Sungrebe

Identificazione

The female is a small, slim bird, averaging about 30 cm (12 in) in length. Sungrebes have lobed toes, and the bare skin of their feet and legs are boldly banded in yellow and black. The body plumage is mostly varying shades of reddish brown, while the head and neck are strikingly patterned with a black crown and nape and white stripes along the sides of its neck, as well as a white throat and chin. The long tail (almost a third of the total length) extends well beyond the body in flight, and sits fanned out on or just below the surface of the water while the bird swims. Females have a rufous patch on the side of the face that brightens to a cinnamon-orange color during the breeding season. Also during the breeding season, her eye ring becomes brighter in color and her lower mandible goes from dark red to bright scarlet. Slightly shorter on average than the male, with a slightly shorter wingspan, 13.77 cm (5.42 in), but slightly more powerfully-built with a higher average mass, 130–140 g (4.6–4.9 oz).<p>The male is similar to the female, but has slightly drabber plumage; in particular the male lacks the bright orange-rufous patch on the cheeks that the female displays, and while his lower mandible turns from pale beige to dark red during the breeding season, it does not get as bright as that of the female. On average he is slightly longer and with a wider wingspan 14.1 cm (5.6 in) than the female, but more lightly built with a lower average mass (110-140g).<p>Juveniles have similar plumage to the male, but are slightly smaller, and with a grayer cast to the body feathers and more white on the cheeks and neck.

Tassonomia

The sungrebe was described by the French polymath Georges-Louis Leclerc, Comte de Buffon in 1781 in his Histoire Naturelle des Oiseaux from a specimen collected in Cayenne, French Guiana. The bird was also illustrated in a hand-coloured plate engraved by François-Nicolas Martinet in the Planches Enluminées D'Histoire Naturelle which was produced under the supervision of Edme-Louis Daubenton to accompany Buffon's text. Neither the plate caption nor Buffon's description included a scientific name but in 1783 the Dutch naturalist Pieter Boddaert coined the binomial name Colymbus fulica in his catalogue of the Planches Enluminées. The sungrebe is now the only species placed in the genus Heliornis that was erected by the French naturalist Pierre Bonnaterre in 1791 with the sungrebe as the type species. The name of the genus combines the Ancient Greek hēlios meaning "sun" and ornis meaning "bird". The specific epithet fulica is Latin for "coot". No subspecies are recognised.<p>There is some debate where the finfoot family, Heliornithidae, fits within Gruiformes. The Sibley–Ahlquist taxonomy of birds, based on DNA-DNA Hybridization, suggested that they are sister taxa to limpkins, the Aramidae, and even placed the limpkins within Heliornithidae in 1990. However, more recent genetic analyses suggests that limpkins are sister taxa to cranes, the Gruidae, and that finfeet are instead sister taxa to rails, the Rallidae. Other studies suggest that finfeet and the Afro-Madagascan flufftails, a group originally thought to be nested within rails, form a lineage called Sarothruridae that separated from each other at the end of the Eocene, probably in Africa. Sarothruridae, in turn, is considered a sister clade to Rallidae.<p>Within Heliornithidae, sungrebes are sister to the Asian finfoot, rather than the geographically closer African finfoot, according to the results of both Mitochondrial and Nuclear DNA sequencing. This adds credence to the idea that finfeet moved from an African origin into Eurasia and then across Beringia and through North America to reach South America, rather than coming across the Atlantic from Africa, or having evolved on Gondwana, separated with the shifting of the continents, and moved north into Laurasia from there. This would also explain the absence of finfeet from Australia, and the success of the Sungrebe at colonizing the continental Neotropics while failing to colonize any major Caribbean islands that do not have glacial land bridges to the mainland.

Nome scientifico

Heliornis fulica

Autorità

(Boddaert, 1783)

Ordine

Gruiformi

Famiglia

Heliornithidae

Genere

Heliornis

Areale e habitat

Sungrebes are found in heavily vegetated, mostly freshwater wetland environments, from northeast Mexico south along the Gulf and Caribbean coasts through Panama, where they live throughout the Canal Zone and Darien, and then along the Pacific coast from Panama through central Ecuador. They are also found throughout the Orinoco and Amazon Watershed, the Pantanal, and the Brazilian Atlantic Rainforests. Aside from Trinidad and Tobago, they are not found in most Caribbean nations, and seem to have difficulty dispersing over long distances of saltwater. Though occasionally recorded at higher elevations, the sungrebe is usually associated with lowlands from sea level to around 500 meters. They are residents throughout their range; they do not seem to migrate.<p>Sungrebes seem to be expanding the northern limit of their range in northeastern Mexico. They were historically found no farther north than central Veracruz, but by the 1940s had established populations throughout Veracruz and into San Luis Potosí. They are now expanding their range further north in Tamaulipas, and an individual was sighted on 13 November 2008 on the Marsh Loop at Bosque del Apache National Wildlife Refuge in New Mexico, USA, the first historical record of Sungrebes in the United States.

Migrazione

Specie stanziale

Comportamento

Comportamento migratorio: Specie stanziale.

Conservazione

Tendenza della popolazione: in diminuzione.

Tendenza della popolazione

in diminuzione