Woodpecker
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Woodpeckers are part of the
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Picidae, which also includes the piculets,
wryneck The wrynecks (genus ''Jynx'') are a small but distinctive group of small Old World woodpeckers. ''Jynx'' is from the Ancient Greek ''iunx'', the Eurasian wryneck. These birds get their English name from their ability to turn their heads almos ...
s, and
sapsucker The sapsuckers are species of North American woodpeckers in the genus ''Sphyrapicus''. Taxonomy and systematics The genus ''Sphyrapicus'' was introduced in 1858 by the American naturalist Spencer Baird with the yellow-bellied sapsucker (''Sphyr ...
s. Members of this family are found worldwide, except for
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
,
New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torres ...
,
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
,
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Afric ...
, and the extreme polar regions. Most species live in
forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
s or
woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...
habitats, although a few species are known that live in treeless areas, such as rocky hillsides and deserts, and the Gila woodpecker specialises in exploiting cacti. Members of this family are chiefly known for their characteristic behaviour. They mostly forage for insect prey on the trunks and branches of trees, and often communicate by drumming with their beaks, producing a reverberatory sound that can be heard at some distance. Some species vary their diet with fruits, birds' eggs, small animals, tree sap, human scraps, and
carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...
. They usually nest and roost in holes that they excavate in tree trunks, and their abandoned holes are of importance to other cavity-nesting birds. They sometimes come into conflict with humans when they make holes in buildings or feed on fruit crops, but perform a useful service by their removal of insect pests on trees. The Picidae are one of nine living families in the
order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...
Piciformes Nine families of largely arboreal birds make up the order Piciformes , the best-known of them being the Picidae, which includes the woodpeckers and close relatives. The Piciformes contain about 71 living genera with a little over 450 species, of ...
, the others being
barbets Barbet may refer to: * Barbet (dog), a dog breed * Various birds in the infraorder Ramphastides ** African barbet, part of the bird family Lybiidae ** New World barbet, the bird family Capitonidae ** Asian barbet, the bird family Megalaimidae ** ...
(comprising three families),
toucan Toucans (, ) are members of the Neotropical near passerine bird family Ramphastidae. The Ramphastidae are most closely related to the American barbets. They are brightly marked and have large, often colorful bills. The family includes five g ...
s, toucan-barbets, and
honeyguide Honeyguides (family Indicatoridae) are near passerine birds in the order Piciformes. They are also known as indicator birds, or honey birds, although the latter term is also used more narrowly to refer to species of the genus ''Prodotiscus''. Th ...
s, which (along with woodpeckers) comprise the
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...
Pici Pici (; ) is thick, hand-rolled pasta, like fat spaghetti.'' Il Devoto-Oli. Vocabolario della lingua Italiana'', edited by Luca Serianni and Maurizio Trifone, Le Monnier. It originates in the province of Siena in Tuscany; in the Montalcino area ...
, and the
jacamar The jacamars are a family, Galbulidae, of near passerine birds from tropical South and Central America, extending up to Mexico. The family contains five genera and 18 species. The family is closely related to the puffbirds, another Neotropical f ...
s and
puffbird The puffbirds and their relatives in the near passerine family Bucconidae are tropical tree-dwelling insectivorous birds that are found from South America up to Mexico. Together with their closest relatives, the jacamars, they form a divergent ...
s in the clade
Galbuli Galbuli is one of the two suborders of the order Piciformes and includes two families Bucconidae (puffbirds) and Galbulidae (jacamars). The other suborder Pici is a global group of piciforms, puffbirds and jacamars are only found in the Neotropic ...
.
DNA sequencing DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. T ...
has confirmed the sister relationships of these two groups. The family Picidae includes about 240
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
arranged in 35
genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
. Almost 20 species are threatened with
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the Endling, last individual of the species, although the Functional ext ...
due to loss of habitat or
habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological process ...
, with one, the
Bermuda flicker The Bermuda flicker (''Colaptes oceanicus'') is an extinct woodpecker from the genus '' Colaptes''. It was confined to Bermuda and is known only by fossil remains dated to the Late Pleistocene and the Holocene. However, an old travel report by ex ...
, being extinct and a further two possibly being so.


General characteristics

Woodpeckers include the tiny piculets, the smallest of which appears to be the
bar-breasted piculet The bar-breasted piculet (''Picumnus aurifrons'') is a species of bird in subfamily Picumninae of the woodpecker family Picidae.Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbin ...
at in length and a weight of . Some of the largest woodpeckers can be more than in length. The largest surviving species is the great slaty woodpecker, which weighs on average and up to , and measures , but the extinct imperial woodpecker, at , and
ivory-billed woodpecker The ivory-billed woodpecker (''Campephilus principalis'') is a possibly extinct woodpecker that is native to the bottomland hardwood forests and temperate coniferous forests of the Southern United States and Cuba. Habitat destruction and hunting ...
, around and , were probably both larger. The
plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...
of woodpeckers varies from drab to conspicuous. The colours of many species are based on olive and brown and some are pied, suggesting a need for
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
; others are boldly patterned in black, white, and red, and many have a crest or tufted feathers on their crowns. Woodpeckers tend to be
sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
, but differences between the sexes are generally small; exceptions to this are
Williamson's sapsucker Williamson's sapsucker (''Sphyrapicus thyroideus'') is a medium-sized woodpecker belonging to the genus '' Sphyrapicus'' (sapsuckers). Habitat and range Breeding habitat is open forested areas with conifers, mainly ponderosa pine, douglas-fi ...
and the
orange-backed woodpecker The orange-backed woodpecker (''Reinwardtipicus validus'') is a bird in the woodpecker family Picidae, found in southern Thailand, Malaya, Sarawak and Sabah in Malaysia, Brunei, Sumatra, and Java. It is monotypic in the genus ''Reinwardt ...
, which differ markedly. The plumage is
moult In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...
ed fully once a year apart from the
wryneck The wrynecks (genus ''Jynx'') are a small but distinctive group of small Old World woodpeckers. ''Jynx'' is from the Ancient Greek ''iunx'', the Eurasian wryneck. These birds get their English name from their ability to turn their heads almos ...
s, which have an additional partial moult before breeding.Gorman 2014, pp. 22–23 Woodpeckers, piculets, and wrynecks all possess characteristic zygodactyl feet, consisting of four toes, the first (hallux) and the fourth facing backward and the second and third facing forward. This foot arrangement is good for grasping the limbs and trunks of trees. Members of this family can walk vertically up tree trunks, which is beneficial for activities such as foraging for food or nest excavation. In addition to their strong claws and feet, woodpeckers have short, strong legs. This is typical of birds that regularly forage on trunks. Exceptions are the
black-backed woodpecker The black-backed woodpecker (''Picoides arcticus''), also known as the Arctic three-toed woodpecker, is a medium-sized woodpecker ( long) inhabiting the forests of North America. Taxonomy The black-backed woodpecker was described and illustrat ...
and the
American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...
and
Eurasian three-toed woodpecker The Eurasian three-toed woodpecker (''Picoides tridactylus'') is a medium-sized woodpecker that is found from northern Europe across northern Asia to Japan. Taxonomy The Eurasian three-toed woodpecker was formally described in 1758 by the Swedi ...
s, which have only three toes on each foot. The tails of all woodpeckers, except the piculets and wrynecks, are stiffened, and when the bird perches on a vertical surface, the tail and feet work together to support it. Woodpeckers have strong bills that they use for drilling and drumming on trees, and long, sticky tongues for extracting food (insects and larvae).Winkler, Hans & Christie, David A. (2002), "Family Picidae (Woodpeckers)" ''in'' del Hoyo, J.; Elliot, A. & Sargatal, J. (editors). (2002). ''
Handbook of the Birds of the World The ''Handbook of the Birds of the World'' (HBW) is a multi-volume series produced by the Spanish publishing house Lynx Edicions in partnership with BirdLife International. It is the first handbook to cover every known living species of bird. ...
. Volume 7: Jacamars to Woodpeckers.'' Lynx Edicions.
Woodpecker bills are typically longer, sharper, and stronger than the bills of piculets and wrynecks, but their morphology is very similar. The bill's chisel-like tip is kept sharp by the
pecking Pecking is the action of a bird using their beak to search for food or otherwise investigate an object or area by tapping it. Pecking can also be used by a bird to attack or fight another bird. Pecking is frequently observed in chickens and oth ...
action in birds that regularly use it on wood. The beak consists of three layers; an outer sheath called
rhamphotheca The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for food, ...
, made of scales formed from
keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up Scale (anatomy), scales, hair, Nail ...
proteins, an inner layer of bone which has a large cavity and mineralised
collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whol ...
fibers, and a middle layer made of porous bone which connects the two other layers. Furthermore, the tongue bone (or hyoid bone) of the woodpecker is very long, and winds around the skull through a special cavity, thereby cushioning the brain. Combined, this anatomy helps the beak absorb mechanical stress. Species of woodpecker and flicker that use their bills in soil or for probing as opposed to regular hammering tend to have longer and more decurved bills. Due to their smaller bill size, many piculets and wrynecks forage in decaying wood more often than woodpeckers. Their long, sticky tongues, which possess
bristles A bristle is a stiff hair or feather (natural or artificial), either on an animal, such as a pig, a plant, or on a tool such as a brush or broom. Synthetic types Synthetic materials such as nylon are also used to make bristles in items such as br ...
, aid these birds in grabbing and extracting insects from deep within a hole in a tree. The tongue was reported to be used to spear grubs, but more detailed studies published in 2004 have shown that the tongue instead wraps around the prey before being pulled out. Many of the foraging, breeding, and signaling behaviors of woodpeckers involve drumming and hammering using their bills. To prevent
brain damage Neurotrauma, brain damage or brain injury (BI) is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors. In general, brain damage refers to significant, undiscriminating t ...
from the rapid and repeated powerful impacts, woodpeckers have a number of physical features that protect their brains. These include a relatively small and smooth brain, narrow
subdural space The subdural space (or subdural cavity) is a potential space that can be opened by the separation of the arachnoid mater from the dura mater as the result of trauma, pathologic process, or the absence of cerebrospinal fluid as seen in a cadaver. ...
, little
cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the ...
surrounding it to prevent it from moving back and forth inside the skull during pecking, the orientation of the brain within the skull (which maximises the contact area between the brain and the skull) and the short duration of contact. The skull consists of strong but compressible, sponge-like bone, which is most concentrated in the forehead and the back of the skull. Another anatomical adaptation of woodpeckers is the enormously elongated
hyoid bone The hyoid bone (lingual bone or tongue-bone) () is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies between the base of the mandible and the third cervical verteb ...
which subdivides, passes on either side of the spinal column and wraps around the brain case, before ending in the right nostril cavity. It plays the role of safety-belt. Computer simulations have shown that 99.7% of the energy generated in pecking is stored in the form of
strain energy In physics, the elastic potential energy gained by a wire during elongation with a tensile (stretching) force is called strain energy. For linearly elastic materials, strain energy is: : U = \frac 1 2 V \sigma \epsilon = \frac 1 2 V E \epsilon ...
, which is distributed throughout the bird's body, with only a small remaining fraction of the energy going into the brain. The pecking also causes the woodpecker's skull to heat up, which is part of the reason why they often peck in short bursts with brief breaks in between, giving the head some time to cool. During the millisecond before contact with wood, a thickened
nictitating membrane The nictitating membrane (from Latin '' nictare'', to blink) is a transparent or translucent third eyelid present in some animals that can be drawn across the eye from the medial canthus to protect and moisten it while maintaining vision. All ...
closes, protecting the eye from flying debris. These membranes also prevent the
retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which the ...
from tearing. Their nostrils are also protected; they are often slit-like and have special feathers to cover them. Woodpeckers are capable of repeated pecking on a tree at high decelerations on the order of (1000 g). Some large woodpeckers such as ''
Dryocopus ''Dryocopus'' is a genus of large powerful woodpeckers, typically 35–45 cm in length. It has representatives in North and South America, Europe, and Asia; some South American species are endangered. It was believed to be closely related to ...
'' have a fast, direct form of flight, but the majority of species have a typical undulating flight pattern consisting of a series of rapid flaps followed by a swooping glide. Many birds in the genus ''
Melanerpes ''Melanerpes'' is a genus of woodpeckers of the family Picidae found in the New World. The 24 members of the genus are mostly colourful birds, conspicuously barred in black and white, with some red and yellow. Taxonomy The genus ''Melanerpes'' ...
'' have distinctive, rowing wing-strokes while the piculets engage in short bursts of rapid direct flight.


Distribution, habitat, and movements


Global distribution

Woodpeckers have a mostly
cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in appropriate habitats. Such a taxon, usually a species, is said to exhibit cosmopolitanism or cosmopolitism. The extr ...
, although they are absent from
Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologic ...
, Madagascar, and
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...
. They are also absent from some of the world's oceanic
island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An isla ...
s, although many insular species are found on
continental island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...
s. The true woodpeckers, subfamily
Picinae Picinae containing the true woodpeckers is one of three subfamilies that make up the woodpecker family Picidae. True woodpeckers are found over much of the world, but do not occur in Madagascar or Australasia. Woodpeckers gained their English n ...
, are distributed across the entire range of the family. The Picumninae piculets have a pantropical distribution, with species in
Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainland ...
, Africa, and the
Neotropics The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In bioge ...
, with the greatest diversity being in South America. The second piculet subfamily, the
Nesoctitinae The Antillean piculet (''Nesoctites micromegas'') is a species of bird in the woodpecker family Picidae. It is monotypic within the genus ''Nesoctites''. The species is evolutionarily distinct from the other piculets and is afforded Monotypic ta ...
, has a single member, the
Antillean piculet The Antillean piculet (''Nesoctites micromegas'') is a species of bird in the woodpecker family Picidae. It is monotypic within the genus ''Nesoctites''. The species is evolutionarily distinct from the other piculets and is afforded its own sub ...
, which is restricted to the
Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean ...
island of
Hispaniola Hispaniola (, also ; es, La Española; Latin and french: Hispaniola; ht, Ispayola; tnq, Ayiti or Quisqueya) is an island in the Caribbean that is part of the Greater Antilles. Hispaniola is the most populous island in the West Indies, and th ...
. The wrynecks (Jynginae) are found exclusively in the Old World, with the two species occurring in Europe, Asia, and Africa.Gorman 2014, p. 15 Most woodpeckers are sedentary, but a few examples of migratory species are known, such as the
rufous-bellied woodpecker The rufous-bellied woodpecker or rufous-bellied sapsucker (''Dendrocopos hyperythrus'') is a species of bird in the family Picidae. This woodpecker has a habit of making a series of small pits on the bark of trees leading to its being considered ...
,
yellow-bellied sapsucker The yellow-bellied sapsucker (''Sphyrapicus varius'') is a medium-sized woodpecker that breeds in Canada and the northeastern United States. Taxonomy The yellow-bellied sapsucker was described and illustrated using a hand-coloured plate by the E ...
, and
Eurasian wryneck The Eurasian wryneck or northern wryneck (''Jynx torquilla'') is a species of wryneck in the woodpecker family. This species mainly breeds in temperate regions of Europe and Asia. Most populations are migratory, wintering in tropical Africa an ...
, which breeds in Europe and west Asia and migrates to the
Sahel The Sahel (; ar, ساحل ' , "coast, shore") is a region in North Africa. It is defined as the ecoclimatic and biogeographic realm of transition between the Sahara to the north and the Sudanian savanna to the south. Having a hot semi-arid cli ...
in Africa in the winter. More northerly populations of
Lewis's woodpecker Lewis's woodpecker (''Melanerpes lewis'') is a large North American species of woodpecker which ornithologist Alexander Wilson named after Meriwether Lewis, one of the explorers who surveyed the areas bought by the United States of America as pa ...
,
northern flicker The northern flicker or common flicker (''Colaptes auratus'') is a medium-sized bird of the woodpecker family. It is native to most of North America, parts of Central America, Cuba, and the Cayman Islands, and is one of the few woodpecker spec ...
, Williamson's sapsucker,
red-breasted sapsucker The red-breasted sapsucker (''Sphyrapicus ruber'') is a medium-sized woodpecker of the forests of the west coast of North America. Description Adults have a red head and upper chest; they have a white lower belly and rump. They are black on the ...
, and
red-naped sapsucker The red-naped sapsucker (''Sphyrapicus nuchalis'') is a medium-sized North American woodpecker. Long thought to be a subspecies of the yellow-bellied sapsucker, it is now known to be a distinct species. Systematics The red-naped sapsucker is one ...
all move southwards in the fall in North America. Most woodpecker movements can be described as dispersive, such as when young birds seek territories after fledging, or eruptive, to escape harsh weather conditions. Several species are altitudinal migrants, for example the grey-capped pygmy woodpecker, which moves to lowlands from hills during winter. The woodpeckers that do migrate, do so during the day.


Habitat requirements

Overall, woodpeckers are arboreal birds of wooded
habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s. They reach their greatest
diversity Diversity, diversify, or diverse may refer to: Business *Diversity (business), the inclusion of people of different identities (ethnicity, gender, age) in the workforce *Diversity marketing, marketing communication targeting diverse customers * ...
in
tropical rainforest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equator ...
s, but occur in almost all suitable habitats, including woodlands,
savannah A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...
s,
scrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity. It ...
s, and
bamboo Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, ...
forests. Even
grassland A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...
s and
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
s have been colonised by various species. These habitats are more easily occupied where a small number of trees exist, or in the case of desert species like the Gila woodpecker, tall
cacti A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Gree ...
are available for nesting. Some are specialists and are associated with
coniferous Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...
or
deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...
woodlands, or even, like the
acorn woodpecker The acorn woodpecker (''Melanerpes formicivorus'') is a medium-sized woodpecker, long, with an average weight of . Taxonomy The acorn woodpecker was formally described in 1827 by the English naturalist William John Swainson under the binomi ...
, with individual tree genera ( oaks in this case). Other species are generalists and are able to adapt to forest clearance by exploiting secondary growth, plantations,
orchard An orchard is an intentional plantation of trees or shrubs that is maintained for food production. Orchards comprise fruit- or nut-producing trees which are generally grown for commercial production. Orchards are also sometimes a feature of ...
s, and parks. In general, forest-dwelling species need rotting or dead wood on which to forage.Gorman 2014, p. 18 Several species are adapted to spending a portion of their time feeding on the ground, and a very small minority have abandoned trees entirely and nest in holes in the ground. The
ground woodpecker The ground woodpecker (''Geocolaptes olivaceus'') is one of only three ground-dwelling woodpeckers in the world (the others are the Andean and campo flickers). It inhabits rather barren, steep, boulder-strewn slopes in relatively cool hilly and m ...
is one such species, inhabiting the rocky and grassy hills of
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...
, and the
Andean flicker The Andean flicker (''Colaptes rupicola'') is a South American species of woodpecker. It is found in grassland, shrubland and ''Polylepis'' woodland at altitudes of in the Puna ecoregion. Together with the campo flicker and ground woodpecker ...
is another. The
Swiss Ornithological Institute The Swiss Ornithological Institute () is a non-profit foundation headquartered in Sempach in the district of Sursee in the canton of Lucerne in Switzerland dedicated to the study and conservation of birds. The Swiss Ornithological Institute w ...
has set up a monitoring program to record breeding populations of woodland birds. This has shown that deadwood is an important habitat requirement for the
black woodpecker The black woodpecker (''Dryocopus martius'') is a large woodpecker that lives in mature forests across the northern Palearctic. It is the sole representative of its genus in that region. Its range is expanding. The black woodpecker is easily the ...
,
great spotted woodpecker The great spotted woodpecker (''Dendrocopos major'') is a medium-sized woodpecker with pied black and white plumage and a red patch on the lower belly. Males and young birds also have red markings on the neck or head. This species is found acro ...
,
middle spotted woodpecker The middle spotted woodpecker (''Dendrocoptes medius'') is a European woodpecker belonging to the genus '' Dendrocoptes''. Taxonomy The middle spotted woodpecker was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the ...
,
lesser spotted woodpecker The lesser spotted woodpecker (''Dryobates minor'') is a member of the woodpecker family Picidae. It was formerly assigned to the genus ''Dendrocopos'' (sometimes incorrectly spelt as ''Dendrocopus''). Some taxonomic authorities continue to list t ...
,
European green woodpecker The European green woodpecker (''Picus viridis'') is a large green woodpecker with a bright red crown and a black moustache. Males have a red centre to the moustache stripe which is absent in females. It is resident across much of Europe and the ...
, and
Eurasian three-toed woodpecker The Eurasian three-toed woodpecker (''Picoides tridactylus'') is a medium-sized woodpecker that is found from northern Europe across northern Asia to Japan. Taxonomy The Eurasian three-toed woodpecker was formally described in 1758 by the Swedi ...
. Populations of all these species increased by varying amounts from 1990 to 2008. During this period, the amount of deadwood in the forest increased and the range of the
white-backed woodpecker The white-backed woodpecker (''Dendrocopos leucotos'') is a Eurasian woodpecker belonging to the genus ''Dendrocopos''. Taxonomy The white-backed woodpecker was described by the German naturalist Johann Matthäus Bechstein in 1802 under the ...
enlarged as it extended eastwards. With the exception of the green and middle-spotted woodpeckers, the increase in the amount of deadwood is likely to be the major factor explaining the population increase of these species.


Behaviour

Most woodpeckers live
solitary Solitary is the state of being alone or in solitude. The term may refer to: * shortened form of solitary confinement * Solitary animal, an animal that does not live with others in its species * Solitary but social, a type of social organization ...
lives, but their behaviour ranges from highly antisocial species that are aggressive towards their own kind, to species that live in groups. Solitary species defend such feeding resources as a
termite Termites are small insects that live in colonies and have distinct castes ( eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blat ...
colony or fruit-laden tree, driving away other conspecifics and returning frequently until the resource is exhausted.
Aggressive Aggression is overt or covert, often harmful, social interaction with the intention of inflicting damage or other harm upon another individual; although it can be channeled into creative and practical outlets for some. It may occur either reacti ...
behaviours include bill pointing and jabbing, head shaking, wing flicking, chasing, drumming, and vocalisations. Ritual actions do not usually result in contact, and birds may "freeze" for a while before they resume their dispute. The coloured patches may be flouted, and in some instances, these antagonistic behaviours resemble courtship rituals. Group-living species tend to be communal group breeders. In addition to these species, a number of species may join
mixed-species foraging flock A mixed-species feeding flock, also termed a mixed-species foraging flock, mixed hunting party or informally bird wave, is a flock of usually insectivorous birds of different species that join each other and move together while foraging. These ar ...
s with other insectivorous birds, although they tend to stay at the edges of these groups. Joining these flocks allows woodpeckers to decrease their anti-predator vigilance and increase their feeding rate. Woodpeckers are diurnal, roosting at night inside holes and crevices. In many species the roost will become the nest-site during the breeding season, but in some species they have separate functions; the
grey-and-buff woodpecker The grey-and-buff woodpecker (''Hemicircus concretus'') is a species of bird in the family Picidae. It is found in Brunei, Indonesia ( Sumatra and Borneo), Malaysia, southern Myanmar, and southern Thailand, but has become regionally extinct ...
makes several shallow holes for roosting which are quite distinct from its nesting site. Most birds roost alone and will oust intruders from their chosen site, but the
Magellanic woodpecker The Magellanic woodpecker (''Campephilus magellanicus'') is a very large woodpecker found in southern Chile and southwestern Argentina; it is resident within its range. This species is the southernmost example of the genus '' Campephilus'', which ...
and acorn woodpecker are cooperative roosters.Gorman 2014, pp. 19–20


Drumming

Drumming is a form of nonvocal communication used by most species of woodpeckers, and involves the bill being repeatedly struck on a hard surface with great rapidity. After a pause, the drum roll is repeated, with each species having a pattern that is unique in the number of beats in the roll, the length of the roll, the length of the gap between rolls, and the cadence. The drumming is mainly a territorial call, equivalent to the song of a
passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...
.Gorman 2014, p. 28 Woodpeckers choose a surface that resonates, such as a hollow tree, and may use man-made structures such as gutters and downpipes. Drumming serves for the mutual recognition of conspecifics and plays a part in
courtship Courtship is the period wherein some couples get to know each other prior to a possible marriage. Courtship traditionally may begin after a betrothal and may conclude with the celebration of marriage. A courtship may be an informal and private m ...
rituals. Individual birds are thought to be able to distinguish the drumming of their mates and those of their neighbours. Drumming in woodpeckers is controlled by a set of nuclei in the forebrain that closely resemble the brain regions that underlie song learning and production in many songbirds.


Calls

Woodpeckers do not have such a wide range of songs and calls as do
passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...
birds, and the sounds they make tend to be simpler in structure. Calls produced include brief, high-pitched notes, trills, rattles, twittering, whistling, chattering, nasal churrs, screams, and wails. These calls are used by both sexes in
communication Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inqui ...
and are related to the circumstances of the occasion; these include courtship,
territorial A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or an ...
disputes, and alarm calls. Each species has its own range of calls, which tend to be in the 1.0 to 2.5 kHz range for efficient transmission through forested environments. Mated couples may exchange muted, low-pitched calls, and nestlings often issue noisy begging calls from inside their nest cavity. The wrynecks have a more musical song, and in some areas, the song of the newly arrived Eurasian wryneck is considered to be the harbinger of spring. The piculets either have a song consisting of a long, descending trill, or a descending series of two to six (sometimes more) individual notes, and this song alerts
ornithologists __NOTOC__ This is a list of ornithologists who have articles, in alphabetical order by surname. See also :Ornithologists. A * John Abbot – US * Clinton Gilbert Abbott – US * William Louis Abbott – US * Joseph H. Acklen – US *Humayun Ab ...
to the presence of the birds, as they are easily overlooked.


Diet and feeding

Most woodpecker species feed on
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...
s and other
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
s living under bark and in wood, but overall, the family is characterized by its dietary flexibility, with many species being both highly omnivorous and opportunistic. The diet includes ants, termites, beetles and their larvae, caterpillars, spiders, other arthropods, bird eggs, nestlings, small rodents, lizards, fruit, nuts, and sap. Many insects and their grubs are taken from living and dead trees by excavation. The bird may hear sounds from inside the timber indicating where creating a hole would be productive.
Crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...
s,
mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000  extant species of molluscs are recognized. The number of fossil species is est ...
s, and carrion may be eaten by some species, including the great spotted woodpecker, and bird feeders are visited for
suet Suet is the raw, hard fat of beef, lamb or mutton found around the loins and kidneys. Suet has a melting point of between 45 °C and 50 °C (113 °F and 122 °F) and congelation between 37 °C and 40 °C (98.6& ...
and domestic scraps. Other means are also used to garner prey. Some species, such as the red-naped sapsucker, sally into the air to catch flying insects, and many species probe into crevices and under bark, or glean prey from leaves and twigs. The rufous woodpecker specialises in attacking the nests of arboreal ants, and the buff-spotted woodpecker feeds on and nests in
termite mounds Mound-building termites are a group of termite species that live in mounds. These termites live in Africa, Australia and South America. The mounds sometimes have a diameter of . Most of the mounds are in well-drained areas. Termite mounds usual ...
. Other species, such as the wrynecks and the Andean flicker, feed wholly or partly on the ground. Ecologically, woodpeckers help to keep trees healthy by keeping them from suffering mass infestations. The family is noted for its ability to acquire wood-boring grubs from the trunks and branches, whether the timber is alive or dead. Having hammered a hole into the wood, the prey is extracted by use of a long, barbed tongue. Woodpeckers consume beetles that burrow into trees, removing as many as 85% of
emerald ash borer The emerald ash borer (''Agrilus planipennis''), also known by the acronym EAB, is a green buprestid or jewel beetle native to north-eastern Asia that feeds on ash species. Females lay eggs in bark crevices on ash trees, and larvae feed undern ...
larvae from individual ash trees. The ability to excavate allows woodpeckers to obtain
tree sap 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * 01'' (Richard Müller album), 2001 * ''01'' (Son of Dave album), 2000 * ''01'' (Urban Zakapa album), 2011 * ''O1'' (Hiroyuki Sawano ...
, an important source of food for some species. Most famously, the sapsuckers (genus ''Sphyrapicus'') feed in this fashion, but the technique is not restricted to these, and others such as the
acorn woodpecker The acorn woodpecker (''Melanerpes formicivorus'') is a medium-sized woodpecker, long, with an average weight of . Taxonomy The acorn woodpecker was formally described in 1827 by the English naturalist William John Swainson under the binomi ...
and
white-headed woodpecker The white-headed woodpecker (''Leuconotopicus albolarvatus'') is a non-migratory woodpecker that resides in pine forests of the mountains of western North America. Description It has a black body (approximately long) and white head. It has whit ...
also feed on sap. The technique was once thought to be restricted to the New World, but Old World species, such as the
Arabian woodpecker The Arabian woodpecker (''Dendrocoptes dorae'') or Sarat woodpecker, is a bird species of the family Picidae, native to the Sarawat Mountains of Saudi Arabia and Yemen. It is the only woodpecker that breeds on the Arabian Peninsula. This species ...
and great spotted woodpecker, also feed in this way.


Breeding

All members of the family Picidae
nest A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic materi ...
in cavities, nearly always in the trunks and branches of trees, well away from the foliage. Where possible, an area of rotten wood surrounded by sound timber is used. Where trees are in short supply, the
gilded flicker The gilded flicker (''Colaptes chrysoides'') is a large-sized woodpecker (mean length of ) of the Sonoran, Yuma, and eastern Colorado Desert regions of the southwestern United States and northwestern Mexico, including all of Baja California, ex ...
and ladder-backed woodpecker excavate holes in cactus, and the Andean flicker and ground woodpecker dig holes in earth banks. The
campo flicker The campo flicker (''Colaptes campestris'') is a species of bird in the woodpecker family. It is found in a wide range of open and semi-open habitats in eastern Brazil, Bolivia, Paraguay, Uruguay and northeastern Argentina, with isolated populati ...
sometimes chooses termite mounds, the rufous woodpecker prefers to use ants' nests in trees and the
bamboo woodpecker The bamboo woodpecker (''Gecinulus viridis'') is a species of bird in the family Picidae. It is found in Myanmar, Laos, Thailand and the Malaysia. Its natural habitats are subtropical or tropical dry forest A forest is an area of land dom ...
specialises in bamboos. Woodpeckers also excavate nest holes in residential and commercial structures and wooden utility poles. Woodpeckers and piculets excavate their own nests, but wrynecks do not, and need to find pre-existing cavities. A typical nest has a round entrance hole that just fits the bird, leading to an enlarged vertical chamber below. No nesting material is used, apart from some wood chips produced during the excavation; other wood chips are liberally scattered on the ground, thus providing visual evidence of the site of the nest.Gorman 2014, p. 22 Many species of woodpeckers excavate one hole per breeding season, sometimes after multiple attempts. It takes around a month to finish the job and abandoned holes are used by other birds and mammals that are cavity nesters unable to excavate their own holes. Cavities are in great demand for nesting by other cavity nesters, so woodpeckers face competition for the nesting sites they excavate from the moment the hole becomes usable. This may come from other species of woodpecker, or other cavity-nesting birds such as swallows and starlings. Woodpeckers may aggressively harass potential competitors, and also use other strategies to reduce the chance of being usurped from their nesting sites; for example, the
red-crowned woodpecker The red-crowned woodpecker (''Melanerpes rubricapillus'') is a resident breeding bird from southwestern Costa Rica, Panama, Colombia, Venezuela, the Guianas and Tobago. Description The adult is long and weighs . It has a zebra-barred black ...
digs its nest in the underside of a small branch, which reduces the chance that a larger species will take it over and expand it. Members of Picidae are typically monogamous, with a few species breeding cooperatively and some
polygamy Crimes Polygamy (from Late Greek (') "state of marriage to many spouses") is the practice of marrying multiple spouses. When a man is married to more than one wife at the same time, sociologists call this polygyny. When a woman is marr ...
reported in a few others.
Polyandry Polyandry (; ) is a form of polygamy in which a woman takes two or more husbands at the same time. Polyandry is contrasted with polygyny, involving one male and two or more females. If a marriage involves a plural number of "husbands and wives" ...
, where a female raises two broods with two separate males, has also been reported in the
West Indian woodpecker The West Indian woodpecker (''Melanerpes superciliaris'') is a species of bird in subfamily Picinae of the woodpecker family Picidae. It is found in the Bahamas, the Cayman Islands and Cuba. Taxonomy and systematics The West Indian woodpeck ...
. Another unusual social system is that of the acorn woodpecker, which is a polygynandrous cooperative breeder where groups of up to 12 individuals breed and help to raise the young. Young birds from previous years may stay behind to help raise the group's young, and studies have found reproductive success for the group goes up with group size, but individual success goes down. Birds may be forced to remain in groups due to a lack of habitat to which to disperse. A pair works together to help build the nest, incubate the eggs, and raise their
altricial In biology, altricial species are those in which the young are underdeveloped at the time of birth, but with the aid of their parents mature after birth. Precocial species are those in which the young are relatively mature and mobile from the mome ...
young. In most species, though, the male does most of the nest excavation and takes the night shift while incubating the eggs. A clutch usually consists of two to five round, white eggs. Since these birds are cavity nesters, their eggs do not need to be camouflaged and the white color helps the parents to see them in dim light. The eggs are incubated for about 11–14 days before they hatch. About 18–30 days are then needed before the chicks are fully
fledge Fledging is the stage in a flying animal's life between hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnera ...
d and ready to leave the nest. In most species, soon after this, the young are left to fend for themselves, exceptions being the various social species, and the
Hispaniolan woodpecker The Hispaniolan woodpecker (''Melanerpes striatus'') is a medium-sized woodpecker endemic to the Caribbean island of Hispaniola (split between the Dominican Republic and Haiti). Description The Hispaniolan woodpecker is a gold and black barred ...
, where adults continue to feed their young for several months. In general, cavity nesting is a successful strategy and a higher proportion of young is reared than is the case with birds that nest in the open. In Africa, several species of honeyguide are
brood parasite Brood parasites are animals that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were it ...
s of woodpeckers.


Systematics and evolutionary history

The Picidae are just one of nine living families in the order Piciformes. Other members of this group, such as the
jacamar The jacamars are a family, Galbulidae, of near passerine birds from tropical South and Central America, extending up to Mexico. The family contains five genera and 18 species. The family is closely related to the puffbirds, another Neotropical f ...
s,
puffbird The puffbirds and their relatives in the near passerine family Bucconidae are tropical tree-dwelling insectivorous birds that are found from South America up to Mexico. Together with their closest relatives, the jacamars, they form a divergent ...
s, Ramphastides, barbets,
toucan Toucans (, ) are members of the Neotropical near passerine bird family Ramphastidae. The Ramphastidae are most closely related to the American barbets. They are brightly marked and have large, often colorful bills. The family includes five g ...
s, and
honeyguide Honeyguides (family Indicatoridae) are near passerine birds in the order Piciformes. They are also known as indicator birds, or honey birds, although the latter term is also used more narrowly to refer to species of the genus ''Prodotiscus''. Th ...
s, have traditionally been thought to be closely related to the woodpecker family (Picinae, true woodpeckers, piculets,
wryneck The wrynecks (genus ''Jynx'') are a small but distinctive group of small Old World woodpeckers. ''Jynx'' is from the Ancient Greek ''iunx'', the Eurasian wryneck. These birds get their English name from their ability to turn their heads almos ...
s, and
sapsucker The sapsuckers are species of North American woodpeckers in the genus ''Sphyrapicus''. Taxonomy and systematics The genus ''Sphyrapicus'' was introduced in 1858 by the American naturalist Spencer Baird with the yellow-bellied sapsucker (''Sphyr ...
s). The clade Pici (woodpeckers, barbets, toucans, and honeyguides) is well supported and shares a Dactyly#Zygodactyly, zygodactyl foot with the Galbuli (puffbirds and jacamars). More recently, several DNA sequence analyses have confirmed that
Pici Pici (; ) is thick, hand-rolled pasta, like fat spaghetti.'' Il Devoto-Oli. Vocabolario della lingua Italiana'', edited by Luca Serianni and Maurizio Trifone, Le Monnier. It originates in the province of Siena in Tuscany; in the Montalcino area ...
and
Galbuli Galbuli is one of the two suborders of the order Piciformes and includes two families Bucconidae (puffbirds) and Galbulidae (jacamars). The other suborder Pici is a global group of piciforms, puffbirds and jacamars are only found in the Neotropic ...
are sister groups. The name Picidae for the family was introduced by English zoologist William Elford Leach in a guide to the contents of the British Museum published in 1820. The phylogeny has been updated according to new knowledge about Convergent evolution, convergence patterns and evolutionary history. Most notably, the relationship of the Picinae genera has been largely clarified, and the
Antillean piculet The Antillean piculet (''Nesoctites micromegas'') is a species of bird in the woodpecker family Picidae. It is monotypic within the genus ''Nesoctites''. The species is evolutionarily distinct from the other piculets and is afforded its own sub ...
was found to be a surviving offshoot of protowoodpeckers. Genetic analysis supports the monophyly of the Picidae, which seem to have originated in the Old World, but the geographic origins of the Picinae is unclear. The Picumninae are returned as Paraphyly, paraphyletic. Morphological and behavioural characters, in addition to DNA evidence, highlights genus ''Hemicircus'' as the sister group of all remaining true woodpeckers, besides a sister-group relationship between the true woodpecker tribes Dendropicini and Malarpicini. The evolutionary history of this group is not well documented, but the known fossils allow some preliminary conclusions; the earliest known modern picids were piculet-like forms of the Late Oligocene, about 25 million years ago (Mya). By that time, however, the group was already present in the Americas and Europe, and they actually may have evolved much earlier, maybe as early as the Early Eocene (50 Mya). The modern subfamilies appear to be rather young by comparison; until the mid-Miocene (10–15 Mya), all picids seem to have been small or mid-sized birds similar to a mixture between a piculet and a wryneck. A feather enclosed in fossil amber from the Dominican Republic, dated to about 25 Mya, however, seems to indicate that the Nesoctitinae were already a distinct lineage by then. Stepwise adaptations for drilling, tapping, and climbing head first on vertical surfaces have been suggested. The last common ancestor of woodpeckers (Picidae) was incapable of climbing up tree trunks or excavating nest cavities by drilling with its beak. The first adaptations for drilling (including reinforced
rhamphotheca The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for food, ...
, frontal overhang, and Process (anatomy), processus dorsalis Pterygoid bone, pterygoidei) evolved in the ancestral lineage of piculets and true woodpeckers. Additional adaptations for drilling and tapping (enlarged Condyle (anatomy), condylus lateralis of the Quadrate bone, quadrate and fused lower mandible) have evolved in the ancestral lineage of true woodpeckers (''Hemicircus'' excepting). The inner Flight feathers#Rectrices, rectrix pairs became stiffened, and the pygostyle lamina was enlarged in the ancestral lineage of true woodpeckers (''Hemicircus'' included), which facilitated climbing head first up tree limbs. Genus ''Hemicircus'' excepting, the tail feathers were further transformed for specialized support, the pygostyle disc became greatly enlarged, and the Bird feet and legs#Toe arrangements, ectropodactyl toe arrangement evolved. These latter characters may have facilitated enormous increases in body size in some lineages. Prehistoric representatives of the extant Picidae genera are treated in the genus articles. An enigmatic form based on a coracoid, found in Pliocene deposits of New Providence in the Bahamas, has been described as ''Bathoceleus hyphalus'' and probably also is a woodpecker.


List of genera

The phylogeny of woodpeckers is still being refined and the positions of some genera continue to be unclear and conflicting findings arose from analyses as of 2016. For more detail, see list of woodpecker species. Family: Picidae * Subfamily: Jynginae –
wryneck The wrynecks (genus ''Jynx'') are a small but distinctive group of small Old World woodpeckers. ''Jynx'' is from the Ancient Greek ''iunx'', the Eurasian wryneck. These birds get their English name from their ability to turn their heads almos ...
s ** ''wryneck, Jynx'' (2 species) * Subfamily: Picumninae – piculets ** ''Picumnus (bird), Picumnus'' – piculets (26 species) ** ''Sasia'' – Asian piculets (3 species) * Subfamily:
Picinae Picinae containing the true woodpeckers is one of three subfamilies that make up the woodpecker family Picidae. True woodpeckers are found over much of the world, but do not occur in Madagascar or Australasia. Woodpeckers gained their English n ...
– true woodpeckers **Tribe Nesoctitini ***''Nesoctites'' – monotypic:
Antillean piculet The Antillean piculet (''Nesoctites micromegas'') is a species of bird in the woodpecker family Picidae. It is monotypic within the genus ''Nesoctites''. The species is evolutionarily distinct from the other piculets and is afforded its own sub ...
**Tribe Hemicircini ***''Hemicircus'' – 2 species **Tribe Picini ***''Micropternus'' – monotypic: rufous woodpecker ***''Meiglyptes'' – 3 species ***''Gecinulus'' – 3 species ***''Dinopium'' – 5 species (flamebacks) ***''Picus (genus), Picus'' – 13 species ***''Chrysophlegma'' – 3 species ***''Pardipicus'' – 2 species ***''Geocolaptes'' – monotypic:
ground woodpecker The ground woodpecker (''Geocolaptes olivaceus'') is one of only three ground-dwelling woodpeckers in the world (the others are the Andean and campo flickers). It inhabits rather barren, steep, boulder-strewn slopes in relatively cool hilly and m ...
***''Campethera'' – 11 species ***''Mulleripicus'' – 3 species ***''
Dryocopus ''Dryocopus'' is a genus of large powerful woodpeckers, typically 35–45 cm in length. It has representatives in North and South America, Europe, and Asia; some South American species are endangered. It was believed to be closely related to ...
'' – 6 species ***''Celeus (bird), Celeus'' – 13 species ***''Piculus'' – 7 species ***''Colaptes'' – 14 species **Tribe Campephilini ***''Campephilus'' – 11 species ***''Blythipicus'' – 2 species ***''Reinwardtipicus'' – monotypic:
orange-backed woodpecker The orange-backed woodpecker (''Reinwardtipicus validus'') is a bird in the woodpecker family Picidae, found in southern Thailand, Malaya, Sarawak and Sabah in Malaysia, Brunei, Sumatra, and Java. It is monotypic in the genus ''Reinwardt ...
***''Chrysocolaptes'' – 9 species (flamebacks) **Tribe Melanerpini ***''Sphyrapicus'' – 4 species (sapsuckers) ***''
Melanerpes ''Melanerpes'' is a genus of woodpeckers of the family Picidae found in the New World. The 24 members of the genus are mostly colourful birds, conspicuously barred in black and white, with some red and yellow. Taxonomy The genus ''Melanerpes'' ...
'' – 24 species ***''Picoides'' – 3 species ***''Yungipicus'' – 7 species ***''Leiopicus'' – monotypic: yellow-crowned woodpecker ***''Dendrocoptes'' – 3 species ***''Chloropicus'' – 3 species ***''Dendropicos'' – 12 species ***''Dendrocopos'' – 12 species ***''Dryobates'' – 5 species ***''Leuconotopicus'' – 6 species ***''Veniliornis'' – 14 species ***''Xiphidiopicus'' – monotypic: Cuban green woodpecker * ''Incertae sedis'' fossils ** Genus: †''Palaeopicus'' (Late Oligocene of France) ** †Picidae gen. et sp. indet. (Middle Miocene of New Mexico, US) ** †Picidae gen. et sp. indet. (Late Miocene of Gargano Peninsula, Italy) ** Genus: †''Palaeonerpes'' (Ogallala Early Pliocene of Hitchcock County, US) – possibly dendropicine ** Genus: †''Pliopicus'' (Early Pliocene of Kansas, US) – possibly dendropicine ** cf. ''Colaptes'' DMNH 1262 (Early Pliocene of Ainsworth, US) – malarpicine?


Relationship with humans

In general, humans consider woodpeckers in a favourable light; they are viewed as interesting birds and fascinating to watch as they drum or forage, but their activities are not universally appreciated.Gorman 2014, pp. 30–32 Many woodpecker species are known to excavate holes in buildings, fencing, and utility poles, creating health and/or safety issues for affected structures. Such activity is very difficult to discourage and can be costly to repair. Woodpeckers also drum on various reverberatory structures on buildings such as gutters, downspouts, chimneys, vents, and aluminium sheeting. Drumming is a less-forceful type of pecking that serves to establish territory and attract mates. Houses with Roof shingle, shingles or wooden boarding are also attractive as possible nesting or roosting sites, especially when close to large trees or woodland. Several exploratory holes may be made, especially at the junctions of vertical boards or at the corners of Tongue and groove, tongue-and-groove boarding. The birds may also drill holes in houses as they forage for insect larvae and pupae hidden behind the woodwork. Woodpeckers sometimes cause problems when they raid fruit crops, but their foraging activities are mostly beneficial as they control forest insect pests such as the woodboring beetles that create galleries behind the bark and can kill trees. They also eat ants, which may be tending sap-sucking pests such as mealybugs, as is the case with the rufous woodpecker in coffee plantations in India. Woodpeckers can serve as indicator species, demonstrating the quality of the habitat. Their hole-making abilities make their presence in an area an important part of the ecosystem, because these cavities are used for breeding and roosting by many bird species that are unable to excavate their own holes, as well as being used by various mammals and invertebrates. The spongy bones of the woodpecker's skull and the flexibility of its beak, both of which provide protection for the brain when drumming, have provided inspiration to engineers; a Flight recorder, black box needs to survive intact when a plane falls from the sky, and modelling the black box with regard to a woodpecker's anatomy has increased the resistance of this device to damage 60-fold. The design of protective helmets is another field being influenced by the study of woodpeckers. One of the accounts of the founding of Rome, preserved in the work known as ''Romulus and Remus#Origo Gentis Romanae, Origo Gentis Romanae'', refers to a legend of a woodpecker bringing food to the boys Romulus and Remus during the time they were abandoned in the wild, thus enabling them to survive and play their part in history.


Status and conservation

In a global survey of the risk of
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the Endling, last individual of the species, although the Functional ext ...
faced by the various bird families, woodpeckers were the only bird family to have significantly fewer species at risk than would be expected. Nevertheless, several woodpeckers are under threat as their habitats are destroyed. Being woodland birds, deforestation and clearance of land for agriculture and other purposes can reduce populations dramatically. Some species adapt to living in plantations and secondary growth, or to open countryside with forest remnants and scattered trees, but some do not. A few species have even flourished when they have adapted to man-made habitats. There are few Wildlife conservation, conservation projects directed primarily at woodpeckers, but they benefit whenever their habitat is conserved. The red-cockaded woodpecker has been the focus of much conservation effort in the southeastern United States, with artificial cavities being constructed in the Pinus palustris, longleaf pines they favour as nesting sites. Two species of woodpeckers in the Americas, the
ivory-billed woodpecker The ivory-billed woodpecker (''Campephilus principalis'') is a possibly extinct woodpecker that is native to the bottomland hardwood forests and temperate coniferous forests of the Southern United States and Cuba. Habitat destruction and hunting ...
is critically endangered and the imperial woodpecker is classified as extinct in the wild, with some authorities believing them extinct, though possible but disputed ongoing sightings of ivory-billed woodpeckers have been made in the United States and a small population may survive in Cuba. A critically endangered species is the Okinawa woodpecker from Japan, with a single declining population of a few hundred birds. It is threatened by deforestation, golf course, dam, and helipad construction, road building, and agricultural development.


Brain impact research


Anatomy

Woodpeckers possess many sophisticated shock-absorption mechanisms that help protect itself from head injury. Micro-CT scans show that plate-like spongy bone are in the skull with an uneven distribution, highly accumulated in the forehead and Occipital bone, occiput but not in other regions.  Along with the long
hyoid bone The hyoid bone (lingual bone or tongue-bone) () is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies between the base of the mandible and the third cervical verteb ...
“safety belt” the woodpecker has uneven beak lengths which drastically reduce strains when compared to equal length. Models have shown that pecking force is changed to strain energy and stored into the body at around 99% absorption while 1% is in the head. The head also has many factors that reduce strain to the brain and small portions of energy is dissipated into the form of heat, therefore the pecks are always intermittent. Tau protein accumulation has been studied as it is associated with chronic traumatic encephalopathy (CTE), this has been studied in sports where athletes suffer repeated concussions. Tau is important as it helps hold together and stabilize brain neurons. Woodpeckers' brains share similarities to humans with CTE showing most build-up in the frontal and temporal lobes of the brain. These accumulations are not known yet if they are pathological or the result of behavioral changes. More research is being done on the subject and the woodpecker is a suitable animal model to study. The orientation of the brain within the skull increases the area of contact when pecking to reduce stress on the brain, and their small size helps, given the acceleration speeds.


Mechanical properties

Straight-line trajectory was theorized to be the reason why woodpeckers do not injure themselves, since centripetal forces were the cause of concussion, but they do not always peck in straight lines, so they produce and resist centripetal forces. Laboratory tests show that the woodpeckers' cranial bone produces a significantly higher Young's modulus and ultimate strength scores compared to other birds its size. The cranial bone has a high bone mineral density with plate-like structures that are thick with high numbers of Trabeculae of bone, trabeculae that are spaced closely together which all may lead to lower deformation while pecking. The jaw apparatus was studied, looking into its cushioning effects. When comparing the same impact to the beak and to the forehead, the forehead experiences an impact force 1.72 times that of the beak, due to the contact time being 3.25 ms in the forehead and 4.9 ms in the beak. This is Impulse-momentum theorem, impulse momentum where impulse is the integral of force over time. The quadrate bone and joints play an important role in extending impact time, which decreases impact load to brain tissue.


Bio-inspired ideas


Beams

Bio-inspired honeycomb sandwich beams are inspired by the woodpecker's skull design; this beam's goal is to withstand continuous impacts without the need of replacement. The BHSB is composed of Carbon-fiber-reinforced plastic, carbon fiber-reinforced plastic (CFRP), this is to mimic the high-strength beak. Next is a rubber layer core for the hyoid bone for absorbing and spreading impact, a second core layer of aluminum honeycomb that is porous and light like the woodpecker's spongey bone for impact cushioning. The final layer is the same as the first a CFRP to act as the skull bone. Bio-inspired honeycomb sandwich beams when compared to conventional beams reduced area damage by 50–80% and carried 40 to 5% of the level of stresses in the bottom layer while having an impact-resistance efficiency 1.65 to 16.22 times higher.


References


Citations


General bibliography

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Further reading

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External links


Woodpecker videos, photos & sounds
on the Internet Bird Collection * * {{authority control Woodpeckers, 01 Picidae, . Pici (taxon) Picinae, . Extant Miocene first appearances Oligocene birds