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STUDY BACKGROUND
BIOLOGY AND BEHAVIOR
WHY ON HOUSES?
DAMAGE AND SIDING
INSECTS
CONTROL METHODS
WOODPECKER FAQ

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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.

Holes made by drumming activities are usually in the form of very small dents in the wood, grouped in clusters along the corners or fascia and trim boards of a house. The holes may sometimes be as large as an inch across, round, cone-shaped, and generally shallow.

resawn

Possible 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.

Holes in cedar clapboards are usually drilled at the seam of two adjacent clapboards. These holes can usually be found dispersed throughout the siding. Holes drilled into board-and-batten siding are usually found on the inverted batten between the two adjacent boards, again often found dispersed throughout the siding, with some preference given to corner excavations. Woodpeckers drilling into tongue-and-groove type sidings show a definite preference to corner holes. These holes are found at the seam of two vertical boards. Resawn shakes and shingles also are more prone to having nesting and roosting holes along corners of the house. Usually these holes are placed between abutting shingles, where the bottom and top of two shingles meet.

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.

If you consider yourself lucky to have your very own woodpecker nesting hole in your siding, you may want to watch the woodpeckers perform courtship behavior, copulations, and drumming behavior, as these usually take place in close vicinity to the nesting site. Later on, after the eggs hatch, you may be able to see the adults bringing food to the young. Eventually, you may catch sight of your very own nestling peering out at you from the pocket in your house while begging and crying to be fed. Vigilant watchers may even be able to witness the fledging of the young, and to feel proud knowing that they had, in some small part, helped in the rearing of these birds.

carpenter bee

Adult Carpenter Bee


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Foraging Holes      
Foraging behavior, too, can be interesting to watch. 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.



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