American Woodcock

识别特征

The American woodcock has a plump body, short legs, a large, rounded head, and a long, straight prehensile bill. Adults are 10 to 12 inches (25 to 30 cm) long and weigh 5 to 8 ounces (140 to 230 g). Females are considerably larger than males. The bill is 2.5 to 2.8 inches (6.4 to 7.1 cm) long. Wingspans range from 16.5 to 18.9 inches (42 to 48 cm).<p>The plumage is a cryptic mix of different shades of browns, grays, and black. The chest and sides vary from yellowish-white to rich tans. The nape of the head is black, with three or four crossbars of deep buff or rufous. The feet and toes, which are small and weak, are brownish gray to reddish brown. Woodcocks have large eyes located high in their heads, and their visual field is probably the largest of any bird, 360° in the horizontal plane and 180° in the vertical plane.<p>The woodcock uses its long, prehensile bill to probe in the soil for food, mainly invertebrates and especially earthworms. A unique bone-and-muscle arrangement lets the bird open and close the tip of its upper bill, or mandible, while it is sunk in the ground. Both the underside of the upper mandible and the long tongue are rough-surfaced for grasping slippery prey.

分类信息

The genus Scolopax was introduced in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae. The genus name is Latin for a snipe or woodcock. The type species is the Eurasian woodcock (Scolopax rusticola).

学名

Scolopax minor

命名信息

Gmelin, JF, 1789

目

Charadriiformes

科

Scolopacidae

属

Scolopax

分布与栖息地

Woodcocks inhabit forested and mixed forest-agricultural-urban areas east of the 98th meridian. Woodcock have been sighted as far north as York Factory, Manitoba, and east to Labrador and Newfoundland. In winter, they migrate as far south as the Gulf Coast of the United States and Mexico.<p>The primary breeding range extends from Atlantic Canada (Nova Scotia, Prince Edward Island, and New Brunswick) west to southeastern Manitoba, and south to northern Virginia, western North Carolina, Kentucky, northern Tennessee, northern Illinois, Missouri, and eastern Kansas. A limited number breed as far south as Florida and Texas. The species may be expanding its distribution northward and westward.<p>After migrating south in autumn, most woodcocks spend the winter in the Gulf Coast and southeastern Atlantic Coast states. Some may remain as far north as southern Maryland, eastern Virginia, and southern New Jersey. The core of the wintering range centers on Louisiana, Mississippi, Alabama, and Georgia. Based on the Christmas Bird Count results, winter concentrations are highest in the northern half of Alabama.<p>American woodcocks live in wet thickets, moist woods, and brushy swamps. Ideal habitats feature early successional habitat and abandoned farmland mixed with forest. In late summer, some woodcocks roost on the ground at night in large openings among sparse, patchy vegetation. <p>Woodcocks migrate at night. They fly at low altitudes, individually or in small, loose flocks. Flight speeds of migrating birds have been clocked at 16 to 28 mi/h (26 to 45 km/h). However, the slowest flight speed ever recorded for a bird, 5 mi/h (8 km/h), was recorded for this species. Woodcocks are thought to orient visually using major physiographic features such as coastlines and broad river valleys. Both the autumn and spring migrations are leisurely compared with the swift, direct migrations of many passerine birds.<p>In the north, woodcocks begin to shift southward before ice and snow seal off their ground-based food supply. Cold fronts may prompt heavy southerly flights in autumn. Most woodcocks start to migrate in October, with the major push from mid-October to early November. Most individuals arrive on the wintering range by mid-December. The birds head north again in February. Most have returned to the northern breeding range by mid-March to mid-April.<p>Migrating birds' arrival at and departure from the breeding range is highly irregular. In Ohio, for example, the earliest birds are seen in February, but the bulk of the population does not arrive until March and April. Birds start to leave for winter by September, but some remain until mid-November.

繁殖区

NA : temperate e Nearctic forest and edge: sw Alberta e to Maritime Provinces (sc to se Canada) and s to se Texas and n Florida (e USA)

非繁殖区

to woodlands and fields of se Texas and s Florida

迁徙

Complete migrants

行为

Woodcocks eat mainly invertebrates, particularly earthworms (Oligochaeta). They do most of their feeding in places where the soil is moist. They forage by probing in soft soil in thickets, where they usually remain well-hidden. Other items in their diet include insect larvae, snails, centipedes, millipedes, spiders, snipe flies, beetles, and ants. A small amount of plant food is eaten, mainly seeds. Woodcocks are crepuscular, being most active at dawn and dusk.<p>In spring, males occupy individual singing grounds, openings near brushy cover from which they call and perform display flights at dawn and dusk, and if the light levels are high enough, on moonlit nights. The male's ground call is a short, buzzy peent. After sounding a series of ground calls, the male takes off and flies from 50 to 100 yd (46 to 91 m) into the air. He descends, zigzagging and banking while singing a liquid, chirping song. This high spiralling flight produces a melodious twittering sound as air rushes through the male's outer primary wing feathers.<p>Males may continue with their courtship flights for as many as four months running, sometimes continuing even after females have already hatched their broods and left the nest. Females, known as hens, are attracted to the males' displays. A hen will fly in and land on the ground near a singing male. The male courts the female by walking stiff-legged and with his wings stretched vertically, and by bobbing and bowing. A male may mate with several females. The male woodcock plays no role in selecting a nest site, incubating eggs, or rearing young. In the primary northern breeding range, the woodcock may be the earliest ground-nesting species to breed.<p>The hen makes a shallow, rudimentary nest on the ground in the leaf and twig litter, in brushy or young-forest cover usually within 150 yd (140 m) of a singing ground. Most hens lay four eggs, sometimes one to three. Incubation takes 20 to 22 days. The down-covered young are precocial and leave the nest within a few hours of hatching. The female broods her young and feeds them. When threatened, the fledglings usually take cover and remain motionless, attempting to escape detection by relying on their cryptic coloration. Some observers suggest that frightened young may cling to the body of their mother, that will then take wing and carry the young to safety. Woodcock fledglings begin probing for worms on their own a few days after hatching. They develop quickly and can make short flights after two weeks, can fly fairly well at three weeks, and are independent after about five weeks.<p>The maximum lifespan of adult American woodcock in the wild is 8 years.<p>American woodcocks occasionally perform a rocking behavior where they will walk slowly while rhythmically rocking their bodies back and forth. This behavior occurs during foraging, leading ornithologists such as Arthur Cleveland Bent and B. H. Christy to theorize that this is a method of coaxing invertebrates such as earthworms closer to the surface. The foraging theory is the most common explanation of the behavior, and it is often cited in field guides. <p>An alternative theory for the rocking behavior has been proposed by some biologists, such as Bernd Heinrich. It is thought that this behavior is a display to indicate to potential predators that the bird is aware of them. Heinrich notes that some field observations have shown that woodcocks will occasionally flash their tail feathers while rocking, drawing attention to themselves. This theory is supported by research done by John Alcock who believes this is a type of aposematism.

保护状况

The American woodcock is not considered globally threatened by the IUCN. It is more tolerant of deforestation than other woodcocks and snipes; as long as some sheltered woodland remains for breeding, it can thrive even in regions that are mainly used for agriculture. The estimated population is 5 million, so it is the most common sandpiper in North America.<p>The American Woodcock Conservation Plan presents regional action plans linked to bird conservation regions, fundamental biological units recognized by the U.S. North American Bird Conservation Initiative. The Wildlife Management Institute oversees regional habitat initiatives intended to boost the American woodcock's population by protecting, renewing, and creating habitat throughout the species' range.<p>Creating young-forest habitat for American woodcocks helps more than 50 other species of wildlife that need early successional habitat during part or all of their lifecycles. These include relatively common animals such as white-tailed deer, snowshoe hare, moose, bobcat, wild turkey, and ruffed grouse, and animals whose populations have also declined in recent decades, such as the golden-winged warbler, whip-poor-will, willow flycatcher, indigo bunting, and New England cottontail.<p>Leslie Glasgow, the assistant secretary of the Interior for Fish, Wildlife, Parks, and Marine Resources from 1969 to 1970, wrote a dissertation through Texas A&amp;M University on the woodcock, with research based on his observations through the Louisiana State University (LSU) Agricultural Experiment Station. He was an LSU professor from 1948 to 1980 and an authority on wildlife in the wetlands.

种群趋势

declining