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Thursday, March 7, 2013

Bear den season: 2013 Part I

John Van Niel with bear cub

A highlight of my spring semester is black bear den season. I teach a Black Bear Management class at Finger lakes Community College in Canandaigua, NY and the students and I partner with the NYS Department of Environmental Conservation to take data on cubs and bear dens. I have written about previous years here. In these previous posts, I explained in more detail the goals of our work and how the bears are processed. With that in mind, I will not repeat all of that again. If you are new to bears or bear dens (or can't get enough of bear photos) I suggest you glance through some of those posts.

On March 5th, we visited two dens with females and cubs. Our first den went as smooth as smooth could be. We drove to the location near Campbell, NY and got our marching orders. We were a smallish group that included DEC personnel, FLCC students and veterinarians from the Seneca Park Zoo. The walk couldn't have been a half mile and was fairly level. We stopped a hundred yards from the den and let the advance crew move ahead. These are the DEC personnel that will actually be chemically immobilizing the adult. We kept our voices low and listened for the pop from the dart gun. Merely eight minutes after the drug was administered, the adult bear was completely under. It doesn't always happen that smoothly!

Black bear sow in den
Here is a photo of the bear's den. She has created a nice little nest here but notice how little cover from weather or predators this site provides. But just because I don't care for the site doesn't mean it isn't the right one. There are a few aspects of the den I would like to point out. First, have a look at the tree to the right of the den. Can you make out all of the chew marks on it? Let's take a closer look:

Is she marking? Is this a result of boredom? Who knows... One of my students even suggested this was done during labor :)
On the back side of the tree were these scratches. Imagine her sitting up in the den and grabbing a hold of the tree in order to bite it.
The den itself is mostly grape vines pushed into a nice bowl shape. Some of the material appears to have been their at the start of construction but some was brought in by the bear. Look at the den and imagine how tight this will get as the cubs get older.

I noted this bear sign at one other den: Branches bitten off as den material. These were broken off within feet of the den. I am determined to find an unused den by first noticing similarly broken branches.
This bear has been collared for three seasons now. Her first litter was only a single cub. This year, she had twin girls. Both seemed of good size and weight for their age. Cubs are never immobilized and are put in fleece bags to stay warm while mom gets her work up.

Once the work is done, the mother and cubs are returned to the den.

 One last shot of the family reunited. Notice the cubs under mom at the lower right.
Our second den was near Wheeler, NY. The den was located right near the large pine tree in the background. Notice how close the den is to the road. Granted, this isn't a major highway, but it isn't a dirt path either.
This bear had triplets. The routine was the same as the last den. An advance crew goes in while we wait for word on the radio. The landowner was on hand and I made a point to thank him for allowing us to come onto his property. He had a few questions about bears in general and asked about the den in particular. Turns out he shared a common misconception with many people I talk to. He envisioned the den to be an excavated site. Although bears do dig dens, those dens are not common in our area. I told him that bears commonly den under brush. Sure enough, this bear was under a blown down tree.

Here, Sasha holds her hand out to the spot where the bear would lie. Again, notice how wide open this den is. At least this one had some substantial cover from the elements.

Above, one of my students (Ben Williams) lies on his back and looks up to estimate the percent cover. We also measure the size of the den, the direction of the opening, and more. But that should be the subject of another entry.

Here is a photo of the den from a distance. We are looking at the "back" of the den. The opening is not visible.
As with all dens, we processed the cubs apart from the mother. They are taken out of their fleece bag only for a moment to tell gender.
The bears in our area are usually born in early January. These cubs weighed a little under four pounds. Check out the canines just starting to emerge
 In this case, the collar was taken off but a new one was not put on. This bear was part of a research project through Cornell University and they are done collecting data.


  1. What an outstanding opportunity for your students! Very cool stuff, JVN!

  2. That den looks like Bird Bird's nest on Sesame Street!!!!


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