Tuesday, November 20, 2012

Adirondack Wildlife: The Ermine and Snow

The near total lack of snow this year has been a disappointment to skiers that enjoy early season outings and big game hunters that like several inches of powder for tracking the movement of deer. For several members of our wildlife community, a forest floor that remains free of snow into the latter part of November becomes problematic, as a dark background contrasts with their newly developed coat of pure white fur.

Among the creatures that change color in autumn as part of a survival strategy is a small, yet especially fierce predator – the short-tailed weasel, better known to trappers and backwoods sportsmen as the ermine.

In summer, the ermine has a thin, light brown coat that causes it to blend into any woodland setting. Additionally, the small size of this sleek carnivore, which is only slightly longer than a chipmunk, makes it difficult to spot as it quickly darts under clumps of leaves, beneath fallen logs and into crevices among rocks. Even though the ermine is an inch or two longer than a chipmunk, its slender body shape results in an average weight that is slightly less.

In early October, the ermine starts to grow its winter coat of long, dense fur. This process is triggered by a certain amount of daylight that occurs during the first weeks of autumn. Temperature is believed to have some impact on the rate of growth of its fur, yet it is the dwindling amount of light that seems to be the major environmental factor regulating the development of its winter coat. The cool weather that our region has experienced over the past several weeks has allowed the process of hair growth and color change to be completed on schedule, as the ermine, along with the long-tailed weasel and the varying hare, is now pure white, except for the black tip on its tail.

While the ermine is considered to be fairly common and widespread across the entire Park, the abundance of mice this past summer has given a boost to the population of this elusive predator. Even though the ermine is not substantially larger than a mouse, it regularly stalks and kills any small rodents it happens to encounter as it prowls the various nooks and crannies throughout its territory.

Because of the ermine’s long and lanky body shape, it dissipates heat at a faster rate than an animal that is plumper or more rounded in stature. While this is an advantage for an active animal in summer, winter can be extremely difficult. The ermine’s incessant need for food forces it to remain on the prowl for prey both night and day in order to maintain a suitable internal body temperature. It is estimated by researchers that the ermine must ingest roughly one-third of its body weight each day in order to avoid hypothermia and death. This is the equivalent of one healthy adult mouse, or two young mice or voles. The ravenous appetite of the ermine in winter forces it to attack a wide variety of ground-dwelling animals ranging in size from shrews to red and gray squirrels, which are substantially larger than the ermine.

Upon spotting a sizeable animal, like a varying hare or grouse, the ermine attempts to sneak up on its quarry and then pounce on the victim’s back, biting its neck and throat. With its set of sharp canine teeth and powerful jaws, the ermine is known to kill creatures that are many times its own body size.

The relatively small stomach of the ermine prevents this carnivore from ingesting large amounts of food after making a kill. Upon getting its fill of fresh meat, the ermine often drags any remains to a secluded spot in the hope that nothing else will find and eat it. The ermine may also pull a few dead leaves and other pieces of debris from the forest floor over the partially eaten carcass in an attempt to conceal it from other animals. If hunting is good, the ermine may never return to cached items, although during the winter in the Adirondacks, such frozen bodies can remain a viable source of food for several months.

This coming week is the perfect time to get out in the woods in the hopes of seeing an ermine. With the ground free of snow and the ermine pure white, except for the tip of its tail, this small, elusive beast is more visible now than at any other time of the year. Additionally, after a summer of eating mice, juvenile ermine are attempting to establish a territory of their own. Once the snow comes, however, this animal will seemingly disappear, leaving behind only a unique set of tracks as a record of its presence here in the Adirondacks.

Photo courtesy Steven Hint (Wikimedia).

Tom Kalinowski

Tom Kalinowski

Tom Kalinowski is an avid outdoor enthusiast who taught field biology and ecology at Saranac Lake High School for 33 years.

He has written numerous articles on natural history for a variety of magazines and wrote a weekly nature column for the Lake Placid News for nearly ten years.

Tom has also written several books which focus on various events that occur among the region’s flora and fauna during very specific times of the calendar year. Along with writing, he also spends time photographing wildlife.



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4 Responses

  1. TiSentinel65 says:

    Yesterday while hunting, I watched a ermine try to prey upon a grey squirrel. It was amusing to watch his repeated failed attempts to catch the squirrel. The squirrel could litterally see him coming. Without snow cover he stuck out like a sore thumb. I spotted the ermine from quite a distance. At first I thought a deer was making its escape with its “flag” waving. Upon closer inspection I was able to observe the ermine as he hunted around rotten logs and stumps. The squirrel seemed to know he had the advantage. Every time the ermine ran him up a tree, he simply waited for the ermine to give up and climb down. The ermine seemingly realising the futility roamed off scavenging the ground for mice. I can only imagine that the ermine would also be in danger of becoming prey himself to owls or other raptors.

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  2. Tom Kalinowski Tom Kalinowski says:

    Hi TiSentinel65: Thanks for reading the Almanack. You are quite fortunate to have been able to see that type of interaction between an ermine and a gray squirrel. Unquestionably, it would have been a different story if the ground were white. You are correct in noting that the ermine is currently an easy target for a wide variety of predators. Hopefully we’ll get some snow soon to benefit the snowshoe rabbit, ermine and those skiers wanting to get out for some exercise.

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  3. TiSentinel65 says:

    I find your articles interesting and educational. Keep them coming.

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  4. Sue says:

    We had the good (or bad, depending on the outcome, which, in our case, was good) fortune to have an ermine in our house one winter a few years back. How it was getting in and for how long I’ll never know. We didn’t know about our house guest until one quiet morning in mid-winter when I noticed our big orange tabby cat intent on the cabinet under the kitchen sink. I heard some rustling and figured a mouse had come up one of the water line holes under the sink. So, I opened the doors and said “go get the mouse” to Morris. I sat back down at my desk and there suddenly ensued a terrific struggle and all sorts of cleaning supplies came flying out onto the floor. “This is no mouse” I thought. Suddenly the cat backed out of the cabinet and I could see white and knew it was an ermine. I, of course, panicked, not knowing how on Earth I’d get this thing out of the house and my husband was not home. Luckily cat wasn’t harmed and he dropped the Ermine, who immediately headed for the nearby stairs down to our bedroom. It’s a very long and interesting story, and two days later we finally trapped the Ermine using smoked salmon for bait, in a Have-a-Heart trap. The little Ermine seemed totally unafraid. It was certainly not struggling and tearing itself apart the way I’ve seen other animals caught in a trap like this. He actually seemed interested in us! To make the story more interesting, my husband let him go outside. The next day it was BACK under the sink! Trapped again, we took it about six miles away, on the other side of a river, and let it go. We’ve not seen any Ermine around our house since. I’m fascinated by these beautiful creatures. Thanks for this article!

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