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Saturday, December 29, 2012

RIP Dustmop...?

Just before the rush of final exams we had a spate of warm weather. I took that opportunity to get some work done in the back field. From atop the tractor I spied a patch of gray fur... it was a dead opossum. I figured it was the dustmop. She had been dead for sometime but that did not deter me from inspecting the carcass. After a cursory examination, I saw no obvious cause of death. I made a mental note to return shortly with camera in hand.
Opossum front foot
(Seneca Falls, NY 12/12)
But then finals week kicked in. Then the snow came. It wasn't until Christmas Eve that I found the time to walk back out to the spot and see if the dustmop was still lying there. By now we had ten inches of snow and I literally had to sweep my boots back and forth through the drifts in order to find her ("What did you do on Christmas Eve?", asked any sane person. "Oh, I crawled around looking for a frozen carcass of an opossum in order to take photos of its feet." said I).
 
 
 
It is a primitive characteristic to have five toes on a limb and the opossum has five on the front and back feet. Sometimes when I say that in class, I get push back from students. We don't like to think of ourselves as "primitive". But the word is not pejorative. Animals with fewer fingers and toes are more specialized. Think of horses with their single toe per limb. They are very good at what they do but do not have the generalizability that we have with our "primitive" hands. Ever get a text message from a horse? I rest my case....
 
The hind foot of the opossum never ceases to amaze me. Check out the opposable big toe. Note that it does not have a nail. This isn't the greatest of shots but the carcass was not cooperating very well.
 
Finally, let's have a quick look at the tail. Naked and semi-prehensile, it is unique in North America. There is no sign of frostbite at the tip so I think this is a young opossum (although we did have a very mild winter last year and perhaps this individual made it through without any freezer burn).
Opossum tail
I was saddened by the loss of the dustmop. Although I only wrote two entries of the opossum and skunk duo, I had literally hundreds of photos from that particular camera set. But it was Christmas Eve. Family was due in an hour and I still had presents to wrap. I trudged back to the house with my head down, concentrating on covering the distance quickly. It was then that I saw the fresh tracks...
 
Opossum trail in snow
(Seneca Falls, NY 12/12)
I knew right away that this was an opossum. Could THIS be dustmop? Was there more than one opossum visiting that carcass (I never photographed more than one at a time)? The tracks led for quite some distance and through deep and shallow snow, thus providing some great tracking opportunities. First, the trail as I initially found it in deep snow. Notice the relatively wide trail width or straddle along with the short legs (short legs are deduced by the belly drag in the trail). In our area, that usually means opossum or skunk. What sealed it as an opossum even at a distance was the numerous tail slaps in the snow. In the photo at right, you can see several tail marks close to the photographer (me) and to the left of the trail. Finally, notice that this animal is not direct registering. In other words, the front and rear feet are not landing in the same spot. Many animals direct register (I have also seen that described as perfect stepping) so this was a clue as well.
 
I was particularly pleased with this identification because I was not identifying tracks, I was identifying the trail. The snow was too deep here for me to make out much int he way of individual tracks. For me, this was a step forward (pun intended) in my journey as a tracker.
 
One more view of the tail slaps:
 
 
 
Opossum trail
(Seneca Falls, NY 12/12)
As the opossum moved into shallow snow, the tracks became more distinct, the belly drag was eliminated and the tail slaps became mere wisps in the powder. In addition, notice that the front and rear feet are ALMOST landing in exactly the same spot. I found that interesting since in the deeper snow, they were so far apart. Have you ever followed the tracks of someone else in deep snow? Its easier to step right where they stepped rather than making your own prints -- that is, unless they have a very different stride than you do. When I break the trail, I try to keep my strides a bit shorter so my wife and daughter will have an easier time following. I think the opossum with his short legs had a hard time in the deep snow even keeping up with his own trail and simply couldn't direct register easily. Last thing to note in this photo: direction of travel. I have learned from several trackers the adage "Long in, short out." Even if a trail is blown in with snow, you can tell the direction of travel because the feet make a long mark on the way in and a short mark on the way out. In this case, the opossum is moving away from the photographer. You can also see that in these wolf tracks from Yellowstone.
 
Here is one more shot in medium-depth snow. Note the tail marks. Moving to the right.
 
Finally, a shot in the shallowest snow I could find. When the opossum got to our backyard, it followed my ATV tracks for a while and went up the driveway and to the road. The two tracks are nearly next to each other, like two incorrect jigsaw puzzle pieces placed together out of frustration. The front foot is on the right and shows the typical sprawling star-like pattern that helps tell these feet from raccoons. The hind track has four toes pointing forward and the opposable big toe actually overlapping the palm pad of the front foot. These were the first distinctive tracks I had seen on the entire trail. I was pleased that I had confirmation of my identification. I wanted to continue on the trail, but a car was pulling into the driveway. My parents had arrived and I was pulled out of my adventure and back into Christmas Eve...

4 comments:

  1. Great blog! I can't wait for winter tracking!

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  2. THis was a really good entry...really liked the perspective of IDing the trail rather than the inidividual track. I didnt have as exciting of a Christmas Eve as you did!

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  3. I'm just curious as to why you cant see a tail slap on the right side of the track in the first picture? Is it just the lighting, since they are on both sides in later pics? (or was this guy just left footed? haha)

    I miss tracking and doing all kinds of fun outdoors stuff!

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  4. Hi Katie, there really were NO tail slaps on the one side at all. Maybe it is like being right or left handed. Maybe the ground was slopped a little making it easier to keep your balance in that particular way. Thanks for the comment!

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