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 size of a large bumblebee, hence the common name “bumblebee bat”.
This bat 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, which is before the Himalayan Mountains had even started to form!
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. At dawn and dusk the bats 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 bumblebee bat has wide wings with long tips which allow it to hover like a hummingbird. The normal foraging range appears to be limited to an area of around 1 km from the roost site.
There are thought to be around 2,000 bats remaining in Thailand. The status of the species in Burma is unknown. Although the species may be locally common in both countries, 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.
EDGE has contributed to the conservation of this species through support of EDGE Fellow Piyathip Payapan. Piyathip’s project focused on questions about the specific characteristics of roost sites and roost caves that the bat requires and their behaviour while staying in the roost caves. This is critical for effective conservation because bumblebee bats spend more than 90% of their lifetime in roost caves.
Under her EDGE Fellowship, Piyathip investigated roost selection of the bumblebee bat and determined activity patterns and time activity budget for roosting activities of this species. Piyathip compared roost sites with non-roost sites and determined which specific characteristics (e.g. geographic location, elevation, position, direction etc) play the most significant role in determining roost selection. Roosting behaviour, activity patterns and activity budgets was determined by comparing roost sites with different levels of human disturbance, and recording activity using infrared-illuminated closed circuit television (IR-CCTV).
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