Wood Stork

Identificazione

The adult wood stork is a large bird which stands 83 to 115 cm (33–45 in) tall with a wingspan of 140 to 180 cm (55–71 in). The male typically weighs 2.5 to 3.3 kg (5.5–7.3 lb), with a mean weight of 2.7 kg (6.0 lb); the female weighs 2.0 to 2.8 kg (4.4–6.2 lb), with a mean weight of 2.42 kg (5.3 lb). Another estimate puts the mean weight at 2.64 kg (5.8 lb). The head and neck of the adult are bare, and the scaly skin is a dark grey. The black downward-curved bill is long and very wide at the base. The plumage is mostly white, with the primaries, secondaries, and tail being black and having a greenish and purplish iridescence. The legs and feet are dark, and the flesh-coloured toes are pink during the breeding season. The sexes are similar.<p>Newly hatched chicks have a sparse coat of grey down (protoptiles) that is replaced by a dense, wooly, and white down (mesoptiles) in about 10 days. Chicks grow fast, being about half the height of adults in three to four weeks. By the sixth and seventh weeks, the plumage on the head and neck turns smokey grey. When fledged, they resemble the adult, differing only in that they have a feathered head and a yellow bill.

Tassonomia

The wood stork was first formally given its binomial name Mycteria americana by Linnaeus in 1758. Linnaeus based his name on a misplaced account and illustration in Historia Naturalis Brasiliae (1648) of the jabiru-guacu. Linnaeus also described Tantalus loculator, which was proven to also apply to the jabiru-guacu, after M. americana based on a 1731 illustration of the wood stork by Mark Catesby under the name of wood pelican. Since these binomials referred to the same species, M. americana and T. loculator are synonymous but M. americana takes priority as it occurs before T. loculator. <p>The accepted genus name Mycteria derives from the Greek μυκτήρ : myktēr, meaning snout or trunk, and the species name americana references the distribution of this stork.<p>This species seems to have evolved in tropical regions; its North American presence probably postdates the last ice age. A fossil fragment from the Touro Passo Formation found at Arroio Touro Passo (Rio Grande do Sul, Brazil) might be of the living species; it is at most from the Late Pleistocene age, a few 10,000s of years ago. North American fossils from that time are of an extinct larger relative, M. wetmorei, which would be distinguished from the wood on the basis of size and on the basis of M. wetmorei's less curved mandible. This was probably a sister species; both occurred sympatrically on Cuba at the end of the Pleistocene. Of the extant members of the genus Mycteria, this bird is basal to the clade yellow-billed stork, which is itself basal to the milky stork and the painted stork. This phylogeny is based on a 1996 study that sequenced the B chromosome and then utilized DNA–DNA hybridization to find the relations between the storks.<p>Likely because of its decurved bill, the wood stork has formerly been called the "wood ibis", although it is not an ibis. It also has been given the name of the "American wood stork", because it is found in the Americas. Regional names include "flinthead", "stonehead", "ironhead", "gourdhead", and "preacher".

Nome scientifico

Mycteria americana

Autorità

Linnaeus, 1758

Ordine

Ciconiformi

Famiglia

Ciconidi

Genere

Mycteria

Areale e habitat

This is a subtropical and tropical species which breeds in much of South America, Central America and the Caribbean. The wood stork is the only stork that breeds in North America. In the United States there are small breeding populations in Florida, Georgia, and the Carolinas. In South America, it is found south to northern Argentina. Some populations in North America disperse after breeding, frequently to South America.<p>This stork is able to adapt to a variety of tropical and subtropical wetland habitats having fluctuating water levels (as that initiates breeding). It nests in trees that are over water or surrounded by water. In freshwater habitats, it primarily nests in forests dominated by trees of the genus Taxodium (in the USA), while in estuaries, it generally nests on trees in the mangrove forests. To feed, the wood stork uses freshwater marshes in habitats with an abundance of Taxodium trees, while in areas with mangrove forests, it uses brackish water. Areas with more lakes attract feeding on lake, stream, and river edges.

Migrazione

Migratori completi

Comportamento

Comportamento migratorio: Migratori completi.

Conservazione

Tendenza della popolazione: in diminuzione.

Tendenza della popolazione

in diminuzione