Damage to Structures
Damage by woodpeckers is easily identified by the pounding noise and excavated holes. Damage to buildings is a relatively infrequent problem nationwide, but may be widespread regionally or locally. Houses or buildings with wooden exteriors near wooded areas or in rural wooded settings most likely will suffer damage by pecking, though structures with synthetic siding also are damaged. Damage to a building typically involves only 1 or 2 birds, but it may involve up to 6 or 8 individuals during a season. Most damage occurs from February through June, which corresponds with the breeding season and the period territories are established, and again in the fall during dispersal and establishment of territories.
Woodpeckers can be destructive, particularly to vacation homes that are vacant during part of the year, because damage may go undetected for long periods of time. For the same reason, barns and other wooden outbuildings also may suffer severe damage. Damage to wooden buildings may take several forms. Holes may be drilled into wood siding, eaves, window frames, and trim boards.
Woodpeckers prefer cedar and redwood siding, but will damage pine, fir, cypress, and others when available. Natural or stained wood surfaces are preferred over painted wood. New houses often are primary targets. Particularly vulnerable to damage are rustic-appearing, channeled plywood with cedar or redwood veneers. Expect new problems to arise as construction techniques and materials change. Woodpeckers have been found to damage plastic used for rooftop solar heating and electric panels.
Imperfections in the layers of laminated plywood exposed by the vertical grooves may harbor insects. Woodpeckers often break these core gaps, leaving characteristic narrow horizontal damage patterns in their search for insects. If a suitable cavity results from feeding, it also may be used for roosting or nesting.
Acorn woodpeckers, found in the west and southwest US, drill closely spaced holes just large enough to accommodate 1 acorn each (Figure 5). They wedge acorns between or beneath roof shakes and fill unscreened rooftop plumbing vents with acorns.
Woodpeckers have damaged elevated plastic irrigation lines in several vineyards in California. Tubes that are used for collection of maple sap also are damaged by woodpeckers. Drilling in utility poles in some regions has necessitated frequent and costly replacement of weakened poles. Similar damage to wooden fence posts can be a serious problem for some farmers and ranchers.
Damage to Livestock and Pets
Some woodpeckers kill young birds and eggs. Occasionally, woodpeckers drill into, and devastate, beehives.
Damage to Landscapes
Sapsuckers bore a series of parallel rows of ¼- to 3/8-inch, closely spaced holes in the bark of healthy trees and use their tongues to remove the sap. Sapsuckers usually feed on just a few ornamental or fruit trees, while nearby trees of the same species may be untouched. Holes may be enlarged through continued pecking and large patches of bark may be removed or sloughed. The girdling of limbs and trunks may kill trees. Wounds of attacked trees may attract insects, porcupines, and tree squirrels. Wounds from feeding also serve as entrances for diseases and wood-decaying organisms. Wood-staining fungi and bacteria may enter the wounds, and causes a grade defect called “bird peck” that lowers the value of hardwoods. Certain species of trees are preferred over others, but the list of trees that are susceptible is extensive.
Vegetable matter constitutes much of the diet of some woodpeckers. Native and cultivated fruits and nuts play an important role in their diet. Birds involved in depredation of orchards often are so few in number that damage is limited only to a small percentage of the crop. Control actions to protect commercial crops are rarely necessary. The crop of isolated backyard fruit or nut trees may, however, be severely reduced. Isolated instances of massive reduction in crop yields mostly occur in the far west, where Lewis’ woodpeckers, whose flocks may number several hundred, are most often implicated.
Health and Safety Concerns
Woodpeckers are not known to be a significant source of disease risk for humans or domestic animals.