America’s biggest rodent: The beaver

When you live long enough you have a chance to witness so many changes. I remember in 1965 hunting rabbits in a dormant pasture. It was graced with goldenrod and prairie grass. Today, no one would recognize this as an old pasture. Trees with 15- to 18-inch diameter trunks are now the dominant plants. Deer and turkey now find refuge there.

Not only plant communities change. Animal populations can crash or make miraculous recoveries as well. I remember Dad taking our family on the post-church Sunday rides. One destination often led us to near Albrightsville to check out a beaver dam. Beavers were very rare in the ’60s. We even got to see a beaver or two occasionally. Beavers actually became extinct in Pennsylvania in the mid-1800s.

Now through regulations, reintroductions and changing fashions, they are found throughout the state. The Lehigh Canal, Beltzville Dam, Lizard and Pohopoco Creeks all harbor them.

The beaver is America’s largest rodent and is the second largest in the world, maturing at about 60 pounds. Like all rodents it has a pair of upper and lower incisors that never stop growing. Rodents must constantly chew to wear down these teeth. (That is one reason small rodents are problem pests in homes.) Beaver’s incisors are covered with orange enamel and are extremely tough.

They are amazing engineers and super industrious. Water offers them safety from predators so building a dam in a stream needs to be accomplished quickly. They drag (float) trees and limbs and use their forefeet to scoop up and carry mud to “pack” into the dam’s openings. They do not use their tail to transport mud. Once a dam starts retaining water they go to work building a lodge in some of the deepest water so they can have an underwater tunnel entrance. They don’t always build dams. Lake and river shores with softer banks are excavated for dens, too.

Beavers have other adaptations besides their teeth. The front feet are more humanlike for grasping and holding. Their back feet are rather large and webbed, allowing them to be excellent swimmers. Their broad, scaly tail is very strong, yet flexible. It serves as a rudder and as importantly, it is a very strong prop, offering leverage as they chew through trunks, etc.

The tails often slap the water surface when they submerge quickly to avoid danger. (Many think it is to warn other beavers, but actually it is because of the 10-inch size.) This fur is extremely thick and fine and was prized by trappers. The beaver was the animal most important for America’s westward expansion.

Beavers eat softwoods, preferring willow, birch and aspen. They avoid conifers. The inner bark is actually what they eat. They also eat streamside plants and branches and leaves of trees. For winter food, they carry limbs, etc. onto the beaver dam bottom to their underwater “pantry” and weigh them down with rocks. They will do the same with tree trunks and you can find a pile of wood chips about every 18 inches as they “cut up” trunks into movable sizes. (No chain saws here) The lodge serves as the nursery and they generally have four young. Eventually the parents chase the maturing offspring away, knowing that the supply of food close to the dam would eventually be exhausted.

Instead of a Sunday drive, take a Sunday afternoon family walk along one of our local aquatic areas and keep your eyes open for beaver activity. You may not see beavers though, they are generally nocturnal. But, keep those nature eyes open.

Test your knowledge: Beavers are so good at felling trees that they never get crushed by the falling tree. True or false?

Last week’s question: The porcupine has few natural predators. However, the fisher is quite adept at avoiding the porcupine’s quills.

Contact Barry Reed at breed71@gmail.com.