October 2019 Natural Mystery Answered

Our October Natural Mystery was an obscure, partial track found on the banks of the Connecticut River near Northfield, Massachusetts. Guesses for who made this print ranged from birds and reptiles to marsupials and rodents. Congratulations to Kim Cabrera, who was the only person to successfully identify the animal that left this print. Kim also identified which foot make this mark. This is the left-hind track of an American Beaver.I'll let Kim take it from here:

"The toes of this animal are wide and rounded at the ends, with a hint of a claw. My first impression was a turkey track, but I ruled that out due to the wider toe marks and blunt claw marks hinted at here. This lead me to think it was a beaver track.

The track has been heavily rained on and is very aged by this weathering. A beaver's tail drag will often obliterate most of the track. When this happens, the outer toes are sometimes all that are seen from the hind tracks. I think that might be the case here. The beaver's tail drag made most of this track disappear before it got rained on. The rain took care of the rest of the micro details. All we are left with for evidence here is the vague toe tracks and some vague impressions from the metatarsals. The marks in the photo that are most prominent are the outer two toes, toes 4 and 5, making this a left-hind foot."

I would add to this two other points. First, we can see a hint of the right-hind foot in the upper right-hand corner of the photo, which helps us confirm that this is the left-side track we are looking at. Second, beavers walk with their weight set well to the outside of their hind feet. The outside toes usually register more deeply and clearly than the inside toes, whether or not the tail further obscures the track. It is fairly common to see only toes 3, 4 & 5 showing in a beaver hind track—even clear, fresh tracks in good substrate.

Kim goes on to make one final note about beaver tracks:

"Beavers also leave some odd-looking tracks when they are swimming in ponds. These tracks in bottom sediments show up when the pond water evaporates. I don't think this is one of those tracks because the toes are relatively clear and don't appear to have been made by a swimming animal."

We saw some of these tracks near by where this photo was taken. Just as Kim suggests, the details in the prints were less crisp. In addition, the track pattern was narrower with a longer “stride,” as if the animal was trotting. You can see an image of that print (though unfortunately not the trott-like track pattern) here on iNaturalist.

Congratulations again to Kim Cabrera for her successful IDs of this very obscure track!

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