Huia ( Heteralocha acutirostris : Callaeidae)-like sexual bill dimorphism in some birds of paradise (Paradisaeidae) and its significance | Notornis and Birds New Zealand

摘要

The rare reversed sexual bill dimorphism of the extinct New Zealand endemic bird species, the Huia (Heteralocha acutirostris: Callaeidae) occurs in two Australian riflebird (Ptiloris) and three New Guinea sicklebill (Epimachus [Drepanornis]) birds of paradise (Paradisaeidae). While less extreme than that of the Huia, the female bill length proportionate to tarsus length is 7-18% longer than in males. In this proportionate bill length, females are longer-billed than males in most typical (polygynous) birds of paradise. More marked examples of reversed sexual hill dimorphism in the Paradisaeidae occur in species with greater proportions of wood-dwelling arthropods in their diets. Ecological studies of these species might provide insights into the way Huia lived and how their bill dimorphism evolved.