Beaver

Beavers are the second-largest rodents in the world and, after humans, the animals that most dramatically modify their environment. Their dams don't just create ponds — they raise water tables, restore wetlands, reduce downstream flooding, filter water, and create habitat for dozens of species. Removing beavers from a watershed has measurable, cascading effects on the entire ecosystem.

Facts you didn't know

• 1

  Beaver dams raise local water tables, rehydrate surrounding soil, create riparian wetlands, and reduce the severity of downstream floods by holding water upstream. A single beaver family can transform a stream corridor into a wetland system supporting hundreds of additional species.

• 2

  Beaver lodges are engineered with purpose — the entrance is always underwater (below the ice line in winter) so predators cannot enter. Inside, there's a raised dry platform above water level, and a separate area where wet animals can dry off before entering the living space.

• 3

  Beavers' orange-colored teeth get their color from iron compounds in the enamel — the iron makes the teeth harder than human teeth and self-sharpening. The lower incisors grow faster than the upper, maintaining a chisel edge as they grind against each other.

• 4

  Beavers communicate using castoreum — a secretion from castor sacs near the tail — which they apply to mud mounds at territory boundaries. Castoreum was used as a food flavoring additive in the 20th century and is FDA-approved as 'natural flavoring.'

• 5

  Beavers can hold their breath for up to 15 minutes and have transparent eyelids (nictitating membranes) they close underwater, allowing them to see while swimming submerged.