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American Beaver

Castor canadensis

 

Do you see pointy-looking stumps on your walks in the park? Trees with bites taken out of them? 


You might have learned about beavers in documentaries about the wild north of our continent, but they are easy to find right here in Philadelphia. 


Description


The American beaver (Castor canadensis) is a large rodent, about fifty pounds and over three feet long. Along with sleek brown fur and huge teeth for chewing through wood, they sport a flat black tail. The tail helps them swim, and they also slap it on the water for a loud CRACK! to warn other beavers of danger. Beavers can close their mouths with their teeth outside to keep chewing underwater, and they have an extra set of clear eyelids, kind of like goggles. 


Diet 

Beavers eat vegetation, including grasses, ferns, and aquatic plants such as water lilies and cattails. Of course, they also eat the inner bark and foliage of trees and branches that they cut down. 


Behavior

They also use those branches to build. They construct lodges to sleep in, and they sometimes dam streams and small creeks to create ponds with plenty of water to swim and feed where predators like coyotes can’t get them.  

Beavers are social animals. Young beavers stay with their parents for a couple of years before heading out on their own. When they’re not busy eating or building, they rest in their lodges or burrows at the edge of the water. The entrances to their burrows or lodges are always underwater, making it harder for predators to get in. 

History with Humans

Beavers have dense, soft, extremely warm fur. Not surprisingly, the Lenape trapped beavers for their pelts for ages before Europeans arrived. The Lenape name for them is “tëmakwe” (which you might recognize from “Tamaqua,” the town in the Poconos). Beaver pelts were the original commodity that attracted European trade in our region, with the Dutch trading for pelts in the early and mid-1600s. The increase in trapping to meet the demands of that trade between the Lenape and Dutch made beavers scarce even by the time the Swedes established their colony in the Delaware Valley in the mid-1600s. Beaver pelts remained in high demand for the next couple of centuries, and they were wiped out in Pennsylvania by the end of the 1800s. In the early 1900s, the PA State Game Commission started importing and releasing beavers. This initiative was a huge success, and beavers began spreading across the state, eventually reaching southeast PA. 


Where They Live 

Today in Philadelphia, beavers live in our rivers and many of our larger creeks, such as Cobbs, Tacony, and Pennypack. You can also find them at work in our tidal marshes, including at the John Heinz National Wildlife Refuge at Tinicum.  

Observing Beavers


Beavers can be hard to spot in the flesh since they are primarily active from dusk to dawn. Luckily it is easy to spot their lodges and the pointy tree stumps and chewed branches they leave behind.


Keep an eye out for this beaver evidence on your next walk along the water. This is true in our more-natural spaces such as Haddington Woods and our more-intensively landscaped parks such as Penn Treaty Park. 


Once you find some stumps and other beaver evidence, see if you can find the trails the beavers use as they leave the water to look for food on land. 


Living with Beavers


Although most city dwellers don’t encounter beavers on their blocks, anything that cleans up our waterways and promotes healthy aquatic ecosystems helps beavers.


Beaver can be a challenge for park stewards and other people cultivating plants near the water. You might think the trees you planted will contribute to the forest canopy for decades to come. The beavers might think they work better as lunch. You might need to protect trees from beavers and plant species like willows that bounce back after getting cut down. 



More resources

PA Game Commission 

Beavers Matter 

iNaturalist Observations

 

Urban Beaver Sign

Learn about how to find beavers in the city and how to see what they've been up to. Thanks to our partners at Grid Magazine for producing the video. Learn more about beavers here, and check out Beaversmatter.org for even more about Philly area beavers. 

 
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Photo credit: Beaversmatter.org