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Identificazione

The shore plover is brown above and white below, with a black (male) or brown (female) mask. There is a distinctive white strip circling its head below its brown skullcap. Its legs and dark-tipped bill are orange, brighter in males.

Tassonomia

The shore plover was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with the plovers in the genus Charadrius and coined the binomial name Charadrius novaeseelandiae. Gmelin based his description on the "New Zealand plover" that had been described and illustrated in 1785 by the English ornithologist John Latham in his A General Synopsis of Birds. The species had been collected near Queen Charlotte Sound. In the early 2000s the shore plover was moved from the original genus Charadrius to the genus Thinornis, along with the hooded plover. A molecular phylogenetic study published in 2015 found Thinornis was embedded within the genus Charadrius. This was confirmed by another study published in 2022, and as a result the shore plover was moved back to Charadrius. The species is monotypic: no subspecies are recognised.<p>Thinornis rossii, supposedly from the Auckland Islands, is now generally considered to be a juvenile shore plover with an incorrectly recorded location. Some authorities consider the shore plover a species of Charadrius, and further genetic evidence will be needed to resolve the issue.

Nome scientifico

Thinornis novaeseelandiae

Autorità

Gmelin, JF, 1789

Ordine

Caradriformi

Famiglia

Caradriidi

Genere

Thinornis

Areale e habitat

Although this species was historically found only on the New Zealand coast, subfossil shore plover bones have been recovered from roosts of the extinct laughing owl near rivers many kilometres inland. Cook's second expedition collected them from opposite ends of the South Island, in Fiordland and the Marlborough Sounds. There are 19th century reports of shore plovers from the South Island and several parts of the North Island, but by the 1870s they had vanished from the mainland, surviving only on the Chatham Islands. Introduced predators such as feral cats and Norway rats were the main culprits.

Migrazione

Resident species

Conservazione

Shore plovers are endangered, with a world population of around 200 birds. The species survived on only one island, Rangatira, in the Chatham Islands, from where it has since been introduced to other offshore islands, such as Mangere Island in the Chathams, Mana Island near Wellington and Motutapu near Auckland. The world population was roughly 70 breeding pairs in 1937 and their habitat was declared a reserve in 1954. The population fluctuated in the 1980s, with only 40 breeding pairs in 1982, rising to 80 pairs in 1987 and a high of 94 pairs in 2010. A second wild population of about 20 birds was discovered in 1999 living on Western Reef off Chatham Island, but it gradually declined, and the last bird was taken into captivity in 2003. As of 2016, the wild population comprised 66 breeding pairs, 56 of them in the Chatham Islands. DOC has a stated goal of increasing the population to 250 in five different habitats.<p>DOC moved a number of captive-reared juveniles to Mana Island, off Wellington's western coast, between March and May 2007. They bred within months of their arrival, and in February 2008 twenty more were translocated. From a high of 87 individuals, the population was reduced to just 10 from the effects of a single Norway rat.<p>Birds had also been translocated since 2000 to Waikawa (Portland Island), a privately owned island off the Māhia Peninsula in Hawke's Bay. In 2012, the population on Waikawa was discovered to have crashed by 75% to just 20 birds, apparently due to predation by a Norway rat. Twelve eggs were rescued for translocation to Mana Island.<p>A total of 42 captive-bred shore plovers were released onto Motutapu Island in 2012 in the hope they would become established there and on other pest-free islands in the Hauraki Gulf. The birds repeatedly flew away, and only five were still present in 2015 when nineteen more were released. Motutapu had its mammalian predators removed in 2010, and the breeding population there increased from one pair in 2015 to three pairs in 2016. These birds are currently the most accessible to the public.<p>Six juveniles were released into the wild in 2018. Four additional juveniles were released in February 2019 with a further 21 due to be released on 25 March, having been bred at the Pūkaha National Wildlife Centre. Five more juvenile birds were transported from a captive breeding program in Christchurch to Mana Island in April 2020.

Tendenza della popolazione

rising