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RESEARCH ARTICLE
Contents Vol 33(1)

Change in the diet of sooty owls (Tyto tenebricosa) since European settlement: from terrestrial to arboreal prey and increased overlap with powerful owls

Rohan J. Bilney A , Raylene Cooke A B and John White A
+ Author Affiliations
- Author Affiliations

A School of Life & Environmental Sciences, Deakin University, 221 Burwood Highway, Burwood, Vic. 3125, Australia.

B Corresponding author. Email: raylene.cooke@deakin.edu.au

Wildlife Research 33(1) 17-24 https://doi.org/10.1071/WR04128
Submitted: 20 December 2004  Accepted: 29 November 2005   Published: 7 March 2006

Abstract

The current diet of the sooty owl (Tyto tenebricosa) was determined by analysing freshly regurgitated pellets collected beneath their roosting sites in East Gippsland, Victoria. Comparisons were then made with: (i) prehistoric and historic diet from bone deposits found in cave roosts, and (ii) diet of a sympatric owl species, the powerful owl (Ninox strenua). Sooty owls consumed a large array of terrestrial mammal species before European settlement, but only three terrestrial species were detected in their current diet, a reduction of at least eight species since European settlement. To compensate, sooty owls have increased their consumption of arboreal prey from 55% to 81% of their diet. Arboreal species are also a major component of the powerful owl diet and this prey shift by sooty owls has increased dietary overlap between these two species. Predation by foxes (Vulpes vulpes) and other feral species is likely to have reduced the amount of terrestrial prey available to sooty owls since European settlement. Investigation of changes in the diet of sooty owls may offer a unique monitoring system for evaluating the ability of fox-control strategies to influence increases in numbers of critical-weight-range mammals.


Acknowledgments

We thank Andy Murray for information and advice on fox-baiting strategies in the study area. Bill Peel and John Burns are thanked for advice on rainforest locations and Ken Aplin is thanked for his assistance with historical bone identification. Julie and Bob Hollingsworth are also thanked for providing information on the Nicholson River powerful owls and the Goldsmith family for giving permission to access their property. Roger, Carolyn and Adam Bilney, Rob Grant, Fiona Hogan, Peter Kambouris and David Hollands are thanked for support in the field and the advice they so willingly provided. This research was undertaken with permits 10002313 and 10002809 from the Department of Sustainability and Environment.


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