Wednesday, January 11, 2017

Bats of Medike by Julio Balona of Gauteng Bat Interest Group

Julio and Erna Balona from the Gauteng Bat Interest Group visited Medike to sample the bat fauna of the Western Soutpansberg and managed to catch 12 species in two nights. We were lucky enough to see these amazing animals up close and learned a lot from Julio and Erna who were eager to share their knowledge and enthusiasm. The following post represents their finds.

 1 Geoffroy’s horseshoe bat (Rhinolophus clivosus)

Geoffroy’s horseshoe bat (Rhinolophus clivosus) Photo: Julio Balona.
Widespread and most commonly found in the temperate regions of southern Africa. This bat tolerates a range of habitats and it is suspected that it is not just one species and there may actually be as many as four different kinds that resemble each other very closely. They are medium sized and their strange ‘nose leaves’ allow them to practice very sophisticated sonar (known as echolocation) in order to navigate and capture their prey of moths, beetles and other insects. They usually roost in true caves or old mine tunnels during the day, but may occasionally use dark abandoned buildings.

 2 Bushveld horseshoe bat (Rhinolophus simulator)
Bushveld horseshoe bat (Rhinolophus simulator) Photo: Julio Balona.
As its name implies, this horseshoe bat is normally found in the warmer savannah and woodland areas of the country and is smaller than Geoffroy’s horseshoe bat. It is also less fussy about roost sites and is often found in the hollow spaces between large boulders, although it will use true caves and old mine tunnels. In addition to their horseshoe shaped nose leaves they have a fleshy horn-like projection called the connecting process. This is known to be used for sonar but its precise function is unclear. It probably feeds mainly on moths and beetles. 

 3 Smithers’s horseshoe bat (Rhinolophus smithersi)
Smithers’s horseshoe bat (Rhinolophus smithersi) Photo: Trevor Morgan (taken at Pafuri)

This beautiful beast is significantly larger than both Geoffroy’s and the Bushveld. It has similar roosting habits to the latter but likely feeds on much bigger prey such as dung beetles. Originally considered one species (the mother of all African horseshoe bats), it was split into five very similar ones that are geographically separated and have distinctly different sonar call frequencies. The individual captured at Medike escaped before it could be photographed.

4 Natal long-fingered bat (Miniopterus natalensis)
Natal long-fingered bat (Miniopterus natalensis) Photo: Julio Balona

The most common and widespread cave bat in southern Africa, it is named for the long finger bone which extends its wing to resemble that of a swallow. Like these birds, long-fingered bats spend a lot of time flying swiftly high above, and often forage low over water and drink from it by skimming the surface. An alternative name for this family is the clinging bat due to its habit of clinging together with others in clumps. Medium sized, they roost in caves almost exclusively and can be found in large colonies of hundreds of thousands. Due to their preference for soft-bodied insects, especially moths, they are an invaluable asset in the control of agricultural pests.

5 Yellow House bat (Scotophilus dinganii)
Yellow House bat (Scotophilus dinganii) Photo: Erna Balona
This placid and rather attractive bat with its yellow underside and velvety olive green dorsal fur is a common woodland species. In the wild it roosts inside natural tree holes or those made by barbets or woodpeckers, but is happy to use roofs, hence its name. With a short muzzle armed with large teeth, it seems adapted to eat hard shelled prey such as beetles.
6 Zulu serotine (Neoromicia zuluensis)
 Zulu serotine (Neoromicia zuluensis) Photo: Erna Balona
One of the ‘little brown jobs’, these bats are extremely difficult to identify without microscopic examination of the teeth and recording of its sonar call. They are quite small, weighing around five grams, and it is believed that they roost under loose bark and probably cracks in tree stems.
They probably subsist on small moths, beetles, mosquitoes and other insects.

7 Long-tailed serotine (Eptesicus hottentotus)
Long-tailed serotine (Eptesicus hottentotus) Photo: Erna Balona
These handsome bats that resemble the ‘little brown jobs’, are much easier to identify with their thick woolly fur and because they are noticeably larger, weighing about twenty five grams.
Always found in mountainous areas, they roost in rock crevices in cliff faces and probably large boulders. They usually feed low over water, most likely due to the greater number of insects that gather there.

8 Little free-tailed bat (Chaerephon pumilus

Little free-tailed bat (Chaerephon pumilus) Erna Balona.
Resembling flying dogs with hairy Hobbit-like feet, the free-tailed bats are full of character. They are so named because unlike almost all other bats, their tails are not enclosed in a membrane and protrude like that of a mouse. The Little free-tail is particularly feisty and will squeak loudly in protest when captured, its sharp teeth are best avoided. They live in colonies of hundreds or thousands of bats in holes in trees and under loose bark, and probably also in rock crevices in cliffs. 

Male Little free-tailed bat bat with his crest raised.(Chaerephon pumilus) Erna Balona.
However they actually seem to prefer the roofs of buildings and that is where they most often found. The male has a cute crest of hair that he can raise at will and is believed to be full of scent which is probably used to attract females or mark territory.

9 Angolan free-tailed bat (Mops condylurus

Angolan free-tailed bat (Mops condylurus) Photo: Erna Balona.
Larger and stockier than the Little free-tailed bat, they are also more localized in distribution – in South Africa they are mainly found on the eastern coast, from Durban northwards and over the lowveld region covered by the Kruger National Park. Their extension into the Soutpansberg brings them to what is most likely the western limit of their distribution at Medike as well as that of the Little free-tail. Both species are fast flyers and have long thin wings, spending most of the time above the trees catching insects such as moths, beetles, mosquitoes and bugs.

The Angolan Free-tailed bat often roosts in building roofs and has been shown to tolerate temperatures of around 40C under hot corrugated iron sheeting in the sun.
10 Rufous Mouse-eared bat (Myotis bocagii

Rufous Mouse-eared bat (Myotis bocagii) Photo: Erna Balona.
An attractive bat with its coppery dorsal fur and cream underside, it is fairly scarce and found only in the warmer, wetter parts of the country. Not much is known about its roosting habits here and it is suspected of hanging in trees, possibly camouflaged amongst dead leaves. In central Africa it is known to roost inside the tubular new leaves of banana plants. It feeds on small moths, beetles and bugs.

Rufous Mouse-eared bat (Myotis bocagii) Photo: Julio Balona.
11 Schlieffen's Twilight bat (Nycticeinops schlieffenii

Schlieffen's Twilight bat (Nycticeinops schlieffenii) Photo: Julio Balona.
Weighing around five grams, this is one of southern Africa’s smallest bats. Although limited to warmer low lying woodland areas of South Africa, it is often the most common bat and one of the first to appear in the evening. Despite its diminutive size, it often snarls aggressively at its captor, which just makes it look more cute than dangerous. They roost under loose bark and in crevices in trees and perhaps also rocks. 
Often feeding near water, they eat small insects and probably consume a lot of mosquitoes.

12 Slit-faced bat (Nycteris spp.

Slit-faced bat (Nycteris spp.)Photo: Trevor Morgan (taken at Pafuri)
One of these bats escaped before it could be properly identified. The incredible ears and slit in the nose make it immediately recognizable but close examination is required to say which species. However, by far the most common member of this family is the Egyptian slit-faced bat (Nycteris thebaica) and it is unlikely to have been another species. 

These special creatures have a number skills. Their sonar is purposefully kept very soft so that insects that can hear bat calls (many moths in particular), cannot hear a hunting slit-faced bat until it is too late. The large ears are also extremely sensitive to other prey sounds such as rustling in leaves which allow them to locate anything from moths to crickets to sun spiders and scorpions. Slit-faced bats are seldom captured in the standard devices of scientists (mistnets and harp traps) because their sonar is usually too sensitive to be fooled. They are therefore typically caught within their roosts which are large or small cavities, such as caves, hollows between large boulders and aardvark burrows.