Smallest mammal
Craseonycteris thonglongyai, Bumblebee bat, Kitti's hog-nosed bat
29 - 33 mm dimension(s)
Thailand ()

The smallest mammal by body length in the world is Kitti's hog-nosed bat (Craseonycteris thonglongyai) aka the bumblebee bat.

It has a head-body length of only 29–33 millimetres (1.14–1.29 inches), a wingspan of approximately 130–145 millimetres (5.1–5.7 inches), and a weight of 1.7–2 grams (0.05–0.07 oz).

It is 80 million times lighter than the world’s largest mammal, the blue whale (Balaenoptera musculus).

Kitti’s hog-nosed bat can only be found in a few select limestone caves on the Khwae Noi River in Kanchanaburi Province, western Thailand and in south-east Myanmar.

It was discovered in 1974 by Thai zoologist Kitti Thonglongya, whom the species is named after.

Its name also refers to its relatively large, pig-like snout.

In addition to having a sizeable snout, Kitti’s hog-nosed bat has relatively large ears and wings in comparison to its small body.

Colony sizes vary widely – many caves contain 10-15 individuals, although the average group size is 100 and the maximum is around 500.

The bats also migrate between caves seasonally.

Within the caves, individuals roost high on walls, far apart from each other.

The activity period of a bumblebee bat is brief. It only leaves its roost for 30 minutes in the evening and 20 minutes at dawn, during which times it forages for food within fields or around the tops of bamboo trees.

Its diet mostly consists of small spiders and flying insects such as mosquitos, moths, and beetles.

Just like most bat species, female bumblebee bats give birth once per year to a single offspring. Births typically occur during the dry season between March and May.

Maternity colonies, comprised of a small number of females, form within cave roosts to provide communal protection for their pups.

When the species was last reviewed in 2019, it was listed as ‘near-threatened’, with a downward trend in population. The main threats it faces are habitat degradation and the disturbance of roosting sites.

The smallest non-flying mammal (and the smallest mammal by mass) is the Etruscan shrew (Suncus etruscus), which has a head and body length of 35–48 mm (1.3–1.8 in), a tail length of 25–30 mm (0.98–1.17 in) and weighs 1.5–2.5 g (0.05–0.09 oz). It is found along the Mediterranean coast and southwards to South Africa.

Header image: Wikimedia Commons