Like a bat out of heaven

Durban - Bats are clean little creatures that spend a lot of time grooming themselves.

“A dirt-covered plane would not fly well. It’s the same with bats. Anything that causes drag during flight expends unnecessary energy,” said mammalogist Leigh Richards, from the Durban Natural Science Museum and permitted bat rehabilitator with the Bat Interest Group of KZN.

Next Saturday (September 2) at 6 pm she will talk about bats at the Burman Bush Scout Camp, Burman Drive, Morningside, as part of the Trees and Seas Festival.

Mass media association of these important mammals with “spooky” movies, witches and Halloween has given them a bad ‒ and inaccurate ‒ press. Their reputation took another hit during the Covid-19 pandemic. However, it has not been scientifically proven that there is a direct link between the human-transmitted virus and bats.

There is also the misguided saying “blind as a bat”: most of these night time hunters have excellent eyesight.

Humans need to be more invested in ensuring they thrive: there is evidence to show that Durban summer evenings would be far less bearable when it comes to mosquitoes were it not for bats; not to mention the disease prevention that insect-eating bats provide in the malaria-endemic north-eastern areas of the KZN province, said Richards.

“Insect bats can eat a third of their body weight each night. Most of the energy from their insect prey goes into flying, the rest into sustenance. A pregnant female can eat half her body weight.

“That can be 1 200 to 2 000 mozzie-sized insects per night per bat.”

Then there’s their contribution to the agricultural production of two significant KZN crops, macadamia nuts and sugar cane. Items on the bat menu are stink bugs that bore through the macadamia nut’s outer covering into the nut itself. South Africa is a leading macadamia nut exporter; farmers cannot sell those nuts with holes, leading to millions of rands lost.

“DNA studies of the insect remains in bat guano have shown bats consume stink bugs in macadamia orchards,” said Richards.

Similarly, genetic studies on the guano of little free-tailed bats and Angolan free-tailed bats showed they primarily feast on moths. Some of the moths consumed may include agricultural pests such as the African sugar cane borer, whose larvae damage sugar cane stems.

“Research shows that some free-tailed bats prefer to forage over sugar cane fields instead of their natural habitats,” said Richards.

Free-tailed bats are regarded as an “urban adapter” species that roost in roof spaces and other man-made structures. Other species such as Mauritian tomb bats favour a warm, face brick wall to rest on, under the eaves of houses.

Recent research shows that another gift from urbanisation are floodlights, particularly at sports stadia, which offer bats a feast of insects attracted to the lights. It helps to be a fast-flying bat species, said Richards. “The slower flying, forest and woodland associated species, may be easy pickings for predators such as owls in urbanised environments with artificial lighting.”

Habitat loss as a result of urbanisation is a threat to more specialised species.

Fruit bats also make quick getaways so as not to attract predators while foraging from a tree at night. “In flight, they process their food, by pressing their tongue (covered in fine hooks much like cats), up against their palate.”

In the process, some food and seeds may spill out and drop to the ground. This “spit out” and the seeds that are defecated, can later grow into more fruit trees. In this way, fruit bats contribute to the regeneration of African rainforests and woodlands which have suffered from slash-and-burn agricultural practices at the hands of humans.

Now humans can be on the lookout to help these mammals: bat pup season is soon approaching, and babies may fall out of their homes and need rescuing and rehabilitation.

Bats are not fast breeders and, apart from the vesper bat species which may bear twins, females generally have only one offspring a year.

“It’s tough being a baby bat. They have a steep learning curve – learning to fly, to echolocate, and to avoid nocturnal predators. More than half of them don’t make it to adulthood”.

Richards is studying the insectivorous bat communities across four Durban landscapes: the large urban reserves, such as Burman Bush; recreational spaces, such as the Botanic Gardens; suburban gardens, and the CBD.

The species most common to Durban are the banana bats weighing a mere 3 to 4g and known for roosting in curled-up banana and strelitzia leaves; free-tailed bats including a specially-protected species the large-eared giant mastiff bat, and Wahlberg’s epauletted fruit bat.

They are among 66 recorded species in South Africa, of which 44 species are found in the province. Limpopo and KZN are the provinces with the highest bat diversity. Among South Africa’s bats, 11 species are listed as Near Threatened, five as Vulnerable, and one as Endangered.

“We have a lot to be grateful for to bats,” said Richards, who believes that “if people are informed about the importance of our bats, they will understand the need to conserve them”.

For more information on bats in KZN, visit https://batskzn.org.za/.

The Independent on Saturday