Reproduction, social behaviour and captive husbandry in the eastern grass owl (Tyto longimembris).

Abstract

The eastern grass owl (Tyto longimembris) has a wide distribution through the Indian sub-continent, southern China, Indonesia, Papua New Guinea and northern and eastern Australia. Despite this broad geographic range it has seldom been studied in the wild and little is known of its reproductive ecology and social behaviour. We studied three nestlings acquired from the wild in 1996, and successfully bred from those birds in the following two years. Breeding commenced at one year of age, with up to three clutches produced in a single breeding season. Clutch size ranged between seven and 10 eggs; incubation commenced after the second egg was laid and lasted 29–31 days. Fertility within clutches varied from 0 to 90% (n=3 clutches, across two years), with clutches laid late in the season having lower fertility. Fledging success varied from 50 to 75% (n=2 clutches, across two years). Evidence of cooperative breeding was observed, with female young of the previous year participating in incubation and chick rearing in the year following their birth.