Dispelling the myths around Earth’s tiny helpers
WHETHER demonic vampires in Hollywood blockbusters, a rabid disease carrier or simply blind – the bat’s reputation has morphed into a dark and evil entity over centuries.
But these little creatures are none of the above and, in fact, are hugely important to human survival.
Today, the Bat Interest Group of KZN goes on its annual field trip in Shongweni. Convener Brenda Angus spoke to The Independent on Saturday about the true nature of “these gentlest wild mammals” and cleared up some “batty myths”.
Angus is a key person in the organisation and fields calls on its Bat Hotline from members of the public who either have a bat in their house, or have found an injured bat.
The most infamous perception is that of the “bloodthirsty vampire bat”.
Angus said: “Sadly, the bat hotline has had a few calls from people looking for bat blood for traditional ceremonies. People don’t understand that the three species of vampire bat so maligned by the movies is a tiny bat, which weighs less than 50g, and lives only in South and Central America.”
Recent medical research found an anti-coagulant factor in the saliva of the common vampire bat (Desmodus rotundus), which is used to help thin the blood of heart attack victims.
Bats carry no known disease. In southern Africa, typical rabies has never been detected in bats. Spores from bat guano can cause mild lung disease and is only potentially life-threatening in one of 100 000 cases.
South Africa has 63 bat species, with an estimated 300 or so in Africa.
Bats are generally divided into either fruit- or insect-eating. All bats have eyes, with some having excellent sight. Bats communicate through echolocation – ultrasonic high-frequency clicks and squeaks.
According to Angus, the most common fruit bat in KwaZulu-Natal is the Wahlberg’s epauletted fruit bat
which weighs about 110g.
It is often seen roosting under the eaves of houses or open, thatched lapas.
The insect-eating bats are much smaller, varying from the tiny 4g Neoromicia nanus (banana bat) to the 28g Taphozous mauitianus (Mauritian tomb bat) which can fit comfortably on the end of your thumb.
“There are about eight species of insect-eating bats in the greater Durban area the public are likely to encounter. We have lovely bat caves in our roofs and if there is a little opening, bats will find a way into a safe, warm, dry roost – and this is where conflict with the homeowner starts.”
Although often unseen in the night skies, they are an important cog in the earth’s life cycle – insect-eating bats are the major predators of night-flying insects, including most crop pests. They consume about 25% of their body weight in insects each night.
“It is believed that our tiny little banana bat can eat about 1 500 mosquitoes per hour, while the free-tailed bats flying high over our sugar-cane fields consume thousands of Eldana moth every night,” said Angus.
And when it comes to organically grown produce, farmers are looking at the bat to help combat insect problems. In De Hoop Guano Cave in Bredasdorp in the Southern Overberg region of the Western Cape, 300 000 are estimated to occupy the cave which consume about 100 tons of insects annually over the area’s wheat fields.
When it comes to fruit-eating bats, about 300 plant species in Africa and Asia depend on them for pollination or seed dispersal.
“Certain bat-dependant trees, such as the baobab, whose white flowers attract the bats at night, are ecologically crucial, supporting dozens of other species. Extinction of the baobabs resulting from extinction of the epaulletted fruit bat could trigger a cascade of linked extinctions.”
It has been estimated that 95% of forest regrowth of cleared land in the tropics is a result of fruit bats spitting out seeds as they fly over open spaces.
KZN has three critically-endangered bats, which are each found only in one place: the short-eared trident bat (Cloeotis percivali) found in a small area of northern KZN; Rendall’s serotine bat (Neoromicia rendalli) only recorded at Bonamanzi Game Reserve in Zululand; and the large-eared free-tailed bat (Otomops martiensseni) found from Ballito and down the coast, and only in roofs of tall, older buildings.
The trip into the Shongweni Tunnel today is the annual training course and has been held since 1999.
“The tunnel is a major roost site for six identified species and we use this opportunity to monitor the bats. With the latest bat detectors, we can do recordings of the bat sonar and later analyse the data.”
Angus said when she met a member of the KZN Bat Group nine years ago, it “opened my eyes to these amazing creatures and their complex and fascinating world. Bats are crucially important to our environment and to our well-being”.