# What is the smallest mammal?

> The Kitti’s hog-nosed bat (bumblebee bat) of Thailand and Myanmar weighs about 2 grams — the smallest mammal by mass. The Etruscan shrew rivals it for smallest body length. The bumblebee bat (Craseonycteris thonglongyai) of Thailand and Myanmar weighs roughly two grams — smaller than many insects.

**Category:** Wildlife  ·  **Updated:** 2026-07-05

## Key takeaways
- Bumblebee bat ~2 g — smallest mammal by weight.
- Etruscan shrew rivals for smallest size.
- Extreme metabolism — constant feeding required.
- Cave-roosting — vulnerable to quarry and disturbance.
- Small size does not mean low extinction risk.
- Micro-species need habitat protection too.

## Answer
Tiny mammals have extreme metabolisms — some shrews must eat every few hours or starve. Bumblebee bats roost in limestone caves vulnerable to tourism and quarrying.

Small size does not mean safe from extinction: restricted-range species can vanish when a single cave system is disturbed.

Mammal size extremes illustrate why conservation must cover both charismatic megafauna and overlooked micro-species.

## Bumblebee bat biology
Craseonycteris thonglongyai roosts in limestone caves in western Thailand and Myanmar — colonies small, often fewer than fifty individuals. Wingspan still reaches roughly 16 cm despite two-gram body — lightweight skeleton and thin membrane. Diet insects near rivers and forest edge. Pig-like snout gives hog-nosed name. Discovery in 1974 highlighted how overlooked microfauna can be — new vertebrates still found in Southeast Asia.

## Etruscan shrew comparison
Suncus etrurus weighs roughly 1.8–3 g with fast heartbeat and respiration — must consume more than its body weight daily in insects. Heart rate can exceed 1,000 beats per minute. Cold or missed meals kill quickly. Shrews occupy broader geography than bumblebee bat but same principle applies: small size means high surface-area-to-volume ratio and energy demand. Neither species is safe from extinction despite minuscule individual footprint — range restriction concentrates risk.

## Why small mammals matter
Conservation funding favours elephants and tigers; microbats and shrews control insects and occupy food webs supporting owls and snakes. Losing a cave system can erase a bat species nationally. Island shrews and rodents face identical local extinction dynamics. IUCN assessments exist for many micro-species — Vulnerable bumblebee bat reflects quarry and tourism pressure on roost caves, not global abundance guesswork.

## Protection challenges
Caves lack charismatic appeal for park designation yet hold entire species. Myanmar political instability complicates Myanmar bat surveys. Thailand protects some roosts but limestone mining continues regionally. Bat research requires specialist mist-netting and acoustic surveys — expensive per species. Documenting smallest mammals teaches that extinction risk scales with range and disturbance, not body size alone.

## FAQ
### What is the smallest mammal?
Kitti's hog-nosed bat (~2 g) — Etruscan shrew rivals by length.

### Where does the bumblebee bat live?
Limestone caves in western Thailand and Myanmar.

### Is the bumblebee bat endangered?
IUCN Vulnerable — cave disturbance and limited range.

### Why do shrews eat so much?
Tiny size means huge energy demand — some must eat every few hours.

### Are small mammals safe from extinction?
No — restricted ranges and habitat disturbance erase species quickly.

### Is a mouse the smallest mammal?
No — many bats and shrews weigh less than common mice.

## Sources
- [IUCN Red List — Craseonycteris thonglongyai](https://www.iucnredlist.org)

Human-readable page: https://worldanimalrescuenetwork.org/answers/what-is-the-smallest-mammal