Family CHIONIDAE Lesson, 1828

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Introduction

This family comprises one genus, with two species, in turn represented by five ultrataxa. In Australian territories there is a single species represented by one subspecies. Chionid distribution is restricted to southern islands of the subantarctic. The characteristic stance and habits of the species is reminiscent of the pigeon and they seldom fly any great distance. Body colour is singularly white, with the legs and beak bluish grey or pink, portraying their lifestyle in a cold environment. The sexes show no sexual dimorphism.

Sheathbills are well dispersed throughout the shorelines of the subantarctic islands where they feed among penguin colonies and other colonial nesting birds or among congregations of mammals. They are gregarious and mostly silent. The chionids are omnivorous, feeding not only on small animal life along the shoreline but taking eggs and cleaning away offal or the remains of dead wildlife.

The nest is a scrape or depression amongst rocks, in crevices and under boulders at ground level. The pyriform eggs usually number two to four per clutch; they have a brown base colour and are marked by dark grey or black flecking; young are semi-precocial, nidifugous and ptilopaedic.

History of changes