Weasels, Skunks and Their Kin
Long-tailed Weasel
Mustela frenata
Description
A long-bodied, short-legged animal.
Brown above; white to deep yellow below. Tail long, often equal to
head and body length; brown with black tip. Feet brownish. In
Southwest, white on face. During winter in northern latitudes, fur
entirely white (but often stained with yellow on hips) except for
black tail tip. Male weighs about twice as much as female. L 11–22"
(280–550 mm); T 3 1/8–6 3/8" (80–160 mm); HF 1 1/8–2" (29–51 mm); Wt
3–9 3/8 oz (85–267 g).
Similar Species
Short-tailed Weasel is smaller,
with shorter tail and white feet. Black-footed Ferret is yellowish
brown, with dark or black mask around eyes. Mink is larger and
darker, with bushy tail and white spotting on throat and
chin.
Breeding
Mates midsummer; development proceeds
for about 15 days to blastula stage; implantation delayed until
following spring; total gestation 205–314 days. 4–8 young born
blind, nearly naked, in April or May; birth weight about 1/16 oz (3
g).
Sign
In deep snow: drag marks; holes where weasel
has plunged under snow. Cache of dead mice or voles under log or in
burrow.
Scat: Dark brown or black, long, slender and segmented,
often tapering at one end; frequently contains hair or bits of bone;
deposited on rocks, logs, or stumps.
Tracks: Hindprints 3/4" (18
mm) wide, 1" (25 mm) long or more, usually with only 4 of 5 toes
printing. Foreprints slightly wider than hindprints, but
approximately half as long. Hindfeet usually placed in or near
foreprints, but sometimes side by side, or with 1 slightly ahead.
Straddle 3" (75 mm). Stride varies as weasels run and bound, often
alternating long and short leaps: when carrying prey or stalking,
12" (300 mm); when running, 20" (500 mm).
Habitat
Varies: forested, brushy, and open areas,
including farmland, preferably near water.
Range
Southern British Columbia, Alberta,
Manitoba, and Saskatchewan south through most of U.S. except se
California, se Nevada, and much of Arizona. Range extends southward
to Bolivia.
Discussion
Like other weasels, the Long-tailed
was once thought to be strictly nocturnal, but in fact is often out
by day, since voles, a primary food item, are mainly diurnal. The
most widespread carnivore in the Western Hemisphere, it preys
largely on mice and voles, while also taking rabbits, chipmunks,
shrews, rats, birds, and poultry, and the occasional insect or
earthworm. When hunting, it follows a zigzag pattern, moving from
burrow to burrow. It does not suck blood, contrary to myth, although
it will often lap it from a wound. The Long-tailed Weasel will
attack animals its own size and larger, but is very careful to
attempt to take larger prey only when opportunity presents itself,
or when smaller quarry is scarce. When attacking, the weasel rushes
in toward the prey, grabs the victim at the base of the skull, and
curls its body around it while grasping it with its forelimbs. It
eats the head and thorax first, and caches the portion not eaten.
Weasels occasionally go on killing sprees, as instinct dictates that
they procure food when available and then store it. For this reason,
a weasel in a chicken yard is disastrous. Like other weasels, the
Long-tailed runs by a series of bounds, with its back humped at each
bound and its tail trailing backward. It makes its dens in the
abandoned burrows of other mammals, often chipmunks, and also ground
squirrels, moles, or pocket gophers. Within the den it constructs a
nest, primarily of hair from prey. The maternity den may also be in
the burrow of another small mammal, or under a stump in a gully. The
Long-tailed Weasel uses a variety of vocalizations: It may screech
and squeal, utter a rapid trill, and purr when content. During the
mating season, females give a reedy, twittering call. When the
animal is alarmed, enraged, or excited by the mating urge, the anal
glands release a powerful malodorous musk. A weasel may drag its
rump on the ground, presumably to leave a scent that informs other
weasels of its sex and perhaps even its identity. The Long-tailed
Weasel male matures during its second summer, the female at three to
four months of age. Only the female brings food to the young, which
disperse at seven to eight weeks, when the males are already larger
than their mother. In the northern part of its range, the
Long-tailed Weasel turns white in winter. The time of the molt is
governed by the length of daylight, and the change is gradual;
weasels are piebald during transition. In the southern part of its
range, within a 600-mile-wide (1,000-km-wide) transcontinental belt,
some individuals molt to white, while others remain brown. In
Pennsylvania, for instance, less than half of the weasels become
white, and south of the Maryland-Pennsylvania border none do. The
color change is evidently genetically determined: If a northern
weasel is captured and taken south, it will still turn white in
winter, while a southern weasel transported north will remain brown.
Weasels are valuable in controlling populations of rodents,
including rats. Hawks, owls, cats, foxes, and snakes prey upon the
Long-tailed Weasel. This animal has also been taken by trappers,
although its pelt is not considered especially
valuable.
Weasels, Skunks and Their Kin