WOODPECKERS

Woodpeckers gained their English name because of the habit of some species of tapping and pecking noisily on tree trunks with their beaks. This is both a means of communication to signal possession of territory to their rivals, and a method of echo-locating grubs under the bark of the tree.

Identification
Woodpeckers belong to the order Piciformes and the family Picidae, which also includes flickers and sapsuckers. Twenty-one species inhabit the United States. Woodpeckers have short legs with two sharp-clawed, backward-pointed toes and stiff tail feathers, which serve as a supportive prop. These physical traits enable them to cling easily to the trunks and branches of trees, wood siding, or utility poles while pecking. They have stout, sharply pointed beaks for pecking into wood and a specially developed long tongue that can be extended a considerable distance. The tongue is used to dislodge larvae or ants from their burrows in wood or bark. Woodpeckers are 7 to 15 inches (18 to 38 cm) in length, and usually have brightly contrasting coloration. Most males have some red on the head, and many species have black and white marks. Identification of species by their markings is quite easy. In most species, flight is usually undulating, with wings folded against the body after each burst of flaps.

Range
Woodpeckers are found throughout the United States. The three most widely distributed species are the hairy woodpecker (Picoides villosus), the downy woodpecker (P. pubescens), and the yellow-bellied sapsucker (Sphyrapicus varius). Different species are responsible for damage in different regions.

Habitat
Because they are dependent on trees for shelter and food, woodpeckers are found mostly in or on the edge of wooded areas. They nest in cavities chiseled into tree trunks, branches, or structures, or use natural or preexisting cavities. Many species nest in human-made structures, and have thus extended their habitat to include wooden fence posts, utility poles, and buildings. Because of this, woodpeckers may be found in localities where trees are scarce in the immediate vicinity.

Food Habits
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, fruit, 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.

General Biology, Reproduction, and Behavior
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 buildings 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 (Melanerpes formicivorus) drills holes in wood simply to store acorns. When sapsuckers drill their numerous rows of 1/4-inch (0.6-cm) holes in healthy trees they are primarily after sap and the insects entrapped by 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.

Woodpeckers breed in the spring, commonly laying in the range of 3 to 5 or 4 to 6 eggs. The incubation period is generally short, lasting from 11 to 14 days. It may be longer for larger species. Most species are born naked; some are born downy. All are tended by both parents. Having 2 broods per year is fairly common and some species may have 3 broods. Apparently, both sexes sleep in cavities throughout the year.

Some species, such as the northern flicker (Colaptes auratus) and the redheaded woodpecker (Melanerpes erythrocephalus), are migratory, but most live year-round in the same area. Most species live in small social groups; a few, such as the Lewis’ woodpecker (Melanerpes lewis), may, in certain seasons, occasionally be seen in flocks of several hundred.

Damage and Damage Identification
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.

The following species of woodpeckers are most generally involved in damaging homes or other wooden, human-made structures:

Red-headed- Melanerpes erythrocephalus
Acorn- Melanerpes formicivorus
Golden-fronted- Melanerpes aurifrons
Red-bellied- Melanerpes carolinus
Ladder-backed- Picoides scalaris
Downy- Picoides pubescens
Hairy- Picoides villosus
Red-cockaded- Picoides borealis
Northern flicker- Colaptes auratus
Pileated- Dryocopus pileatus

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 inter-core 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. If a suitable cavity results from woodpecker activities, it may also be used for roosting or nesting.

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.

Relatively new damage problems are arising where damage-susceptible materials such as plastic are used for rooftop water-heating solar panels or where electrical solar panels are used. Woodpeckers have also reportedly damaged elevated plastic irrigation lines in several vineyards in California.

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 predominantly a springtime activity. Drumming substrates 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 (0.6- to 1.0-cm) 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 wounds 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 wounds, 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.

In recent times, controls against woodpeckers to protect commercial crops have only rarely been necessary. Published accounts suggest that these isolated instances occurred mostly in the fruit-growing states of the far West where the Lewis’ woodpecker (Melanerpes lewis), whose flocks may number several hundred, is most often implicated.

Economics of Damage and Control
Little has been published on the economics of damage to buildings and other human-made structures. Most of what does exist relates to damage to utility poles because companies keep good records of these losses and the cost of replacements. For example, from 1981 to 1982 the Central Missouri Electric Cooperative replaced 2,114 woodpecker-damaged poles in their system at an estimated cost of $560,000. Economic losses to the timber industry in terms of damaged trees and reduction in wood quality have also been documented in several regions. Such published information is of a localized nature; the extent of damage on a nationwide basis is unknown. Little is published on the economic damage to buildings, although it is known to be substantial in some instances. In a survey of woodpecker damage to homes, homeowners reported an average loss of $300 per bird incident. Damage to homes was estimated at $50,000 to $500,000 annually in Michigan, a conservative $50,000 in Louisiana, and over $100,000 in Wisconsin. The economics of control are relatively unknown because in most situations it is difficult to predict what the damage might have been if no control was undertaken.

Some success has been achieved with the placement of cavity-type nest boxes on the building in the vicinity of damage by northern flickers. A thick layer of sawdust should be placed in the bottom of the box; better yet, some have found that filling the box completely full of sawdust entices the bird to remove the sawdust to the desired level. Possibly, the bird is fooled into thinking it is constructing its own nest. Working against the nest box is the fact that with primary cavity nesters, the preparation of the new cavity often seems a part of the breeding ritual. New cavities are often constructed even where preexisting empty cavities are available.

The use of nest boxes is definitely worth trying in an area where visual or sound methods have failed and where woodpecker populations are desired. Nesting woodpeckers defend their territories and keep other woodpeckers away. What effect such boxes will have on increasing local woodpecker populations is unknown.

Nest boxes are constructed of wood with an entrance hole 16 to 20 inches (40 to 50 cm) above the floor and about 2 1/2 inches (6 cm) in diameter. Inside floor dimensions should be about 6 x 6 inches (15 x 15 cm) and the total height of the box is 22 to 26 inches (56 to 66 cm). A front-sloping hinged roof will shed rain and provide easy access. Place the boxes at about the same height as the height of the structural damage.

Legal Status
Woodpeckers are classified as migratory, nongame birds and are protected by the Federal Migratory Bird Treaty Act. The red-cockaded woodpecker (Picoides borealis) and the ivory-billed woodpecker (Campephilus principalis) are on the Endangered Species list and are thus offered full protection. When warranted, woodpeckers other than the endangered species can 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 species, however, cannot be harassed.


Damage Prevention and Control Methods

Exclusion
Netting. Metal barriers.

Frightening
Visual. Sound.

Repellents
Olfactory. Taste. Tactile.

Toxicants
None are registered.

Fumigants
None are registered.

Trapping
Rat snap trap.

Shooting
Effective where shooting can be conducted safely. Permits are required.

Other Methods
Suet as alternative food. Nest boxes as alternative cavities. Insecticides for indirect control.




ACKNOWLEDGEMENTS
The above information was adapted from PREVENTION AND CONTROL OF WILDLIFE DAMAGE with permission of the editors, Scott E. Hygnstrom, Robert M. Timm, and Gary E. Larson (Cooperative Extension Division, Institute of Agriculture and Natural Resources University of Nebraska-Lincoln, United States Department of Agriculture Animal and Plant Health Inspection Service, Animal Damage Control, Great Plains Agricultural Council Wildlife Committee).