Crittering 
Tracking the Ermine
The short-tailed weasel (Mustela erminea) is Colorado’s smallest native carnivore. In summer, this diminutive weasel sports a chocolate brown coat with a light underbelly. In winter, it transforms to pure white except for a black tipped tail. In this white phase, the short-tailed weasel is often referred to as an ermine.
A long-tailed weasel in Rocky Mountain National Park.
I have now photographed 56 species of the 70 species in my Colorado Mammals Project. Of the 14 species that remain, ten are incredibly rare, if they even exist in Colorado at all. The other four include the recently reintroduced Canada lynx, the Virginia opossum (our only marsupial), the invasive feral pig, and the short-tailed weasel (a.k.a. ermine). It is the winter white ermine that I have set my sights on this winter and hope to photograph next.
Despite its tiny size, the short-tailed weasel is a formidable hunter and its slender body allows it pursue small mammals into their burrows. The majority of its diet consists of mice, and voles, but it is capable of taking larger prey including cottontail rabbits when given an opportunity. Like other mustelids, the short-tailed weasel hunts daily to fuel its high metabolism. Contrary to popular belief, weasels do not kill for fun and in the wild surplus food is cached for later consumption.
The Holarctic (circumpolar) distribution of the short-tailed weasel.
The short-tailed weasel ranges across the northern latitudes of North America, Europe, and Asia in a Holarctic distribution. In the late 1800s short-tailed weasels were introduced to New Zealand by European settlers in an attempt to control the rabbit population (also introduced). The impact on New Zealand’s native ground nesting bird populations has been disastrous.
In Colorado, the short-tailed weasel can be found throughout much of the state, particularly in mountainous regions. Data from the Colorado Parks and Wildlife Natural Diversity Information Source (NDIS) suggests that the short-tailed weasel is most abundant in Douglas, Teller, Gilpin, Summit, Lake, and Routt counties.
Abundance of the short-tailed weasel in Colorado by county.
Colorado is home of two species of weasels: the short-tailed weasel and the long-tailed weasel (Mustela frenata). Short-tailed weasels have short tails, and long-tailed weasels have, well, you know. Technically, the length of a short-tailed weasel’s tail is 44% or less of the length of its head and body. Anything longer than 44% and you are looking at a long-tailed weasel. Long-tailed weasels are also about 50% larger, but both species can vary greatly in size and males are significantly larger than females.
Mustela erminea specimens at Denver Museum of Nature and Science.
I have encountered and photographed several long-tailed weasels in the wild. They are most easily seen in the summer months hunting pikas and rodents amongst the talus in locations such as Rocky Mountain National Park. When I have encountered them, I have always been impressed and amused by their boldness and curiosity. I have yet to lay eyes on a short-tailed weasel in Colorado or elsewhere but I have recently observed tracks at several locations that give me hope.
Because of their slender body and high surface to weight ratio, weasels easily lose heat to the elements. During the cold and windy Rocky Mountain winter, the ermine spends much of its time tunneling in and under the snow hunting rodents beneath the snowpack. This allows the ermine to save energy, but makes them even harder to observe.
Just another windy winter day on Niwot Ridge.
Still, they can be seen ducking and diving in and out of the snow, and with time and patience I believe that I will be able to photograph one. A promising number of skiers I have talked to have seen an ermine while on the slopes or from chairlifts. Arapaho Basin Ski Area even has a run called “Weasel Way”, although I didn’t see any sign of weasels when I was there in December. Nevertheless, I plan to continue my ski based ermine search until I succeed or the snow melts.
Crittering 
I’ve seen em on red mountain pass! Bring your camera. A
I saw 2 in north western Colorado this past week. I have video of one.
Would love to see the video, please share a link if you post it online!
I’m fairly sure that I saw one in by backyard this morning. I’m in Garfield County, Glenwood Springs. My backyard borders the Flattops BLM lands.
Ray Schmahl
Saw one at Mountain House parking lot at Keystone this morning!
How cool! I’ve seen their tracks at Keystone, but never face to face.
Reblogged this on Mammalwatching.Com Weblog and commented:
A nice post on looking for Short-tailed Weasels (aka Stoats or Emrine) in Colorado.
“squeaking” can be a good way to attract these animals from out of rock crevices. Worth trying in the right habitat… for more on squeaking see https://mammalwatching.wordpress.com/2013/09/11/squeaking-for-mammals/
Thanks for sharing that, Jon. I’ve had some success with “squeaking”. Mustelids sure are curious.
Well I know my ferrets go nuts with dog squeek toys. Can’t imagine it’d hurt to try!
We saw one, while playing putt putt last night in Colorado Springs! I will try to post the pictures on my blog on Monday, so you can see it. It’s belly was very yellow. And fur on top was dark brown.
How cool! Maybe I should be playing more putt putt! Looking forward to seeing the photos!
I seen a white one this morning in Black Forest.
We saw one, not sure if long or short tailed, while playing putt putt last night in Colorado Springs. He had a yellow belly and dark brown fur. I will try to post pictures on my blog on Monday.
I live in Western Colorado near Hotchkiss. I saw a Weasel for the first time on my daily walk at the edge of our field.. At first i thought it was a prairie dog. but it had a light yellow belly.
I just had two under my deck, I don’t want them there. They were very aggressive and stinky but cute. Will try to trap and release.
On the other hand, you won’t have any mice!
We also have them around our deck. Saw one of them late morning running across the drive and two racing back and forth on the covered deck then off into the tall grasses. I want them to keep the rodent population down; what a nice surprise. Live in big Cimarron valley Gunnison County. Chad.
I live off of county line road North of Colorado Springs and watched what I believe could have been an ermine just out of the back of my house this morning. The little white fella looked to be looking for food under the snow, but did seem to take a little time to play. Little guy was all white and only about 10 inches long. The end of the tail looked “tufted”, but not black. Last year we did see weasels on the property at night. So we know they live in the area.
Sounds like an ermine to me! Keep an eye out over the winter for their bounding tracks and tunnels in the snow.
I just saw a white on yesterday, had to get online and figure out what it was that I saw. It was on Crystal mountain rd west of fort collins/loveland. It was in the road, snacking on a roadkill rabbit. amazing little creature, I am excited i got to see it, seems like a bit of a rarity to see a white one.
Thanks for the article . . . I was not aware we had them here as I’ve never seen one in my 11 years of living here . . . until this morning (hence, why I searched for info on them). I saw one with its winter coat a couple of yards down from ours, sitting up on its hind legs by some bushes. I actually backed up the car to take a better look (I did not have my camera with me, and my phone was in my pocket). It dashed under the bush once I stopped the car.
I too now hope to capture one (digitally, of course) especially given its proximity. For reference, I live on the Palmer Divide near I-25, and this specimen is living in a subdivision of half-acre lots. I was a little surprised to see it because nearly everyone has dogs. My yard being dogless and offering small game, I’m hoping one will take residence here.
Best of luck in capturing a photo of your ermine! If you are successful, I’d love to see it. If you get a good look at the tail, it would be interesting to know if it was a short-tailed weasel or long-tailed weasel. Keep an eye out for fresh tracks in the snow, too!
It was too quick a look for me to notice anything other than the black tip. I’ll link back if I can manage a photo.
This one just showed up on the porch,makes a very cute sound and then hisses when he got scared. I can’t get the picture here. It was white with a black tip tail, thin and long.
So cute. Ran across deck then under deck.
Thanks for this post, we definitely have a small one all white now with a black tip tail living in our yard. Do you have any idea if they would attack our chickens? He seems rather small and content with the vols. We live up in Evergreen.
ermine here in snowmass village, co. white with black tail. What a sight to see.
Omg The most adorable white ermine just peaked out from under my stove . He most probably a she though ( kinda petite ) Short tailed ( only about a third of its body length ) black tip. Kept watching me coming out more and more almost seemed friendly Since I didn’t move she darted out and under the cabinets and disappeared. I of course found a hole Under the cabinet I hadn’t known about . Can’t believe she came in have a big cat who is a ratter and two big dogs with high prey drive. Live in Evergreen out by Tall grass spa.
Wow! How cool! Thanks for sharing your encounter!
My sons and I saw one come out from under our deck; so cute! It will be well-fed with all of the voles in the yard. You can see its tracks and tunnels go in and out of the snow. Seems to be a new resident as we just noticed the tracks the past couple of days. Glenwood Springs
We have one in our backyard. I’ll try to get a picture. Avon CO
Good luck! Let me know if you get any photos!
We saw one yesterday while skiing at Sunlight, in Glenwood. I had no idea what it was. It darted under the lift and went into the trees. I had never seen one before. Cute little devils!
Ive heard the lift operators often see ermine and martens while on the job!
We saw one downtown Telluride last Friday. We saw it while driving through a neighborhood and backed the car up. It was like it wanted us to feed it or something and was going in and out of a thicket bush where lots of squealing was going on. We assumed babies but now that I read they don’t have babies till spring maybe there were more adults or another type of baby nest???? We took pictures and asked locals what it was and only one said she had seen one from a chair lift. It was very cool to see and Im glad my husband didn’t pick it up now that I know about the teeth:)
We just saw a white one in the Colorado National Monument
We’ve been able to get pictures while he’s hunting for voles first thing in the morning. Glenwood Springs
Would love to see them! Do you have a link?
I seen one in Black Forest, white with a black tipped tail…
Believe it or not I have seen ermine in the highway medians where 6 th ave and Colfax meet. Don’t know who was more surprised? Me or the ermine.
An ermine boldly suprised me by brushing up against my pant leg. I looked down and there was this theatrical looking weasel. We had a moment and it slither-bopper from one tree to another. This was last Saturday 6/18, around 7pm, in Briargate – north east of the 25 corridor, Colorado Springs.
I just saw five short-tailed weasels in my back yard in Meeker Park (near Estes Park). At least I’m assuming that’s what they are, because they are small, about 7 or 8 inches in length. Four of them had black tipped tails but the fifth was a completely solid color–kind of tawny. I saw the tawny one with a young rabbit in its mouth, at least three times the size of the weasel. Unfortunately, I wasn’t able to get photos.
I discovered a small ermine last night in the house I was staying in near Black Hawk! I knew it by the black tipped tail. I couldn’t catch the little bugger to put him out.
I work on a property in Aspen, Colorado where an ermine (already units white winter coat against the brown scrub oak, poor guy) lives underneath a compost heap (it sits up on a pallet). I think it likes the warmth and the wood cave. If you’d like to take a ski/photo trip, we have some of the best mountains in the country. And short-tailed weasels, apparently.
Nicole, thank you for sharing this! I’d love the chance for a photo op. Contact me through my website at http://www.jamesbeissel.com so that I can email you directly.
I was just hunting in the White River National Forest and while hiking, I saw a white ermine squandering around us. It was a gorgeous animal, pure white with a black tipped tail. It really didn’t seem bothered by us at all, as it stayed about 15 feet away from us. I really loved my encounter with it! Actually, it was extremely warm for elk hunting and this animal was the highlight of my hunt this year!
My partner and I just saw an ermine today! We watched it for quite a while … what fun as it zipped around looking for food ! We were hiking at Willow Park about one hour up willow trail in Crestone, CO…..first time in 11 years of hiking that trail.
Got some good pictures of one that just took a cotton tail. It’s surprising how much bigger the rabbit was.
I think I just saw one in my forested back yard in the Monument area (northern El Paso County). I’ve lived here 29 years and never seen one. It was white and of course with snow on the ground – tough to get a good look at as it was hopping away.
Just got a picture of a white weasel of some sort in El Paso County. Not really sure how to tell what it is. I can email you the picture if you would like so see it
I’d enjoy seeing a photo – feel free to post a link or email me.
Just got a picture of a white weasel of some sort in El Paso County. Not really sure how to tell what it is. I can email you the picture if you would like so see it
Saw one just now out the window at 8300′ elevation, just west of Blue Mesa Lake, Gunnison County! Had about 8-10″ snow last 24 hours, All white with it’s little black tip on tail. Have seen some in summers past, the brown and tan color.
I live in Monument and spotted a short tailed hunting Voles this morning after a light dusting of snow. I am attempting to capture some great pictures on my Trail Cam.
Thanks for sharing! If you capture any photos I’d enjoy seeing them.
I have seen several at our shoot camp here in Colorado both in summer and winter. … just saw him again this weekend. …. he stays pretty much in the same campsite when we go up. …
I saw what I think was a Ermine by Needle rock at the west elk lodge in Crawford Colorado at first I thought it was a ferret it is pure white and has a back tip on its tail. I looked it up on the internet. The pitchers looked like what I saw,but the trail didn’t look like it was short.It looked kind of long with a black tip. It was beautiful ,and I’m grateful to have seen it definitely a god thing………
Just saw an Ermine on Mill Castle trail near Gunnison about 2 miles from the trailhead. Beautiful animal and seemed very playful jumping in and out of the snow. Seemed like he would be considered a long tail and had a black tip at the end of his tail.
Just saw one today between Pagosa and Wolf Creek Pass.
I saw one on Roller Coaster Road in Monument / Colorado Springs area last week!
Cool! I saw one a month or so ago in Monument near Fairplay and Caribou Drive.
I saw one last weekend at the very top of Berthoud Pass right where the parking lot with the warming hut is. It ran across the road in front of my truck, pure white with a black tipped tail. Cute little thing
How cool! I have often stopped there and looked for sign, but never seen one firsthand!
Saw one today while on lift 6 at Loveland running north to south across the Roulette trail!
I believe I saw an albino one (all white from head to tail) today running across a busy street in Briargate next to Focus on the Family in Colorado Springs.
I have one in my office today! We tried to catch him but he found a little hole to get into the crawl space! Tiny little guy but sooooo cute! Maybe a baby?? He was very curious and was hanging out under my bosses desk at her feet! She didn’t even see it until I did and pointed him out! Totally white (as he should be, we have had about 15 feet of snow!) 🙂 Almont, CO (few miles south of Crested Butte, CO)
I just saw one in the academy hotel parking lot in Colorado Springs!
Saw one just east of Russellville road a few weeks ago – on Anderson road about 3 miles southeast of Castlewood Canyon state park. About a half mile from the Elbert County line. I’ve seen ermines in the mountains on more than one occasion but never before in western Elbert Cty.
We were skiing at Beaver Creek and saw one running around on one of the runs. Very cute! I couldn’t get my camera out on time, but don’t think white on white would have been too great anyway.
I saw one yesterday from halfway up the Centennial chairlift at Beaver Creek!
I Saw one today in Boulder on the South Boulder Creek Trail. He was peeking out from a prairie dog hole. We were face to face for a minute then I panicked and shuffled for my phone. I could have gotten a great photo but I only got one from a distance as it ran off during my shuffling.
I have one of these cute guys living in the drainage tubes in our retention walls in the back yard. i live in Castle Rock and was very surprised the first time I saw that cute little face look out of the pipe.