Like many other animals, beavers are territorial, and use scent to mark ownership. On the shore of their pond, they create piles of leaves, sticks and other debris, much of it dredged up with mud from the bottom of the pond. Some of these mounds are small piles as you can see here, while others are large, conical heaps, occasionally exceeding 18 inches in height, as in the photo below. Beavers carry small amounts of debris in the mouth, and tote larger loads between the front paws and chin, as you will see in the video. They stack it onto the mound, then straddle the top as they anoint it with castoreum from the caster glands, secretions from the anal scent glands, or both. You might recognize the characteristic odor when you visit a beaver pond. The smell is most intense in spring, when beavers are zealously scent marking to announce to dispersing young beavers that this area is already occupied. In fact, you may be able to follow your nose to a beaver scent mound, once you learn the characteristic odor.

Beaver tending to a scent mound on the shore of his pond.

Finding a beaver scent mound is nice, but observing its construction is utterly fascinating. Earlier this month (April) I placed my camera near the biggest, smelliest pile at the shore of a beaver pond in Massachusetts, in order to get a good look at this activity. Six days later, I was excited to find that a beaver had added debris and “freshened” it with scent up to several times a day.

Video of Beaver Scent Mound Construction

Watch the video – I think it’s rather comical. The mound is already quite tall (about 2 feet, but I’ll have to measure it accurately when next I visit it), yet the persistent beaver struggles to make it even more impressive. Notice that sometimes his “load” slides down as he descends, and he tries to pull it back to the top. Also note the little butt waggle after he positions the debris on top. I believe this is when he is depositing secretions. It reminds me of the way otters deposit scent on their mounds, paddling with hind feet. Compare this beaver action to river otter scent marking, in the video in this post.

I’ve still got a camera stationed at this mound and hope to see what the activity is like as the season progresses. I’m also wondering if the parents will bring their kits to the pile, for a lesson in staking claim with stink. Stay tuned.