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Wednesday, July 20, 2011

Black Bear Trail Research PART II: Camera Trap Results

This is the second post regarding the black bear work my students did in early July in Massachusetts. You really should check out my first post here before you read this post :)

On our second day with Nick, we returned to the same location as the day before in order to retrieve our cameras and take some measurements of the part of the trail that showed clear, repeatedly used footfalls. Nick led us along to the location leisurely, providing interesting natural history facts along the way. As we approached the trail, we had kind of strung out into two groups, separated by about 10 yards.  I was in the second group when I heard someone ahead of me yell "BEAR!". When I looked up, I could see a black bear changing direction to move away from us about 20 yards ahead. The perspective from the members of the first group was even more dramatic: we had actually walked up on a black bear using the ritual trail! The lead group was literally ten yards from the bear before the people noticed it. The bear was so focused on what it was doing that it didn't notice us either. We all got great views of the bear as it walked away from us and dissolved into the forest.

Black bear using ritual trail
(Massachusetts,  7/11)
Seeing the bear was amazing, but it was also important for our research. First, we had camera traps set at both ends of the habitually used part of the trail. We disrupted the bear before it got to the second camera location, but s/he walked right past our first camera (my first camera trap of a black bear, BTW). The camera was set at the edge of a wallow. In the photo, that would be to the right. However, this bear skirted the far edge of the wallow and started in on the ritual trail dry. The time and date stamp on the photo to the right are correct.... it was so dark in the forest the infrared flash went of causing the photo to be colorless. As you can imagine, the students and instructors alike were pumped. This was far more than we had bargained for! I had already warned the students that measuring black bear sign is far easier than actually seeing the animals. Now I fear they are spoiled, but to put it in perspective, Nick told us that in his eight years of measuring these trails, this was the first time he ever saw a bear actually on one.
FLCC students measuring fresh black bear tracks
(Massachusetts, 7/11)
The other aspect of this encounter that was so useful for us as researchers is that we now had actual footprints to measure. I watched as several students placed their hands in the freshly made tracks in a show of empathetic tracking. It was a powerful moment for us and really connected these divots and marks on the trees to the flesh and blood animals that made them. To use the trails "properly"(meaning that a bear would put its feet into the existing footfalls on the trail) requires the bear to walk in what is called a direct register. This means that the rear foot falls into the track made by the front foot. In essence, this means the front track is destroyed or covered, so we were only able to measure the size of the rear track. Exclusive of the claws, the rear track measured 5 1/4 inches wide and 7 1/4 inches long. This is a good size track for an adult black bear. In the photo above, you can see that we have used toothpicks to outline one of the tracks.

Measuring footprints of black bear, Brian Cole (left) and
JVN (right) (Photo by: Sasha Mackenzie, 7/11)
Nick said something interesting on our first day together. His many years of measuring the bear trails has lead him to believe that the way they are putting their feet down when using these trails is different than "normal". He feels that the length of the stride and straddle (width) of the trail indicates the bear is doing something other than walking in a relaxed manner (and more in a ritualized way). Rather, the numbers do not "add up" with the numbers he gets when measuring a bear trail say in the mud or snow, in an area where there is NO ritual trail. We adopted Nick's method for measuring the steps and trail width. We used toothpicks and Popsicle sticks to outline the tracks when they were visible and we centered an imaginary track into the deep, existing footfall when a fresh track was not present. Our results bore out what Nick had stated: the stride and straddle simply did not match what would be expected of a "normal" gait when compared with the published literature. I will discuss how we interpreted those results in my next post.

Black bear using ritual trail
(Massachusetts, 6/11)
More Camera Trap results: We mailed Nick two camera traps before our trip. Regular readers of this blog know that I use Cuddeback Capture cameras. We chose to send him two IR cameras so there would be no visible flash to interrupt the bears' behavior or to alert it to the presence of the cameras. This means any low light images will be in black and white. Results? Nick placed the cameras on two different ritual trails for five days before we arrived. One camera produced no bear results, but the other captured two images of black bear on the trail. Whether this was one bear photographed twice or two different bears, we may never know. Here are those images:
The first photograph is from June 29th at 920 am. This looks to me like an adult bear. Young bears give the impression of having large ears because they have such a small head by comparison.
Black bear photographed using a ritual trail
(Massachusetts, 7/11)
The second photograph is from several days later and used the IR flash. What clues would I have to tell if this was a different bear than the one from the 29th? They were captured in such different poses that it is difficult to tell size properly. Nick felt that maybe there was a difference in the muzzle between the two bears, but I lack his experience and am not confident in making that determination at all.
Black bear using ritual trail
(Massachusetts, 7/11)
I shared the photograph of the bear we saw at the beginning of this post. Please note that that photograph was taken many miles away from these others, on a completely different ritual trail. We left a camera with Nick when we left and he placed it back in the location closer to his home, where he had already gotten the above two photographs. Nick emailed me a few days ago and sent me two more photos from that trail. He agreed to leave it out "until the snow flies" so it will be interesting to document the activity on that one trail. See that large tree in the center of the photos, behind the bears? That is a marked tree with scratches, bites and evidence of rubs. It may only be a matter of time before we get a nice image of a bear adding to the marks..... Sure wish I had video :)

4 comments:

  1. Very cool trip and fun experience for the students, JVN!

    Never heard of a ritual trail before. Very informative.

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  2. Hey John,

    Thought you might be interested in this: http://www.sitkanature.org/wordpress/2011/12/19/bear-trail-mystery/

    My brother noticed recently that one of the ritual bear trails up where he lives has different vegetation than what surrounds the trail. I wonder if you've noticed that in any of the trails you've come across.

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  3. Thanks Jonathan! I appreciate the info. Is that a black or grizzly bear trail?

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  4. That is a coastal brown bear trail.

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