Home Range, Habitat and Behaviour of the Masked Owl Tyto novaehollandiae Near Newcastle, New South Wales

Abstract

A 14 month study of a pair of Masked Owls Tyto novaehollandiae in a fragmented mosaic of urban bushland (dry open-forest) near Newcastle found high site-fidelity during two autumn-winter breeding seasons. The birds spent long periods of most nights during May-September 1994 and March-July 1995 in a particular patch of bushland where, by day, they roosted inside the large hollows of old eucalypts. The spectacular aerial courtship display of the male was observed on seven nights during March-July. Breeding did not occur in 1994. Courtship displays occurred earlier in the 1995 season than in 1994 but nesting had not begun by the end of the study in July 1995. The adult female was radio-tagged in September 1994 and tracked for a total of 14 weeks until December 1994. The home range of this bird was estimated as 1017-1178 ha. The presumed breeding area was located on the edge of the non-breeding home range. The radio-tagged owl spent three-quarters of its time at night in bushland or within 100 m either side of the bushland edge and the remainder more than 100 m from any bushland. More than half (59%) of its time was spent within 100 m of ecotones between bushland and open country (e.g. roads and fields) or between bushland and residential areas. The radio-tagged owl spent 82% of its time in, or next to, environments that had been extensively modified by man. During the non-breeding season, it roosted among the dense foliage of several introduced trees occurring on residential properties. The diet of these owls consisted mainly of introduced species of small terrestrial mammals, particularly Rattus rattus, but several birds were also taken.