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Salicylic acid

Beavers Posting Their Land

It’s not as neat nor as tall a mound as it typically is, but the vegetation you see on the bank of this pond is a beaver’s way of posting its territory.  In two to three months, around the time that beavers give birth, the two-year-old beavers inhabiting a lodge typically leave to seek greener pastures in the form of unclaimed ponds or to form their own pond.  No-one is quite sure whether parents encourage this departure, or whether the young beavers take it upon themselves to leave, but especially when the food supply is limited, the two-year-olds disperse.

Older, established beavers, having experienced this exodus themselves when they were young, are well aware that two-year-olds will be scouting for a new spot to set up residence in the spring.  In order to discourage any potential intruders, beavers build one or more “scent mounds” on the shore of their pond or stream that consist of mud and vegetation they’ve gathered from the bottom of the pond or stream.  They then walk over these mounds and excrete liquid castoreum from castor glands (located near their anal glands) onto it.  The scent of castoreum is very distinctive and conveys information to beavers passing by that tells them that this location has been claimed and to move on. (If you come upon a scent mound, I encourage you to smell it – castoreum has, to some people, a very pleasing scent.)

Interestingly, castoreum contains salicylic acid, which is the active ingredient in aspirin. Salicylic acid is found in willows (which beavers eat), and native Americans used willow bark to treat headaches.

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