Bats are the only mammals capable of sustained flight, and the order Chiroptera encompasses an extraordinary range of sizes, from species with wingspans stretching over five feet to those barely larger than a common insect. This diversity naturally leads to the question of which species represents the lower limit of mammalian size.
Identifying Kitti’s Hog-Nosed Bat
The smallest bat in the world is the Kitti’s hog-nosed bat, known scientifically as Craseonycteris thonglongyai. This species is also commonly referred to as the bumblebee bat due to its incredibly diminutive stature. It is the sole member of its own family, Craseonycteridae, a classification that underscores its unique evolutionary position.
An adult Kitti’s hog-nosed bat typically measures just 29 to 33 millimeters (1.1 to 1.3 inches) in head and body length. Its weight is equally astonishing, ranging from only 1.7 to 2.0 grams (0.06 to 0.07 ounces). The wingspan of this tiny flier generally spreads to about 15 centimeters (6 inches).
Size Comparisons and Context
The Kitti’s hog-nosed bat’s size makes it a contender for the title of the world’s smallest mammal, a distinction that depends on the exact metric used. Its body length, measured from the tip of the nose to the base of the tail, consistently ranks it as the smallest mammal on Earth. It also holds the record for the smallest skull size of any mammal.
However, the Etruscan shrew (Suncus etruscus) often challenges the bat for the title of smallest mammal by mass. The shrew can weigh as little as 1.2 grams, making it potentially lighter than the bat, yet its body is longer, measuring up to 53 millimeters.
Ecology and Unique Adaptations
The geographic range of Kitti’s hog-nosed bat is highly restricted, occurring only in a handful of limestone cave systems along rivers in western Thailand and southeastern Myanmar. They prefer to roost high up on cave ceilings or in small crevices. While colony sizes can vary, they often average around 100 individuals.
The bat is an insectivore, with its diet consisting primarily of small flying arthropods like flies, spiders, and beetles. Its foraging behavior is distinctive, as it leaves its roost for only two very brief periods: approximately 30 minutes at dusk and another 20 minutes at dawn. During these short excursions, the bat forages in nearby forest areas, typically remaining within one kilometer of its cave.
Morphologically, the bat is easily recognized by its distinctive, pig-like snout with two crescent-shaped nostrils, which gives the species its common name. This specialized nasal structure is associated with its use of high-frequency echolocation, which it uses to navigate and detect prey. Unlike many other bats, it lacks a visible tail, but it does possess a large membrane of skin, the uropatagium, between its hind legs that assists with flying.
Conservation Status and Habitat Threats
Due to its extremely localized and specific habitat requirements, the Kitti’s hog-nosed bat is particularly vulnerable to environmental changes. The International Union for Conservation of Nature (IUCN) currently classifies the species as Near Threatened.
A primary threat comes from human disturbance of its cave roosts, which can be caused by unmanaged tourism and scientific collection. The small bat also faces threats from industrial activities, such as limestone mining and quarrying, which destroy its unique cave environment. Furthermore, the surrounding foraging habitat is degraded by deforestation for agricultural expansion and the practice of annual forest burning.