Ecology of the Little Black Cormorant, Phalacrocorax sulcirostris, and Little Pied Cormorant, P. melanoleucos, in Inland New South Wales I. Food and Feeding Habits.

Abstract

The food and feeding habits of two species of cormorant were studied on a group of freshwater lakes in inland New South Wales. P. sulcirostris fed mainly on exotic fish (69% of live weight of prey), captured while fishing communally in the deeper waters. P. melanoleucos fed mainly on native decapod crustaceans (60% of prey) captured while fishing individually in the shallow parts of the lakes, and in nearby billabongs and farm dams. P. sulcirostris took larger common carp Carassius auratus, redfin Perca fluviatilis and yabby Cherax destructor than its congener. Seasonal changes in the diet of P. sulcirostris were similar in each year; its major prey, common carp and redfin, were least available during winter and spring, as fry grew too large to be captured and swallowed. Changes in diet of P. melanoleucos were irregular, as the availability of yabby, its major prey, was influenced by the turbidity, level and temperature of water. Seasonal changes in diets of both cormorants were attributed to changes in prey availability, and not changes in food preference. Food of nestlings sometimes differed from that of adults.