A sudden decline in the critically endangered southern bent-wing bat population is troubling experts. Approximately 5,000 fewer bats than usual were recorded at Naracoorte’s “bat cave” this summer, a key maternity site in South Australia.
This drop represents a 14-16% decrease from the average peak population of 28,600 adults observed at Naracoorte over the last five years. Nicola Bail, a bat ecologist coordinating the species recovery team at Zoos Victoria, stated that a significant number of adults have been lost, and the cause of this decline is currently unknown.
The southern bent-wing bat, a russet-toned microbat, roosts in caves and forages for insects across south-west Victoria and south-east South Australia. Population counts at the World Heritage listed Naracoorte site date back to the 1960s, when up to 200,000 bats were recorded. Severe declines since then have led to the species being listed as critically endangered.
Possible explanations for the recent decline include habitat clearing, drought, reduced availability of flying insects, or human disturbance at non-breeding caves. Risks such as collisions with wind turbines and the potential introduction of diseases like white-nose syndrome, which has not been detected in Australia, also pose threats to the species.