There are more than 200 species of woodpecker worldwide, all of which are cavity nesters and all of which have one key feature in common: they all peck wood. But what reasons do these ultra-efficient carpenters have for drilling holes in tree trunks, and do woodpeckers ever get injured when pecking wood? To understand more, please do read on.
The three main reasons for woodpeckers to peck wood are to find food, to excavate a nest cavity and as a way of communication with other woodpeckers. Woodpeckers exert a huge amount of force when drumming against tree trunks and have specially adapted anatomy so they do not sustain injuries.
By hammering against tree trunks, woodpeckers are able to access any insects and larvae living beneath the bark by drilling holes in the wood and using their sticky, barbed tongues to lift out their prey.
Ladder-backed woodpecker foraging for food in the tree tunk
Larger chambers are drilled into tree trunks to form nest cavities in which woodpeckers lay their eggs and raise their young. New cavities are excavated each year, so all the effort of drilling out a hollow in early spring will be repeated the following year rather than a previous nest being reused.
Drumming against hard wooden surfaces is the equivalent of conversation for woodpeckers, with lengthy series of rapid tapping used to advertise availability in the breeding season and assert a claim to a territory.
To find out more about just why woodpeckers peck wood and how they are adapted to limit any injuries or damage to their skulls, beaks and brains, then please continue reading.
Close up of a male Downy Woodpecker excavating a nesting cavity in a tree
Woodpeckers are so named because of their distinctive typical behavior of pecking and drilling into wood, particularly tree trunks and larger branches.
They have evolved with particular adaptations that allow them to efficiently chisel out hollows to live in and deep holes in which they can access food resources that are out of reach of other bird species.
Woodpeckers peck for a variety of reasons, including foraging for food, excavating nest cavities in which they can lay eggs, raise young, or roost, and communicating with other woodpeckers, to find a mate or assert a claim to a territory.
Insects living beneath the bark of trees are a popular food for woodpeckers, including ants, beetles and their larvae. By using their bills to drum against the wood, bark can be removed or thin holes chiseled into the trunk or branches of a tree so that any bugs living beneath the surface can be caught and eaten.
Some woodpecker species are particularly attracted to sap and drill holes to tap into the sticky substance beneath the outer bark, as well as any insects that may be living in the sap.
Woodpeckers have uniquely structured tongues that allow them to feed on insects beneath the surface of bark on tree trunks, as well as serving as shock absorbers to cushion the impact of repeated fast-paced drumming.
These long, flexible tongues extend beyond the length of their bill, allowing them to reach deep into crevices to extract insects and larvae. The tip of the tongue is often barbed or features sticky salivary glands, which act as a glue to trap the prey.
The woodpecker’s tongue wraps around the inside of its head, which helps to protect its brain against the impact of the force of the drumming. This unique positioning keeps the woodpecker’s tongue in place without impeding its breathing, allowing it to extract prey from deep, narrow holes.
Great Spotted Woodpecker foraging on a tree with its tongue out
Woodpeckers raise their young in nest cavities that they excavate themselves in the trunks of trees. Dead or dying trees are preferred as the wood is softer and less effort is needed to drill out a suitable cavity, although living trees are also sometimes chosen.
Woodpeckers hollow out large chambers, which they line with bark chippings or twigs, and lay their eggs inside. Cavities offer a safer space in which young can be raised with a lower chance of predation, due to being hidden out of sight.
Nest cavities also provide important shelter against the elements, including extreme heat, cold and rain. Outside of the breeding season, woodpeckers may continue to use nest cavities for roosting overnight.
Northern Flicker excavating a nesting cavity for nesting season
Ahead of the breeding season, drumming can frequently be heard in woodlands as woodpeckers explore territories and begin to think about finding mates and asserting their position among rival woodpeckers.
Rhythmic drumming sounds are made by pecking on branches and trunks as a form of communication, to establish territorial boundaries, signal their presence in a particular spot or to advertise their availability to potential mates. Each woodpecker species has its own unique drumming pattern, which is recognizable to others of the same species.
Drumming contests may sometimes be heard, thought to be a communication exchange between rivals. In such contests, male woodpeckers take turns to hammer out rapid drumming on a tree trunk, as a way of showing dominance and resolving territorial disputes.
A pair of Greater Flameback woodpeckers
Woodpeckers have a series of specialized anatomical features that allow them to peck wood, drill holes and generate drumming sounds without causing themselves long-term injury or damage to their bill or body.
They have a specialized strong, sturdy bill that can withstand the impact of prolonged and repetitive pecking without becoming damaged or blunted. The elongated shape allows them to absorb the forces generated by repeatedly striking against hard wooden tree trunks.
Woodpeckers’ skulls are made from a thick, spongy bone, and cased with muscles and tissue that absorb the shock from sustained drumming and pecking, protecting the brain from injury and trauma.
The muscles in a woodpecker’s neck are exceptionally strong, which enables them to rapidly pound their bills into wooden branches and tree trunks, moving their heads backwards and forwards to generate the powerful strikes required for drilling holes.
Other anatomical features of woodpeckers that allows them to remain in position while they perform their extended periods of excavating and drumming include specialized feet and tail feathers. Their stiff tail feathers act as a stabilizing support helping them to balance against a tree trunk. Their feet usually have two toes facing backward and two facing forward, which enable a powerful grip against the bark, allowing long bouts of pecking without the risk of slipping.
Acorn Woodpecker close up
Woodpeckers have a number of anatomical adaptations that prevent them from getting headaches or brain injuries while pecking wood. Their skull is thick and spongy, and features a layer of muscles and tissues that serve as shock absorbers, which dissipate the forces created during pecking and reduce any impact on their brains.
A woodpecker’s tongue wraps around the inside of its skull, offering additional cushioning between the brain and skull.
Woodpeckers strike a tree or another hard surface with a deceleration force of about 1,200 to 1,400 times the force of gravity. For comparison, a g-force of 60 to 100 is enough to give a human concussion. Pileated woodpeckers are known to have a particularly powerful peck.
Different woodpecker species have different pecking speeds, up to a maximum of 16 to 24 km/h (10 to 15 mph), or a rate of 10 to 20 pecks per second.
Not all woodpeckers drill out cavities or drum at this rate; for example, northern flickers have a much more leisurely drumming pace. One of the fastest-drumming woodpeckers is the Japanese pygmy woodpecker, which drums at an astonishing rate of one strike every 28 to 43 milliseconds.
The Japanese Pygmy Woodpecker is the fastest drumming woodpecker in the world
All woodpecker species nest in cavities in tree trunks, and drill these out themselves by excavating holes in tree trunks. Pecking wood is a fundamental behavior of all woodpeckers, and although some, such as the green woodpecker are mainly seen foraging for food on the ground, pecking wood is still an instinctive part of their behavior, in order to create nest cavities and communicate with other woodpeckers.
Woodpeckers are a diurnal species and are typically active during the day, and rest during hours of darkness. Drumming is not usually heard at night, ceasing at dusk and beginning at dawn.
Pecking wood, drilling holes and drumming are not behaviors that are restricted to male woodpeckers. Females drill to forage for beetles, other insects and sap, and also in many species take active roles in excavating nest cavities.
Female woodpeckers also engage in drumming to respond to males’ calls for mates, or to advertise their own presence in a particular territory.
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