Wednesday, January 11, 2012

Busy New Jersey Beavers photo
The beaver is the second largest rodent in the world. Even children are familiar for its wide, flat tail, trre-gnawing and for building dams.

Those tails are useful for slapping the surface of the water to warn other beavers of approaching danger. Although these critters are rather awkward on land, they can navigate quickly under water and can stay submerged if necessary for up to 20 minutes.

Trees (bark and leaves) are their favorite winter food, but in summer other vegetation, especially aquatic plants like water lilies, make up their diet.

Beavers are known for their engineering of dams on rivers and streams. Their intent is to build their lodges (homes) in their preferred pond setting. They ingeniously place vertical poles, and then fill in the spaces between the poles with horizontally placed branches. Then, they further fill in the gaps with a combination of weeds and mud to hold back the water around their lodge. They have even been known to create "canals" in order to float larger tree materials they need rather than dragging them over land.

Their powerful front teeth are cartoonish but they are effective for cutting trees and plants for building and for food.

Though beavers are found throughout New Jersey, it is likely that many residents have never actually encountered one in the wild. Children and adults might mistake a groundhog for a beaver.

NJ's beaver population is strong because they generally coexist well with humans and they have few natural predators. 

Not all cases of beaver building have been met with amazement by humans. There have been reports over the years of busy beavers encroaching on human activities.  In Camden County, beavers on Kirkwood Lake created dams that made the water rise so that homes that normally had about 100 feet of land between them and the lake wound up with only a few feet of land.

In Middlesex County, a beaver blocked a culvert on a road in the Jamesburg Park Conservation Area and built a dam between two cranberry bogs. The town wanted to avoid flooding that had occurred in previous years. In that case, the town got a permit to trap the beaver out of season. They snared a 31.5-pound, 40-inch-long female beaver in an underwater trap.

This past year, in Princeton Township, human intervention with beavers also made the news.
A pair of busy beavers killed by a local animal control officer activated animal lovers who wondered why the beavers were not relocated rather than killed.

The beaver pair were contributing to flooding at the Pettoranello Gardens section of Community Park North, which has a pond and several streams. Workers tried to dismantle the dams, but the beavers got busy and rebuilt.

It didn't help that the state Division of Fish and Wildlife said the Princeton animal control department had not gotten the proper permit prior to killing the beavers. It seems odd but, according to a spokesman for the department, beavers trapped either in conibear traps, which kill them, or in live traps, still must be euthanized and may not be relocated.

As said earlier, our state beaver population is healthy. The state regularly surveys the 30 hunting and trapping zones in the state. Permits obtained from the Division of Fish and Wildlife are required to trap beaver and/or otter.

During the 2009-2010 season, more than 600 beavers were trapped and killed. The beaver season runs from the end of December to early February. (The duration of the trapping season for beaver on 23 Wildlife Management Areas is January 1 through February 9, 2012, but if the anticipated harvest of beaver and/or otter has not been accomplished during this season, up to 14 additional days may be authorized by the Director.)

More on "Beavers as Master Builders of Wildlife Habitats"

North American beaver (Castor canadensis)


  1. Thanks! I took my 4 year old son to a park in our neighborhood in Mickleton (Gloucester County) after work tonight. I told him we should check out the marsh and stream that run through it and see if any "swamp creatures" were lurking there. A large beaver was in the middle of the water near some fallen trees eating a sapling! How am I ever going to repeat that trick?! Hopefully that animal will have a happy home in our park (no chance of flooding etc).

  2. AnonymousMay 26, 2017

    do you know what kind of beavers live in new jersey?

    1. The North American beaver (Castor canadensis) is native to North America and is our largest rodent species. It is often referred to as simply the American Beaver.

  3. Just wanted to let you know that beavers are coming back strong in CamCo by Laurel Lake (Laurel Springs/Lindenwold) as my dumb dog was just harassing one in my back yard. I saw it was a bit beat up as my dumb dog is a GINORMOUS White German Shepherd & was trying to beat it up like her stuffed toys (I think she was disappointed that it lacked a squeaker) & I brought her inside after setting up a tree limb for it to climb up & over our chain link fence. It looked to be a young male & probably eager to chomp away at the trees in our yard which is up a hill from the lake. We are also dealing w/ a huge influx of deer & a small, brown bear was seen near the woods by the rarely used train tracks (not the SpeedLine). We’ve also had an invasion of moles since 2016. Perhaps Southern NJ wildlife is rebounding & this is a good sign. All I know is that the owls, hawks, eagles & vultures are all looking well fed in recent years.