The presence of several important bat species has been confirmed in the Mapungubwe National Park in the north of South Africa, using acoustic detection.

According to Prof Dan Parker from the School of Biology and Environmental Sciences at the University of Mpumalanga bats are an extremely under-studied group of mammals.

“They are also very hard to study and so assessing their diversity and species richness in a key national park is important,” he told the FBIP.

The study highlights the important role acoustic detection has to play in bat diversity assessments as 13 out of 22 species known from the region were positively identified.

In addition, the approach detected four to potentially seven species which have not been collected as museum specimens from the area and there is at least one species recorded acoustically which appears to be new to science (Rhinolophus sp. 100 kHz).

The study was published in the journal Mammalia and formed part of a study funded by the Foundational Biodiversity Information Programme.

Bat echolocation

There are approximately 900 species of bats globally and more than half of them rely on the use of sound to navigate (i.e. echolocation) to detect obstacles in flight, find their way into roosts, and forage for food.

Echolocation is the active use of sonar (sound, navigation, and ranging) along with special physical features and physiological adaptations which allow bats to “see” with sound.

Bat experts like Prof Dan Parker use acoustic detectors to detect the presence of bats by converting their ultrasound signals to audible frequencies usually in the range of about 15 kHz to 125 kHz.

In many cases bat calls are unique to particular species, though there are cases of overlap where it is difficult to differentiate between species. In these cases additional methods like live capture of specimens for identification is needed.

Capture myopathy

Historically, studies of bat species richness and overall community structure in Africa have relied heavily on the ‘live-capture’ of specimens to infer diversity.

“This is significant because when only using live-capture to assess the species richness of bats, species may be missed and it may be difficult to detect rare species,” the authors said.

Additionally, the use of acoustic detectors avoids the necessity for handling the relatively small mammals that can suffer from capture myopathy – i.e. muscle damage resulting from extreme exertion, struggle, or stress associated with handling by humans.

The study recommends the compilation of a comprehensive – and perhaps open access – bat call reference library for southern Africa.

“Such a database would potentially obviate the need to always combine acoustic surveys with live-captures, and would be a far more ethical approach to bat sampling in a time when we continue to lose biodiversity at a rapid rate,” the study concluded.

Dane McDonald

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