Beaver teeth are coated with iron!

Beavers are amazing builders and, according to this evening’s episode of Nature, can eat through a tree trunk in an hour or two. But what astonished me on tonight’s episode is that their teeth are made with iron and are therefore orange!

They have favorite kinds of trees to eat such as quaking aspen, cottonwood, willow, alder, birch, maple and cherry trees. They also eat sedges, pondweed and water lillies. (From Wikipedia)

“A beaver’s teeth grow continuously so that they will not be worn down by chewing on wood. Their four incisors are composed of hard orange enamel on the front and a softer dentin on the back. The chisel-like ends of incisors are maintained by their self-sharpening wear pattern.”

On researching the iron in their teeth, I discovered that seven million year old fossils of beaver teeth have recently been discovered in Oregon pushing back the date that beavers arrived in North America from Europe by two million years (from the Oregonian.)

And on the Wikipedia page, there is a section detailing urban beavers. The Bronx River, San Francisco’s Alhambra Creek and Chicago’s Lincoln Park have become home to beavers moving back in and attempting to return the areas to their native state. In Chicago, which used to be a big swamp before African-American and European settlers moved in, the beavers have been met with anxiety over their powerful engineering and tree-eating skills. I wonder if the residents of this fair city prefer landscaping over adorable muddy beavers slapping their tails.