Lesser Hawaii Akialoa (Hemignathus obscurus)
The Lesser Hawaii Akialoa, so named for the fact that there was yet another closely related, but not yet described species occurred sympatrically on the island of Hawai’i, reached a size of about 17 cm, it was mainly olive-green, the sexes were quite similar. The bird had a somewhat elongated and down-curved beak.
The bird inhabited probably all sorts of native forest, and used its beak to probe the bark of the trees for hidden insects and spiders, but sometimes took nectar from flowers, especially from the ‘ohia lehua (Metrosideros polymorpha Gaudich.).
The clutch consisted, as in most ‘drepanidid birds’, of just one or two eggs. Thus, the reproduction rate was very low and the birds were incapable to compensate larger losses which happened after the introduction of cats and rats to the Hawai’i Islands. The reasons for the extinction of this wonderful bird are the same as for all extinct ‘drepanidine‘ finches: habitat loss, alteration of the remaining habitat, introduction of cats and rats, introduction of deadly bird diseases, and – last but not least – the incredible incompetence of the Hawaiian government to save their unique wildlife!
The Lesser Hawaii Akialoa is mentioned for the first time by Captain James Cook in 1979 in a text passage that gives an overview of the birdlife (also described for the first time) the crew of his ships met with on the island of Hawaii.:
“The birds of these islands are as beautiful as any we have seen during the voyage, and are numerous, though not various. There are four, which seem to belong to the trochili, or honey-suckers of Linnaeus; one of which is something larger than a bullfinch; its colour is a fine glossy black, the rump-vent and thighs a deep yellow. It is called by the natives hoohoo [Drepanis pacifica]. Another is of an exceeding bright scarlet colour; the wings black, and edged with white; and the tail black; its native name is eeeeve [Drepanis coccinea]. A third, which seems to be eighter a young bird, or a variety of the foregoing, is variegated with red, brown, and yellow. The fourth is entirely green, with a tinge of yellow, and is called akaiearooa [Hemignathus obscura].There is a species of thrush, with a grey breast [Myadestes obscurus]; and a small bird of the flycatcher kind [Chasiempis sandwichensis]; a rail, with very short wings and no tail, which, on that account, we named rallus ecaudatus [Zapornia sandwichensis]. Ravens are found here, but they are very scarce; their colour is dark brown, inclining to black; and their note is different from the European [Corvus hawaiiensis]. Here are to small birds, both of one genus, that are very common; one is red, and generally seen about the cocoa-nut trees, particularly when they are in flower, from whence it seems to derive great part of its subsistence [Himatione sanguinea]; the other is green [Hemignathus virens (?)]; the tongues of both are long and ciliated, or fringed at the tip. A bird with a yellow head, which, from the structure of its beak, we called a parroquet, is likewise very common. It, however, by no means belongs to that tribe, but greatly resembles the lexia flavicans, or yellowish cross-bill of Linnaeus [Psittirostra psittacea]. Here are also owls [Asio flammeus ssp. sandwichensis], plovers of two sorts, one very like the whistling plover of Europe; a large white pigeon [?]; a bird with a long tail, whose colour is black, the vent and feathers under the wing (which is much longer than is usually seen in the generality of birds, except the birds of paradise) are yellow [Moho nobilis]; and the common water or darker hen [Fulica alai].” 
 The three voyages of Captain James Cook round the world. Complete in seven volumes. London: printed for Longman, Hurst, Rees, Orme, and Brown, Paternoster Row 1821
 R. C. L. Perkins: Notes on Collecting in Kona. The Ibis 6(5): 101-111. 1893
 D. Luther: Die ausgestorbenen Vögel der Welt. Westarp Wissenschaften 1986
 H. D. Pratt; P. L. Bruner; D. G. Berrett: A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton University Press 1987
 E. Fuller: Extinct Birds. Penguin Books (England) 1987
 H. D. Pratt: The Hawaiian Honeycreepers: Drepanidinae. Oxford Univ. Pr. 2005