Olfactory Enthrallment

One of the first steps to understanding animal behavior is to recognize that many species interact with the world through their noses. Beavers are a prime example. Once they establish a territory, they’ll mark it by making little piles of mud and then squatting and depositing scent from their castor glands. These castor mounds serve as posted signs, telling other beavers to stay away, and also as a basic means of communication with other beavers in a flowage. Studies have shown that beavers can recognize family members by their smell, and also distinguish strangers from neighbors. [To learn more about castor mounds check out this article by Dietland Müller-Schwarze.]

We figured that to get a good picture of a beaver we should pretend to be a beaver, so we visited a trapper and procured some fresh castor gland. These glands are located near the anus, and in mature beavers in springtime they’re swollen and impossible to miss. There are two sets of glands in this picture, each worth around $5 to $10 to a gland dealer. They’re used in the perfume industry.

We ground the glands and added a little oil sac, on the trapper’s recommendation. The castor smells sweet – it’s made of recycled plant compounds – and the oil sac smells slightly bitter.

We then set the camera up at the edge of an active beaver pond near the office and set to work making a fake castor mound. Here, editor Dave Mance III starts things off by making it look as if a beaver were coming in and out of the water. The real teachable moment, though, is that if you’re going to be involved in a photo essay, you should really remember to wear a belt.

Here, Mance flings mud up on to the bank, all the while grimacing strangely as if the mud offended him somehow. An actual beaver would have carried the mud wedged between his front paws and chin, all the while looking placidly rodent-like.

Mance then flattens the mud using his hand like a beaver tail…

And then applies a dollop of castor while Stella the dog and Northern Woodlands co-founder Ginny Barlow look on.

Barlow asks to smell the castor…

...and confirms…

...that it smells sweet, all the while strategically keeping her face out of the photo, as she’s wont to do.

Then everyone goes home and waits.

Five hours later an adult beaver shows up – probably the male. He smelled the pile and circled it three times, each time knocking it down with his tail. He then squatted over the mud smear and deposited his own castorium, then raked things with his hind feet. The whole process took 12 minutes.

One hour later, two sub-adults showed up. The first one did a modified scent marking routine that took 3 minutes. As he left, the second beaver came ashore, squatted, scent-marked, then left. It took this second beaver only 1 minute to do his business.

The next morning a pair of mallards came to investigate.

Then a random person we didn’t know.

Then Stella, who in this series takes in the new scents, licks everything, rolls in the castor mound, gives a blissful look that only a dog could understand, then finishes it off with a guilty look, in conjunction with her owner’s cry, that says: “Oh right, I’m not supposed to roll in stuff like this.”

  1. Mary Holland → in Hartland, VT
    Apr 14, 2016

    Outstanding experiment!!!

  2. Jennifer Lovett → in Stamford,VT
    Apr 15, 2016

    Although an interesting experiment, I would have liked the article much better if you had located an existing scent mound to use as your source of castoreum and had not involved a trapper. Trapping beaver is an inhumane, obsolete, and unnecessary tradition that has no place in today’s world.  People should be encouraged to co-exist with wildlife, especially those that are important to maintaining ecosystems like the keystone species, Castor canadensis.

  3. MM → in Maine
    Apr 16, 2016

    Great series of photos!

  4. Karin U Edmondson → in West Kill, NY
    Apr 16, 2016

    Gland dealer? Disturbing. Does the beaver have to die for the human trapper to get the olfactory gland to sell to the perfume industry? Hoping not.

  5. Cindy → in Middleton, NH
    Apr 17, 2016

    This is great.  Thank you!  (Though sad about the poor scent gland donating beaver.)  :(

    Loved the humor!

  6. Dave → in Corinth, VT
    Apr 18, 2016

    I strongly disagree with your thoughts about trapping, Jennifer. That said, I agree wholeheartedly with the idea that beavers are an important keystone species, and that people should be encouraged to co-exist with all wildlife. Most of the trappers I know would agree with this, too. Much better to find common ground, I think, than to promote division.

  7. Justin Valaske → in Putney, VT
    Apr 22, 2016

    Northern Woodlands magazine has published many wonderful pieces regarding hunting and trapping, including the history of the foothold trap in the January, 2016 issue. One of my favorite writers of this magazine, Dave Mance III (the author of this article), is an avid outdoorsman and sportsman.

    If we’re going to discuss the important roll hunting and trapping plays in conservation, it would be good to remember the financial side. Here are some excerpts from an article Dave published on the subject:

    “My old boss Walter Medwid recently published this op-ed raising the issue of Fish and Wildlife funding in Vermont. It’s a wonky issue, I’ll grant you, but it’s something that everyone who cares about nature ought to be at least peripherally interested in, no matter what state you live in. We published an extensive piece by Tovar Cerulli on the subject last year that includes all the background you need to know.

    I’m glad Walter raised the issue and I agree with much of what he said, though I’d put a finer point on the degree to which hunters, anglers, and trappers are carrying the financial burden of protecting, conserving, and studying wildlife. In Vermont, only around 10 percent of the Fish and Wildlife budget comes from the general fund; 72 percent comes either out of sportsmans’ pockets directly in the form of a license fee, or indirectly, through a federal trust that’s been accruing money since the 1930s from taxes on guns, ammo, and fishing equipment. In Maine, about 5 percent comes from the general fund. In New Hampshire and Massachusetts, 0 percent.

    While I don’t have a percentage to give you that breaks down the time/resources the Department spends/allocates catering directly to hunters/anglers/trappers versus time spent on the public good, it’s safe to say that the general public is not paying a proportionate share.
    And so it seems to me that the first step to bringing more non-consumptive users to the policy table is to figure out a way to make them financial stakeholders.

    The other point I’d make in response to Walter’s op-ed is a cynical one…I’m trying to think of a nice way to say that I don’t trust the collective wisdom of the masses. As a sportsman, I’m all for non-consumptive users paying more into the system, and in exchange, the Department broadening its focus to include even more non-game habitat and conservation and recreation-focused work. This would undoubtedly enrich human and animal lives. The elephant in the room, though, is the animal rights faction of society who actively loathes hunting, fishing, and trapping and who will be demanding their seat at the table. You just saw an example of this in Maine, where The Humane Society of the United States, a Washington D.C.-based animal rights group, spent almost $2 million dollars trying to ban three forms of bear hunting on “ethical” grounds. They lost the vote by just four percentage points – the second time this has happened in 10 years.

    The point is that if we’re going to try to make fish and wildlife departments more diverse, the sporting community is going to need some assurance that traditional activities like hunting, fishing, and trapping are not going to come under threat from big moneyed outside interests. Figuring out a way to do this seems like another first, crucial step toward reform.”

    Vermont residents and sportspersons are very clearly not interested in suggestions from animal rights activists.  To put it simply once again, if you want a seat at the table then begin by paying your fair share. Beyond that, the idea that a person with zero experience in the activities of hunting, trapping, or fishing will govern the laws regarding those activities is completely irresponsible and unrealistic.

  8. Dave → in Corinth, VT
    Apr 26, 2016

    Just a friendly reminder, folks, that we’re not going to post comments that contain personal attacks, or off-topic screeds.

Join the discussion

To ensure a respectful dialogue, please refrain from posting content that is unlawful, harassing, discriminatory, libelous, obscene, or inflammatory. Northern Woodlands assumes no responsibility or liability arising from forum postings and reserves the right to edit all postings. Thanks for joining the discussion.

Please help us reduce spam by spelling out the answer to this math question
three plus three adds up to (3 characters required)