South African bats are losing their trees, UP research shows

Posted on December 18, 2021

Trees are the basis of all life. For bats, trees contribute to survival by providing food (fruits and insect habitat), places to roost and landmarks for navigating and commuting.

Research by Dr Mariette Pretorius, a postdoctoral researcher at the University of Pretoria’s (UP) Centre for Viral Zoonoses and the Mammal Research Institute, highlights why the current lack of cave-specific conservation in South Africa is significant. “Tree loss results in habitat fragmentation and decreased food availability for bats, whilst agricultural and urban intensification exposes bats to pesticides and other pollutants. These impacts may have far-reaching consequences for bat health and survival. In an era where land cover change increases pandemic-likelihood, our research is an important step towards the formal protection of bat-inhabited caves to safeguard both bats and humans,” she explains.

“Worldwide, trees are an essential resource for humans as well; harvested for timber products, firewood and to clear land for agriculture and housing. Tree harvesting is causing the destruction of natural habitat, bringing wild animals like bats into closer contact with humans than ever before. Notably, habitat destruction is the leading cause for new emerging zoonotic diseases. In South Africa, at least two species are being studied for their variety of potentially zoonotic viruses; the Natal long-fingered bat (Miniopterus natalensis) and the Egyptian Rousette (Rousettus aegyptiacus). These species are cave-dwelling and are widespread throughout the country, although current population trends are unknown and no formal conservation actions are being taken to safeguard these bats or their caves.”

Dr Pretorius explains that she investigated some of the anthropogenic pressures these species face around their caves. “Using freely-available land-cover datasets from the Department of Environmental Affairs, we determined the extent of land-cover change within five kilometres around 47 bat-inhabited caves between 2014 and 2018. The results showed an overall 4% decrease in trees around all caves, whilst agricultural and urban areas increased by 2.13% and 0.96% respectively. Additionally, the majority of roosts are not located in protected areas, leaving caves vulnerable to disturbance, vandalism and destruction,” she concluded.

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