Woodpeckers
Woodpeckers
Status of selected woodpecker species
Woodpeckers are birds in the family Picidae, which includes about 200 species of true woodpeckers, wrynecks, and the diminutive piculets. Woodpeckers are widespread in the world’s forested areas, occurring everywhere except Australia, New Zealand, New Guinea,
Madagascar, and Antarctica. Birds in the woodpecker family range in size from the relatively enormous imperial woodpecker (Campephilus imperialis) of Mexico, with abody length of 21.7in(55 cm) and weight of 1.1 lb (550 g) to tropical piculets only 3.2 in (8 cm) long.
Instinctive behavior
Woodpeckers spend a great deal of their time pecking wood and chiseling bark off trees. They do this for several reasons—to search for their principal food of wood-boring arthropods, to excavate their nesting and roosting cavities, and to proclaim their territory and impress potential mates by loud drumming. Woodpeckers accomplish these tasks by hammering vigorously at softer, fungal-rotted parts of living and dead trees, using their chisel-shaped bill. In their territorial drumming, however, woodpeckers tend to choose more resonant, unrotted trees. Some woodpeckers habitually use telephone poles and tin roofs as their sonorous drumming posts. Both males and females engage in drumming displays, which may be supplemented by loud, raucous, laughing calls. Woodpeckers use their cavities for both nesting and roosting. Although both sexes participate in brooding the eggs and young, only the male bird spends the night in the nesting cavity.
Physical adaptations
Woodpeckers have a number of adaptations that permit them to hammer vigorously on wood without injuring themselves. Their skull is thick-walled and the brain is cushioned by absorbent tissue, which helps it withstand the physical shocks of their head blows. The tongue of the woodpecker is long, barbed, and sticky to help extract insects from crevices, and the organ is supported by an extended hyoid bone and its muscles. The bill of woodpeckers is stout and pointed, and it grows continuously because of the wear to which it is subjected. As an adaptation for gripping vertical bark surfaces, woodpeckers have feet in which two toes point forward and two backward. The stiff, downward-propping tail feathers of woodpeckers also provide mechanical support while they are pecking.
Most woodpeckers live in forests, eating arthropods in or on trees, but a few species occur in more open habitats, where they often forage on the ground for arthropods. Some species are at least partly herbivorous, seasonally eating soft fruits and nuts. Many species of woodpeckers are migratory, while others are resident throughout the year in or near their territories. All of the true woodpeckers nest in cavities that they excavate in the soft, rotted interior of living or dead trees. However, some birds in the family use natural cavities or are secondary users of the abandoned excavations of other birds.
Woodpeckers in north america
About 21 species of woodpeckers regularly breed in North America. The largest species is the 18 in (46 cm) American ivory-billed woodpecker (Campephilus principalis) of the southeastern United States. This species was thought to be extinct until a recent sighting of one bird in 2005. Conservationists are studying the area to see if more birds can be found.
The pileated woodpecker (Dryocopus pileatus) is another large species, with a body length of 15 in (38 cm). This species is still widespread, although uncommon throughout its range.
The northern flicker (Colaptes auratus) occurs very widely across North America. The yellow-shafted flicker is a subspecies (C. a. borealis) with bright yellow underwing feathers and is predominant in the eastern and northern range, while the red-shafted flicker (C. a. cafer) is southwestern in distribution. Flickers often feed on the ground, eating ants and other insects.
The yellow-bellied sapsucker (Sphyrapicus varius) drills a horizontal series of holes in trees, which then ooze sugary sap that attracts and ensnares insects. These are later eaten by the sapsucker, as is some of the sap. The acorn woodpecker (Melanerpes formicivorus) occurs in oak forests of the southwestern United States. This species collects and caches acorns for future consumption, storing them in small holes that it excavates in tree bark. The acorn woodpecker lives in social groups of four to 10 closely related individuals. These cooperating birds engage in communal defense of a breeding territory, and they collect and store their acorns together.
The hairy and downy woodpeckers (Picoides villosus and P. pubescens) are the most widespread species in North America, occurring in almost every forest. The downy woodpecker is more abundant and familiar, often occurring in suburban environments. Both species will feed on suet and peanut butter at feeders.
Woodpeckers and humans
Woodpeckers have sometimes been regarded as pests. Sapsuckers occasionally cause damage when their horizontal rows of drillings girdle trees and prevent the free flow of sap and water. Pileated woodpeckers can damage wooden utility poles, sometimes requiring their premature replacement. Overall, woodpeckers provide more benefit than detriment to humans because they feed on injurious insects, provide nesting cavities for a wide range of other species of wildlife, and have positive aesthetics for birdwatchers and other people who enjoy sightings of these interesting and personable birds.
The populations of some species of woodpeckers have decreased greatly as a result of human activities. The American ivory-billed woodpecker may never have been very abundant in the North American part of its range, and it quickly declined when its preferred habitat of bottom land forests of angiosperm trees and swamps of cypress were cleared for agriculture or harvested for lumber. This species has not been seen with certainty in North America since the 1940s, although a controversial videotape shot in an Arkansas swamp in 2004 is considered by some to be evidence that the species still exists in North America. The subspecies known as the Cuban ivory-billed woodpecker (Campephilus principalis bairdii) is also critically endangered, as is the closely related imperial woodpecker of Mexico.
The red-cockaded woodpecker (Picoides borealis) occurs in old-growth pine forests in the southeastern United States. This species breeds colonially, and has a relatively complex social system, involving clan-helpers that aid in the rearing of broods. There have been large reductions in the pine forests that satisfy the relatively stringent habitat requirements of the redcockaded woodpecker, because these ecosystems have been converted to agricultural uses, plantation forests, and residential developments. The diminished populations of red-cockaded woodpeckers are now extremely vulnerable to further losses of their habitat through human activities or because of natural disturbances such as wildfire and hurricanes, and the species is listed as endangered. To prevent the extinction of this species, it is necessary to protect suitable habitat, and to manage these protected areas sustainably. In other areas of suitable habitat lacking protection, it is necessary to greatly restrict the types of forestry that are permitted in the vicinity of known colonies of this endangered species.
Beyond the specific case of the endangered redcockaded woodpecker, intensive forest management poses a more general risk to woodpeckers. This happens because the birds require a forest habitat that contains standing dead trees (snags), in which they can excavate cavities, feed, and display. Forestry tends to greatly reduce the numbers of snags in the forest, because dead trees can pose a tree-fall hazard to workers, and because they take up space without contributing to the economically productive forest resource. This is especially true of forestry plantations, where large snags may not be present at all, thus depriving woodpeckers of an opportunity to utilize these industrial forests. One of the sensible accommodations that will have to be made by foresters to encourage woodpeckers (and the many other species of birds and mammals that utilize dead wood in forests) will be the provision of snags in managed forests to allow the native animals to sustain breeding populations. This would mean the integrated management of the land for both forest products and for woodpeckers and other species of wildlife.
Status of selected woodpecker species
- Acorn woodpecker (Melanerpes formicivorus). Population appears stable.
- Black-backed woodpecker (Picoides arcticus). Local populations rise and fall with changes in the food supply, but the overall population appears stable.
- Downy woodpecker (Picoides pubescens). A common and widespread woodpecker. The population appears stable. Does not nest in birdhouses.
- Gila woodpecker (Melanerpes uropygialis). The population in California declined in the twentieth century, but this species remains abundant in Arizona.
- Golden-fronted woodpecker (Melanerpes aurifrons).This bird was once shot by railroad personnel because it was considered a telephone pole pest (soft pine is much easier to drill holes in than mesquite), and many were shot in Texas in the early 1900s. Today, the population appears stable.
- Great spotted woodpecker (Dendrocopos major). An Alaskan stray.
- Hairy woodpecker (Picoides villosus). Has declined in some areas due to loss of nesting sites. Starlings and house sparrows sometimes take over the nesting cavities.
- Ivory-billed woodpecker (Campephilus principalis). May be close to extinct. Any surviving populations in the U.S. or Cuba are likely to be tiny.
- Ladder-backed woodpecker (Picoides scalaris). Indications are that there has been a slight decline in number in recent years, but the population today appears stable.
- Lewis’s woodpecker (Melanerpes lewis). Found erratically, so populations have been hard to monitor. There is some indication, however, that populations have declined in recent years. This woodpecker is sometimes considered an orchard pest.
- Nuttall’s woodpecker (Picoides nuttallii). Population appears stable.
- Pileated woodpecker (Drycopus pileatus). The population declined in the East in the eighteenth and nineteenth centuries due to deforestation. This woodpecker has made a gradual comeback since 1900, becoming once again common in some areas.
- Red-bellied woodpecker (Melanerpes carolinus). The population in the North declined over the first half of the twentieth century, but this trend has recently reversed itself. The overall population appears stable, and may actually be increasing.
KEY TERMS
Cavity nester —A bird that builds its nest in a hollow in a tree. Woodpeckers excavate their own cavities, but other species of birds and some mammals use natural cavities, or excavations created and abandoned by other species, especially woodpeckers.
Integrated management —A management system that focuses on more than a single economic resource. In forestry, integrated management might be designed to enhance the resource of lumber and pulpwood, as well as the needs of hunted animals such as deer, non-hunted animals such as song birds and woodpeckers, the aesthetics of landscapes, and other values.
Snag —An erect but dead tree.
- Red-cockaded woodpecker (Picoides borealis). Endangered. The total population is estimated at less than 10,000, with many local groups facing extinction. The cause of this woodpecker’s decline has been the suppression of natural fires and over-cutting of the pine forests in the Southeast.
- Red-headed woodpecker (Melanerpes erythrocephalus). The population has been in decline for a number of years, probably due to loss of nesting sites and competition with starlings for nest cavities. This woodpecker avoids birdhouses.
- Strickland’s woodpecker (Picoides stricklandi). The population in the United States appears stable.
- Three-toed woodpecker (Picoides tridactylus). Local variations in population. Although usually uncommon, this woodpecker may become abundant during periods of heavy insect infestation. Appears stable in remote northern range.
- White-headed woodpecker (Picoides albolarvatus). Population appears stable.
- Northern flicker (Colaptes auratus). Abundant and widespread, but there may have been some decline in population. The flicker competes at a disadvantage with the starling for new nesting sites. The yellow-and red-shafted subspecies appear stable.
- Williamson’s sapsucker (Sphyrapicus thyoideus). Population appears stable.
- Red-breasted sapsucker (Sphyrapicus ruber). Although the population may have declined due to cutting of forests of the Northwest, this species is still fairly numerous.
- Yellow-bellied sapsucker (Sphyrapicus varius). Although this bird has disappeared from some traditional southern nesting areas, it is still fairly numerous.
- Red-naped sapsucker (Sphyrapicus nuchalis). Population appears stable.
Resources
BOOKS
Backhouse, Frances. Woodpeckers of North America. Richmond Hill, ON: Firefly Books, 2005.
Bent, A.C. Life History of North American Woodpeckers (Deluxe Edition). Bloomington: Indiana University Press, 1992.
Brooke, M. and T. Birkhead. The Cambridge Encyclopedia of Ornithology. Cambridge, UK: Cambridge University Press, 1991. del Hoyo, J., A. Elliott, and J. Sargatal. Handbook of the Birds of the World. Vol. 7, Jacamars to Woodpeckers. Barcelona: Lynx Edicions, 2002.
Ehrlich, Paul R., David S. Dobkin, and Darryl Wheye. The Birder’s Handbook. New York: Simon & Schuster Inc., 1988.
Forshaw, Joseph. Encyclopedia of Birds. 2nd ed. New York: Academic Press, 1998.
Godfrey, W.E. The Birds of Canada. Toronto: University of Toronto Press, 1986.
Jackson, Jerome A. In Search of the Ivory-billed Woodpecker. New York: HarperCollins, 2006.
Sibley, David Allen. The Sibley Guide to Birds. New York: Knopf, 2000.
Winkler, Hans, David A. Christie, and David Nurvey. Woodpeckers: A Guide to the Woodpeckers of the World. Boston, Houghton Mifflin, 1995.
PERIODICALS
Sibley, David A., et al. “Comment on ‘Ivory-billed Woodpecker (Campephilus principalis) Persists in Continental North America’.” Science 311 (March 17, 2006): 1555.
Bill Freedman
Randall Frost
Woodpeckers
Woodpeckers
Woodpeckers are birds in the family Picidae, which includes about 200 species of true woodpeckers, wrynecks , as well as the diminutive piculets. Woodpeckers are widespread in the world's forested areas, occurring everywhere but Australia , New Zealand, New Guinea, Madagascar, and Antarctica . Birds in the woodpecker family range in size from the relatively enormous imperial woodpecker (Campephilus imperialis) of Mexico, with a body length of 21.7 in (55 cm) and weight of 1.1 lb (550 g), to tropical piculets only 3.2 in (8 cm) long.
Instinctive behavior
Woodpeckers spend a great deal of their time pecking wood and chiseling bark off trees. They do this for several reasons—to search for their principal food of wood-boring arthropods , to excavate their nesting and roosting cavities, and to proclaim their territory and impress potential mates by loud drumming. Woodpeckers accomplish these tasks by hammering vigorously at softer, fungal-rotted parts of living and dead trees, using their chisel-shaped bill. In their territorial drumming, however, woodpeckers tend to choose more resonant, unrotted trees. Some woodpeckers habitually use telephone poles and tin roofs as their sonorous drumming posts. Both males and females engage in drumming displays, which may be supplemented by loud, raucous, laughing calls. Woodpeckers use their cavities for both nesting and roosting. Although both sexes participate in brooding the eggs and young, only the male bird spends the night in the nesting cavity.
Physical adaptions
Woodpeckers have a number of adaptations that permit the vigorous hammering of wood without damaging the bird. Their skull is thick-walled and the brain is cushioned by absorbent tissue , which helps withstand the physical shocks of their head blows. The tongue of the woodpecker is long, barbed, and sticky to help extract insects from crevices, and the organ is supported by an extended hyoid bone and its muscles. The bill of woodpeckers is stout and pointed, and it grows continuously because of the wear to which it is subjected. As an adaptation for gripping vertical bark surfaces, woodpeckers have feet in which two toes point forward and two backward. The stiff, downward-propping tail feathers of woodpeckers also provide mechanical support while they are pecking.
Most woodpeckers live in forests , eating arthropods in or on trees, but a few species occur in more open habitats, where they often forage on the ground for arthropods. Some species are at least partly herbivorous, seasonally eating soft fruits and nuts. Many species of woodpeckers are migratory, while others are resident throughout the year in or near their territories. All of the true woodpeckers nest in cavities that they excavate in the soft, rotted interior of living or dead trees. However, some birds in the family use natural cavities or are secondary users of the abandoned excavations of other birds.
Woodpeckers in North America
About 21 species of woodpeckers regularly breed in North America . The largest species is the 18 in (46 cm) American ivory-billed woodpecker (Campephilus principalis) of the southeastern United States, although this species is rare and may even be extinct.
The pileated woodpecker (Dryocopus pileatus) is another large species, with a body length of 15 in (38 cm). This species is still widespread, although uncommon throughout its range.
The northern flicker (Colaptes auratus) occurs very widely across North America. The yellow-shafted flicker is a subspecies (C. a. borealis) with bright yellow underwing feathers and is predominant in the eastern and northern range, while the red-shafted flicker (C. a. cafer) is southwestern in distribution. Flickers often feed on the ground, eating ants and other insects.
The yellow-bellied sapsucker (Sphyrapicus varius) drills a horizontal series of holes in trees, which then ooze sugary sap that attracts and ensnares insects. They are later eaten by the sapsucker, as is some of the sap. The acorn woodpecker (Melanerpes formicivorus) occurs in oak forests of the southwestern United States. This species collects and caches acorns for future consumption, storing them in small holes that it excavates in tree bark. The acorn woodpecker lives in social groups of four to 10 closely related individuals. These cooperating birds engage in communal defense of a breeding territory, and they collect and store their acorns together.
The hairy and downy woodpeckers (Picoides villosus and P. pubescens) are the most widespread species in North America, occurring in almost every forest. The downy woodpecker is more abundant and familiar, often occurring in suburban environments. Both species will feed on suet and peanut butter at feeders.
Woodpeckers and humans
Woodpeckers have sometimes been regarded as pests . Sapsuckers occasionally cause damage when their horizontal rows of drillings girdle trees and prevent the free flow of sap and water . Pileated woodpeckers can damage wooden utility poles, sometimes requiring their premature replacement. Overall, woodpeckers provide more benefit than detriment to humans because they feed on injurious insects, provide nesting cavities for a wide range of other species of wildlife , and have positive aesthetics for birdwatchers and other people who enjoy sightings of these interesting and personable birds.
The populations of some species of woodpeckers have decreased greatly as a result of human activities. The American ivory-billed woodpecker may never have been very abundant in the North American part of its range, and it quickly declined when its preferred habitat of bottom land forests of angiosperm trees and swamps of cypress were cleared for agriculture or harvested for lumber. This species has not been seen in North America since the 1940s, and it is probably extirpated. The subspecies known as the Cuban ivory-billed woodpecker (Campephilus principalis bairdii) is also critically endangered, as is the closely related Imperial woodpecker of Mexico.
The red-cockaded woodpecker (Picoides borealis) occurs in old-growth pineforests in the southeastern United States. This species breeds colonially, and has a relatively complex social system, involving clan-helpers that aid in the rearing of broods. There have been large reductions in the pine forests that satisfy the relatively stringent habitat requirements of the red-cockaded woodpecker, because these ecosystems have been converted to agricultural uses, plantation forests, and residential developments. The diminished populations of red-cockaded woodpeckers are now extremely vulnerable to further losses of their habitat through human activities or because of natural disturbances such as wildfire and hurricanes, and the species is listed as endangered. To prevent the extinction of this species, it is necessary to protect suitable habitat, and to manage these protected areas sustainably. In other areas of suitable habitat lacking protection, it is necessary to greatly restrict the types
of forestry that are permitted in the vicinity of known colonies of this endangered species .
Beyond the specific case of the endangered redcockaded woodpecker, intensive forest management poses a more general risk to woodpeckers. This happens because the birds require a forest habitat that contains standing dead trees (snags), in which they can excavate cavities, feed, and display. Forestry tends to greatly reduce the numbers of snags in the forest, because dead trees can pose a tree-fall hazard to workers, and because they take up space without contributing to the economically productive forest resource. This is especially true of forestry plantations, where large snags may not be present at all, therefore depriving woodpeckers of an opportunity to utilize these industrial forests. One of the sensible accommodations that will have to be made by foresters to encourage woodpeckers (and the many other species of birds and mammals that utilize dead wood in forests) will be the provision of snags in managed forests to allow the native animals to sustain breeding populations. This would mean the integrated management of the land for both forest products and for woodpeckers and other species of wildlife.
Status
- Acorn woodpecker (Melanerpes formicivorus). Population appears stable.
- Black-backed woodpecker (Picoides arcticus). Local populations rise and fall with changes in the food supply, but the overall population appears stable.
- Downy woodpecker (Picoides pubescens). A common and widespread woodpecker. The population appears stable. Does not nest in birdhouses.
- Gila woodpecker (Melanerpes uropygialis). The population in California declined in the twentieth century, but this species remains abundant in Arizona.
- Golden-fronted woodpecker (Melanerpes aurifrons). This bird was once shot by railroad personnel because it was considered a telephone pole pest (soft pine is much easier to drill holes in than mesquite), and many were shot in Texas in the early 1900s. Today, the population appears stable.
- Great spotted woodpecker (Dendrocopos major). An Alaskan stray.
- Hairy woodpecker (Picoides villosus). Has declined in some areas due to loss of nesting sites. Starlings and house sparrows sometimes take over the nesting cavities.
- Ivory-billed woodpecker (Campephilus principalis). Almost certainly extinct. The last confirmed sitings in the United States were in the 1950s; reports persisted, however, of sitings in Cuba into the 1980s.
- Ladder-backed woodpecker (Picoides scalaris). Indications are that there has been a slight decline in number in recent years, but the population today appears stable.
- Lewis's woodpecker (Melanerpes lewis). Found erratically, so populations have been hard to monitor. There is some indication, however, that populations have declined in recent years. This woodpecker is sometimes considered an orchard pest.
- Nuttall's woodpecker (Picoides nuttallii). Population appears stable.
- Pileated woodpecker (Drycopus pileatus). The population declined in the East in the eighteenth and nineteenth centuries due to deforestation . This woodpecker has made a gradual comeback since 1900, becoming once again common in some areas.
- Red-bellied woodpecker (Melanerpes carolinus). The population in the North declined over the first half of the twentieth century, but this trend has recently reversed itself. The overall population appears stable, and may actually be increasing.
- Red-cockaded woodpecker (Picoides borealis). Endangered. The total population is estimated at less than 10,000, with many local groups facing extinction. The cause of this woodpecker's decline has been the suppression of natural fires and overcutting of the pine forests in the Southeast.
- Red-headed woodpecker (Melanerpes erythrocephalus). The population has been in decline for a number of years, probably due to loss of nesting sites and competition with starlings for nest cavities. This woodpecker avoids birdhouses.
- Strickland's woodpecker (Picoides striclandi). The population in the United States appears stable.
- Three-toed woodpecker (Picoides tridactylus). Local variations in population. Although usually uncommon, this woodpecker may become abundant during periods of heavy insect infestation. Appears stable in remote northern range.
- White-headed woodpecker (Picoides albolarvatus). Population appears stable.
- Northern flicker (Colaptes auratus). Abundant and widespread, but there may have been some decline in population. The flicker competes at a disadvantage with the starling for new nesting sites. The yellow- and red-shafted subspecies appear stable.
- Williamson's sapsucker (Sphyrapicus thyoideus). Population appears stable.
- Red-breasted sapsucker (Sphyrapicus ruber). Although the population may have declined due to cutting of forests of the Northwest, this species is still fairly numerous.
- Yellow-bellied sapsucker (Sphyrapicus varius). Although this bird has disappeared from some traditional southern nesting areas, it is still fairly numerous.
- Red-naped sapsucker (Sphyrapicus nuchalis). Population appears stable.
Resources
books
Bent, A.C. Life History of North American Woodpeckers (Deluxe Edition). Indiana University Press, 1992.
Brooke, M., and T. Birkhead. The Cambridge Encyclopedia of Ornithology. Cambridge, UK: Cambridge University Press,1991.
Ehrlich, Paul R., David S. Dobkin, and Darryl Wheye. The Birder's Handbook. New York: Simon & Schuster Inc., 1988.
Forshaw, Joseph. Encyclopedia of Birds. New York: Academic Press, 1998.
Godfrey, W.E. The Birds of Canada. Toronto: University of Toronto Press, 1986.
Sibley, David Allen. The Sibley Guide to Birds. New York: Knopf, 2000.
Bill Freedman
Randall Frost
KEY TERMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .- Cavity nester
—A bird that builds its nest in a hollow in a tree. Woodpeckers excavate their own avities, but other species of birds and some mammals use natural cavities, or excavations created and abandoned by other species, especially woodpeckers.
- Integrated management
—A management system that focuses on more than a single economic resource. In forestry, integrated management might be designed to enhance the resource of lumber and pulpwood, as well as the needs of hunted animals such as deer, non-hunted animals such as song birds and woodpeckers, the aesthetics of landscapes, and other values.
- Snag
—An erect but dead tree.
woodpecker
wood·peck·er / ˈwoŏdˌpekər/ • n. a strong-billed, stiff-tailed bird that climbs tree trunks to find insects and drums on dead wood to mark territory. The woodpecker family (Picidae) also includes the wrynecks, flickers, and sapsuckers.