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Three
Reasons Why Woodpeckers Drill Holes on Houses:
Drumming Holes
Many siding types are potential instruments for woodpecker drumming
behavior. These include houses with aluminum siding, as well
as the trim boards and fascia boards of any wood, brick, and
stucco homes. Also attractive to woodpeckers are metal downspouts,
gutters, chimneys, and vents. Drumming behavior is often more
annoying than damaging, though it can be fun and informative
to observe. If you hear a woodpecker banging on your house, you
will know it if you hear it -- you may be able to run outside
and catch some exciting territorial or breeding behaviors without
having to trek through the woods as many people are inclined
to do. Listen for any accompanying calls the woodpecker may give
and look around for a mate or possible competitor.
Roosting/nesting
attempts along with drumming damage on cedar shakes
Roosting and
Nesting Holes
Roosting holes and nesting holes are most often begun in houses
that are in close proximity to wooded areas, have natural wood
or a dark-colored stain, and have either a clapboard siding,
a board-and-batten siding, a tongue-and-groove siding, and less
often, resawn shakes and shingles. Woodpeckers are more drawn
to redwood and cedar wood types than to composite wood or Masonite.
Roosting and nesting holes, though similar in size and shape,
are specific to the type of siding in terms of their location
on the house.
When beginning
to drill nesting or roosting holes, woodpeckers often make several
attempts, initiating an excavation only to leave off and start
a new one just inches away from the first, or in an entirely
new location on the house. This may be because the specific requirements
needed for a nesting site or roosting site are not met, and it
is in this way that a house may accumulate multiple holes.
While excavating
holes, a woodpecker first digs through the outer siding, followed
by the sheathing and then plywood layers, directly into the insulation.
It is here that the nesting or roosting area is hollowed out.
It has been speculated that woodpeckers prefer to build their
holes in houses for a variety of reasons:
1 The heat that
is trapped in the insulation from the house awards extra protection
from cold weather.
2 The proximity of the hole to other trees grants extra protection
from predators.
3 There may be few to no suitable trees available for nesting
or roosting purposes in the outlying areas.
4 Houses are usually made from a soft wood into which woodpeckers
can easily dig.
Nesting holes
are usually built in the beginning of the breeding season between
late April and May. Roosting holes are usually built in the late
summer and fall in preparation for winter. Larger holes may be
surrounded by smaller half-finished holes, or by clusters of
tiny holes at corners, on eaves and on corner boards. These are
often the results of drumming activity.
Foraging Holes
There are a few siding types that are more susceptible to insect
infestation, thereby attracting woodpeckers to hunt for food
on the house. Grooved plywood siding, also known as Type 111,
mimics the look of boards backed by battens. It is made from
sheets of plywood into which vertical grooves are cut in the
lumbering process. These grooves expose horizontal gaps in the
core of the plywood. Insects such as the leaf-cutter bee and
grass bagworm crawl into these gaps to overwinter, pupate, or
hide from predators. Woodpeckers searching for insects will create
almost perfectly horizontal rows of holes along the siding following
the core gaps. Wooden shakes and shingles also have many nooks
and crannies that attract insects, thereby enticing woodpeckers.
Insects will follow cracks between adjacent shakes upward underneath
the overlapping upper shake in order to lay eggs, hide, pupate,
and overwinter. Woodpeckers in search of these insects will drill
straight lines of vertical holes, anywhere from three to six
holes in a line depending on the size of the shake, directly
up the middle of one of the overlapping shakes.
Copyright ©
2002 Cornell Lab of Ornithology
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