Occupancy patterns of an apex avian predator across a forest landscape

Abstract

Apex predators are integral parts of every ecosystem, having top-down roles in food web mainte-nance. Understanding the environmental and habitat characteristics associated with predator occurrence is para-mount to conservation efforts. However, detecting top order predators can be difficult due to small populationsizes and cryptic behaviour. The endangered Tasmanian masked owl (Tyto novaehollandiae castanops) is a noctur-nal predator with a distribution understood to be associated with high mature forest cover at broad scales. Withthe aim to gather monitoring data to inform future conservation effort, we trialled an occupancy survey design tomodel masked owl occurrence across~800 km2in the Tasmanian Southern Forests. We conducted 662 visits toassess masked owl occupancy at 160 sites during July–September 2018. Masked owl site occupancy was 12%,and estimated detectability was 0.26 ( 0.06 SE). Cumulative detection probability of masked owls over four vis-its was 0.7. Occupancy modelling suggested owls were more likely to be detected when mean prey count washigher. However, low detection rates hindered the development of confident occupancy predictions. To informeffective conservation of the endangered Tasmanian masked owl, there is a need to develop novel survey tech-niques that better account for the ecology of this rare, wide-ranging and cryptic predator. We discuss the poten-tial to combine novel census approaches that exploit different aspects of masked owl ecology to obtain morerobust and detailed data Show more