Becconero di Maui

Identificazione

The Maui parrotbill is one of the larger Hawaiian honeycreepers, measuring 14 centimetres (5.5 in) and with a mass of 20–25 grams (0.71–0.88 oz). The bird is yellow on the breast, cheeks, and belly, olive-green on the wings, crown, tail, and back, and has a bright yellow supercilium. The upper mandible of the bird's beak is hooked and dark gray, while the lower mandible is chisel-like and pale ivory. Males are longer-winged, larger-billed, and heavier than females. Juveniles are gray-green above and light gray ventrally.<p>Its call is a short “chip”, which is similar to the Maui Nui ʻalauahio, chirped every three to five seconds. It song consists of “cheer” notes that are slower and richer than the ʻākepa. It also has a short song that sounds like “cheer-wee”.

Tassonomia

Nome scientifico

Pseudonestor xanthophrys

Autorità

Rothschild, 1893

Ordine

Passeriformi

Famiglia

Fringillidae

Genere

Pseudonestor

Areale e habitat

The Maui parrotbill currently lives only in undisturbed wet forests dominated by ʻōhiʻa lehua (Metrosideros polymorpha) and small patches of ʻōhiʻa-koa (Acacia koa) mesic forest. Its habitat exhibits a dense understory of small trees, shrubs, epiphytes, ferns, and sedges, centered between Puʻu ʻAlaea, Kuhiwa Valley, Lake Waianapanapa, and upper Kīpahulu Valley, an area less than 2,020 hectares (5,000 acres), at elevations of 1,310–2,070 metres (4,300–6,790 ft).

Migrazione

Resident species

Conservazione

The Maui parrotbill's natural habitat is mesic and wet forests. It is threatened by habitat loss. Much of the land in the parrotbill's historic range was changed for agricultural purposes, timber production and animal grazing. Introduced pests, such as mosquitoes, rats, and feral ungulates directly and indirectly affect the parrotbill's survival. Mosquitoes spread avian malaria, which the parrotbill is susceptible to, rats prey upon the birds' eggs and young, and feral pigs uproot the low-lying vegetation that the parrotbill forages in. Pigs additionally create wallows, which serve as breeding grounds for avian malaria-infected mosquitoes.<p>The Maui parrotbill was listed as an endangered species in 1967 under the Endangered Species Preservation Act. It is also part of the Maui-Molokai Bird Recovery Plan in 1984, which led to fencing areas of East Maui and removing feral ungulates. The recovery plan also included a captive breeding program, which produced its first chick in 2003. Field research is primarily done by the Maui Forest Bird Recovery Project.<p>A 2009 survey of the Waikamoi Preserve estimated that there were about 20 birds per square kilometer in the windward preserve near the summit of Haleakala, indicating that the population was holding steady or possibly increasing. A contributing factor is that native shrub cover in Waikamoi has tripled in the past 15 years. A previous study found about half the density. The preserve contains about 25 percent of the population, while most of the rest is in the Hanawi Natural Area Reserve. The birds were once found throughout Maui and Molokai. A 2019 effort is underway to reintroduce Maui parrotbill to leeward Maui, where it had been previously extirpated. However, more recent studies have found that the population in fact dramatically declined after 2001, as climate change has made more of the higher-elevation forests that the kiwikiu inhabits more hospitable to mosquitoes. A translocation effort to a restored area on the leeward slopes of Haleakalā in 2019 failed after most birds succumbed to avian malaria, despite otherwise doing well in the habitat. <p>It has been predicted that if the mosquito population continues increasing, Maui parrotbills may face functional extinction in the wild by 2027. Due to this, there have been several conservation efforts planned by the Maui Forest Bird Working Group, including at least temporarily fostering a sizeable captive population on zoos in the mainland United States (previous ex-situ conservation efforts were limited to only Hawaii), including potentially the National Aviary in Pennsylvania, Smithsonian Conservation Biology Institute in Virginia and the Tracy Aviary in Utah, potentially introduce a wild population to the island of Hawaii as a backup, manage and restore more habitat in Maui for eventual release, develop predator control tools, and perform landscape-scale mosquito control in the bird's native habitat. The captive population will consist of 15 male and 15 female wild birds; removing such a large number of birds from an already-small wild population may accelerate the timeline of the species' possible extinction in the wild, but it can allow for a safe population to be bred in captivity away from avian malaria.

Tendenza della popolazione

declining