According to the American Society of Mammalogists, there are 16 weasel species in the world – 10 of them have the word “weasel” in their name.
The 2 species of weasels found in California are the short-tailed weasel and the long-tailed weasel.
Despite sharing many similarities, these two also have several key differences. Here are their photos, fun facts, and a short guide on how to recognize each in case you meet them in the wild.
Note: The weasel (Mustelidae) family also includes badgers, otters, ferrets, martens, minks, and wolverines – we will just focus on “true” weasels in this article.
Table of Contents
2 Weasel Species In California
1. Long-tailed Weasel
Long-tailed weasels are the largest weasel species found in California. They can be seen in most parts of the state except the Mojave desert.
Also known as bridled weasels, masked ermines, or big stoats, they are one the most widespread of any North American mustelid (carnivorous mammals like weasels, otters, fetters, minks, etc.).
Identify long-tailed weasels by their long and slender bodies, long necks, flattened heads, short legs, short and rounded ears, prominent whiskers, and black eyes.
They also have dense brown fur that is white-yellow below – their brown tails have black tips and measure almost half the total body size.
During winter, in northern parts of the USA, long-tailed weasels can turn white, occasionally with yellow tints – their tails keep the black tips.
- Scientific Name: Neogale frenata
- Length: 11-22 in
- Weight: 3-9 oz
- Tail Length: 3-6 in
Long-tailed weasels resemble short-tailed weasels but lack a white line on the inside of their legs.
They are common in different habitats, including woodlands, thickets, and brushy fencerows close to water.
Long-tailed weasels are carnivores and will take what they can get – they feed on squirrels, chipmunks, rabbits, birds, reptiles, insects, fish, and especially small rodents like mice and voles.
These large weasels breed from July to August and have one litter per year with 1-12 young. The newborns are born naked, blind, 0.1 oz heavy (similar to a size of a hummingbird), and open their eyes at around 5 weeks of age.
Fun Fact: Long-tailed weasels can delay the implantation of the embryo after fertilization and can have a pregnancy that lasts between 205 and 337 days!
They are active during the day and the night – their black eyes glow bright emerald green when caught in a spotlight at night.
Predators of long-tailed weasels include coyotes, foxes, wolves, wildcats, northern goshawks, and barred and great-horned owls.
2. Short-tailed Weasel
Short-tailed weasels are mostly found in northern California and parts of Sierra Nevada.
They are also known as stoat weasels, Eurasian ermines, Beringian ermines, or simply ermines.
Identify short-tailed weasels by their elongated bodies, short legs, pointed faces, very long whiskers, and long tails.
They also have silky light brown fur that is white below in the summer; when the winter comes, it turns white and the tail that keeps a black tip year-round is around 30% of the total body length.
- Scientific Name: Mustela erminea
- Length: 6.7-12.8 in
- Weight: 6.3-9.1 oz
- Tail Length: 3-4.7 in
Short-tailed weasels are smaller in size compared to long-tailed weasels, have shorter tails, and are not as common.
They are common in different habitats, ranging from wooded areas to grasslands – they prefer areas with heavy cover and avoid dense forests.
Short-tailed weasels are omnivores that feed on chipmunks, rats, rabbits, shrews, voles, insects, and frogs. Males are larger than females and tend to catch larger prey – the species might also eat some fruit and carrion when there is no prey available.
Fast and agile hunters with bodies build to enter any burrow or a narrow opening, these animals will chase and grab prey at impressive speeds. That comes at a cost – to be that fast, weasels need to consume a lot of food.
Several studies discovered that ermines need to consume 15-37% of their body weight per day – if there’s not enough food available or a weasel gets trapped somewhere, it may starve in a matter of days.
Short-tailed weasels breed from late spring to early summer and have one litter per year with 4-18 young.
Similar to other weasel species, short-tailed weasels can delay their pregnancy until the following spring; they are not monogamous species and will often have litters with mixed paternity.
Fun Fact: Due to their fast metabolisms and the need to constantly hunt, weasels will stockpile food if they make extra kills – this has led to their unjust reputation of being bloodthirsty animals that kill for sport!
Predators of short-tailed weasels include coyotes, foxes, goshawks, great-horned owls, and even long-tailed weasels.
Weasels VS Minks VS River Otters
New York is also home to other types of mustelids that resemble weasels with one of them being the river otter. These creatures share a similar brown color and body shape.
One easy way to distinguish between them is by size. Among the three, the short-tailed weasel is the smallest. Long-tailed weasels are bigger than them but smaller than otters; they can grow three to five times the size of weasels!
Detecting the presence and distribution of weasels and minks in CA may pose a challenge due to their small size, swift movements, and knack for staying hidden.
River otters can be identified by their short legs, webbed toes, and strong, flattened tails. They range in color from light to dark brown and have 5 toes and a horseshoe-shaped heel pad.
Otters can be sometimes confused with weasels, but they are far more sizable, weighing 10 to 30 pounds, measuring 26-31 inches long, and having blunted noses and tails that are thick at the base and taper.
They can be seen around rivers, creeks, lakes, ponds, and swamps.
- Scientific Name: Lontra canadensis
- Length: 26-42 in
- Weight: 10-30 lb
- Tail Length: 12-20 in
Read More: Weasel species seen in KY
California is home to 2 types of weasels, the long-tailed weasel and the short-tailed weasel.
Unfortunately, North America’s weasel populations may be in serious decline. According to a 2019 study, their numbers have been going down and long-tailed weasels may have disappeared from large parts of their range.
You might spot them beneath short decks, porches, or other low structures, which they can use to sneak into buildings. They track the smell of mice that they’re hunting and sometimes end up indoors. One way to know they’ve been around is by their long, twisty droppings.
These animals typically den in hollow logs, rock piles, or abandoned buildings like barns. Weasels love to hunt and eat different animals that might cause damage to crops – that’s why many farmers and homeowners welcome these animals.
The only thing they need to look out for is unsecured chickens and rabbits, weasels might catch them too!