Hawaiian honeycreepers (birds), consisting of 50 species, some of which are now extinct, represent a much more diverse lineage than hawaiian thrushes. honeycreepers have a remarkable variation in bill morphology, whereas hawaiian thrushes exhibit far less morphological variation. bill morphology is strongly linked to the resources available for these birds to eat. this suggests that in honeycreepers may have occurred as a result of

a) sexual dimorphism: leksb) allopatric speciation; hybrid zonesc) sexual selection; monogamous pair bondsd) adaptive radiation; dietary specializatione) adaptive radiation; poor dispersal ability