Poo-uli

Its diet consisted mostly of snails, insects, and spiders and it nested in native ‘ōhi‘a lehua (Metrosideros polymorpha) forests.

In the past, according to fossil records, it seems that the bird lived on the dry half of the island of Maui, across southwestern slope of Haleakalā at altitudes of 275–1,350 metres (902–4,429 ft). Fossil show that the Po'ouli once lived on Maui at low elevations in dry/mesic habitats on a likely diet of native tree snails and insects. The arrival of lethal mosquito-borne avian malaria in Hawaii exterminated low elevation Po'ouli forcing a population shift to mountain rainforests and possibly a snail diet instead of insects. When the species was first discovered, 100–200 poʻo-uli were estimated to exist. There were only 76 birds per km. By 1981, there were only 15 birds per km. By 1985, there were only 8 per km. That meant that from 1975, when it was first discovered, to 1985, only ten years later, the population had dropped by over 90 percent. In the 1980s, the poʻo-uli disappeared from the easternmost part of its range and was only found in the western branch of the Hanawi Stream. To preserve the poʻo-uli and other endangered fauna and flora, the State of Hawaii established the 9,500-acre (38 km) Hanawi Natural Area Reserve. This connected several protected areas to make one larger protective area. This protection effort was only possible due to the work of several groups: the government, Maui County, the National Park Service, The Nature Conservancy, and several private companies. The land was fenced off and by June 1996 they began to clear out the pigs from the closed areas. Four years and 202 pigs later, the poʻo-uli pen was completely cleared of pigs. As more pigs were removed from the other two pens, the population of native species that lived there, e.g. the Maui parrotbill and ʻākohekohe, rose slightly faster than they otherwise would have. Rats, cats, and goats were still being removed from the poʻo-uli pen. By 1997, only three individuals were known to exist. These had home ranges within the Hanawi Natural Area Reserve and the adjacent Haleakala National Park. In 2002, one of these, a female, was captured and taken to a male's home range in an attempt to get them to breed. The female, however, had flown back to her own territory, which was 1.5 miles (2.4 km) away, by the next day. There was also a ten-day expedition in 2004. The goal of this was to capture all three birds and bring them to a bird conservation center on the island, in the hope they would produce offspring. On September 9, 2004, one of the remaining birds, a male, was captured and taken to the Maui Bird Conservation Center in Olinda, in an attempt to breed the bird in captivity. However, biologists could not find a mate for the male before it died on November 26, 2004. It is uncertain whether the other two birds that remained at the time were a male and female, or both the same sex. Since 2004, extensive surveys failed to locate these or other individuals of this species, indicating a possible extinction. However, it remained listed as critically endangered by BirdLife International (and thereby the IUCN) until additional surveys had confirmed its extinction beyond reasonable doubt. Tissue samples were taken from the male captured in 2004 for possible future cloning. The dramatic population decline has been attributed to a number of factors, including habitat loss, mosquito-borne diseases, predation by pigs, rats, cats, and small Asian mongooses, and a decline in the native tree snails that the poʻouli relied on for food. In 2019, after continued habitat degradation, presence of disease and invasive species, and a long period with no sightings, the IUCN classified this bird as Extinct.