Wildlife Wednesday -- Tale of Two Weasels
By Andy Ames
The tale of two weasels. The Estes Valley is the home to both the Short-tailed and Long-tailed weasels. At first glance they look nearly identical. The Long-tailed is larger overall, however, at about 12 to 18 inches nose to tip of tail, while the Short-tailed weasel ranges from 8 to 10 inches. The tail of the Long-tailed weasel also makes up a greater proportion of its length. (Of course, weasels are very fast and the tail length is only helpful if you can see the its tail). Although rarely seen, weasels are active all year round, day and night. Breeding takes place in late summer and with the help of delayed implantation, births do not occur until late spring to early summer. Kits develop rapidly and females are able to mate the same year as their birth.
How they got here is also an interesting tale. The Short-tailed weasel evolved in Eurasia. During periods of low sea levels, it dispersed into North America and now encompasses a Holarctic distribution in northern parts of Europe, Asia, and North America. This might help explain its many names. The Short-tailed weasel is also referred to as a stoat or ermine. The Long-tailed weasel, however, evolved in North America and can now be found from southern Canada, throughout the United States, down through Mexico and even into parts of South America. Unlike the Short-tailed weasel, the Long-tailed did not cross northern continents. This could be because its larger size and greater surface area to volume contributes to a higher energetic cost making it less suited to northern climates. Here is the Estes Valley, both weasels molt twice a year, growing a white coat in the winter and a brown and tan coat in the summer. In warmer climates, the Long-tailed weasel keeps a consistent color year round or features a mottled winter phase.
Don’t let that innocent face fool you. Weasels are very capable hunters. Above ground, they grasp their prey with all four feet while giving a paralyzing bite to the base of the skull. Prey caught below ground is suffocated with bites to the throat. Weasels are known to cache excess prey for later consumption.
The weasel’s menu consists of a wide variety of animals — voles, mice, shrews, chipmunks, pocket gophers, ground squirrels, pikas, rabbits, and even birds and their eggs. Weasels are known to eat insects, carrion, and bits of fruit, as well.
The elongated head and body of the weasel allows it to “follow prey home” in burrows. Weasels are active year round and energetically forage for periods of about an hour followed by rest. In the winter I often see weasel tracks going from one wood or rock pile to the next and bush to bush and tree to tree. While they often follow the paths and tunnels of their prey, they are able to tunnel themselves through snow to stay undetected. It is amazing how much ground weasels are able to cover!
Both the Long-tailed and Short-tailed weasels have a black tipped tail. This is thought to confuse predators in hopes that they would be attracted to the end of the tail rather than the weasel’s body.
The length of the tail is the best way to distinguish the Short-tailed from the Long-tailed weasel. While tail length can vary between individuals, in general if the tail is 44% or greater compared to the length of the head and body it is a Long-tailed weasel. If it is 44% or less, it is a Short-tailed weasel. (This was the best photo I could get for comparison’s sake).