It is one of four remaining finch-billed Hawaiian honeycreepers and is closely related to the smaller Nihoa finch.

It is almost impossible to confuse the Laysan finch with any other bird in the field as it is the only passerine species found on the few islands it lives on.

The fossil record shows that the finch once had a greater range in Hawaiʻi, reaching as far as Oʻahu, and that birds on Laysan represent a relict population.

They actively take the eggs of smaller seabirds such as those of white tern (Gygis alba) and the endemic Laysan duck (Anas laysanensis).

[2] The birds also suffered a loss of heterozygosity following founding events on other islands which may have caused an accumulation of deleterious recessive alleles in the populations.