Hiking Nature

I have finally come to a rock-solid conclusion as to the species of the elongate mammal I filmed as it ran up a steep hill along the South Cove trail at Radnor Lake.

It was an otter — specifically, a northern river otter — for certain. The giveaway was the tail!

I came very close to deleting the second photograph I snapped of this animal as it ran; after all, the shot was lousy because the mammal just happened to be directly behind a large tree as the light pattern was digitally recorded. But at the last minute I decided to open the image to see if any part of the animal was visible, especially the tail.

At this point, I had been told by Radnor Lake park ranger Leslie Ann of the differences in the tails of the mink and the otter. It turns out the tail is one of the main ways to tell the two mammals apart.

The mink’s tail is somewhat bushy. The otter’s tail is thick and not so bushy, and flattened horizontally to propel itself through the water by waving the tail up and down.

It is rather interesting to me that the otter’s tail apparently does not go back and forth. It seems back and forth would be the most natural way to use the tail for acceleration or movement through the water. Alligators, snakes, and other animals use a back-and-forth motion.