Ibis dal collo rosso

Identificazione

The red-naped ibis is a large black bird with long legs and a long downcurved bill. The wing feathers and tail are black with blue-green gloss while the neck and body are brown and without gloss. A white patch on the shoulders stands out and the top of the featherless head is a patch of bright red warty skin. The warty patch, technically a caruncle, is a triangular patch with the apex at the crown and the base of the triangle behind the nape that develops in adult birds. The iris is orange red. Both sexes are identical and young birds are browner and initially lack the bare head and crown. The bills and legs are grey but turn reddish during the breeding season. The toes have a fringing membrane and are slightly webbed at the base.<p>They are usually silent but call at dawn and dusk and more often when nesting. The calls are a series of loud braying, squealing screams that descend in loudness. Nocturnal calling is rare and has been observed in urban settings.<p>This species can be confused with the glossy ibis when seen at a distance but the glossy ibis is smaller, more gregarious, associated with wetlands and lacks the white on the wing and has a fully feathered head.

Tassonomia

The species was first given its scientific name by Temminck in 1824. He placed it in the genus Ibis but it was separated into the genus Inocotis created by Reichenbach and this was followed by several major works including the Fauna of British India although the genus Pseudibis in which Hodgson had placed the species had precedence based on the principle of priority. The species included the white-shouldered ibis as a subspecies P. papillosa davisoni from 1970s but that is now treated as a full, although closely related species. The main morphological difference between the two species is seen in the crown and the upper neck. While P. papillosa has a patch of red tubercles on the back of the crown, P. davisoni lacks it. Also, adult P. papillosa have a narrow, bright red mid-crown that becomes broader on the hindcrown, whereas, adult P. davisoni has a bare pale blue middle hindcrown that extends to the upper hindneck and forms a complete collar around the upper neck. Using nuclear and mitochondrial DNA, the species has been placed within the subfamily Threskiornithinae in a clade that includes both New and Old World members.

Nome scientifico

Pseudibis papillosa

Autorità

(Temminck, 1824)

Ordine

Pelecaniformi

Famiglia

Threskiornithidae

Genere

Pseudibis

Areale e habitat

The red-naped ibis is widely distributed in the plains of the Indian Subcontinent. In Rajasthan, it is common along the Aravalli mountains but entirely avoids using the trees on the mountains. The red-naped ibis uses lakes, marshes, riverbeds, irrigated farmlands, dry fallow fields, villages, towns and cities. More wetlands on the landscape attract a greater number of red-naped ibises, but birds forage largely in dry fields increasing use of wetlands for foraging during summer. In semi-arid areas, it is commonly seen in small flocks of 2-4, which could be family groups, with larger groups being relatively rare. Fewer ibises were counted in wetter locations and seasons. <p>It is a common breeding resident in Haryana, Punjab, Rajasthan and the Gangetic plains. It extends into southern India but is not found in the forested regions or the arid zone of the extreme southeast of the peninsula or Sri Lanka. In lowland Nepal, most foraging red-naped ibis were seen in agricultural fields, but most nests were seen in forests. Red-naped ibis commonly use villages, towns and mega-cities seeking food, nesting and roosting. <p>The red-naped ibis is largely diurnal in its foraging and other activities, at night roosting communally on trees or on islands. Nocturnal activities such as loud calling is rare.

Migrazione

Resident species

Conservazione

The species has declined greatly in Pakistan due to hunting and habitat loss. The species has been largely unaffected in India and they are traditionally tolerated by farmers and people in cities. DDT levels in blood plasma was 19 ng/mL in red-naped ibis - the lowest among 13 bird species sampled in a project in India. <p>Estimates of population density of red-naped are mostly derived from volunteer counts at wetlands. These estimates are not useful since the majority of red-naped ibis populations use upland and more dry habitats. The only robust field-based monitoring exercise for the species conservatively provides the population estimate at 20,81,800 (95% CI: 17,45,340 - 25,41,460), and this makes the red-naped ibis among the most populous endemic waterbird species anywhere. The widely varying seasonal numbers of the species makes it a challenging species to monitor. Though most ibises forage in upland and other dry habitats, more of them occur in places with more wetlands on the landscape. Red-naped ibis do not appear to have preferences for particular sized wetlands, thought having a few large wetlands on the landscape benefits populations in semi-arid areas where all the smaller wetlands dry up in the summer. <p>Studies in urban areas are showing the ability of Red-naped ibis to exploit city-based foods, and nest on artificial structures such as lighting poles even if these are located in busy marketplaces. Red-naped ibises may be benefitting from expanding urban areas as long as urban greening continues to provide them with nesting trees, especially in arid and semi-arid areas where tall trees for nesting are sparse on the countryside, and people continue not to persecute the birds. Expanding cereal agriculture has led to decline of trees across large areas, but red-naped ibis continue to proliferate in such areas using artificial nesting substrates such as electricity powerline towers and cell phone towers. The studies collectively suggest that the red-naped ibis may be increasing in numbers due to their behavioural plasticity, especially their ability to use a range of human-modified habitats and areas. <p>A few zoos including the ones at Frankfurt, Singapore (Jurong park) have successfully bred the species in captivity. An individual lived in captivity at Berlin zoo for 30 years.

Tendenza della popolazione

declining