Roost site selection by southern forest bat Vespadelus regulus and Gould’s long-eared bat Nyctophilus gouldi in logged jarrah forests; south-western Australia

Abstract

Informationonroostingrequirementsandresponsestoforestmanagementisintegraltoeffectivelyconserveandmanagebatpopulations.Treehollowsareespeciallyimportantforroostingbatsgiventhelong time taken for hollows to form. We used radiotelemetry to compare roost site selection in two species, Vespadelus regulus and Nyctophilus gouldi, in logged jarrah forests of south-western Australia. We comparedcharacteristicsofroosttreesandforeststructurearoundroosttrees(n=48)withrandomlylocated plots at a local roost tree level (n=90) in February and March 2009. For landscape features, we compared roost trees with randomly selected trees in the broader landscape that had cavities or exfoliating bark (n=204). V. regulus roosted solely in hollows that were located predominantly in contemporarily unlogged buffers and mature forest while N. gouldi used a broader range of roost types, located in contemporarilyunloggedbuffersandmatureforestandinretainedhabitattreesingapreleaseandshelterwood creation silvicultural treatments. In contrast with N. gouldi, which selected hollows or crevices underbarknearthegroundandclosetovegetation,V.regulususedhollowsthatwerehighaboveground and had little surrounding vegetation. Both species preferred large trees, in intermediate or advanced stages of decay and crown senescence. Bats changed roosts frequently, with short distances between subsequent roosts, suggesting a degree of spatial fidelity. Contemporarily unlogged buffers and mature forestcontainedhigherdensitiesoftreeswithhollowsthangapreleaseandshelterwoodcreationareas, potentiallyprovidingmorealternatebatroosts.Ourresultsdemonstratetheimportanceofmatureforest and unlogged buffers as bat roost sites in logged jarrah forests of south-western Australia, but the area of old forest required by these and co-occurring bat species remains to be determined.