How woodpeckers peck without brain injury, and the species of Bangladesh

In December 2025 Jagonews24 carried a nature feature by Sanjana Rahman Juthi on one of the most familiar birds of rural Bangladesh: the woodpecker. Published on 13 December 2025 in the paper's agriculture and nature section, it set out how the bird strikes wood again and again without hurting its brain, why it pecks at trees, how it makes its nest holes, which species are found in Bangladesh, and why the writer feared for the bird as trees disappear from villages and towns.

The writer's central point was that the woodpecker's very long tongue, which loops round the back of the skull, acts like a seat belt for the head. Biomechanics research published over the previous decade and a half supports that idea in part, while also pointing to other features of the skull and beak, and to some open questions. This report sets out the feature's account alongside what ornithological references and peer-reviewed studies published before December 2025 say about the bird.

Woodpeckers belong to the family Picidae in the order Piciformes. Banglapedia, the national encyclopaedia of Bangladesh, describes them as slender birds with very flexible necks, strong chisel-tipped bills and very long tongues that can be pushed far out of the mouth. Most live in trees, gripping the bark with long claws and bracing the body against long, stiff tail feathers while they probe for insects or dig out a nest. Banglapedia puts the family at about 204 species worldwide; a 2025 study in the journal Ecology and Evolution, citing a 2014 reference work, counts 214 species, found in forests across the world except Australia and Antarctica.

The feature said woodpeckers can peck more than a hundred times a minute and strike trees thousands of times a day. Laboratory work puts figures on this. A 2011 study in PLoS ONE by Lizhen Wang and colleagues at Beihang University in Beijing and the Hong Kong Polytechnic University filmed Great Spotted Woodpeckers with two high-speed cameras running at 2,000 frames a second and measured the force of each peck with a sensor. Their paper notes that a woodpecker hits a tree trunk at 6 to 7 metres a second with a deceleration of about 1,000 g, drums in bouts of 10 to 20 pecks, each peck taking about 50 milliseconds, and drums about 12,000 times a day on average. The peck force measured in their experiment was about 8.1 newtons.

A 2016 study in Acta Biomaterialia by Jae-Young Jung and colleagues at the University of California campuses in San Diego and Riverside, summarising earlier research, gives head speeds of up to 7 metres a second, decelerations of up to 1,200 g and pecking rates of 20 times a second, all without concussion or brain damage.

Woodpeckers do not peck only to feed. Banglapedia notes that most species have loud voices, and that they drum with the bill, particularly in the nesting season and when they find a surface that resonates. A 2018 study in Proceedings of the Royal Society B by Meredith Miles and colleagues at Wake Forest University in the United States describes drumming as a territorial display, produced when a bird rapidly hits its bill on a hard surface. Drums differ between species in the number of beats and in their speed, and the study found that body size limits how fast a species can drum but not how long a drum lasts.

The most striking part of the feature was its description of the tongue: so long that it is coiled round the back of the brain, passing behind the head and coming forward again. Anatomists describe this structure as the hyoid apparatus, the set of tongue bones with their cartilage, muscles and other tissue whose basic job in all birds is to anchor the tongue and let it extend.

In most birds, Jung's team explain, the hyoid apparatus has five distinct bones and ends at the base of the skull. In woodpeckers it is greatly lengthened and wraps around the skull from the beak end to the back of the head and over the top, ending in the ridge between the eyes. In the specimens they compared, the epibranchial bones, the long rear arms of the apparatus, made up 61 percent of the length of the hyoid bones in a woodpecker against 37 percent in a domestic chicken. One bone found in most birds, the urohyal, is absent in woodpeckers. Using X-ray micro-computed tomography and nanoindentation, they found four distinct bone sections joined at three joints, each bone having a stiff core inside a more pliant outer shell, and a highly flexible rear section that they suggest helps absorb impact.

Wang's 2011 study found that in the Great Spotted Woodpecker the sling-like hyoid runs right over the top of the head and into the nasal cavity, reaching about 80 millimetres, longer than the tongue apparatus of the Eurasian Hoopoe, a bird of similar size that probes soil rather than wood. Their computer model of the head showed the hyoid taking stress late in each impact, and the authors concluded that the long hyoid bone plays the role of a safety belt for the head, especially after impact. Jung's paper also cites a modelling study by Oda and colleagues which found that the hyoid bones may lower compressive and tensile stresses in the brain by up to 40 percent during pecking.

Banglapedia adds that the tongue tip is barbed, so that the bird can pull grubs out of the holes it opens. The feature's statement that the tongue is sometimes almost twice the length of the beak could not be checked against a reference source for the species of Bangladesh and is not repeated here.

The tongue is only one of several features that researchers have linked to the woodpecker's tolerance of impact. Wang's team found that the brain sits tightly packed in a relatively dense skull, with a smooth, nearly ellipsoid outline, and that the spongy bone of the skull is plate-like rather than rod-like as in the hoopoe, and concentrated in the forehead and the back of the head. They also found that the upper and lower halves of the beak differ in length: the outer horny layer of the upper beak was 1.6 millimetres longer than that of the lower beak, while the bony core of the upper beak was about 1.2 millimetres shorter. In their model, beaks of unequal length reduced the strain on the brain compared with beaks of equal length.

Jung's review of earlier work lists further adaptations: a brain that is small and light compared with its surface area, the very short duration of each impact, a small volume of fluid around the brain, strong neck muscles that guard against rotational forces, and a spongy layer inside the upper beak. A 2020 computational study by Shailesh Ganpule and colleagues in Frontiers in Bioengineering and Biotechnology grouped the main explanations into four: the small size of the brain, the long beak, the hyoid bone and the dome-shaped skull.

Not every scientist accepts that the woodpecker escapes harm entirely. In 2018 George Farah and colleagues at Boston University School of Medicine examined the preserved brains of ten woodpeckers and five Red-winged Blackbirds, a non-pecking species used as a control, in PLoS ONE. They found silver-stained deposits in eight of the ten woodpecker brains and accumulations of tau, a protein linked to repeated head injury in human athletes, in two of the three woodpeckers tested for it, and none in the control birds. The authors said this suggested that pecking may cause tau to build up in the woodpecker brain, and that more research was needed to understand the relationship.

The interest is practical as well as scientific. Jung's paper cites engineers who built a woodpecker-inspired shock-absorbing system for electronic devices that showed a 1 percent failure rate at 60,000 g, against 26 percent for a hard resin system, and Farah's study notes that the assumption of a protected woodpecker brain has been used in developing sports safety equipment such as football helmets.

The feature explained that woodpeckers peck wood mainly to find food, living on insects inside trees, and that they are popularly called the doctors of trees because removing those insects helps a tree live longer. Banglapedia describes woodpeckers spending most of their time climbing trunks and branches to dig out wood-boring insects and grubs, with a thick chisel-like bill, a tuft of feathers over the nostrils that keeps wood dust out of the nose, and the long barbed tongue for drawing grubs from their tunnels.

The IUCN Bangladesh Red List of 2015 records what the country's woodpeckers eat. The Black-rumped Flameback forages by pecking on trees and probing the ground, feeding on ants, termites, beetle pupae, caterpillars, fruit pulp and nectar. The Greater Flameback forages on tree bark, especially dead wood, mainly for ants, termites, other insects and nectar. The Great Slaty Woodpecker feeds on the pupae and larvae of wood-boring beetles. So the bird's diet is not limited to insects in wood, and several species also take fruit and nectar.

Research elsewhere shows how much woodpeckers can affect wood-boring pests. A 2013 study in PLoS ONE by researchers at the University of Maryland and the United States Department of Agriculture (USDA) looked at the emerald ash borer, an invasive beetle that has killed millions of ash trees in North America. Ash trees from which woodpeckers were excluded by screens or cages had significantly lower predation on the beetle larvae, and woodpecker predation was a greater source of beetle deaths where infestations were well established, although the authors concluded that predation alone may not be a substantial factor in controlling the beetle. Banglapedia also notes that not all woodpeckers feed in trees: the Green Woodpecker of Europe and the flickers of the Americas take insects on the ground, and the South African Ground Woodpecker lives in open country.

According to the feature, small pecks mean a woodpecker is looking for food, while a large hole means it is building a home, and woodpeckers make a new nest each season, leaving the old holes to other birds. Banglapedia describes the nest as a hole chiselled into a tree trunk, in which usually two whitish eggs are laid on the bare wood without any added nest material, although some species lay as many as eight or ten. Both parents share the nesting duties, and the chicks hatch naked. The Eurasian Wryneck, a winter visitor to Bangladesh, is the only member of the family that does not dig its own nest; it uses natural cavities or old woodpecker and barbet holes.

Scientists call woodpeckers ecosystem engineers for this reason. A 2021 study in Ecology and Evolution by Faith Hardin and colleagues at Texas A&M University notes that woodpeckers create several partly and fully formed cavities each year, and that once abandoned these are used by secondary cavity-nesting species, animals that need a hole to nest in but cannot make one. In five years of monitoring in southern Texas, every secondary cavity-nesting bird species studied had a higher chance of nesting success in an abandoned woodpecker hole than in a cavity formed by decay.

The same pattern is recorded in Bangladesh. The IUCN Bangladesh Red List notes that the Asian Barred Owlet nests in natural tree hollows or takes over woodpecker or barbet holes, that the Collared Scops Owl nests in natural hollows and in holes abandoned by woodpeckers and barbets, and that the Rose-ringed Parakeet uses natural hollows, old barbet or woodpecker nests and crevices in old buildings. The 2025 Nepal study adds that woodpecker cavities in South Asia shelter birds such as nuthatches, tits and owlets, mammals such as squirrels and bats, and insects.

The feature said several species of woodpecker live in Bangladesh and named five of them. Banglapedia lists 22 species for the country, 21 resident and one migratory, the Eurasian Wryneck. The IUCN Bangladesh Red List of 2015, prepared with the Bangladesh Forest Department, counts 20 species of woodpeckers in the order Piciformes, alongside five barbets. The five named in the feature, with the local names used in the IUCN Bangladesh Red List, are:

• Black-rumped Flameback (Dinopium benghalense), Bangla Kaththokra: very common and widely distributed throughout the country, in gardens, light forest, mango groves, roadside trees, villages and farms, including homestead trees; it breeds from February to July. Assessed Least Concern.
• Greater Flameback (Chrysocolaptes guttacristatus), Boro Kaththokra: common and widespread, found in the forests of the south-east, south-west, north-east and central regions, often among mixed flocks of insect-eating birds; it breeds from March to May. Assessed Least Concern.
• Grey-capped Pygmy Woodpecker (Dendrocopos canicapillus), Metetoopi Batkurali: a small, common resident found in suitable habitat all over the country, from mangroves to evergreen, deciduous and secondary forests, where it forages clinging to thin branches. Assessed Least Concern, although the assessment notes that its forest habitat is declining through logging and the spread of farming.
• Himalayan Flameback (Dinopium shorii), Himaloee Kaththokra: recorded in the forests of Dhaka and Sylhet divisions, with only two reliable recent sighting reports. Assessed Data Deficient.
• Yellow-crowned Woodpecker (Leiopicus mahrattensis), Holdechandi Kathkurali: a very rare resident; after older published records, there were no recent records until one was photographed in acacia trees by the Karnaphuli river in Chattogram in March 2002. Assessed Data Deficient.

Banglapedia adds that the country's woodpeckers range from the size of a sparrow to that of a crow, are usually boldly patterned in black and white or olive, often with red on the head, and fly with a heavy, undulating flight. Other species on its list include the Rufous Woodpecker, the Fulvous-breasted Woodpecker, the Streak-throated Woodpecker, the Greater and Lesser Yellownapes, the Bay Woodpecker, the Common Flameback of the hill forests and the Sundarbans, and two tiny piculets, the Speckled Piculet and the White-browed Piculet.

The feature closed with a warning: woodpeckers are rarely heard amid the noise of cities but are well known in the countryside, and with trees disappearing from villages as well as towns, the writer said the bird's numbers were falling towards extinction. She urged tree planting to conserve woodpeckers and other birds.

The national assessment gives a more mixed picture. The IUCN Bangladesh Red List of 2015 assessed 566 bird species and found 424 of them Least Concern. Its table for the order Piciformes, the woodpeckers and barbets, shows no threatened species, two Near Threatened, 20 Least Concern and three Data Deficient. Common species such as the Black-rumped Flameback were judged secure because they thrive on varied food and survive in many habitats, including homestead trees.

The pressure the writer described is real for the forest specialists, however. The Great Slaty Woodpecker (Mulleripicus pulverulentus), a rare resident of the hill forests of the north-east and south-east, was assessed Near Threatened in Bangladesh because it depends on large trees for feeding and breeding, which makes it vulnerable to logging for commercial plantations, the conversion of forest to farmland and urban growth. The Red List names it as one of four resident birds of Bangladesh that are globally Vulnerable. The 2025 study from western Nepal describes it as the largest woodpecker species in the 14 South and South-East Asian countries where it occurs, notes its Vulnerable listing on the global IUCN Red List and Endangered status in Nepal, and links its decline to the loss of large, mature trees, habitat degradation and fragmentation.

The IUCN Bangladesh assessment also describes how bird habitat has changed. Much of the country's sal forest holds young trees without a dense canopy, with undergrowth cleared or trampled and leaf litter collected, so that its value as bird habitat has greatly diminished; these degraded forests still support a few woodpecker species. Traditional village homesteads, with an orchard, bamboo grove, vegetable garden and pond, have long been good bird habitat, and woodpeckers are among the birds still seen in many villages, but the assessment notes that many villages are turning into small townships.

Woodpeckers, like other wild birds, were protected in December 2025 under the Wildlife (Conservation and Security) Act 2012. Section 6 of the Act says no person shall hunt any wild animal without a licence or permit under the Act, and the Act defines hunting to include killing, capturing or poisoning a wild animal, attempting to do so, injuring it, and collecting or destroying the nests or eggs of wild birds. Under section 39, breaking section 6 is punishable with imprisonment of up to one year, a fine of up to 50,000 taka, or both, and for a repeat offence imprisonment of up to two years, a fine of up to one lakh taka, or both.

Photo: AR Ebrahim / Wikimedia Commons (CC BY-SA 4.0)

Sources: Jagonews24 (feature by Sanjana Rahman Juthi, 13 December 2025), Banglapedia, IUCN Bangladesh Red List of Bangladesh Volume 3: Birds (2015), PLoS ONE (Wang et al. 2011; Jennings et al. 2013; Farah et al. 2018), Acta Biomaterialia (Jung et al. 2016), Proceedings of the Royal Society B (Miles et al. 2018), Frontiers in Bioengineering and Biotechnology (Ganpule et al. 2020), Ecology and Evolution (Hardin et al. 2021; Great Slaty Woodpecker study, 2025), Wildlife (Conservation and Security) Act 2012