Living with Washington's
Wildlife: Tree Squirrels
(Part 2)
(Editor’s note: WDFW’s Seattle-area
urban wildlife biologist Russell Link is compiling a series of “Living
With Washington’s Wildlife” fact sheets for distribution
at regional offices, eventual posting on our web site, and part of
a new book, “Living With Wildlife in the Pacific Northwest.”
This newsletter regularly features excerpts from that work. This second
of three parts on tree squirrels focuses on dealing with problems
that squirrels create when searching for food or nesting material;
the spring 2003 edition will address what to do when a squirrel’s
search for a nest site takes it into your attic or chimney.)
A tree squirrel’s search for food or nesting
material may bring it to a bird feeder, orchard, or flower garden.
The most effective way to prevent conflicts is to modify the habitat
around your home so it will not attract squirrels. Examples include:
Don’t feed squirrels.
Squirrels that are artificially fed may lose their fear of humans
and could become aggressive. Artificial feeding also tends to concentrate
tree squirrels in a small area; overcrowding can encourage diseases
and parasites. In addition, these squirrels might approach a neighbor
who doesn’t share your appreciation of the animals. The neighbor
might even choose to remove these squirrels.
Prevent access to bird feeders.
There are many feeder designs on the market advertised to be squirrel-resistant.
Some are effective, but many are not. One type is a tube feeder enclosed
in a cage that allows small birds to pass through freely; such cages
may also be purchased separately for use with existing feeders. However,
this style of feeder will block access to large birds and may not
exclude small and immature squirrels.
To prevent squirrels from jumping to a feeder, place the feeder at
least 6 feet off the ground and at least 10 feet from the nearest
tall shrub, tree limb, deck, or other structure. To prevent squirrels
from climbing the wires, poles, or chains on which feeders are mounted,
suspend a commercially available dome- or cone shaped“squirrel
baffle” above and/or below the feeder to prevent squirrels from
climbing.
A home-made version is to suspend your feeder from
a horizontal wire, placing two, 24-inch lengths of 1-inch PVC pipe
around the wire on either side of the feeder. Two large soda bottles
strung on either side of the feeder may also work.
Use heavy gauge wire to hang the feeder, squirrels
will chew through almost anything else, dropping the feeder to the
ground.
Another way to discourage squirrels from eating birdseed
is to offer birds foods that squirrels do not like. For example, squirrels
will sometimes ignore safflower seed, millet, and plain suet (without
nuts or peanut butter). However, these foods may not be as popular
with the bird species you want to attract, and squirrels may eat them
if they are hungry.
Prevent nesting
in birdhouses.
Attach a pre-drilled metal plate (available from stores catering
to the bird feeding public) over the hole, or attach aluminum flashing
to the front and drill an entry hole of the correct size through
the flashing. File down any sharp edges. Boxes with entry holes
large enough to accommodate large birds (and squirrels) should be
put out only when the desired bird species is seen, or during its
known nesting season. To prevent squirrels from climbing up a pole
or other structure supporting a birdhouse, install a commercially
available barrier. A home-made version is a 24-inch-tall aluminum
flashing cylinder placed at least 6 feet up the tree trunk or other
support. The cylinder should have overlapping edges and be secured
so that it can expand to allow for tree growth. (This will not work
if there is a tall tree or structure within 6 feet.)
Protect plants.
If squirrels are removing the bark of certain trees to use as food
or nesting material, apply a commercially
available repellant to the vulnerable areas or loosely wrap them
with 1-inch chicken wire. If they are climbing trees to eat fruit
or nuts, remove lower branches and install an aluminum flashing
cylinder as described above. Seeds and seedlings can be covered
with a temporary wire cage or netting. Where bulbs are being dug
up, chicken wire can be laid down, securely staked, and lightly
mulched. A commercial repellant, available from nurseries and hardware
stores, can also be used in the area.
Prevent access to your home.
Repair or replace loose or rotting siding, boards, and shingles.
Cover vents with 1/2-inch welded-wire mesh (hardware cloth), and
keep tree branches 10 feet away from the sides and tops of buildings.
Note: Dryer vent screens need to be cleaned frequently or
replaced with models designed to exclude animals without lint clogging.
Cap your chimney with a commercially designed
and engineered chimney cap. (Most hardware stores carry them.)
Squirrels can be stopped from traveling on wires
by installing three-foot sections of 2-3 inch diameter plastic pipe.
Split the pipe lengthwise, spread the opening apart, and place it
over the wire. The pipe will rotate on the wire and the squirrel
will tumble off. Do not attempt to install pipe over high voltage
wires. Contact your local electricity/utility company for assistance.
Public Health Concerns.
Tree squirrels might carry diseases that could affect humans but
actual cases are rare. Rabies has not been found in any tree squirrel
populations in Washington. If you see a tree squirrel engaging in
unusual behavior, such as repeatedly falling over or circling a
small area, such behavior may result from an injury, poisoning,
or inflammation of the brain (encephalitis) caused by a parasite.
If a person is bitten or scratched by a squirrel,
immediately clean the wound by thoroughly scrubbing it with soap
and water. Flush the wound liberally, using clean tap water. If
the person was bitten, contact a physician and the local health
department. If you can place a large bucket over the squirrel and
secure the bucket with a heavy object, the animal can then be held
for inspection.
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