Ermine, also known as short-tailed weasels or stoat, are pound for pound probably one of the fiercest predators in New England. These petite creatures weigh in at roughly a half a pound but are able to take down rabbits which weigh more than twice that! These incredible creatures sport a reddish brown coat in summer to blend in with the forest under story, and transition to a stark white coat (except for a black tail tip!) for the snowy season. Most mustelids exhibit sexual dimorphism - meaning that there is a large difference in size between the sexes where females are roughly half the weight of the males. The little lady seen here was clearly partway changed from her summer to winter coat when we met!

With a remarkably high metabolism, these very active mustelids devote a lot of time to hunting. Rodents are favorite prey, but they are opportunistic and will take down anything they feel capable of subduing - whether a shrew, mouse, vole, rabbit, or the chickens in a coop. They cache their prey so that it is available for a rainy day -- and will kill everything available to them, hiding the carcasses in a "safe place" for later. The evidence of a successful day of hunting can still be seen on the fur of this beautiful little weasel. Skilled and capable predators, they use their tubular body to wind through the underground burrows of their prey, seeking them out in their dens. In general, if the head can fit - so can the ermine. Females are perfectly sized and shaped to enter the tunnels made by their favorite meals - voles. Some ermines located near water have even been seen to be eating fish! When you burn as many calories as an ermine, anything is fair game. Although their body shape gives them a tremendous advantage in accessing dens, it also causes them to have a large surface area for their petite size, requiring them to eat huge numbers of calories especially during the winter months and while caring for young.

I watched this animal aggressively hunting a series of burrows in a rocky area -- entering one hole and coming out another some distance away, often with prey in her mouth. Taking photos was almost like playing whack-a-mole, I never knew where she would come back out! She was able to bound 6-8 feet even carrying meals that closely matched her own body weight - and ermine are capable of travelling at up to 8mph! After bounding past with her prey, she would disappear into the woods, and then return to resume the hunt -- leaving no burrows or cracks or crevices in the rocks unexplored. It was not unusual to simply have a view of the almost black tip of the tail as she closely examined each opening to determine it's hunting potential. Ermine must consume somewhere between 19-32% of their body weight every day, and starvation is a common cause of mortality -- so hunting and caching is critical to their survival.

Ermine live a fairly consolidated life cycle, with females reaching sexual maturity at 3-4 months and males closer to 12 months. Many males survive for only a single breeding season, while females may reproduce for at least 2. Breeding success is highly dependent on the availability of food -- with rodent abundant years resulting in more kits produced. Like many in the weasel family, ermines experience "delayed implantation" - and although they are fertilized during the summer months, the embryos aren't implanted until roughly March - making them virtually always pregnant with a gestation period of 280 days! The majority of development occurs in the 28 days before delivery of a litter of up to 13 (average is 6) babies during April or May. Young leave the burrow at about 6-8 weeks to start exploring but nurse for up to 12 weeks. Nests are most typically in the burrow of a small rodent (after it's owner has been consumed!) and is lined with rodent hair for insulation. Alternatively, they may choose to den in a rock pile, hollow logs, or dense underbrush where they feel safe and are close to food. Snow can be an important insulator in colder climates such as in Northern Maine.

Interestingly, sometimes the most confusing part about short-tailed weasels is actually identifying them! Ermine (short-tailed weasels) differ primarily from long-tailed weasels and least weasels by their size and tail length. Long-tailed weasels are largest (total length 300-350 mm), ermine are medium sized (total length males 225-340 mm, females 190-290 mm), while least weasels are smallest (total length less than 250 mm in males and less than 225 mm in females).  Long-tailed weasels have a tail longer than half their body length with a black tip, ermine have a tail length around a third of their body length with a black tip, and least weasels have a tail length around a quarter of their body length and lack a black tip.  So if you see a small weasel with a black tip on the tail, you could be looking at either a short or long-tailed weasel -- and a closer look at both body size and tail length will be needed to identify it. And to add to the confusion - -all 3 species experience sexual dimorphism, so a long-tailed female might be almost the same size as a short-tailed male! Yikes!

Given the agility and skill of the ermine, few species regularly will take it as prey. The occasional Great-horned Owl, Goshawk, fox, coyote, or long-tailed weasel will kill an ermine, but the largest source of predator mortality is humans with a desire for the pelt, a status symbol of wealth. However, given their small size, many individuals are needed in order to create garments of any size. Another source of mortality is from rodenticides which are toxic not only to the rodents but also the predators that consume them. Given that a single individual will, on average, occupy a 10-40 acre area alone, it is easy to see how quickly a local population can be reduced.

May one of these mysterious mustelids choose to dine some Thanksgiving calories nearby so that you, too, can enjoy the magic of watching them work - periodically turning their searching eyes in your direction for a brief but intense moment of connection.