Picidae

(vertebrate zoology) The woodpeckers, a large family of birds in the order Piciformes; adaptive modifications include a long tongue and hyoid mechanism, and stiffened tail feathers.

(Picidae)

Class: Aves

Order: Piciformes

Family: Picidae

Thumbnail description
Small to medium, primarily arboreal; often with patterns of brown, green, or black-and-white; woodpeckers (Picinae) and piculets (Picumninae) often sexually dichromic, males with red or yellow on the head and females lacking it or with less color; wrynecks (Jynginae) sexes similar; woodpeckers have stiff rectrices used for support while climbing on tree surfaces; wrynecks and piculets do not; most have four toes, arranged two forward and two back (zygodactyl)

Size
Wrynecks: 6.3–7.5 in (16–19 cm); 0.78–2.1 oz (22–59 g); piculets: 3–6.3 in (7.5–16 cm);0.24–1.2 oz (6.8–33 g); woodpeckers: 4.7–24 in (12–60 cm); 0.6–21+ oz (17–600+ g)

Number of genera, species
26 genera, 213 species; wrynecks, 1 genus, 2 species; piculets, 2 genera, 29 species; woodpeckers, 23 genera, 182 species

Habitat
Forests, woodlands, parks, and savannas; a few species found in grasslands and deserts

Conservation status
Critically Endangered: 3 species; Endangered: 1 species; Vulnerable: 7 species; Near Threatened: 12 species

Distribution
Worldwide except absent from Australia, New Zealand, New Guinea, Madagascar, Ireland, many oceanic islands, and treeless polar regions; wrynecks limited to Eurasia and Africa; piculets to Asia, Central and South America, and Hispaniola

Evolution and systematics

The picids are an ancient, very distinctive, and thus easily recognized group. Early picids were present at least by the Eocene in both Northern and Southern Hemispheres, but the fossil record is limited and sheds little light on picid relationships. Within the Piciformes they seem to be most closely related to the barbets (Capitonidae), toucans (Ramphastidae), and honeyguides (Indicatoridae). Wrynecks are considered the most primitive picids and they lack many adaptations of the family for tree-climbing and excavation. Woodpeckers may have originated in the New World and there are incredible parallels between Neotropical and African woodpecker groups.

Physical characteristics

Wrynecks are cryptically colored above in brown, gray, and black, and lighter below. They have a slender, pointed bill, rounded wings, and a relatively long tail with rounded tail feathers that lack the stiffness found in woodpecker rectrices. They have short legs and four toes in a zygodactyl (two toes forward, two back) arrangement. Sexes are alike.

Piculets are like miniature woodpeckers, but tail feathers, though pointed, are not stiff and are not used for support. Piculet plumage tends to be soft, and brown and black dominate their color patterns. As with woodpeckers, the sexes are often distinguished by the presence of red on the head of the male. Also like woodpeckers, mechanical tapping on wood is sometimes used for communication.

Woodpeckers have a relatively large head, a straight, sharply pointed to chisel-tipped bill, and a long cylindrical tongue that is often barbed or brushlike at the tip for extracting insect prey from tunnels and crevices. Short legs and three or four toes in a zygodactyl arrangement, and strongly curved claws facilitate climbing. Stiff rectrices are used as a prop for climbing on vertical surfaces and probably also as a "spring" to maximize efficiency of pecking motions. The major tail feathers are mostly black, the melanin adding strength that is needed to counter wear resulting from contact with tree surfaces. Many species are crested, such as the pileated woodpecker (Dryocopus pileatus).

Distribution

Woodpeckers are found in forested regions throughout the world except for Madagascar, the Australian region, and some oceanic islands. Some woodpeckers (e.g., flickers, Colaptes) extend beyond the limits of forest, making nest and roost cavities in utility poles, fence posts, or dirt banks. Wrynecks are confined to the Old World, and piculets to the tropics.

Habitat

Picidae habitats include virtually any environment with woody vegetation, and some without. A major component of woodpecker habitats that has been given little attention but is worthy of consideration is water. High relative humidity, frequent precipitation, and the local presence of standing or running water contribute to abundance and diversity of picid species within regions. The link between water and picids is the requisite moist wood for fungal decay, which facilitates cavity excavation and provides suitable habitats for the wood-boring arthropods that so many picids depend on. Larger woodpeckers, of course, need larger trees in which to excavate their nest and roost cavities. They also often feed on larger prey and need more extensive habitat in order to find adequate food resources. Some smaller woodpeckers that have become specialized for unique habitat conditions also have extensive habitat needs. The red-cockaded woodpecker (Picoides borealis) can require 200–1,000 or more acres (80–400 ha) of pine forest per pair depending on habitat quality.

Behavior

Flight of picids is often undulating, but the largest woodpeckers tend toward less undulation and more level flight. Picid wings tend to be relatively short and rounded, providing better control for maneuvering in forest habitats. Some species, such as the yellow-bellied sapsucker (Sphyrapicus varius) and northern flicker (Colaptes auratus) in North America are migrant (at least in northern populations). The yellow-bellied sapsucker shows a distinct pattern of differential migration by the sexes, females going farther south. Others such as the three-toed woodpecker (Picoides tridactylus) are somewhat irruptive, departing areas when food supplies are low and moving to areas of food concentration such as epidemic beetle outbreaks. Most occupy similar habitats year round, but some can make drastic seasonal shifts. The red-headed woodpecker (Melanerpes erythrocephalus), for example, is generally a bird of very open habitats where it feeds on beetles, grasshoppers, other arthropods, and some fruit during summer, but in winter it often moves to bottomland forest and focuses its foraging on acorns and other mast (nuts found on the forest floor).

Vocalizations are often simple, with single notes often used as contact calls between mates and "whinny" or "rattle" calls found with some variation across the family. In social species such as the California woodpecker (Melanerpes formicivorus) and red-cockaded woodpecker, the vocal repertoire can be more complex. Communication by production of mechanical sounds through tapping on resonant wood is common in picids and the loud, rolling tattoo of such large species as the black woodpecker (Dryocopus martius) of Eurasia and the pileated woodpecker of North America are truly magnificent.

Feeding ecology and diet

The diet of picids is heavily biased toward forest insects and other arthropods, but also includes varying, and sometimes substantial, proportions of fruit, nuts, and tree sap. Many of the physical adaptations of picids are specializations for obtaining food from tree surfaces and subsurfaces. A chisel-like bill is used for excavating to retrieve wood-boring beetle larvae, ants, termites, and other invertebrates from within wood or other substrates. It is also used to reach mast and produce sap wells from which the birds obtain liquid nourishment. The exceptionally long vermiform tongue with a barbed tip is used like a rake to retrieve prey from tunnels and crevices, its efficiency enhanced by a coating of sticky saliva produced by the large salivary glands that characterize the group. The barbs at the tip of a sapsucker's tongue are short and abundant, making the tongue more "brushlike," aiding in obtaining liquid nourishment provided by sap.

Reproductive biology

All members of the Picidae are cavity nesters. Most excavate their own nest and roost cavities, a process that takes about two weeks and is shared by monogamous pair members. The wrynecks do not excavate cavities, but may enlarge one. They also differ from typical woodpeckers by sometimes adding grass or moss as a nest lining. In the red-cockaded woodpecker, cavity excavation, which is characteristically in a living pine, can take several years. A woodpecker nest cavity is usually the roost of the male. No nest material is brought in, though woodpeckers generally leave a layer of fresh chips on the bottom of the cavity and may add more chips, excavated from cavity walls during laying, incubation, and brooding of small nestlings. All picids lay shiny white eggs. At first these are somewhat translucent and may even appear pinkish; with development they become opaque. Clutch size varies within and among species, but usually averages three to five eggs. Incubation begins with laying of the last egg and is shared by both parents. Incubation periods are very short, usually 10–12 days. Young are very altricial and remain naked and with closed eyes for four to seven days. Nestlings fledge at three to six weeks and may be dependent on parents for weeks to months. Nesting success is generally high, although brood reduction through starvation of the last-hatched chick is common.

Conservation status

Seventeen woodpecker and five piculet species or sub-species were included on the 2000 IUCN Red List of Threatened Species. The ivory-billed (Campephilus principalis), imperial (Campephilus imperialis), and the Okinawa woodpecker (Sapheopipo noguchii) are Critically Endangered by loss of old-growth forest. The red-cockaded, Arabian (Dendrocopos dorae), helmeted (Dryocopus galeatus), and Sulu (Picoides ramsayi) woodpeckers are all classified as Vulnerable as a result of habitat losses. The red-cockaded is classified as Endangered under the U.S. Endangered Species Act. Ten other woodpecker species are listed by IUCN in their Lower Risk category. The tawny (Picumnus fulvescens), ochraceous (Picumnus limae), and speckle-chested (Picumnus steindachneri) piculets are all listed as Vulnerable, and the rusty-necked (Picumnus fuscus) and mottled (Picumnus nebulosus) piculets are included as Lower Risk.

The greatest threat to picids is habitat destruction and modification. Clearing of forests for non-forest uses reduces and fragments populations and allows invasion of forest-edge species that compete with woodpeckers for cavities or that prey on woodpeckers. Clearcutting followed by harvesting of trees before they reach natural maturity reduces habitat quality, availability of nest sites, and abundance, diversity, and stability of food supplies. All endangered and threatened woodpecker species are suffering impacts of habitat losses. Introduction of exotic secondary cavity-nesting species, such as the European starling (Sturnus vulgaris), has increased competition for woodpecker cavities and contributed to population declines and possibly shifts in woodpecker nesting phenology that further upset woodpecker roles within ecosystems. For example, starling competition with earlynesting red-bellied woodpeckers (Melanerpes carolinus) seems to have resulted in later renesting of that species, placing it in greater competition with the later nesting red-headed woodpeckers.

Significance to humans

The brilliant red feathers on the head of many male woodpeckers have been sought by indigenous peoples in many areas of the world. In North America, the scalps and bills of ivory-billed woodpeckers were sought and traded far outside the range of the species to be used to adorn war pipes and ceremonial dress. Red-headed woodpecker feathers were similarly used by the Ojibway Indians of Canada. In California, scalps of woodpeckers became essentially the basis of a monetary system among indigenous peoples. Woodpecker tongues and other body parts have been used in folk medicine and woodpeckers have been eaten in many cultures. In Italy, however, the tapping of woodpeckers is considered unlucky, a belief perhaps handed down from the Romans. At the end of the nineteenth century, skins of rare species such as the ivory-billed and imperial woodpeckers had a high market value and were the subject of intense collecting pressure. In the late twentieth century the endangered red-cockaded woodpecker of the southeastern United States became a symbol of conflict between the forest industry and environmental action groups. Several species of woodpeckers have been eaten by local cultures, including flickers, pileated woodpeckers, and ivory-billed woodpeckers in North America. The latter two were both known to early settlers in North America as "Indian hens," perhaps a reference to their edibility. One early writer suggests that ivory-billed woodpecker tasted as good as "pintail duck."

Woodpeckers are very important components of forest ecosystems because of their role in providing nest and roost sites for many secondary cavity-nesting species, their control of forest insect pests, and to some extent dispersal of seeds. Woodpeckers are also blamed for considerable damage to buildings, some damage to crops (including sugar cane, cacao, corn, oranges, and other fruit), to commercially valuable trees, and sometimes to eggs of poultry. Often, however, the perceived damage is a perception only and the "services" provided by the birds far outweigh any real damage. Woodpeckers have a lot of popular appeal and have contributed to human culture in such diverse ways as through the cartoon "Woody Woodpecker" (patterned after the pileated woodpecker), door-knockers shaped like woodpeckers, and toothpick dispensers that include a miniature woodpecker that picks up a toothpick for the user. In Brazil, muzzle-loading shotguns are called "woodpeckers."

Species accounts

Resources

Frugis, S., G. Malaguzzi, G. Vicini, and P. Cristina. Guida ai Picchi del Mondo. Torino, Italy: Museo Regionale di Scienze Naturali, Monografia VII, 1988.

Fry, C. H., S. Keith, and E. K. Urban., eds. The Birds of Africa. Vol. 3. New York: Academic Press, 1988.

Garrido, O. H., and A. Kirkconnell. Field Guide to the Birds of Cuba. Ithaca: Cornell University Press, 2000.

Jackson, J. A. "Ivory-billed Woodpecker Campephilus principalis principalis." In Rare and Endangered Biota of Florida: Birds, edited by J. A. Rodgers and H. W. Kale, II. Gainesville: University of Florida Press, 1996.

MacKinnon, J., and K. Phillipps. A Field Guide to the Birds of Borneo, Sumatra, Java, and Bali. Oxford: Oxford University Press, 1993.

Moore, W. S., and V. R. DeFilippis. "The Window of Taxonomic Resolution for Phylogenies Based on Mitochondrial Cytochrome b." In Avian Molecular Evolution and Systematics, edited by D. P. Mindell. San Diego: Academic Press, 1997.

Sick, H. (translated by W. Belton). Birds in Brazil. Princeton: Princeton University Press, 1993.

Snow, D. W., and C. M. Perrins et al. The Birds of the Western Palearctic. Vol. 1. Concise edition. Oxford: Oxford University Press, 1998.

Winkler, H., D. A. Christie, and D. Nurnie. Woodpeckers: A Guide to the Woodpeckers of the World. Boston: Houghton Mifflin Company, 1995.

Jackson, J. A. "Red-cockaded Woodpecker Picoides borealis." Birds of North America 85 (1994).

Bent, A. C. Life Histories of North American Woodpeckers. United States National Museum Bulletin 174, 1939.

Lawrence, L. D. K. A Comparative Life-History Study of Four Species of Woodpeckers. AOU Ornithological Monographs No. 5, 1967.

Short, L. L. Woodpeckers of the World. Greenville, Delaware: Delaware Museum of Natural History, Monograph Series Number 4, 1982.

Tanner, J. T. The Ivory-billed Woodpecker. Research Report Number 1, New York: National Audubon Society, 1942.

[Article by: Jerome A. Jackson, PhD]

The noun has one meaning:

Meaning #1: woodpeckers
  Synonym: family Picidae