Wikipedia
The akepa (Loxops sp.) are a group of one of the smallest Hawaiian forest birds, at four inches long and weighing 10 grams. They are placed in the genus Loxops. Previously considered the same taxa, the group was split into distinct species by the NACC of the AOU in 2015. Found only in high elevation old growth rainforest, these nonmigratory passerines have rounded heads, black eyes, and black wings and tail. Adult males sport one of the most brilliant orange colors found in any bird, a plumage which takes four years to develop. Females are greenish gray on back, lighter gray on front, with varying amounts of yellow and sometimes pale orange on the breast and belly. Juveniles appear similar to females, though are generally duller in color.
All akepa have an unusual cross-bill. When closed, the upper bill tip slightly overlaps the lower bill tip to one side (this cannot be seen in the field). When opening the bill, as in prying open leaf buds to extract small caterpillars, the bills swing dramatically sideways, and this is easily seen in the hand. Some birds cross one way, and some the other, apparently randomly. The akepa cross-bill operates similarly to that in the North American crossbills (genus Loxia), but is much less obvious when the bill is closed.
Akepa are usually found from 1,500 to 2,200 meters above sea level. They are non-territorial, and group male displays have often been observed in the beginning of the breeding season. They participate in mixed-species flocks during the non-breeding season. They are highly endangered. Akepa is a Hawaiian term meaning "agile", befitting their active foraging at branch tips.