Crawlies with Cri: American beaver

(Photo by Christy Solo for the Illinois Valley News)

American beaver (Castor canadensis)

This week’s crawly is long overdue for an introduction. Meet the American beaver (Castor canadensis), our very own state animal and the largest rodent in North America.
Fun fact: While Oregon got the nickname “The Beaver State” around 1849 and the American beaver was on the state seal and flag, they weren’t officially named the state animal until 1969.
It’s also quite possible that you’ve never had the luck to see a beaver out in the wild. Our state animal is quite secretive and loves the nightlife. While beavers can be active at any time, they do most of their daily tasks between dusk and dawn.
They are also wary of humans, which makes sense because we are their number one predator. An adult beaver’s size (up to 60 lbs.!) deters most predators, but both kits and adults are hunted by people, wolves, wolverines, lynx, river otters, bears and fishers.
Still, most beavers live to between 10 and 20 years of age in the wild. Their sneakiness is not without reward.
While you may not have seen a beaver, you know one has seen you if you hear their patented tail slap. When threatened they’ll bring down that big old flat tail on the water’s surface and it sounds a lot like a shotgun blast. No wonder it’s an effective predator deterrent and warning alarm for other nearby beavers.
If you do see, or hear, one beaver, you can bet there are others nearby. Beavers live in family units called colonies. These are made up of a monogamous pair of adults, their newborn kits and their older kids (up to two years of age.)
Both parents do most of the feeding of the younger children, while the adolescents help with food gathering, kit care (babysitting), dam and lodge building and repair.
Another fun fact: Beavers do not eat wood. They eat the green inner bark of trees and woody shrubs and the roots of tuberous aquatic plants.
They cut down trees for a variety of reasons: To get to the good eatin’ parts, to use for building materials and to keep their teeth in shape. A beaver’s teeth grow throughout their lifetime, so they need to grind them down to keep them at a manageable size.
Beavers’ teeth are yellow, but not due to poor dental hygiene. The color comes from iron in their diet.
Beavers always live near water; they can be found by rivers, lakes, ponds and streams. Generally, they’ll only build dams in smaller waterways, creating ponds in which they can build their lodges. However, they will also build lodges on islands or shorelines partially in the water. Lodges are cozy and will have two entrances.
In addition to water, beavers need a food source; they prefer cottonwood, aspen, willow, alder and maple.
They are perfectly suited to their nocturnal aquatic life. They have thick outer guard hairs, and a soft undercoat that traps air and keeps them warm. They also produce oil from special glands which they use to coat their fur and repel water. They don’t hibernate, but in winter often spend most of their time below the ice. Burr!
An American beaver can stay underwater for up to 15 minutes before they need to come up for air. They have a few fabulous features that allow them to navigate in their underwater world. Both their ears and nose have valves which close when the beaver is submerged. They have clear membranes that cover their eyes – built-in goggles.
They are swift and adept swimmers thanks to their webbed hind feet and tiller of a tail.
Final fun fact: Beavers are a keystone species, known as the “ecosystem engineers” of our forests. By creating new wetlands and ponds with their dams, they provide amazing areas for other animals to use and thrive in.
To see some entertaining and educational videos of American beavers you can follow the Oregon Zoo on Facebook and/or Twitter.
If you have beavers visiting your property and have questions, check out the Oregon Department of Fish and Wildlife’s “Living with Wildlife: Beavers” page with downloadable pamphlets here: https://www.dfw.state.or.us/wildlife/living_with/beaver.asp.