Establishing a captive flock of the Nihoa shouldd some calamity befall their present habitat. A typical songbird the male has a yellow throat and breast, while females have brownish with faint greenish yellow breasts. A clutch of 3 eggs at one season. Male Laysan finches have grayish-brown backs and rumps, gray collars, whitish bellies, and bright yellow heads, throats, and breasts. Adult females have darkly streaked crowns, some streaking on the flanks, a gray collar, yellowish throat and breast, and dark brown spots on the back.
Adult plumage is attained in the third year.
In general in the molt sequence the amount of yellow increases with age in both sexes, and males gradually lose their spots. However, with experience, it is possible to age and sex the bids with a high degree of accuracy according to the plumage characters. Males are slightly longer in wing and tail measurements than females, and bill dimensions and weights are greater. Also this song has been said to have a calear metallic note. The laysan finch is a non-migratory bird.