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Order : CHIROPTERA
Family : Vespertilionidae
Species : Kerivoula spp.

Forearm Length : up to 4.9 cm
Weight : up to 13 grams

Woolly Bats (Kerivoula spp.) are mainly small insectivorous bats which, in Southeast Asia, inhabit primary and secondary forest.

Globally there are more than 20 species of Kerivoula. Shepherd (2012) lists 12 species as occurring in Southeast Asia. Another 3 species occur in New Guinea, and 7 more in Africa.

Woolly Bats are characterised by long, thick,  fluffy fur which covers much of the face. Fur colour is variable both between species and within species, but is typically orange-brown.

The ears are somewhat rounded, funnel-like and barely extend above the fur on top of the domed skull. The distinctive tragus (a bony projection inside the ear) is narrow, pointed and projects upwards (see figure 4).

The eyes are tiny and the mouth is small. The tail is fully enclosed in the flight membrane.

In Southeast Asia's forests, these bats typically roost in small tree holes, or in clumps of hanging vegetation such as dead leaves. Figures 1 to 4 are of a woolly bat found, rather unusually, roosting on a tree trunk, 4 metres from the ground - perhaps its regular roost had been disturbed in some way earlier in the day.

Hardwicke's Woolly Bat K. hardwickii (see figure 6) is the most widespread species in the region occurring in India, Sri Lanka, Myanmar, southern China, Thailand, Laos, Vietnam (and probably Cambodia), Peninsular Malaysia, Singapore and parts of Indonesia. Francis (2008) indicates that K. hardwickii is probably a species complex: further work will likely reveal hidden, undescribed species.

Figs 1 and 2 : Kerivoula sp. from lowland secondary forest in Singapore. The pelage (fur) of this bat appears more grey than is typically reported.  Note the pointed tragus inside the ear, which confirms this bat as a Kerivoula sp.

Fig 3 : Habitat in typical lowland secondary forest, in Singapore's central forests. The red arrow indicates the location of the bat shown in figures 1 and 2.  Daytime roosting on tree trunks is not considered typical behaviour for woolly bats.

Fig 4 : Close-up of the same specimen, showing the pointed tragus inside the ear.

Fig 5 : Kerivoula sp. - either the Small Woolly Bat K. intermedia or Least Woolly Bat K. minuta. (These two species occur in Peninsular Malaysia and Borneo. K. minuta also extends to southern Thailand.)

Fig 6 : Hardwicke's Woolly Bat K. hardwickii, from lowland secondary forest, Singapore.

Fig 7 : Frequency modulated (FM) call with a start frequency of 245 kHz and an end frequency of 70 kHz, recorded in secondary forest, Singapore. (The frequency scale, on the left side, is from 0 to 250 kHz, and the time scale at bottom is 0-42 milliseconds). This call is identified as Kerivoula hardwickii with reference to Table 11 in Douangboubpha et al (2016).


Thanks to Matt Struebig of the School of Biological & Chemical Sciences, Queen Mary, University of London for his assistance.


References : M2, M3, M8

Douangboubpha, B., Bumrungsri, S., Satasook, C., Wanna, W., Soisook, P. & Bates, P. J. (2016). Morphology, genetics and echolocation calls of the genus Kerivoula (Chiroptera: Vespertilionidae: Kerivoulinae) in Thailand. Mammalia, 80(1), 21-47.