Rats and Mice
Rats and mice can be a problem in urban, suburban and rural
areas. They infest old buildings and crowded, unsanitary areas that
exist in an urban environment. However, they can also be a problem
even where newer homes and sanitary conditions exist. Since these
rodents eat practically anything humans eat, they get plenty of
food from home gardens, fruit or nut trees and even parts of some
ornamental shrubs and flowers. Rats and mice have long been a
problem on farms where food is plentiful and convenient nesting
sites are both numerous and hard to eliminate.
There are six major problems caused by rats and mice:
- They eat food and contaminate it with urine and excrement.
- They gnaw into materials such as paper, books, wood or
upholstery which they use as nest material. They also gnaw plastic,
cinder blocks, soft metals such as lead and aluminium, and wiring
which may cause a fire hazard.
- Rats occasionally bite people and may kill small animals.
- They, or the parasites they carry, (such as fleas, mites and
worms) spread many diseases.
- Rats can damage ornamental plants by burrowing among the roots,
or feeding on new growth or twigs. They also eat some garden
vegetables, such as corn and squash.
- Rats and mice are socially unacceptable. These rodents have
been a problem for centuries, chiefly because they have an
incredible ability to survive and are so difficult to eliminate. In
addition, they are extremely compatible with human behaviour and
needs.
Mighty Mouse and Super Rat!
Here are just a few of the abilities that have enabled rats and
mice to survive people's constant attempts to eliminate them:
A female rat can have up to 84 young in her life span, which
averages about a year in the wild. They can burrow long distances
from nest to food sources, reducing their exposure to predators.
The tunnels may extend 4 vertical feet into the earth. They can
scale walls and walk across telephone wires with ease. They are
excellent swimmers--capable of navigating a half mile through open
water. They are amazingly resilient, easily surviving falls up to
50 feet.
Rats - Description
There are two primary species of rats present in the UK The
Norway rat and the Black or Ship rat. The Ship Rat is now very
rare.. The Norway rat is both larger and heavier than the Ship rat.
It has a wider distribution and is more common. Norway rats build
their nests in burrows under buildings, low shrubs or ground cover,
wood piles, yard accumulations of junk, and garbage dumps. The Ship
rat, on the other hand, is a better climber than the Norway rat and
is more likely to build its nest in walls, attics, vines or
trees.
Norway rat (Rattus norvegicus)
13-18 1/2 inches total length, with its tail being shorter than
its head and body combined. An adult Norway rat weighs about 3/4 to
1-1/4 pounds. It is mostly brown, with a lighter coloured stomach.
The tail is semi-naked and darker above than below, giving it a
two-toned effect.
Ship rat (Rattus rattus)
also 13-18 1/2 inches total length, with its tail being longer
than its head and body combined. An adult roof rat weighs about 3/4
to 2/3 pound. It is mostly black with some grey below, although
there are some variations. The tail is also semi-naked, but of one
colour.
Mice - Description
We also have two species of mice that cause problems. The House
Mouse and the Field Mouse.
House mouse (Mus musculus)
The house mouse looks somewhat like a young roof rat, but
smaller. It is approximately 5-1/2 to 7-1/2 inches total length.
Like the roof rat, its tail is as long or longer than the head and
body combined. However, mice have proportionately smaller heads and
feet than those of a ship rat. The colour of the house mouse
depends upon its habitat; if it lives indoors it will usually be
dark grey with a light grey stomach; outdoors it will usually be a
sandy brown colour. House mice do not pose as serious a problem to
the householder as rats, but they can be quite a nuisance. They
also eat and contaminate food with their urine and droppings; may
gnaw on wiring creating a fire hazard, and they can transmit some
diseases.
Field Mice
The Field Mouse is a generic term for a range of mice in the UK.
The true field mouse is the Long Tailed Field Mouse, or Wood Mouse
and it is one of our most endearing / or terrifying animals
depending on your point of view. It does however provide a vital
food source for many of the UK’s carnivorous creatures as well as
being a major pest.
They have a dark brown fur with enormous eyes and ears for their
size. They grow to about 10cm long and weigh 30 grams or so full
grown.
The Wood Mouse will live just about anywhere there is food and
shelter. It traditionally roams fields, hedgerows, forests and
grass lands where it can find plenty of food. They are omnivorous
and will eat a range of seeds, berries, invertebrates, worms,
carrion and other similar food. It tends to have a short life in
the wild as so many different creatures prey on them, with an
average age between 6 and 12 months, although they live longer in
captivity and when conditions are favourable.
They can reproduce quite frequently with the gestation period
around 25 days. They give birth to between 4 and 7 mice which are
soon out on their own after 4 weeks or so. This short parenthood
period means that wood mice can reproduce several times per
year.
They nest wherever there is cover and warmth, this usually means
below ground but they can also be found in hedgerows, buildings,
car radiators and other similar dwellings.
They are generally nocturnal animals with superb hearing and
vision (hence the large eyes and ears), because of this they are a
vital source of food for other larger nocturnal hunters such as
owls.
Rodent Control
the most important steps in controlling rodents involve
sanitation and elimination of their home sites.
Sanitation
- Store garbage in rodent-proof containers. Make sure your
garbage cans have tight fitting lids so dogs or wildlife can't tip
them.
- Clean up spilled or unused pet food. Store pet food in
rodent-proof containers. Failure to do this may lead to serious
insect infestations of the feed that rodents often carry into the
walls. Also, clean up pet excrement, as rats will eat it if they
have to.
- Do not scatter food for wildlife such as birds or squirrels.
Use rodent-proof bird feeders. If rats are a serious problem,
eliminate all bird feeders.
- Compost piles should be properly managed to ensure rapid
decomposition of potential rat foods.
- Clean up fallen fruits or nuts from trees. Prune seed pods from
lilac and other shrubs.
- Store garden/lawn seed, bone meal, etc. in rodent-proof
containers.
Eliminate shelters
- Employ rodent-proofing features in new buildings.
- To rodent-proof existing buildings, you should do the
following:
- repair any cracks or small holes in the foundations
- repair broken windows and doors
- repair broken sewers
- seal any holes, where pipes or wires enter the building, with
sheet metal collars or concrete. Repair screens and cover
foundation vents with rodent proof screen material.
- Elevate compost, lumber and wood piles at least 12 inches above
ground.
- Remove unmanaged blackberries or brush near buildings.
- Prune ornamental shrubs away from the ground and avoid planting
ground covers that afford shelter (ivy).
Population Control
Choosing between traps and poison for rodent control will depend
upon the severity of the problem, the location and the experience
of the householder.
Traps are often preferred over poison baits for the following
reasons:
- Poison baits, carelessly used, can harm children, pets and
non-target animals.
- Sick rodents may escape to areas between walls or under floors
where they die and decompose, causing odour and insect
problems.
- Traps are often especially preferred for controlling
easy-to-trap mice, since they eat less than rats and sometimes do
not ingest enough foeticide to make it effective.
Snap traps are recommended and should be placed in areas that
are frequented by rodents. These areas can be identified by looking
for gnaw marks, rodent tracks, droppings, urine stains, burrows or
grease smudges along walls. An effective method of baiting snap
traps is to bind a small wad of gauze into the trigger with thread
and then work peanut butter into the gauze until saturated. The
gauze acts to entangle the rodent's teeth so they can't escape
before tripping the trap mechanism. Set the trap AFTER you place
the bait on the trigger!
Rat traps should be baited and left UNSET until rodents begin
feeding. This will help ensure success. Traps should be tied down
or anchored in some way, as rats may drag the trap away if they are
only partially (non-fatally) caught.
Gum drops, bacon, nuts, oats and dried fruit may be used in
addition to peanut butter for bait. When trapping mice, make the
bait in each trap about pea-size and attach it to the tripping
mechanism with thread or thin wire if necessary. Traps should be
baited with fresh material regularly to remain attractive to the
pests. There should be many more traps than rodents for trapping to
be effective. It is best to place traps close to each other (every
5 - 10 feet for mice - no more than 20 feet for rats) and move them
every few days if no rodents are caught. Be aware, though, that
older rats MAY avoid a newly placed trap for over a week so, for
rats, you may want to leave traps in place for two weeks before
trying another place. Success is enhanced by placing traps with the
trigger-end against walls where the rodents like to run. This
allows the pests to run across the trigger from both directions.
Traps can be reused without special cleaning.
Rodenticide Baits
Always read the label before using any pesticide! There
are many rodent baits available on the market. These are usually
ready-to-use baits containing an anticoagulant poison. When using
rodent baits, they should be kept out of reach of children, pets
and wildlife. The best way to make them inaccessible is to use
well-constructed bait boxes with two access openings, just large
enough to admit rats or mice (about two inches).
Follow the directions on the label for the correct dosage.
If poisons are used, eliminate all other food sources, i.e.
garbage, dog food, fallen fruit, compost, dog droppings, etc. If
the bait is not touched for a few days, wait. Rats sometimes avoid
a new bait for long periods before starting to feed.
Professional pest control operators also handle baiting or
trapping programmes.