Lesser Brown Horseshoe Bat (Rhinolophus stheno)
HB: 54-58; T:16-18;
FA: 45-48; E:16-17; HF: 8.5-9.2.
As a medium-sized member of the horseshoe bat family, this species is characterised by its complex nose leaf. The nose leaf consists of a broad, flat horseshoe-shaped area over the nostrils, a horn-like projection above, and a shorter, rounded projection in between. The function of the nose leaf is to emit echolocation calls for orientation and hunting. The nose leaf is relatively small, and the lancet is low and bluntly pointed rather than very long and acutely pointed as in malayanus. The ears are large and black, and the eyes extremely small, dwarfed by the nose leaf. The natural fur colour is dark brown, but this batís habit of roosting in caves can lead to chemical bleaching, leaving the fur orange. The braincase is rather long and slender, and the skull shows an extraordinary abrupt projection of the anterior nasal swellings; the posterior swellings are much reduced. The first and third lower premolars are in contact, with the lower premolars outside the tooth row; the upper front premolar is in the tooth row and as a very large cusp.
This species occurs in Myanmar (Struebig et al. 2005),
Vietnam, Thailand, Lao PDR, Peninsular Malaysia, Sumatra and Java
(Indonesia). It has not yet been recorded but probably also occurs in Cambodia.
It inhabits degraded forest to primary deciduous forest in Thailand
Bumrungsri pers. comm.). It is associated with limestone in Myanmar in degraded
habitats including agricultural areas (P. Bates pers. comm.).
Indonesia (Jawa, Sumatera); Lao People's Democratic Republic; Malaysia (Peninsular Malaysia); Myanmar; Thailand; Vietnam
It tends to be found in small groups in Myanmar and Viet Nam
(P. Bates and G. Csorba pers. comm.). It is locally common in
one population of 1,000 individuals was found there, and also common in Lao PDR
(C. Francis pers. comm.).
Population Trend: Stable
Biology and Ecology
This species feeds on insects, hunting at night using echolocation to locate prey items and move amongst the dense jungle vegetation. It calls at a constant ultrasonic frequency of 86 kHz, enabling it to detect the flutter of an insectís wings. In Peninsular Malaysia, the majority of pregnant females of the lesser brown horseshoe bat have been found between February and April, and are with young pups between May and July. A single pup is born to each female, who cares for it for up to a year. At birth it weighs a massive one quarter of its motherís weight, and she may continue to carry it on feeding flights for two months.
There are no major threats to this species, although the
species is hunted in northeast Thailand but this is not at a level that
is considered a threat to the species (S. Bumrungsri pers. comm.).
It is known from a number of protected areas in Thailand and throughout its range.