Home-range, habitat use and diet of the Tasmanian Masked Owl Tyto novaehollandiae castanops

Abstract

Estimates of home-range are reported for the Tasmanian Masked Owl Tyto novaehollandiae castanops using radio-telemetry in a modified agricultural land–forest landscape in south-eastern Tasmania. Home-range sizes for two female Owls were 1991 ha and 1896 ha using the Minimum Convex Polygon method, and 2507 ha and 2320 ha, respectively, using the Kernel Estimator method. The 50% isopleth Kernel estimated a core area of 174 ha and 309 ha for each Owl, respectively. Both Owls used two core areas within their home-range reflecting frequent foraging and roosting sites. The location and configuration of the home-ranges within the landscape, and areas of core use, suggest that Masked Owls are responding to geomorphology, heterogeneity of forest patches, forest structure and abundance and accessibility of prey. Both Owls preferentially foraged at forest edges, riparian zones and small forest patches. Frequently used foraging locations were in open forest with minimal understorey vegetation and a pasture groundcover, which probably reflects increased prey abundance, diversity and accessibility in this habitat type. The diet of both Owls was dominated by locally abundant native and introduced ground-dwelling eutherian mammals and marsupials. The strong association with riparian zones of both Owls in this study highlights the potential importance of retaining streamside vegetation to the conservation of the Tasmanian Masked Owl.