throated—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 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.
Black Phoebe—rarely uses natural structures for nesting. Prefers buildings, bridges and culverts, where they build a nest cemented with mud to a vertical wall of the site. Top of nest is most often close to protective ceiling. Common to all nest sites are 1) ceiling that protects nest from weather and provides concealment, 2) placement near or directly over water, 3) placement close to a source of mud for construction material, 4) area surrounding site suitable for foraging. Behaviors Ash-throated—flight is generally rapid and direct with continuous flapping and without undulations. Engages in acrobatic aerial maneuvering and hovering in pursuit of prey, during courtship chases, and in territorial disputes. Typically aggressively defends 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. A solitary species that does not flock, and is generally intolerant of other species nesting in close proximity. Black Phoebe—accomplishes most locomotion via flight which is direct with steady wing-beats. Rarely moves on the ground, but occasionally lands on the ground near potential prey and hops several centimeters to capture prey item. Both sexes preen frequently throughout the day, often during or between foraging bouts, or after leaving nests during incubation. Territories are aggressively defended using vocalizations and chase. During incubation, males will perch near nests throughout the day. As a species, they are nonsocial except in association with mate during breeding season. Pair bonds are not maintained after breeding season. References 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. |
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