Twelve beaver facts, fact-checked
Beavers are the second-largest rodents alive, and one of very few animals that reshape a landscape on purpose. Full profile in our beaver guide.
1. Their teeth contain iron
Iron in the enamel makes the incisors orange and exceptionally hard, and they self-sharpen because the softer rear surface wears faster.
2. Teeth never stop growing
Continuous growth is why beavers must gnaw constantly.
3. They are keystone engineers
Dams create ponds and wetlands used by fish, amphibians, invertebrates, birds and mammals that were not there before.
4. Dams reduce flooding and drought
Slowing water reduces downstream flood peaks and holds it through dry periods — beaver reintroduction is now used deliberately as flood management.
5. They filter water
Ponds trap sediment and excess nutrients, measurably improving downstream water quality.
6. Running water triggers building
Beavers respond to the sound of running water — they will build against a loudspeaker playing it.
7. Lodges have underwater entrances
Reached only by diving, keeping predators out. Some are built into banks instead.
8. Transparent eyelids
A nictitating membrane acts as built-in goggles, and the lips seal behind the incisors so they can gnaw underwater.
9. The tail is a tool
Slapped on water as an alarm signal, used as a rudder and prop, and stores fat for winter.
10. They can hold their breath 15 minutes
Long dives let them move safely beneath ice.
11. Fur trapping nearly ended them
Eurasian beavers fell to around 1,200 animals before protection; North American beavers were also devastated.
12. Reintroduction is spreading
They have been returned to rivers across Britain and Europe, deliberately, for flood mitigation and biodiversity.
Read the full beaver wildlife guide for IUCN status, population context and sources — or donate to WARN to help fund the partner teams protecting wildlife on the ground.
