Chris Cooper was in the woods in Michigan when he saw a shy white weasel peek out of a hole in a tree to say hello. Weasels are a type of mustelid that live in the southern part of Canada, all of the United States and Mexico, all of Central America, and the northern part of South America. The long-tailed weasel results from a process that started 5–7 million years ago when northern forests were cleared to make way for grasslands. This led to a rapid increase in small, burrowing rodents. The long-tailed weasel’s ancestors were bigger than they are now, but they got smaller so they could eat the new food.
The long-tailed weasel first appeared in North America about 2 million years ago. Just before its mirror image, the stoat, appeared in Eurasia. During the Ice Age, this species did well because its small size and long body made it easy to move under snow and hunt in burrows. The long-tailed weasel grows quickly. By the time they are three weeks old, the babies are well-furred, can crawl out of the nest, and can eat meat.
Right now, the kits weigh between 21 and 27 grams. When a kitten is five weeks old, its eyes open, and it starts to move around and talk. Weaning starts at this stage, and a week later, the kits leave the nest and go with the mother on hunting trips.