Woodpecker

For other uses, seeWoodpecker (disambiguation).

Woodpecker Temporal range:Late Oligoceneto present
Pileated woodpecker
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Piciformes
Suborder:	Pici
Infraorder:	Picides
Family:	Picidae Leach,1819
Type genus
Picus Linnaeus,1758
Subfamilies
Jynginae– wrynecks Picinae– true woodpeckers Picumninae– piculets Sasiinae - piculets

Woodpeckersare part of thebirdfamilyPicidae,which also includes thepiculets,wrynecksandsapsuckers.Members of this family are found worldwide, except forAustralia,New Guinea,New Zealand,Madagascarand the extreme polar regions. Most species live inforestsorwoodlandhabitats, although a few species are known that live in treeless areas, such as rocky hillsides and deserts, and theGila woodpeckerspecialises in exploiting cacti. Woodpeckers are known as the loudest birds of the forest.

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, andcarrion.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 theorderPiciformes,the others beingbarbets(comprising three families),toucans,toucan-barbets, andhoneyguides,which (along with woodpeckers) comprise thecladePici,and thejacamarsandpuffbirdsin the cladeGalbuli.DNA sequencinghas confirmed thesister relationshipsof these two groups. The family Picidae includes about 240speciesarranged in 35genera.Almost 20 species are threatened withextinctiondue to loss of habitat orhabitat fragmentation,with one, theBermuda flicker,being extinct and a further two possibly being so.

General characteristics

Ablack-rumped flamebackusing its tail for support

Woodpeckers include the tinypiculets,the smallest of which appears to be thebar-breasted piculetat 7.5 cm (3.0 in) in length and a weight of 8.9 g (0.31 oz).Some of the largest woodpeckers can be more than 50 cm (20 in) in length. The largest surviving species is thegreat slaty woodpecker,which weighs 430 g (15 oz) on average and up to 563 g (19.9 oz), and measures 45 to 55 cm (18 to 22 in), but the extinctimperial woodpecker,at 55 to 61 cm (22 to 24 in), andivory-billed woodpecker,around 48 to 53 cm (19 to 21 in) and 516 g (18.2 oz), were probably both larger.

Theplumageof woodpeckers varies from drab to conspicuous. The colours of many species are based on olive and brown and some are pied, suggesting a need forcamouflage;others are boldly patterned in black, white, and red, and many have a crest or tufted feathers on their crowns. Woodpeckers tend to besexually dimorphic,but differences between the sexes are generally small; exceptions to this areWilliamson's sapsuckerand theorange-backed woodpecker,which differ markedly. The plumage ismoultedfully once a year apart from thewrynecks,which have an additional partial moult before breeding.

Woodpeckers, piculets, and wrynecks all possess characteristiczygodactyl 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 theblack-backed woodpeckerand theAmericanandEurasian three-toed woodpeckers,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 strongbillsthat they use for drilling and drumming on trees, and long, sticky tongues for extracting food (insects and larvae).Woodpecker bills are typically longer, sharper, and stronger than the bills of piculets and wrynecks, but theirmorphologyis very similar. The bill's chisel-like tip is kept sharp by thepeckingaction in birds that regularly use it on wood. The beak consists of three layers; an outer sheath calledrhamphotheca,made of scales formed fromkeratinproteins, an inner layer of bone which has a large cavity and mineralisedcollagenfibers, 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 barbs, 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.

Diagram showing the hyoid bone ofDendrocopos major

Many of the foraging, breeding, and signaling behaviors of woodpeckers involve drumming and hammering using their bills.To preventbrain damagefrom 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, narrowsubdural space,littlecerebrospinal fluidsurrounding 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 elongatedhyoid bonewhich 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 ofstrain energy,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 thickenednictitating membranecloses, protecting the eye from flying debris.These membranes also prevent theretinafrom 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 highdecelerationson the order of 10,000m/s²(33,000ft/s²) (1000g).

Some large woodpeckers such asDryocopushave 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 genusMelanerpeshave distinctive, rowing wing-strokes while the piculets engage in short bursts of rapid direct flight.

Distribution, habitat, and movements

Use ofcactifor breeding and roosting holes allows some woodpeckers to live in treeless deserts, such as theladder-backed woodpecker,which uses cacti for nesting.

See also:List of Piciformes by population

Global distribution

Woodpeckers have a mostlycosmopolitan distribution,although they are absent fromAustralasia,Madagascar, andAntarctica.They are also absent from some of the world's oceanicislands,although many insular species are found oncontinental islands.The true woodpeckers, subfamilyPicinae,are distributed across the entire range of the family. The Picumninae piculets have a pantropical distribution, with species inSoutheast Asia,Africa, and theNeotropics,with the greatest diversity being in South America.The second piculet subfamily, the Sasiinae, contains theAfrican piculetand two species in the genusSasiathat are found in Southeast Asia.The wrynecks (Jynginae) are found exclusively in the Old World, with the two species occurring in Europe, Asia, and Africa.

Most woodpeckers are sedentary, but a few examples ofmigratoryspecies are known, such as therufous-bellied woodpecker,yellow-bellied sapsucker,andEurasian wryneck,which breeds in Europe and west Asia and migrates to theSahelin Africa in the winter.More northerly populations ofLewis's woodpecker,northern flicker,Williamson's sapsucker,red-breasted sapsucker,andred-naped sapsuckerall 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 thegrey-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 woodedhabitats.They reach their greatestdiversityintropical rainforests,but occur in almost all suitable habitats, including woodlands,savannahs,scrublands,andbambooforests. Evengrasslandsanddesertshave 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, tallcactiare available for nesting.Some are specialists and are associated withconiferousordeciduouswoodlands, or even, like theacorn woodpecker,with individual tree genera (oaksin this case). Other species are generalists and are able to adapt to forest clearance by exploitingsecondary growth,plantations,orchards,and parks. In general, forest-dwelling species need rotting or dead wood on which to forage.

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. Theground woodpeckeris one such species, inhabiting the rocky and grassy hills ofSouth Africa,and theAndean flickeris another.

TheSwiss Ornithological Institutehas set up a monitoring program to record breeding populations of woodland birds. This has shown thatdeadwoodis an important habitat requirement for theblack woodpecker,great spotted woodpecker,middle spotted woodpecker,lesser spotted woodpecker,European green woodpecker,andEurasian three-toed woodpecker.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 thewhite-backed woodpeckerenlarged 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.

Behavior

Most woodpeckers livesolitarylives, but their behavior 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 atermitecolony or fruit-laden tree, driving away otherconspecificsand returning frequently until the resource is exhausted.Aggressivebehaviors include bill pointing and jabbing, head shaking, wing flicking, chasing, drumming, and vocalizations. Ritual actions do not usually result in contact, and birds may "freeze" for a while before they resume their dispute. The colored patches may be flouted, and in some instances, these antagonistic behaviors resemble courtship rituals.

Group-living species tend to be communal group breeders.In addition to these species, a number of species may joinmixed-species foraging flockswith 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; thegrey-and-buff woodpeckermakes 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 theMagellanic woodpeckerand acorn woodpecker are cooperative roosters.

Drumming

The sound of a woodpecker (Picidae) tapping, with a few background sounds as well. Species/location unknown, presumably from the continental United States.

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 apasserine.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 incourtshiprituals. Individual birds are thought to be able to distinguish the drumming of their mates and those of their neighbors.Drumming can be reliably used to distinguish between multiple species in a region, even if those species are phenotypically similar. Cadence (or the mean number of drum beats per second) is heavily conserved within species.Comparative analyses within species between distant geographic populations have shown that cadence is heavily conserved across species' respective ranges, indicating that there likely are not 'dialects' as seen in passerine song.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.A 2023 study revealed a strong association between extractive foraging and relative brain size across the FamilyPicidae,indicating that a larger brain does not necessarily result in more powerful drumming abilities, but is implicated in foraging behaviors, as the act of sensing and retrieving wood-boring larvae from woody substrates likely requires an increase in sensory and motor control capabilities.

Calls

Woodpeckers do not have such a wide range ofsongs and callsas dopasserinebirds, 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 incommunicationand are related to the circumstances of the occasion; these include courtship,territorialdisputes, and alarm calls. Each species has its own range of calls, which tend to be in the 1.0 to 2.5kHzrange 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 alertsornithologiststo the presence of the birds, as they are easily overlooked.

Diet and feeding

Holes bored by feeding woodpeckers

Most woodpecker species feed oninsectsand otherinvertebratesliving 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.Crustaceans,molluscs,and carrion may be eaten by some species, including the great spotted woodpecker, and bird feeders are visited forsuetand 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 thebuff-spotted woodpeckerfeeds on and nests intermite mounds.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% ofemerald ash borerlarvae from individual ash trees.

The ability to excavate allows woodpeckers to obtaintree sap,an important source of food for some species. Most famously, the sapsuckers (genusSphyrapicus) feed in this fashion, but the technique is not restricted to these, and others such as theacorn woodpeckerandwhite-headed woodpeckeralso feed on sap. The technique was once thought to be restricted to the New World, but Old World species, such as theArabian woodpeckerand great spotted woodpecker, also feed in this way.

Breeding

A maleblack woodpeckerattending its chicks

All members of the family Picidaenestin 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, thegilded flickerandladder-backed woodpeckerexcavate holes in cactus, and the Andean flicker and ground woodpecker dig holes in earth banks. Thecampo flickersometimes chooses termite mounds, the rufous woodpecker prefers to use ants' nests in trees and thebamboo woodpeckerspecialises 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.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, thered-crowned woodpeckerdigs 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 somepolygamyreported in a few others.Polyandry,where a female raises two broods with two separate males, has also been reported in theWest Indian woodpecker.Another unusual social system is that of the acorn woodpecker, which is apolygynandrouscooperative 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.

Great spotted woodpeckerfeeding its chick, Russia

A pair works together to help build the nest,incubatethe eggs, and raise theiraltricialyoung. 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 fullyfledgedand 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 theHispaniolan woodpecker,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 arebrood parasitesof woodpeckers.

Systematics and evolutionary history

Lesser goldenback (Dinopium benghalense) in Guwahati, India

The Picidae are just one of nine living families in the orderPiciformes.Other members of this group, such as thejacamars,puffbirds,barbets,toucans,andhoneyguides,have traditionally been thought to be closely related to the woodpecker family (true woodpeckers,piculets,wrynecks,andsapsuckers). The clade Pici (woodpeckers, barbets, toucans, and honeyguides) is well supported and shares azygodactyl footwith the Galbuli (puffbirds and jacamars). More recently, severalDNA sequenceanalyses have confirmed thatPiciandGalbuliare sister groups.

Thephylogeneticrelationship between the woodpeckers and the eight other families in theorderPiciformesis shown in the cladogram below.The number of species in each family is taken from the list maintained byFrank Gill,Pamela C. Rasmussenand David Donsker on behalf of theInternational Ornithological Committee(IOC).

Piciformes	Galbulidae– jacamars (18 species) Bucconidae– puffbirds (38 species) Indicatoridae– honeyguides (16 species) Picidae– woodpeckers (240 species) Megalaimidae– Asian barbets (35 species) Lybiidae– African barbets (42 species) Capitonidae– New World barbets (15 species) Semnornithidae– toucan barbets (2 species) Ramphastidae– toucans (43 species)

The name Picidae for the family was introduced by English zoologistWilliam Elford Leachin a guide to the contents of theBritish Museumpublished in 1819.The phylogeny has been updated according to new knowledge aboutconvergencepatterns and evolutionary history.Most notably, the relationship of the Picinae genera has been largely clarified, and theAntillean piculetwas found to be a surviving offshoot of protowoodpeckers. Genetic analysis supports themonophylyof the Picidae, which seem to have originated in the Old World, but the geographic origins of the Picinae is unclear. The Picumninae are returned asparaphyletic.Morphological and behavioural characters, in addition to DNA evidence, highlights genusHemicircusas 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 LateOligocene,about 25million 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 theEarly 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 fossilamberfrom theDominican 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 reinforcedrhamphotheca,frontal overhang, andprocessusdorsalispterygoidei) evolved in the ancestral lineage of piculets and true woodpeckers. Additional adaptations for drilling and tapping (enlargedcondyluslateralis of thequadrateand fused lower mandible) have evolved in the ancestral lineage of true woodpeckers (Hemicircusexcepting). The innerrectrixpairs became stiffened, and thepygostylelamina was enlarged in the ancestral lineage of true woodpeckers (Hemicircusincluded), which facilitated climbing head first up tree limbs. GenusHemicircusexcepting, the tail feathers were further transformed for specialized support, the pygostyle disc became greatly enlarged, and theectropodactyl toe arrangementevolved. 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 Enigma tic form based on acoracoid,found inPliocenedeposits ofNew Providenceinthe Bahamas,has been described asBathoceleus hyphalusand probably also is a woodpecker.

The followingcladogramis based on the comprehensivemolecular phylogeneticstudy of the woodpeckers published in 2017 together with the list of bird species maintained byFrank Gill,Pamela Rasmussenand David Donsker on behalf of theInternational Ornithological Committee(IOC). TheCuban green woodpeckerin themonotypicgenusXiphidiopicuswas not included in the study.The relative positions of Picumninae, Sasiinae and Picinae in the cladogram are uncertain. In the 2017 study the results depended upon which of two different statistical procedures were used to analyse the DNA sequence data. One method found that Sasiinae wassisterto Picinae (as shown below), the other method found that Sasiinae was sister to a clade containing both Picumninae and Picinae.

Picidae

Jynginae Jynx– 2 species (wrynecks) Picumninae Picumnus– 26 species (piculets) Sasiinae Verreauxia– African piculet Sasia– 2 species (piculets) Picinae Nesoctitini Nesoctites– Antillean piculet Hemicirini Hemicircus– 2 species Picini Micropternus– rufous woodpecker Meiglyptes– 4 species Gecinulus– 3 species Dinopium– 5 species (flamebacks) Picus– 14 species Chrysophlegma– 3 species Pardipicus– 2 species Geocolaptes– ground woodpecker Campethera– 11 species Mulleripicus– 4 species Dryocopus– 6 species Celeus– 13 species Piculus– 7 species Colaptes– 14 species Campephilini Campephilus– 12 species Blythipicus– 2 species Reinwardtipicus– orange-backed woodpecker Chrysocolaptes– 9 species Melanerpini Sphyrapicus– 4 species (sapsuckers) Melanerpes– 24 species Picoides– 3 species Yungipicus– 7 species Dendrocoptes– 4 species (includingLeiopicus) Chloropicus– 3 species Dendropicos– 12 species Dendrocopos– 12 species Dryobates– 5 species Leuconotopicus– 6 species Veniliornis– 14 species

List of genera

Ochre-collared piculet
(Picumnus temminckii)

Red-crowned woodpecker
(Melanerpes rubricapillus rubricapillus)
female,Tobago

The woodpecker family Picidae contains 37 genera.For more detail, seelist of woodpecker species.

Cuban green woodpecker
(Xiphidiopicus percussus)
female,Cuba

Campo flicker
Colaptes campestris
female,Brazil

Family: Picidae

• Subfamily: Jynginae–wrynecks
  • Jynx(2 species)
• Subfamily: Picumninae–piculets
  • Picumnus– piculets (25 species)
• Subfamily: Sasiinae
  • Verreauxia– African piculet
  • Sasia– Asian piculets (2 species)
• Subfamily:Picinae– true woodpeckers
  • Tribe Nesoctitini
    • Nesoctites– monotypic:Antillean piculet
  • Tribe Hemicircini
    • Hemicircus– 2 species
  • Tribe Picini
    • Micropternus– monotypic:rufous woodpecker
    • Meiglyptes– 4 species
    • Gecinulus– 3 species
    • Dinopium– 5 species (flamebacks)
    • Picus– 14 species
    • Chrysophlegma– 3 species
    • Pardipicus– 2 species
    • Geocolaptes– monotypic:ground woodpecker
    • Campethera– 11 species
    • Mulleripicus– 4 species
    • Dryocopus– 6 species
    • Celeus– 13 species
    • Piculus– 7 species
    • Colaptes– 14 species
  • Tribe Campephilini
    • Campephilus– 12 species
    • Blythipicus– 2 species
    • Reinwardtipicus– monotypic:orange-backed woodpecker
    • Chrysocolaptes– 10 species (flamebacks)
  • Tribe Melanerpini
    • Sphyrapicus– 4 species (sapsuckers)
    • 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 sedisfossils
  • 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.ColaptesDMNH 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.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 withshinglesor 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 oftongue-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 thewoodboring beetlesthat create galleries behind the bark and can kill trees. They also eat ants, which may be tending sap-sucking pests such asmealybugs,as is the case with the rufous woodpecker in coffee plantations in India.Woodpeckers can serve asindicator 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; ablack boxneeds 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 thefounding of Rome,preserved in the work known asOrigo Gentis Romanae (unknown),refers to a legend of a woodpecker bringing food to the boysRomulus and Remusduring the time they were abandoned in the wild, thus enabling them to survive and play their part in history.

Popular culture

Woody Woodpeckeris an animated character that appeared in theatrical short films produced between 1940 and 1972.

The Pokémon Pikipek was introduced in the seventh generation gamesPokémon Sun and Moon.In addition to being a visual homage to apileated woodpecker,entries in the game'sPokédexencyclopedia describes the smallFlying-typeas analogous to its real-world counterpart.Its later forms (called "evolutions" in the series) Trumbeak and Toucannon resemble ahoneyguideandtoucan,respectively, perhaps as a tongue-in-cheek reference to the phylogenetic relationship woodpeckers share with thesePiciformesfamilies.

Status and conservation

Theivory-billed woodpeckeris classified as critically endangered by theIUCN,and some authorities believe it may already be extinct.

In a global survey of the risk ofextinctionfaced 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 fewconservationprojects directed primarily at woodpeckers, but they benefit whenever their habitat is conserved.Thered-cockaded woodpeckerhas been the focus of much conservation effort in the southeastern United States, with artificial cavities being constructed in thelongleaf pinesthey favour as nesting sites.

Two species of woodpeckers in the Americas, theivory-billed woodpeckeris critically endangered and theimperial woodpeckeris 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 Statesand a small population may survive in Cuba.A critically endangered species is theOkinawa woodpeckerfrom 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 them from head injury. Micro-CT scans show that plate-like spongy bones are in the skull with an uneven distribution, highly accumulated in the forehead andocciputbut not in other regions.Along with the longhyoid bone“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 are dissipated into the form of heat; therefore the pecks are always intermittent.Others dispute shock-absorption in the head (which reduces the force of pecking) but instead point to adaptations within the brain itself.

Tau proteinaccumulation is associated withchronic traumatic encephalopathy(CTE), and thus 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.It is not yet known whether these accumulations 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, sincecentripetal forceswere the cause ofconcussion,but they do not always peck in straight lines, so they produce and resist centripetal forces.Laboratory tests show that the woodpeckers'cranial boneproduces 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 oftrabeculaethat 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 isimpulse momentumwhere 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 ofcarbon 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.

Cited sources

• Gorman G (2014).Woodpeckers of the World: A Photographic Guide.Firefly Books.ISBN978-1-77085-309-6.

Further reading

• Dufort MJ (January 2016). "An augmented supermatrix phylogeny of the avian family Picidae reveals uncertainty deep in the family tree".Molecular Phylogenetics and Evolution.94(Pt A): 313–26.doi:10.1016/j.ympev.2015.08.025.PMID26416706.
• Fuchs J, Pons JM (July 2015). "A new classification of the Pied Woodpeckers assemblage (Dendropicini, Picidae) based on a comprehensive multi-locus phylogeny".Molecular Phylogenetics and Evolution.88:28–37.doi:10.1016/j.ympev.2015.03.016.PMID25818851.
• Fuchs J, Pons JM, Bowie RC (March 2017)."Biogeography and diversification dynamics of the African woodpeckers".Molecular Phylogenetics and Evolution.108:88–100.doi:10.1016/j.ympev.2017.01.007.PMID28089840.
• Gorman G (2004).Woodpeckers of Europe: a study of European Picidae.Chalfont St Peter, Bucks.: Bruce Coleman.ISBN978-1-872842-05-9.
• Gorman G (2011).The Black Woodpecker: a monograph on Dryocopus martius(1st ed.). Lynx.ISBN978-84-96553-79-8.
• Gorman G (2020).The green woodpecker: a monograph on Picus viridis.Great Britain: Amazon/Picus Press.ISBN9798676711870.
• Koenig WD, Haydock J (1999). "Oaks, acorns, and the geographical ecology of acorn woodpeckers".Journal of Biogeography.26(1): 159–165.Bibcode:1999JBiog..26..159K.doi:10.1046/j.1365-2699.1999.00256.x.S2CID5068060.
• Lemaitre J, Villard MA (2005). "Foraging patterns of pileated woodpeckers in a managed Acadian forest: a resource selection function".Canadian Journal of Forest Research.35(10): 2387–2393.doi:10.1139/x05-148.
• Michalek KG, Winkler H (2001). "Parental care and parentage in monogamous great spotted woodpeckers (Picoides major) and middle spotted woodpeckers (Picoides medius) ".Behaviour.138(10): 1259–1285.doi:10.1163/15685390152822210.
• Shakya SB, Fuchs J, Pons JM, Sheldon FH (November 2017)."Tapping the woodpecker tree for evolutionary insight".Molecular Phylogenetics and Evolution.116:182–191.doi:10.1016/j.ympev.2017.09.005.PMID28890006.
• Stark RD, Dodenhoff DJ, Johnson EV (1998)."A quantitative analysis of woodpecker drumming"(PDF).Condor.100(2): 350–356.doi:10.2307/1370276.JSTOR1370276.
• Webb DM, Moore WS (August 2005). "A phylogenetic analysis of woodpeckers and their allies using 12S, Cyt b, and COI nucleotide sequences (class Aves; order Piciformes)".Molecular Phylogenetics and Evolution.36(2): 233–48.doi:10.1016/j.ympev.2005.03.015.PMID15869887.
• Wiebe KL, Swift TL (2001)."Clutch size relative to tree cavity size in northern flickers".Journal of Avian Biology.32(2): 167–173.doi:10.1034/j.1600-048X.2001.320210.x.
• Yom-Tov Y, Ar A (1993)."Incubation and fledging durations of woodpeckers"(PDF).Condor.95(2): 282–287.doi:10.2307/1369350.JSTOR1369350.

External links

• Woodpecker videos, photos & soundson the Internet Bird Collection
• "Woodpecker".The American Cyclopædia.1879.
• "Woodpecker".The New Student's Reference Work.1914.