Hog-nosed Bat
(Craseonycteris thonglongyai)
The smallest mammal in the world, this tiny bat weighs less than 2 grams. Its body is about the size of a large bumblebee, hence the common name “bumblebee bat”. Since it was first described in 1974 this tiny mammal has been disturbed by collectors and tourists wanting to see the world’s smallest mammal. Today the main threats are from burning of the forest areas near the limestone caves in which it lives.
Urgent Conservation Actions
Surveys are required to locate colonies of these bats and protect them from further human disturbance.
Western Thailand and south-east Myanmar.
Associated Blog Posts
13th Jun 10
The smallest mammal in the world is EDGE Mammal number 49 and is today's Species of the Day. This tiny bat weighs less than 2 grams. Its body is about the si...  Read

6th Apr 08
Researchers from the Institute of Zoology;  Dr Kate Jones and Alanna Maltby have just returned back from a recent trip to Thailand where they were par...  Read

12th Mar 08
Piyathip Piyapan our Thai EDGE Fellow currently studying the roost selection of Bumblebee bats  (otherwise known as Kitti's hog-nosed bat) sent the EDGE Te...  Read

Evolutionary Distinctiveness
Order: Chiroptera
Family: Craseonycteridae
This species constitutes the sole known representative of an entire family of bats (Craseonycteridae). It is thought to have last shared a common ancestor with other species around 43 million years ago. Molecular studies indicate that this family belongs to the superfamily Rhinolophoidea. Within this group, the families Hipposideridae and Rhinopomatidae are probably the closest relatives of the Craseonycteridae. Craseonycteris most closely resembles species of the genus Rhinopoma.
Head and body length: 29-33 mm
No tail
Forearm length: 22-26 mm
Weight: 2 g
Roughly the size of a large bumblebee, this tiny bat is arguably the world’s smallest mammal. It has a swollen, pig-like nose, relatively large ears and small eyes, which are usually concealed by fur. The species is reddish-brown or grey in colour above, with paler underparts. Its relatively wide wings are darker in colour, and have long tips which enable the bat to hover like a hummingbird. The species has a large web of skin between its hind legs (the 'uropatagium'), which is thought to help with flying and catching insects. Unlike other bats with similar uropatagia, bumblebee bats do not have visible tails or elongated anklebones which can control this structure in flight.
These bats roost at the back of small caves or remote caverns. Group size varies from as few as 10 individuals to as many as 500, although most caves contain around 100 bats. The bats spread out across the ceiling of the caves so that they do not come into contact with one another. At dawn and dusk they leave their caves for around 20-30 minutes to forage for food. The bats primarily use echolocation to hunt small insects on the wing, although they may also glean small spiders and beetles from plant leaves. The normal foraging range appears to be limited to an area of around 1 km from the roost site. Little is known of the reproductive system of these bats. Females are believed to give birth to a single young late in the dry season (late April) each year.
Roosts in limestone caves within areas of dry evergreen or deciduous forests near rivers. Foraging occurs in nearby fields of cassava or kapok.
Found in a small area along the Khwae Noi River (‘River Kwai’), in Sai Yok National Park and adjacent areas, Kanchanaburi Province, western Thailand. The species has also been reported from south-east Myanmar.
Population Estimate
There are thought to be around 2,000 bats remaining in Thailand. The status of the species in Myanmar is unknown, but recent surveys indicate that this population numbers greater than 2,000.
Population Trend
Classified as Endangered (EN B1+2c, C2b) on the 2006 IUCN Red List of Threatened Species.
Although the species may be locally common it has a very restricted distribution and is therefore vulnerable to a range of threats. Some populations declined following tourist disturbance of certain roost sites throughout the 1970s, collection for scientific purposes and the sale of bats as tourist souvenirs. Today, the main threat to the Thai population comes from the annual burning of forest areas near the caves. The main threats to the Myanmar population are currently unknown.
Conservation Underway
The species is protected under the Wild Animals Reservation and Protection Act (WARPA) in Thailand. The 500 km² Sai Yok National Park was created in 1980 specifically to help conserve the species. However, some populations occur outside of the park and are not protected. Very little is known about the status of the Myanmar population.

This project supports in-country EDGE Fellows to help conserve relevant EDGE species

Conservation Proposed
The IUCN/SSC Chiropteran Specialist Group recommends that all trade and non-essential scientific collection be prohibited and that a management policy be developed for habitats used as flight paths and foraging areas. Cave disturbances should be minimised and key roost sits protected with fences or grilles if necessary. Information on the importance of protecting the species should be made available to visitors of the National Park. The group also recommends that further research be conducted on the status, distribution and habitat requirements of the species. A monitoring programme should be developed to identify population change in relation to environmental factors. Very little is known about the Myanmar population. Further surveys are recommended to determine whether this population is an isolated relict or whether it is part of a larger population with a range that includes both Thailand and Myanmar. Some researchers have suggested that the Myanmar population might be a separate species altogether. Further molecular research is therefore required to determine the relationship between the two populations.
Associated EDGE Community members

Paul is an expert on mammal ecology especially with regards to bats

Piyathip Piyapan is from Thailand, where she is currently studying the bumblebee bat

Bates, P.J.J., Nwe, T., Swe, K.M. and Bu, S.S.H.. 2001. Further new records of bats from Myanmar (Burma), including Craseonycteris thonglongyai Hill 1974 (Chiroptera: Craseonycteridae). Acta Chiropterologica 3(1): 33-41.

Chiroptera Specialist Group. 1996. Craseonycteris thonglongyai. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. Downloaded on 09 August 2006.

Hulva, P. and Horá?ek, I. 2002. Craseonycteris thonglongyai (Chiroptera: Craseonycteridae) is a rhinolophoid: molecular evidence from cytochrome b. Acta Chiropterologica 4(2): 107-120

Hutson, A. M., Mickleburgh, S. P. and Racey, P. A. (Compilers). 2001. Microchiropteran Bats: Global Status Survey and Conservation Action Plan. IUCN/SSC Chiroptera Specialist Group. IUCN: Gland, Switzerland.

Nowak, R.M. 1999. Walker's Mammals of the World. Sixth edition. The Johns Hopkins University Press, Baltimore and London.

Distribution map based on data provided by the IUCN Global Mammal Assessment.

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