Food and Feeding Range of the Australasian Gannet Morus serrator (Gray)

Abstract

Regurgitations analysed over three seasons (1978-80) indicated that Pilchards Sardinops neopilchardus, both numerically and by weight, were the most common prey species of the Australasian Gannet at Motukaramarama. The next most common species were: numerically, Anchovies Engraulis australis and by weight, Jack Mackerel Trachurus novaeselandiae. It is thought that relative abundance of prey analysed reflects their abundance. Prey between 11-20 cm comprised 77% of the Gannet's diet.

A further two prey species: Sprat Sprattus antipodum and Kahawai Arripis trutta were recorded, bringing the known food of the Gannet to 15 species.

The average adult Gannet regurgitated food equal to 11% of its body weight (or 259 g and 2,000 Kj), whereas the average daily energy requirements were estimated at 2,844 Kj/day, or 353 g of food.

An average feeding range of 268 km (range = 86-450 km) was estimated from the time adults spent away from the colony, resighting of marked birds and from recoveries of banded, breeding adults.