Physiological correlates of habitat selection in Australian cormorants.

Abstract

The relation of habitat and food preferences to relative size of the nasal salt glands and adrenal glands in 5 Australian cormorant species has been investigated. The diet of the Little Pied Cormorant in particular differs in the marine/estuarine and fresh-water habitats. The mean relative nasal gland size of both Black and Little Pied Cormorants is significantly different in these contrasting habitats, while other species show apparently consistent trends. Within species there is no significant correlation of relative adrenal size with relative nasal salt gland size. Implications of the data in relation to population movement and the hormonal regulation of extrarenal excretion are discussed.