This cute little guy is a long-tailed weasel at Bear River Migratory Bird Refuge in Utah. While he might look sweet, the long-tailed weasel is fierce. The sharp teeth, keen eyesight and scrappy character make this species a highly skilled predator. During the winter, their fur changes from brown to white to better protect them. Photo by Jana M. Cisar, USFWS. Posted on Tumblr by the US Department of the Interior, 2/5/16.