Swinny’s horseshoe bat (Rhinolophus swinnyi)
|Size||Head-body length: 42 mm (2)|
Forearm length: 40 mm (2)
Tail: 18 – 29 mm (3)
Swinny’s horseshoe bat is classified as Least Concern (LC) on the IUCN Red List (1).
This small horseshoe bat has the characteristic horseshoe-shaped noseleaf for emitting ultrasonic echolocation calls. The noseleaf does not extend over the whole muzzle and is made up of elaborate folds of skin which are sparsely covered with hair. The ears are large and pale greyish-brown and do not meet at the centre of the head. The eyes are very small and the pointed top of the noseleaf runs between them. The upperparts are greyish-brown, fading to pale grey on the underside. The membranous wings are chocolate brown. There are three subspecies: Rhinolophus swinnyi swinnyi, Rhinolophus swinnyi piriensis and Rhinolophus swinnyi rhodesiae. The latter is known to have a bright orange colour variant (3).
This species is found in Zimbabwe, Mozambique, Malawi, Zambia, South Africa, Democratic Republic of Congo, Zanzibar and Tanzania (3).
Swinny’s horseshoe bat roosts in caves and old mines within savanna woodland (3).
Swinny’s horseshoe bat lives in groups of around five individuals, although many groups may congregate in a roost. Very little is known of their behaviour, diet or reproductive cycle (3).
The horseshoe bats have highly-developed echolocation systems which are able to decipher Doppler-shifted echoes. The Doppler shift is the change in pitch heard when the source of a sound and its receiver are either getting closer together or further apart. If a source of sound and an individual hearing that sound are getting closer together, the receiver will hear a higher pitched sound than if they remained at a constant distance. As a bat flies towards its prey, it is listening for the echo of the pulses of sound it emits. These echoes increase in frequency as the bat approaches its prey. However, horseshoe bats have an optimal frequency of sound to which they are especially sensitive and so to ensure their echoes return at this frequency, they compensate for the Doppler shift by emitting a lower frequency; the faster they fly, the lower the pitch (4). For Swinny’s horseshoe bat, the echo will always return at 115 kHz, although the frequency of the emitted sounds varies with flight speed (3). Whereas other bat species cannot emit and receive echolocation signals at the same time, being able to compensate for the Doppler shift enables horseshoe bats to use longer, overlapping calls to build up a more detailed picture of their cluttered forest environment (4).
As with many African bat species, habitat loss is the greatest threat to Swinny’s horseshoe bat (5).
Swinny’s horseshoe bat is found in several national parks across its range and if habitat loss continues, the survival of this species will depend on sustained good management of these parks (5).
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- Echolocation: detecting objects by reflected sound. Used for orientation and detecting and locating prey by bats and cetacea (whales and dolphins).
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
- Ultrasound: sounds that are above the range of human hearing.
IUCN Red List (June, 2009)
- Gough, L.H. (1908) On a new species of Rhinolophus from Pondoland. Annals of the Transvaal Museum, 1: 71 - 72.
- Csorba, G., Ujhelyi, P. and Thomas, N. (2003) Horseshoe bats of the world. Alana Books, Bishop’s Castle, Shropshire.
- Macdonald, D. (2001) The New Encyclopedia of Mammals. Oxford University Press, Oxford.
- Happold, M. and Happold, D.C.D. (1997) New records of bats from Malawi, east-central Africa, with an assessment of their status and conservation. Journal of Natural History, 31(5): 805 - 836.