A fierce long-tailed weasel, gone in a flash

I am fascinated by uncommon or unusual critters – animals that stand out with a specific feature or unique characteristic. That brings me to several encounters I had with a very distinctive animal during my recent photo tours in Yellowstone National Park this winter.

The long-tailed weasel (Neogale frenata) is one of those fascinating creatures that are often heard about but rarely seen. It is also known as the masked ermine or simply an ermine. It is often mistaken for the stoat, but the stoat – also called the short-tailed weasel (Mustela erminea) – is smaller and has a shorter tail.

The long-tailed weasel in summer is brown with a whitish belly. Its tail is also brown with a distinct black tip. But one of the most fascinating traits of this species is that it turns completely white in winter – except for the black tip of its tail.

In southern regions, long-tailed weasels do not change color in winter, while those in transition zones only turn partially white. This extreme adaptation to the environment is called erminism. The process is triggered by the amount of available daylight. As the days grow shorter in the fall, the weasel produces a hormone called melatonin, which suppresses melanin production. This prevents the new growing fur from developing its usual pigmentation, resulting in a white coat. In spring, the process reverses, and the newly growing fur turns brown.

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The long-tailed weasel is a predator – make no mistake about that. It is an aggressive hunter, constantly moving in search of its next meal. It primarily hunts small mammals such as mice and voles but will also prey on animals as large as a rabbit.

Long-tailed weasels are obligate carnivores, meaning they do not scavenge from dead animals. They are true hunters

Occasionally, they will hunt small birds, especially ground-nesting species, but it is not unheard of for these weasels to climb trees. In fact, they often climb trees when pursued by larger predators such as foxes, coyotes and bobcats. And yes, some small predators are hunted by larger ones.

The long-tailed weasel dens in underground burrows, inside rock piles and under tree stumps, but mostly in burrows made by other animals. They do not dig their own burrows and typically do not use one for long. Their nomadic lifestyle depends on the availability of prey. One of their favorite burrows is that of a chipmunk. They fit inside easily and often use the fur of their prey to line the nesting chamber.

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They are members of the weasel family, which means they have well-developed scent glands that produce a strong, musky odor similar to that of a skunk. Unlike skunks, weasels cannot spray their musk. Instead, they rub their scent glands on surfaces such as rocks and logs, leaving the odor behind. 

During my photo tour of Yellowstone this winter, I found three long-tailed weasels over a three-week period. Seeing just one is remarkable, as nearly all encounters with long-tailed weasels are quick. Often, they are seen running and jumping before disappearing within seconds.

The first two encounters were just like that – brief glimpses before the weasels vanished. But the third was slightly different. One darted across the road and dove into a snowbank. Just as quickly as it had disappeared, it popped out of the snow and took off across the road again. This time, it jumped over the snowbank at the road’s edge and ran to the base of a fallen branch, where it paused just long enough for me to capture a few images.

As funny as it might sound, this brief but exciting encounter with the long-tailed weasel was one of the highlights of this year’s winter trip to Yellowstone – even with multiple wolf sightings. Until next time …

Editor’s note: Stan Tekiela’s NatureSmart column appears twice a month in the Eden Prairie Local News. Tekiela is an author, naturalist, and wildlife photographer who travels extensively across the United States to study and capture wildlife images.

You can follow his work on Instagram and Facebook. He can be contacted via his website at www.naturesmart.com.