Most woodpeckers feed on tree-living or wood-boring insects; however, some feed on a variety of other insects. Some flickers obtain the majority of their food by feeding on insects from the ground, especially ants. Others feed primarily on vegetable matter, such as native berries, fruits, nuts, and certain seeds. In some areas, the diet includes cultivated fruit and nuts. The sapsuckers, as the name suggests, feed extensively on tree sap as well as insects.
Woodpeckers are an interesting and familiar group of birds. Their ability to peck into trees in search of food or excavate nest cavities is well known. They prefer snags or partially dead trees for nesting sites, and readily peck holes in trees and wood structures in search of insects beneath the surface. One common misconception is that they peck holes in building only in search of insects. While they do obtain insects by this means, many species will drill holes in sound dry wood of buildings, utility poles, and fence posts where few or no insects exist. The acorn woodpecker drills holes in wood simply to store acorns. When sapsuckers drill their numerous rows of 1/4 inch holes in healthy trees they are primarily after sap and the insects entrapped in the sap.
Woodpeckers have characteristic calls, but they also use a rhythmic pecking sequence to make their presence known. Referred to as "drumming", it establishes their territories and apparently attracts or signals mates. Drumming is generally done on resonant dead tree trunks or limbs; however, buildings and utility poles may also be used.
Woodpecker damage to buildings is a relatively infrequent problem nationwide, but may be significant regionally and locally. Houses or buildings with wood exteriors in suburbs near wooded areas or in rural wooded settings are most apt to suffer pecking and hole damage. Generally, damage to a building involves only one or two birds, but it may involve up to six or eight during a season. Most of the damage occurs from February through June, which corresponds with the breeding season and the period of territory establishment. Woodpeckers can be particularly destructive to summer or vacation homes that are vacant during part of the year, since their attacks often go undetected until serious damage has occurred. For the same reason, barns and other wooden outbuildings may also suffer severe damage.
Damage to wooden buildings may take one of 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 the choices are limited. Natural or stained wood surfaces are preferred over painted wood, and newer houses in an area are often primary targets. Particularly vulnerable to damage are rustic-appearing, channeled (grooved to simulate reverse board and batten) plywoods with cedar or redwood veneers. Imperfections (core gaps) in the intercore plywood layers exposed by the vertical grooves may harbor insects. The woodpeckers often break out these core gaps, leaving characteristic narrow horizontal damage patterns in their search for insects.
The acorn woodpecker, found in the West and Southwest, is responsible for drilling closely spaced holes just large enough to accommodate one acorn each. Wedging acorns between or beneath roof shakes and filling unscreened rooftop plumbing vents with acorns are also common activities. Widespread damage from nest cavities and acorn holes in utility poles in some regions has necessitated frequent and costly replacement of weakened poles. Similar damage to wooden fence posts can also be a serious problem for some farmers and ranchers. Occasionally, woodpeckers learn that beehives offer an extraordinary food resource and drill into them.
Drumming, the term given to the sound of pecking in rapid rhythmic succession on metal or wood, causes little damage other than possible paint removal on metal surfaces; however, the noise can often be heard throughout the house and becomes quite annoying, especially in the early morning hours when occupants are still asleep. Drumming is predominately a springtime activity. Drumming sites are apparently selected on the basis of the resonant qualities. They often include metal surfaces such as metal gutters, downspouts, chimney caps, TV antennas, rooftop plumbing vents and metal roof valleys. Drumming may occur a number of times during a single day, and the activity may go on for some days or months. Wood surfaces may be disfigured from drumming but the damage may not be severe.
Sapsuckers bore a series of parallel rows of 1/4 to 3/8 inch closely spaced holes in the bark of limbs or trunks of healthy trees and use their tongues to remove the sap. The birds usually feed on a few favorite ornamental or fruit trees. Nearby trees of the same species may be untouched. Holes may be enlarged through continued pecking or limb growth, and large patches of bark may be removed or sloughed off. At times, limb and trunk girdling may kill the tree.
On forest trees, the wound of attacked trees may attract insects as well as porcupines or tree squirrels. Feeding wounds also serve as entrances for diseases and wood-decaying organisms. Wood-staining fungi and bacteria may also enter the wound, reducing the quality of the wood when cut. Woodpecker damage to hardwood trees can be costly. Wounds cause a grade defect called "bird peck" that lowers the value of hardwoods. Damage occurs to both commercial hardwoods and softwoods. Certain tree species are preferred over others, but the list of susceptible trees is extensive.
As mentioned previously, vegetable matter makes up a good portion of the food of some woodpeckers, and native fruits and nuts play an important role in their diet. Cultivated fruits and nuts may also be consumed. Birds involved in orchard depredation are often so few in number that damage is limited to only a small percentage of the crop. The crop of a couple of isolated backyard fruit or nut trees may, however, be severely reduced prior to harvest.
Woodpeckers are classified as migratory, nongame birds and are protected by the Federal Migratory Bird Treaty Act. The red-cocaded woodpecker and the ivory billed woodpecker are on the Endangered Species list and are thus offered full protection. When warranted, woodpeckers, other than the endangered species, may be killed but only under a permit issued by the Law Enforcement Division of the US Fish and Wildlife Service upon recommendation of USDA-APHIS-Animal Damage Control personnel. Generally, there must be a good case to justify issuance of a permit. Woodpeckers are commonly protected under state laws, and in those instances a state permit may be required for measures that involve lethal control or nest destruction. Other methods of reducing woodpecker damage do not infringe upon their legal protection status. Threatened or endangered, however, cannot be harassed.
Metal sheathing or plastic sheeting placed over the pecked areas on building siding to offer permanent protection from continued damage. Like all repelling methods, metal barriers work best if installed as soon as damage begins. Occasionally the birds will move over to an unprotected spot and the protected must be expanded. Aluminum flashing is easy to work with to cover damaged sites. Woodpeckers will sometimes peck through aluminum if they can secure a foothold from which to work. Metal sheathing can be disguised with paint or simulated wood grain to match the siding.
Quarter inch hardware cloth has also been used to cover pecked areas and prevent further damage. It can be spray painted to match the color of the building. The wire can either be attached directly to the wood surface being damaged, or raised outward from the wood siding with 1 inch wood spacers. Once woodpeckers have been discouraged, frightened away, or killed, the damaged spots on houses should be repaired by filling in the holes with wood patch or covering them to prevent woodpeckers from being attracted to the damaged site at some future time.
Some of the harder compressed wood or wood-fiber siding materials cannot be damaged by woodpeckers. Presumably, their hardness and or smooth surface serve as deterrents. Aluminum siding can also be used as an alternative to wood siding.
To protect trees from sapsuckers, wrap barriers of 1/4 inch hardware cloth, plastic mesh, or burlap around injured areas to discourage further damage. This method may be practical for protecting high-value ornamental or shade trees. In orchards and forested areas it may be best to let the sapsuckers work on one or more of their favorite trees. Discouraging them from select trees may encourage the birds to disperse to others, causing damage to a greater number of trees.
Frightening Devices
Visual. devices such as stationary model hawks or owls, fake and simulated snakes, and owl and cat silhouettes are generally considered ineffective as repellents. Toy plastic twirlers or windmills fastened to eaves, and aluminum foil or brightly colored plastic strips, bright tin lids, and pie pans hung from above, all of which repel by movement and/or reflection, have been used with some success, as have suspended falcon silhouettes, especially if put in place soon after the damage starts. The twirlers and plastic strips rely on a breeze for motion. Stretching reflective mylar tape strips across a damaged area, or attaching them to the eaves and letting them hang down (weighted or unweighted) is a recent alternative to aluminum strips. Large rubber balloons with owl-like eyes painted on them are included in the recent array of frightening devices used to scare woodpeckers.
A good deal of attention has recently been given to round magnifying-type shaving mirrors installed over or adjacent to damaged areas to frighten woodpeckers with their larger-than-life reflections. Contrarily, woodpeckers are not discouraged from damaging wooden window frames or casings very near window panes where their own reflection would frequently by seen. In fact, some believe that seeing their own reflection intensifies the damage as a result of defensive territorial behavior.
Loud noises such as handclapping, a toy cap pistol, and banging on a garbage can lid have been used to frighten woodpeckers away from houses. Such harassment, if repeated when the bird returns, may cause it to leave for good. Around homes, portable radios have been played with little success in discouraging woodpeckers. Expensive high-frequency sound producing devices are marketed for controlling various pest birds but rarely provide advertised results. High-frequency sound is above the normal audible hearing range of humans but, unfortunately, above the range of most birds too.
Woodpeckers can be very persistent and are not easily driven from their territories or selected pecking sites. For this reason, visual or sound types of frightening devices for protecting buildings-if they are to be effective at all--should be employed as soon as the problem is identified and before territories are well established. Visual and sound devices often fail to give desired results and netting may have to be installed.
Repellents
Many chemicals that have objectionable tastes as well as odors have been tested for treating utility poles and fence posts to discourage woodpeckers. Most have proven ineffective or at least not cost-effective.
Naphthalene (mothballs) is a volatile chemical that have been suggested for woodpecker control. In out-of-door unconfined areas, however, it is of doubtful merit. It is unlikely that high enough odor-repelling concentrations of naphthalene could be achieved to effectively repel woodpeckers. Odorous and somewhat toxic wood treatments, such as creosote and pentachlorophenol, which are frequently used to treat utility poles and fence posts, do not resolve the woodpecker problem.
Sticky or tacky bird repellents smeared or placed in wavy bands with a caulking gun on limbs or trunks where sapsuckers are working, will often discourage the birds from orchard, ornamental, and shade trees. These same repellents can be effective in discouraging birds if applied to wood siding and other areas of structural damage. The birds are not entrapped by the sticky substance but rather dislike the tacky footing. A word of caution: some of the sticky bird repellents will discolor painted, stained, or natural wood siding. Others may run in warm weather, leaving unsightly streaks. It is best to try out the material on a small out-of-sight area first before applying it extensively. The tacky repellents can be applied to a thin piece of pressed board, ridged clear plastic sheets, or other suitable material, which is then fastened to the area where damage is occurring. Woodpecker problems can be resolved without toxicants and none are registered for such use. Based on the premise that woodpeckers are after insects, some control bulletins suggest treating insect-infested siding with an appropriate insecticide as a remedy for damage. While this may have some merit with insect-infested wood, woodpeckers often attack siding, poles, and posts that are sound and without insects. The use of insecticides for indirect control in these instances would be unfounded. Depending on their chemical nature, insecticides may have an adverse effect on the birds. Where the situation warrants the application of an insecticide, it should be selected on the basis of its safety for birds.
Please contact the Farm Advisor’s office with your agricultural questions at 209/754-6477 or through our website at http://www.uccecalaveras.org.