Meet the White Mountain Ermine

The Feistiest Little Weasel of the Whites

Words by Matt Maloney, Tin Mountain Conservation Center

Photography by John Rondeau  (images captured in the northern White Mountains)

The ermine belongs to a group of small weasels that are often overlooked by locals and visitors in our area. Also known as the stoat, or short-tailed weasel, the ermine is a mammal of the genus Mustela of the family Mustelidae native to Eurasia and North America. When seen, though, they often invoke curiosity and questions of, “What was that small creature I just saw?” What, at first glance, might seem like a squirrel, on second look, appears to be a smallish, weasely looking critter. If you suspect the creature is a small weasel, you may well have seen an ermine.

Ermines are a relatively common creature, but overlooked, and far more secretive than chipmunks and squirrels, the most commonly seen small mammals. Ermines are predators like all weasels and can be seen at any time of year. They turn all white in the winter months, making them particularly beautiful when seen in the winter sunlight. The black tip of their tail can confirm it’s a weasel to the eye. More later about the ermine’s look-alike cousin, the long-tailed weasel, which also has a black-tipped tail. If you see one of these fascinating creatures, you have probably run into it as it prowls for prey.

Ermines are out and about in the daytime when they are on a scent, often tunneling through the snow tunnels of rodents beneath the snowpack, looking to make a kill. I have often run into their little bounding patterned tracks dead-ending in a tunnel presumably made by a mouse, vole, or shrew. 

If you have a woodpile or just mice around your house, there is a good chance an ermine will pay a visit. Those small rodents that can so often become pesky around our homes are kept in check, in large part, by efficient predators such as ermine. Ermine can even catch prey up to five times their size! They can catch and eat waterfowl, muskrats, and even cottontail rabbits (Tracking & the Art of Seeing; Rezendes). 

A wonderful time to look for signs of ermine is when there is fresh snow on the ground in winter. Being an active predator, ermine tracks can lead the curious tracker into and through all kinds of out-of-the-way areas full of downed logs, brambles, and assorted deadfalls, as they seek out the homes of small mammals, and perhaps even a hibernating chipmunk.

The next time you’re on snowshoes or skis, take some time to look for the small, bounding tracks of the ermine. The footprints leave only a 1- to 2-inch-wide corridor and there can be anywhere from 9 to 35 inches between their strides. Bring a tape measure if you’re dedicated, but either way, they will be tiny tracks that appear with the footprints, side by side or slightly staggered, a sign of the bounding manner in which all weasels move.

Their prints can sometimes lead you to a tiny hole where an ermine has cached some prey, an exciting find. They sometimes cache prey in their own dens, as well. I’ve found blood drips in the snow from fresh ermine kills before, outside of tunnels where they’ve tracked down the occupants within. These under-snow or subnivean tunnels, as they’re often referred to, provide a warm pocket of air for rodents as well as safe haven from owls, hawks, and other predators. However, ermines can fit inside these holes perfectly, especially the smaller female ermines. Whatever you may find, tracking an ermine is a fascinating experience. 

Seeing an ermine is the greatest joy, of course. I’ve come across them darting across ski trails in winter and darting over snowy roads while driving. When someone wonders what that little creature near their woodpile or barn is, I suggest it’s probably an ermine. If it’s white and looks like a weasel, it’s almost sure to be an ermine or long-tailed weasel. 

The ermine is one of three species of weasels in New Hampshire that includes long-tailed weasels, and pine marten. Weasels are part of the Mustelidae family, which includes otters, fishers, skunks, and minks in New Hampshire. Ermines are very difficult to tell apart from their close relative, the long-tailed weasel. To make things more confusing, ermines are also known as short-tailed weasels. As the name implies, short-tailed weasels (ermines) have shorter tails. Ermines are typically 7 to 8 inches in length, while long-tailed weasels are 11 to 12 inches long. Both weasels are sexually dimorphic, with female ermines about 50 percent smaller than males. This makes telling the two species apart even harder!

Another confusing similarity between ermines and long-tailed weasels is that both have brown fur with white bellies and black-tipped tails—and turn all white in the winter! Size is the only real discernible aid to the eye, and that can be difficult to distinguish at a glance. For the purposes of this article, we’ll focus on ermines, but you can encounter either of these two weasels when you’re out and about. 

The ermine, like any predator, needs habitat where it can find potential prey. For an ermine, that means brushy areas in the forest or overgrown fields and meadows where they can find prey under the cover. Their prey items consist primarily of mice, voles, and shrews, which consist of about 80 percent of their diet in New Hampshire (www.nhfishandwildlife.com, NH’s Weasels, Eric P. Orff). Ermines will, however, eat any prey they can track down and kill, including snakes, frogs, and the aforementioned larger prey, such as cottontail rabbits. Ermines, in turn, are preyed upon by coyote, bobcat, fox, owls, hawks, and even mink.

Ermines will kill their prey by biting the back of the neck. They have been known to raid chicken coops occasionally and even take out all of the chickens. The upside of an ermine around human habitats is that they will control those mice and chipmunks!

Ermines used to be highly valued for their pelts, and still are in some areas, though trapping has greatly declined—to the benefit of ermine populations. Ermine fur was considered the highest quality of fur there was, and many ermine were trapped and killed for the production of just one fur coat. When we bring ermine pelts into schools at Tin Mountain, students are enthralled at how soft the ermine fur is to the touch.

The number of weasels, such as ermine and marten, and the closely related mink trapped in North America, has not always been sustainable; many of New Hampshire’s desired furbearers (including beaver) suffered drastic declines in populations as a result. The monetary value of the furs has declined greatly, and trapping has a low impact on ermine population numbers today. Due to the highly forested and rural landscape that still covers much of New Hampshire, there still is abundant habitat for ermine. As long as the habitat that can support small prey remains, hopefully we can all have a chance at catching a glimpse of an ermine.

Here in the Mt. Washington Valley, the nearby vast forested areas of the White Mountains provide plenty of habitat, as do the rural forest edge meadows that can be found along many of the back roads in the areas, such as West Side Road. If you have a house, barn, or woodshed, there is a chance you will have an ermine on your property. They will even get into the walls of old structures sometimes, as they root out and look to capture mice and flying squirrels that take cover. Consider an ermine your friend if this occurs.

Like all wild animals, the reproductive success of ermines depends on food availability. Good wildlife habitat will allow for abundant small mammals, which in turn, will allow a high reproductive success for ermines. Another factor is prey competition. Those small mammals that ermine depend on are also being chased by fox, coyote, fisher, hawks, and owls, to name a few. Changes in wildlife composition in a forest can affect ermine populations because of too much competition at times. Right now, ermine populations in our areas seem healthy and stable.

Ermine have a litter of four to 13 young that are born after a four-week gestation period. Six is the most typical liter size (“The Color-Changing Weasel”—www.akwildlife.org). Ermine typically mate between late spring and early summer, but the female’s egg undergoes delayed implementation. This means embryo development stops for eight to nine months, after which the egg is implanted in the uterus wall for the gestation period. The young are born in April or May and cared for by the female ermine. She will nurse the babies for seven to 12 weeks. They will live in a nest, usually fashioned from a small rodent burrow and lined with the hairs of rodents and other prey. The young ermine will leave the nest after six to eight weeks.  

Many of the photos used in this article are of an ermine named, Twist. Twist was born on the property owned by wildlife photographer, John Rondeau.  John tells us that one summer the ermine became trapped in a rain barrel and his grandson noticed it and saved its life. He named her Twist and she has continued to visit since. 

An adult ermine is mostly a solitary creature outside of the mating season. Females are sexually mature after only three to four months, while males are sexually mature around 12 months. Females typically survive two breeding seasons, while males only breed once (AKwildlife.org). An ermine’s life is not one of longevity; reproductive success is the key to their survival as a species.

Ermine are tough and adaptable creatures. They can live at most elevations below treeline in the White Mountains, and their range extends throughout much of Canada and Alaska to the north, and south to Colorado and Pennsylvania. The closely related long-tailed weasel has a range that extends from just north of the border to the tropic.

The best way to consistently detect the presence of ermine is in wintertime, when you can find their tracks in the snow. When you’re in the outdoors this winter, the trails and woods of the White Mountains and Mt. Washington Valley are great places to gain experience with tracking wildlife, and one will come to appreciate all the wildlife hidden within that escapes our sight. Remember to keep an eye out for the tracks of ermine, often betrayed by their occasional tendency to spiral and circle in all kinds of directions, as these beautiful creature dart and dash in search of prey. A good field guide to tracks helps, and if you’re lucky, you may spot an ermine in its pure winter coat of white.

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Tin Mountain Conservation Center, a non-profit environmental education and conservation organization, provides programs for children, families, adults, and communities that create greater awareness and understanding of the natural environment. Since 1980, the center has offered hands-on programs in schools, at summer camps,  and within communities throughout northern New Hampshire and western Maine. Tin Mountain fosters future generations of environmental stewards and responsible outdoor enthusiasts.