Weasels
General Weasel Facts
Birth/Reproduction
Weasels will have two litters a year, one in late spring and the 2nd in late summer. Two to ten babies are born from in a litter. Their nest is lined with fur from animals that the weasel has killed. The young from the first litter may breed within their first year.
Diet
Weasels hunt for rabbits, rats, birds, frogs, ground squirrels, pica, meadow mice, voles, shrews, and eggs. They also like to hunt under cover. They will go into another animals burrow and kill and eat it there.
Other
They cause severe damage to chicken coops, but are useful for killing mice. It lives in a den in a hole under rock or logs, and is a nocturnal, solitary animal.
Identification
Weasels belong to the Mustelidae family,
which also includes mink, martens,
fishers, wolverines, badgers, river otters,
black-footed ferrets, and four species
of skunks. Although members of
the weasel family vary in size and
color (Fig. 1), they usually have long,
slender bodies, short legs, rounded
ears, and anal scent glands. A weasel’s
hind legs are barely more than half as
long as its body (base of head to base
of tail). The weasel’s forelegs also are
notably short.
Damage and Damage
Identification
Occasionally weasels raid poultry
houses at night and kill or injure domestic
fowl. They feed on the warm
blood of victims bitten in the head or
neck. Rat predation on poultry usually
differs in that portions of the body
may be eaten and carcasses dragged
into holes or concealed locations.
Damage Prevention and
Control Methods
Exclusion
Block all entrances 1 inch (2.5 cm) or
larger with 1/2-inch (1.3-cm) hail
screen or similar materials.
Trapping
Set No. 0 or No. 1 leghold traps inside
a protective wooden box.
Range
Three species of weasels live in North
America. The most abundant and
widespread is the long-tailed weasel.
Some that occur in parts of Kansas,
Oklahoma, Texas, and New Mexico
have a dark “mask” and are often
called bridled weasels. The short-tailed
weasel occurs in Canada, Alaska, and
the northeastern, Great Lakes, and
northwestern states, while the least
weasel occurs in Canada, Alaska, and
the northeastern and Great Lakes
states.
Habitat
Some authors report finding weasels
only in places with abundant water, although
small rodents, suitable as food,
were more abundant in surrounding
habitat. Weasels are commonly found
along roadsides and around farm
buildings. The absence of water to
drink is thought to be a limiting factor
(Henderson and Stardom 1983).
A typical den has two surface openings
about 2 feet (61 cm) apart over a
burrow that is 3 to 10 feet (0.9 to 3 m)
long. Other weasel dens have been
found in the trunk of an old uprooted
oak, in a bag of feathers, in a threshing
machine, in the trunk of a hollow tree,
in an old mole run, a gopher burrow,
and a prairie dog burrow (Henderson
and Stardom 1983).
Food Habits
The weasel family belongs to the order
Carnivora. With the exception of the
river otter, all members of the weasel
family feed primarily on insects and
small rodents (Fig. 4). Their diet consists
of whatever meat they can obtain
and may include birds and bird eggs.
As predators, they play an important
role in the ecosystem. Predators tend
to hunt the most abundant prey,
turning to another species if the numbers
of the first prey become scarce. In
this way, they seldom endanger the
long-term welfare of the animal populations
they prey upon.
Long-tailed weasels typically prey on
one species that is continually available.
The size of the prey population
varies from year to year and from season
to season. At times, weasels will
kill many more individuals of a prey
species than they can immediately eat.
Ordinarily, they store the surplus for
future consumption, much the same as
squirrels gather and store nuts.
Pocket gophers are the primary prey of
long-tailed weasels. In some regions
these gophers are regarded as nuisances
because they eat alfalfa plants
in irrigated meadows and native
plants in mountain meadows where
livestock graze. Because of its predation
on pocket gophers and other
rodents, the long-tailed weasel is
sometimes referred to as the farmer’s
best friend. This statement, however, is
Weasel population densities vary with
season, food availability, and species.
In favorable habitat, maximum
densities of the least weasel may
reach 65 per square mile (169/km2);
the short-tailed weasel, 21 per square
mile (54/km2); and the long-tailed
weasel, 16 to 18 per square mile (40 to
47/km2). Population densities fluctuate
considerably with year-to-year
changes in small mammal abundance,
and densities differ greatly among
habitats.
Weasels, like all mustelids, produce a
pungent odor. When irritated, they
discharge the odor, which can be detected
at some distance (Jackson 1961).
Long-tailed weasels mate in late summer,
mostly from July through
August. Females are induced
ovulators and will remain in heat for
several weeks if they are not bred.
There is a long delay in the implantation
of the blastocyst in the uterus, and
the young are born the following
spring, after a gestation period averaging
280 days. Average litters consist of
6 young, but litters may include up to
9 young. The young are blind at birth
and their eyes open in about 5 weeks.
They mature rapidly and at 3 months
of age the females are fully grown.
Young females may become sexually
mature in the summer of their birth
year.
Legal Status
All three weasels generally are considered
furbearers under state laws, and a
season is normally established for fur
harvest. Check local and state laws
before undertaking weasel control
measures.
Weasels prefer a constant supply of
drinking water. The long-tailed weasel
drinks up to 0.85 fluid ounces (26 ml)
daily.
General Biology,
Reproduction, and
Behavior
Weasels are active in both winter and
summer; they do not hibernate.
Weasels are commonly thought to be
nocturnal but evidence indicates they
are more diurnal in summer than in
winter.
Home range sizes vary with habitat,
population density, season, sex, food
availability, and species (Svendsen
1982). The least weasel has the smallest
home range. Males use 17 to 37 acres
(7 to 15 ha), females 3 to 10 acres (1 to
4 ha). The short-tailed weasel is larger
than the least weasel and has a larger
home range. Male short-tailed weasels
use an average of 84 acres (34 ha), and
females 18 acres (7 ha), according to
snow tracking.
The long-tailed weasel has a home
range of 30 to 40 acres (12 to 16 ha),
and males have larger home ranges in
summer than do females. The weasels
appear to prefer hunting certain
coverts with noticeable regularity but
rarely cruise the same area on two consecutive
nights.
Damage Prevention and
Control Methods
Weasels can be excluded from poultry
houses and other structures by closing
all openings larger than 1 inch (2.5 cm).
To block openings, use 1/2-inch (1.3-
cm) hardware cloth, similar wire
mesh, or other materials.
Trapping
Weasels are curious by nature and are
rather easily trapped in No. 0 or 1 steel
leghold traps. Professional trappers in
populated areas use an inverted wooden
box 1 or 2 feet (30 or 60 cm) long, such as
an apple box, with a 2- to 3-inch (5- to 8-
cm) round opening cut out in the lower
part of both ends (Fig. 5). Dribble a trail
of oats or other grain through the box.
Mice will frequent it to eat the grain and
weasels will investigate the scent of the
mice. A trap should be set inside the box,
directly under the hole at each end of the
box. Keep the trap pan tight to prevent
the mice from setting off the trap.
Alternatively, make a hole in only one
end of the box and suspend a fresh meat
bait against the opposite end of the box.
Set the trap directly under the bait.
Trap sets in old brush piles, under outbuildings,
under fences, and along stone
walls are also suggested, since the
weasel is likely to investigate any small
covered area. Trap sets should be protected
by objects such as boards or tree
limbs to protect nontarget wildlife.
Weasels can also be captured in live
traps with fresh meat as suitable bait.
If trapping to alleviate damage is to be
conducted at times other than the
designated season, the local wildlife
agency representative must be notified.
Economics of Damage
and Control
Svendsen (1982) writes:
“Overall, weasels are more of an
asset than a liability. They eat quantities
of rats and mice that otherwise
would eat and damage additional
crops and produce. This asset is
partially counter-balanced by the
fact that weasels occasionally kill
larger nontarget species.
beneficial animals and game species.
The killing of domestic poultry
may come only after the rat population
around the farmyard is diminished.
In fact, rats may have
destroyed more poultry than the
weasel. In most cases, a farmer lives
with weasels on the farm for years
without realizing that they are even
there, until they kill a chicken.”
*The above information was taken from a University of Nebraska Web site with
express permission of Stephen Vatassel, wildlife damage project coordinator. |
