Mink tracks have been noted along the Nenana River, but over most of the eastern half of the park the mink is rare.
River Otter
Lutra canadensis yukonensis
The otter is rare in the park. It was reported present in Wonder Lake some years ago and tracks in the snow were reported at Savage River. It probably occurs in the Nenana River, along the eastern park boundary.
The otter, a member of the weasel family, has become adapted to life in the water. His body is about 3 feet long, and his long muscular tail is over a foot long. His cousin, the sea otter, plentiful in the Aleutian Islands, is much larger and more specialized for an aquatic life.
I have watched a family of otters in Grand Teton Park fishing for an hour or longer. They kept diving steadily, and occasionally one would come up with a small fish which he would proceed to eat, beginning at the head. Larger fish are taken ashore. Trout, chubs, and suckers were available but numerous droppings showed that the otter were feeding chiefly on the chubs and suckers. The fish taken were no doubt those most easily captured. A few crayfish were also eaten. This particular family was living in a large beaver house also occupied by beavers. They entered their chamber by land and apparently lived upstairs above the beaver’s part of the house with its underwater entrance.
In winter the otter frequently travels over the snow from one piece of water to another. In these travels he slides on his belly down all slopes and sometimes even on the level. In play, a family may repeatedly climb a mudbank or a snowbank to course down a slide leading into water.
Short-Tailed Weasel
Mustela erminea arctica
Two species of weasel occur in the park. The larger one with a black-tipped tail is called the short-tailed weasel, and the smaller one with an extremely short and all-white tail is the least weasel.
Both weasels are brown in summer and white in winter, a protective coloration no doubt useful in escaping detection. In some southern parts of their ranges these weasels remain brown all year, and in intermediate areas part of the population turns white in winter and part of it remains brown. It is apparent that climate has an effect on coat color, the specific factor being the presence or absence of snow on the ground.
It has been pointed out that the short-tailed weasel is much larger in the north than in the southern part of the range. In Wyoming and Colorado, where the tiny least weasel is absent, the short-tailed weasel approaches the least weasel in size and probably fills that weasel’s niche in the environment.