The house mouse originated in the arid
grasslands of Southeast Asia. Three
subspecies similar in appearance are
generally referred to under the name of
one species, the Mus Musculus. Like
their larger counterparts, rats, they
are nocturnal creatures, feeding at
night to avoid predation. Mice are
timid, social, and territorial.
The most common house mouse observed in
the US is an ancestor of the white mouse
used for scientific experimentation. In
its wild state, the house mouse is
approximately 6.5 inches long, including
the tail. When found indoors, it can be
larger due the availability of better
nutrition. These mice are usually
yellowish-gray and sometimes streaked
with black. Occasionally, the deer
mouse, harvest mouse, and pocket mouse
may invade buildings located near
fields. They are commonly mistaken with
house mice when this happens.
The behavior of mice is often hard to
predict, which is true for all rodents.
However, some generalizations can be
made of mice living in and around
buildings.
In urban areas, mice can spend their
entire lives in buildings. When inside,
mice can be found living in their nests,
which are almost always close to a food
source, in closets, walls, ceiling
voids, large appliances, bureaus, the
upholstery of furniture, behind or above
the insulation in attics, and in
basements. Suburban and rural areas may
promote the same kind of complete indoor
living as in the city, but mice can live
outdoors among weeds and shrubbery, near
building foundations, in storage sheds,
garages, or in crawl spaces beneath
structures.
Nests serve the purpose of providing
warmth and protection for female mice
when they give birth to their pups.
Nests can be made from all sorts of
materials including paper, insulation,
the stuffing from furniture, or any soft
material that can be chewed to bits for
the purpose of building a soft bed. If
mice nest outside, they will build their
homes in ground burrows or among debris.
Once a nest is established and the
population grows, territory becomes an
important factor. The process of
establishing territory is started when a
dominant male in the population sets up
an area to be controlled. Each territory
has a distinct make-up comprised of a
dominant male, one or more females,
several weak males, and a number of
young. When a young mouse leaves the
territory, he must fight with the
dominant male controlling another
territory for control, or search for an
unclaimed area to set up his own
territory. This is how mouse
infestations spread throughout a
building.
The size of a territory depends on
several different factors. These factors
include the physical arrangement of the
environment, availability of food, and
the number of mice in the area.
Generally, however, a mouse’s territory
ranges from 10-30 feet. The more food
available, the less territory a mouse is
bound to have. This is also true of the
number of mice occupying an area-- the
more mice, the less territory. Mice will
not travel more than a few feet from
their nest when food and other mice are
plentiful.
Mice explore and re-explore their
territories on a daily basis, becoming
extremely familiar with the area. Every
pathway to and from water and food
becomes ingrained, along with the
locations of any burrow entrances and
protective hiding spots. Therefore, if
any changes occur, they must investigate
the alterations and refamiliarize
themselves with the area.
In order to implement a truly successful
rodent control program, it is important
to understand the biology of the pest
you want to rid. When there are good
living conditions for mice, including
plenty of food, water, and shelter, they
can multiply rapidly. If the opposite is
true, population growth is slowed
considerably.
After carrying her babies for
approximately 19 days, a female mouse
will give birth to anywhere from 4-7
pups per litter. Following 7-10 days of
being furless, they become furry and
open their eyes and ears. Three to four
weeks after birth, the pups are weaned
and begin short trips to explore their
surroundings.
Female mice are ready to start the
mating and birth cycle 5-8 weeks after
they are born. Although females are
technically capable of giving birth
every 26 days, they usually produce 8
litters in their lifetime of about 1
year. It is because of these prolific
mating habits that mice can quickly
become a problem. Females can
potentially produce 65-75 offspring in
their 1-year lifespan.
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