Pinguino minore

Identificazione

Like those of all penguins, the wings of Eudyptula species have developed into flippers used for swimming. <p>Eudyptula species typically grow to between 30 and 33 cm (12 and 13 in) tall and on average weigh 1.5 kg (3.3 lb). The head and upper parts are blue in colour, with slate-grey ear coverts fading to white underneath, from the chin to the belly. Their flippers are blue in colour. The dark grey-black beak is 3–4 cm long, the irises pale silvery- or bluish-grey or hazel, and the feet pink above with black soles and webbing. An immature individual will have a shorter bill and lighter upperparts.<p>Like most seabirds, the Eudyptula species have a long lifespan. The average for the species is 6.5 years, but flipper ringing experiments show that in very exceptional cases they may live up to 25 years in captivity.<p>Eudyptula minor does not have the distinct bright blue feathers that distinguish Eudyptula novaehollandiae. In addition, the vocalisation patterns of the New Zealand lineage located on Tiritiri Matangi Island vary from the Australian lineage located in Oamaru. Females are known to prefer the local call of the New Zealand lineage.<p>There are also behavioural differences that help differentiate these penguins. Those of the Australian lineage will swim together in a large group after dusk and walk along the shore to reach their nesting sites. This may be an effective predator avoidance strategy by traveling in a large group simultaneously. This has not been seen by those of the New Zealand lineage. Eudyptula minor only recently encountered terrestrial vertebrate predators, while Eudyptula novaehollandiae would have had to deal with carnivorous marsupials.<p>Australian Eudyptula novaehollandiae have been observed to double brood. Birds will double brood by laying a second clutch of eggs after the first has fledged to increase their reproductive success. They may also do this due to the increasing sea surface temperatures and changing sources of food that are available. This behaviour has also been observed in the Otago population, indicating this may be genetically-mediated behaviour in the populations of Australian lineage.

Tassonomia

The little penguin was first described by German naturalist Johann Reinhold Forster in 1781. Several subspecies are known, but a precise classification of these is still a matter of dispute. The holotypes of the subspecies E. m. variabilis and Eudyptula minor chathamensis are in the collection of the Museum of New Zealand Te Papa Tongarewa. The white-flippered penguin (E. m. albosignata or E. m. minor morpha albosignata) is currently considered by most taxonomists to be a colour morph or subspecies of Eudyptula minor. In 2008, Shirihai treated the little penguin and white-flippered penguin as allospecies. However, as of 2012, the IUCN and BirdLife International consider the white-flippered penguin to be a subspecies or morph of the little penguin.<p>Little penguins from New Zealand and Australia were once considered to be the same species, called Eudyptula minor. Analysis of mtDNA in 2002 revealed two clades in Eudyptula: one containing little penguins of New Zealand's North Island, Cook Strait and Chatham Island, as well as the white-flippered penguin, and a second containing little penguins of Australia and the Otago region of New Zealand. Preliminary analysis of braying calls and cluster analysis of morphometrics partially supported these results. A 2016 study described the Australian little penguin as a new and separate species, Eudyptula novaehollandiae. E. minor is endemic to New Zealand, while E. novaehollandiae is found in Australia and Otago. A 2019 study supported the recognition of E. minor and E. novaehollandiae as separate species.

Nome scientifico

Eudyptula minor

Autorità

(Forster, JR, 1781)

Ordine

Sfenisciformi

Famiglia

Spheniscidae

Genere

Eudyptula

Areale e habitat

Eudyptula minor breeds along most of the coastline of New Zealand, including the Chatham Islands. However, Eudyptula minor does not occur in Otago, which is located on the east coast of New Zealand's South Island. The Australian species Eudyptula novaehollandiae occurs in Otago. E. novaehollandiae was originally endemic to Australia. Using ancient-DNA analysis and radiocarbon dating using historical, pre-human, as well as archaeological Eudyptula remains, the arrival of the Australian species in New Zealand was determined to have occurred roughly between AD 1500 and 1900. When the E. minor population declined in New Zealand, it left a genetic opening for E. novaehollandiae. The decrease of E. minor was most likely due to anthropogenic effects, such as being hunted by humans as well as introduced predators, including dogs brought from overseas.<p>It has been determined that the population of Eudyptula novaehollandiae in Otago arrived even more recently than previously estimated due to mulitlocus coalescent analyses.<p>Overall, little penguin populations in New Zealand have been decreasing. Some colonies have become extinct, and others continue to be at risk. Some new colonies have been established in urban areas. The species is not considered endangered in New Zealand, with the exception of the white-flippered subspecies found only on Banks Peninsula and nearby Motunau Island. Since the 1960s, the mainland population has declined by 60-70%; though a small increase has occurred on Motunau Island. A colony exists in Wellington Harbor on Matiu / Somes Island.

Migrazione

Resident species

Comportamento

Little penguins feed by hunting small clupeoid fish, cephalopods, and crustaceans, for which they travel and dive quite extensively including to the sea floor. Important little penguin prey items include arrow squid, slender sprat, Graham's gudgeon, red cod, and ahuru.

Conservazione

Eudyptula species are classified as "at risk - declining" under New Zealand's Wildlife Act 1953.

Tendenza della popolazione

stable