Lanai Hookbill

The Lānaʻi hookbill is only known to have eaten the fruit of the ōpuhe. The type specimen was caught while feeding on the plant, and its berries were subsequently discovered in its stomach. It is considered likely that the hookbill additionally ate ʻakoko fruits due to their similarity in size and shape to those of the ōpuhe. However, the hookbill's unique bill is considered unlikely to have evolved if the species was purely frugivorous, and it has been suggested that the hookbill specialized in eating snails. The species was very active while searching for food, constantly flying from tree to tree. While perched it shifted restlessly. Based upon the structure of the bill, it has been suggested that this unique bill was used as a pincer, with the tips of both mandibles touching. The hookbill could have used this movement to pluck fruits or flowers for consumption, or it may have been used to extract snails from their shells. It is also possible that the bird could have crushed a snail shell between its mandibles and then used its tongue to ingest the meat and expel the shell out of the open sides of the beak. There is no recorded information on the Lānaʻi hookbill's breeding behavior. However, the other Hawaiian honeycreepers are remarkably uniform in their breeding behavior, and it is therefore likely that the hookbills also bred from early winter through the end of summer in August, with pair bonding being completed by January or February. The males likely defended a territory that moved along with his bonded female and became a centered around the nest after the female constructed it. It is hypothesized that the hookbill laid two to three eggs and that its young were altricial.

The Lānaʻi hookbill was endemic to the island of Lānaʻi in Hawaii. All recorded sightings of the species were made from the southwestern end of Lānaʻi's forests, which included the Kaiholena Valley and Waiakeakua. These sightings were between 2,000 and 2,600 feet (610 and 790 m) in elevation. However, the species' habitat once covered thousands of acres on Lānaʻi, and it is possible that the species once had a broader range on the island. The species was non-migratory. It is believed that the Lānaʻi hookbill inhabited montane dry forests on Lānaʻi dominated by ʻakoko (Euphorbia species) and ōpuhe (Urera glabra). The unique shape of the hookbill's bill, particularly when compared with the ʻōʻū's bill, and its apparent rarity suggested that the species was an extreme specialist and was therefore restricted to this habitat.

Historically, the hookbill was only recorded three times. All three sightings were made by George C. Munro; the first was when he collected a single bird on February 22, 1913, and the other two sightings came on March 16, 1916 and August 12, 1918. The only existing specimen is in the Bernice P. Bishop Museum in Honolulu. The species was not recorded by the native Hawaiians. The fact that Munro, an excellent observer who spent years on Lānaʻi, only saw the bird three times implies that it was already very rare by the 1910s. From 1900 to 1940 nearly all of Lānaʻi's forests were converted into pineapple fields. This conversion reduced the area of the hookbill's potential habitat, and is believed to be the biggest contributor to the species' extinction. It has also been suggested that avian malaria, which began affecting Lānaʻi's birds in the 1920s, may have contributed to the species' decline. Likewise, the introduction of feral cats and rats to Lānaʻi may have led to a decline in the hookbill's population. The extinction of local snails through human intervention could also have led to the Lānaʻi hookbill's extinction.