In 1879, a small, rotund yellow-green Hawaiian honeycreeper with a fine, short bill was discovered and collected by Finsch on the island of Maui, but this new species was not described until 1893 ( Rothschild 1893a ). In 1888, a very similar-looking bird was found to be common at higher elevations on the island of Läna‘i, and 5 specimens were collected by Wilson, who subsequently described them in 1889 ( Wilson and Evans 1890 , Banko 1979c ). Eventually, it was decided that the birds on Läna‘i and Maui were two subspecies of the same species (Paroreomyza montana; American Ornithologists' Union 1983 ). The Läna‘i birds became known as the nominate subspecies P. m. montana, while the birds on Maui were described as the subspecies P. m. newtoni . Early naturalists referred to them as “creepers,” because of their foraging behavior, but in 1993 the American Ornithologists' Union adopted the traditional Hawaiian name of ‘alauahio (Am. Ornithol. Union American Ornithologists' Union 1993 , American Ornithologists' Union 1998a ).
The Läna‘i ‘Alauahio (pronounced lah-NA-ee ah-lau-ah-HEE-oh) was last sighted in 1937 and is now considered extinct ( Munro 1944a , Hirai 1978a ). Unfortunately, little was recorded of its ecology, although we presume it would have been similar to that of the Maui ‘Alauahio.
At the time of its discovery, the Maui ‘Alauahio (pronounced Mow-ee ah-lau-ah-HEE-oh) was abundant at higher elevations on both east and west Maui. In 1997, it was still one of the most abundant birds in the montane forests of east Maui, but was last reported from west Maui around 1900 and is now considered extirpated from there ( Perkins 1903 , Scott et al. 1986 ). Little was known of the ecology of the Maui ‘Alauahio until an intensive study by HB and PEB began in 1994. Until this time there were only 2 published records of nests, and very little information on any other aspect of their ecology and behavior ( Van Riper 1972 , Berger 1981 ).
Both sexes of adult Maui ‘Alauahio are similar in size and plumage coloration, but most males have brighter yellow plumage on the face and breast than females, and some are slightly larger than females. They do not breed until their third year, and like some other honeycreepers, do not attain full adult plumage for several years ( Morin 1992b , Lepson and Freed 1995 , HB and PEB).
The breeding season begins in late March; most nest building occurs during late April and early May, and is over by August. Maui ‘Alauahio have one of the most interesting social systems of all the Hawaiian honeycreepers: helpers at the nest. If a pair successfully rear young in one year these immature birds will assist at the following year's nest by feeding the female and nestlings. Helpers stay with the family group until the following autumn or winter, and then disperse to find mates in preparation for their first breeding season.
Highly sedentary, both sexes aggressively defend their mutual home range throughout the year. Almost entirely insectivorous, with great agility they glean invertebrates from woody and leafy parts of a wide-variety of plants.
Male Maui ‘Alauahio have a distinctive song that is often given during short display flights. The song may be heard all year round, but is most frequent from April through July, when birds are nesting. The species also makes a loud and often rapidly repeated chip call that may be used to keep in contact with family members, neighboring birds, and to warn of danger, especially while nesting.
Most of the information presented here refers to the Maui ‘Alauahio, and is based on unpublished data collected over a 4 yr period (1994–1997), including data from close monitoring of over 80 nests by HB and PEB.