Measurement of roost entrance activity of Pilbara leaf-nosed bats (Rhinonicteris aurantia) using passive integrated transponder tags

Abstract

Until recently, little was known about the ecology, foraging patterns and regional movement of the Pilbara leaf-nosed bat (Rhinonicteris aurantia, Pilbara form). Its only known permanent diurnal roosts are in deep caves or disused underground mines that offer a very specific microclimate. There are few suitable roosts and, as a result, the Pilbara form of this species is under pressure from development and mining and is listed under Commonwealth and State legislation as a vulnerable mammal. In 2017 a recording system was installed at the permanent Ratty Spring Roost near Paraburdoo, and 18 adult bats (11 males and 7 females) were fitted with passive integrated transponder (PIT) tags. The roost entrance activity of the bats was then monitored for over two years and the movement patterns of the bats were recorded. Variations in timing of first departures after dusk, last arrivals before dawn, total time out of the roost, the number of foraging bouts out of the roost and the number of exit and re-entry pairs on a nightly, monthly and seasonal basis were determined for the colony and for both males and females separately. This is the first activity data collected from individuals of this conservation-significant species at its roost cave entrances.