Gura di Victoria

Identificazione

The Victoria crowned pigeon is a deep blue-grey colour with a small, black mask. Its feather crest (the signature feature of crowned pigeons other than their size) is conspicuously white-tipped. On the wing coverts is a row of feathers that are a paler blue-gray with maroon tips. These form a distinct wing bar. The chest is a deep purple-maroon color. As in all crowned pigeons, melanism has been observed. The other two crowned pigeons are somewhat superficially similar, but only the western crowned pigeon overlaps in range with the Victoria species. The Scheepmaker's crowned pigeon does not. In the western species, the crown is more scraggly and hair-like, the chest is a uniform blue-gray and not maroon, and a less distinct wing-bar is present. Both sexes are similar.<p>This species is typically 73 to 75 cm (29 to 30 in) long. Some specimens may exceed a length of 80 cm (31 in) and a weight of 3.5 kg (7.7 lb). It is marginally larger than the two other crowned pigeons on average, at a mean of 2.39 kg (5.3 lb) in adult body mass, thus is considered the largest surviving species of pigeon on Earth. The standard measurements among pigeons on mainland New Guinea are: the wing chord is 36–39 cm (14–15 in), the tail is 27–30.1 cm (10.6–11.9 in), the bill is 3.2–3.5 cm (1.3–1.4 in) and the unfeathered tarsus is 8.5–9.8 cm (3.3–3.9 in).<p>Like other crowned pigeons, this species makes a loud clapping sound when it takes flight. The mating calls of this species are also similar to the other two species of crowned pigeons, consisting of a deep hoota-hoota-hoota-hoota-hoota sound. When defending their territories, these birds make a resounding whup-up, whup-up, whup-up call. Their contact call is a deep, muffled, and rather human-like ummm or hmmm.<p>The two subspecies of the Victoria crowned pigeon are G. v. beccarii found on the mainland of New Guinea and G. v. victoria, the nominate race, found on the islands of Yapen, Biak and Supiori. The nominate subspecies is markedly smaller, with a wing chord measurement of 31.6–33.2 cm (12.4–13.1 in), with less robust legs and feet and darker overall plumage. The nominate has a sparser crest with black on the wing coverts and right above the tail.

Tassonomia

Nome scientifico

Goura victoria

Autorità

(Fraser, 1844)

Ordine

Columbiformi

Famiglia

Columbidae

Genere

Goura

Areale e habitat

The Victoria crowned pigeon is distributed in the lowland and swamp forests of northern New Guinea and surrounding islands. It usually occurs on areas that were former alluvial plains, including sago forests. Though typically found at or near sea level, occasionally birds of this species may venture up in the hills to an elevation up to about 3,000 feet.

Migrazione

Resident species

Comportamento

Like other crowned pigeons, the Victoria crowned pigeon is a gregarious species. They usually travel in pairs or small parties as they search for food. They walk with an unhurried gait along the forest floor. Their food typically consists of fallen fruit. Birds of this species in captivity are particularly fond of eating figs. Seeds and invertebrates may occasionally supplement the diet. When disturbed, these birds fly straight up into the canopy or a large horizontal branch of a large forest tree. After being disturbed, they may remain on their perch for a considerable time engaging in contact calls and flicking their tails. In the wild, this species tends to be shier than the western crowned pigeon, but can still occasionally be quietly approached. The males regularly engage in aggressive displays to establish dominance. In these interactions, the pigeons puff up their chests and repeatedly raise their wings as if preparing to strike their opponent. They also make short dashes at each other and may actually hit one another, but rarely make contact and can be completely peaceful towards other males outside of the early mating season.

Conservazione

Tendenza della popolazione

declining