Limpkin

Identificazione

The limpkin is a somewhat large bird, 64–73 cm (25–29 in) long, with a wingspan of 101–107 cm (40–42 in). Body mass ranges from 900 to 1,300 g (2.0 to 2.9 lb), averaging 1,080 g (2.38 lb). The males are slightly larger than the females in size, but no difference in plumage is seen. Its plumage is drab—dark brown with an olive luster above. The feathers of the head, neck, wing coverts, and much of the back and underparts (except the rear) are marked with white, making the body look streaked and the head and neck light gray. It has long, dark-gray legs and a long neck. Its bill is long, heavy, and downcurved, yellowish bill with a darker tip. The bill is slightly open near but not at the end to give it a tweezers-like action in removing snails from their shells, and in many individuals the tip curves slightly to the right, like the apple snails' shells. The white markings are slightly less conspicuous in first-year birds. Its wings are broad and rounded and its tail is short. It is often confused with the immature American white ibis.<p>This bird is easier to hear than see. Its common vocalization is a loud wild wail or scream with some rattling quality, represented as "kwEEEeeer or klAAAar." This call is most often given at night and at dawn and dusk. Other calls include "wooden clicking", clucks, and in alarm, a "piercing bihk, bihk...".

Tassonomia

The limpkin is placed in the family Aramidae, which is in turn placed within the crane and rail order Gruiformes. The limpkin had been suggested to be close to the ibis and spoonbill family Threskiornithidae, based upon shared bird lice. The Sibley–Ahlquist taxonomy of birds, based upon DNA–DNA hybridization, suggested that the limpkin's closest relatives were the Heliornithidae finfoots, and Sibley and Monroe even placed the species in that family in 1990. More recent studies have found little support for this relationship. More recent DNA studies have confirmed a close relationship with particularly the cranes, with the limpkin remaining as a family close to the cranes and the two being sister taxa to the trumpeters.<p>Although the limpkin is the only extant species in the family today, several fossils of extinct Aramidae are known from across the Americas. The earliest known species, Aramus paludigrus, is dated to the middle Miocene, while the oldest supposed members of the family, Aminornis and Loncornis, have been found in early Oligocene deposits in Argentina, although whether these are indeed related is not certain; in fact, Loncornis seems to be a misidentified mammal bone. Another Oligocene fossil from Europe, Parvigrus pohli (family Parvigruidae), has been described as a mosaic of the features shared by the limpkins and the cranes. It shares many morphological features with the cranes and limpkins, but also was much smaller than either group, and was more rail-like in its proportions. In the paper describing the fossil, Gerald Mayr suggested that it was similar to the stem species of the grues (the cranes and limpkins), and that the limpkins evolved massively long bills as a result of the specialisation to feeding on snails. In contrast, the cranes evolved into long-legged forms to walk and probe on open grasslands.<p>Between 1856 and 1934, the limpkin was treated as two species, one in South America (Aramus guarauna) and the other found in Central America, the Caribbean, and Florida (Aramus pictus). Today, it is treated as a single species with four subspecies. Along with the nominate subspecies A. g. guarauna, A. g. dolosus, A. g. elucus (both J. L. Peters, 1925), and A. g. pictus (F. A. A. Meyer, 1794) are recognized. The difference between the subspecies are related to slight differences in size and plumage.

Nome scientifico

Aramus guarauna

Autorità

(Linnaeus, 1766)

Ordine

Gruiformi

Famiglia

Aramidae

Genere

Aramus

Areale e habitat

The limpkin occurs from peninsular Florida (and the Okefenokee Swamp in southern Georgia) and southern Mexico through the Caribbean and Central America to northern Argentina. In South America, it occurs widely east of the Andes; west of them its range extends only to the Equator.<p>It inhabits freshwater marshes and swamps, often with tall reeds, as well as mangroves. In the Caribbean, it also inhabits dry brushland. In Mexico and northern Central America, it occurs at altitudes up to 1,500 m (4,900 ft). In Florida, the distribution of apple snails is the best predictor of where limpkins can be found.<p>The limpkin undertakes some localized migrations, although the extent of these is not fully understood. In some parts in the northern part of the range, females (and a few males) leave the breeding areas at the end of summer, returning at the end of winter. In Brazil, birds breeding in some seasonal marshes leave during the dry season and return again with the rains. Birds may also migrate between Florida and Cuba, as several limpkins on the Florida Keys and Dry Tortugas have been reported, but these records may also represent vagrants or postbreeding dispersal. One study in Florida using wing tags found limpkins dispersed up to 325 km (202 mi) away from the breeding site. This tendency may explain vagrant limpkins seen in other parts of the United States and at sea near the Bahamas.

Migrazione

Migratori completi

Comportamento

Comportamento migratorio: Migratori completi.

Conservazione

Tendenza della popolazione: stabile.

Tendenza della popolazione

stabile