Many of you may have seen woodpeckers striking trees while they search for their meals. They can hear grubs moving in the wood and it is thought that they can smell the odor of formic acid excreted by insects. But did you know that woodpeckers have adapted over time to protect their brains from damage when they repeatedly peck away at wood and trees?
Banded woodpecker (Picus miniaceus) spotted by Roy Sim in Singapore
These adaptations include small brain size, the placement of the brain within the bird’s skull, and a short duration of contact between the brain and skull when pecking. Just before they make contact with wood, their eyes are also protected from flying debris by the closing of a thick nictitating membrane and their nostrils are protected by special feathers for the same purpose. The force of the drilling impact is further mediated by strong muscles at the base of the beak, which act as shock absorbers. This is helpful as they may tap on wood, as well as utility poles, trash cans, rain gutters and other resonant objects, up to 8,000-12,000 times a day (22 times per second) as they search for food, make nests and drum on trees and other objects as part of their courting behavior. In fact, scientists who studied the golden-fronted woodpecker’s head and neck to determine how the bird withstood this pounding used their findings to design a mechanical shock absorption system to protect microelectronics.
Golden-fronted woodpecker (Melanerpes aurifrons) spotted in Mexico by Maria de Bruyn
This interesting bird species attracts people’s attention and has become the subject of a famous cartoon (Woody woodpecker, seen in countries such as Brazil, Germany, Japan, Mexico, Russia, the United States and Yugoslavia), as well as of proverbs. For example, in Malawi, people are advised that “When a dead tree falls, the woodpeckers profit from his death,” whereas a Malayan saying warns that “When a dead tree falls, the woodpeckers share in its death.”
The IUCN and Birdlife International have assessed 172 species of woodpeckers and listed four as critically endangered: the imperial, ivory-billed, Kaempfer’ and Okinawa woodpeckers. Six more species are considered vulnerable: the Fernandina’s, Arabian, Sulu, Helmeted, and Red-cockaded woodpeckers. The imperial woodpecker (Campephilus imperialis), last seen in Mexico in 1956, preferred open montane forests comprising pine and oak trees. Mating pairs needed about 10 square miles (26 km2) of untouched mature forest to survive. It likely became extinct due to habitat loss and hunting for use in folk medicine; the nestlings were also consumed as a delicacy by some ethnic groups. About 160 museum specimens are all that remain of this bird.
Imperial woodpecker (Campephilus imperialis) photographed by Christine Fisher at the Moore Laboratory of Zoology in California
Woodpeckers live in all areas of the world except for Australia, Madagascar, New Zealand, some oceanic islands and the distant polar regions. Most of them are found in wooded habitats, save for a few species that live in deserts and on rocky hillsides. Their life spans average about 4-11 years. They vary in color, with some having spots and others patches of color.
Philippine pygmy woodpecker (Dendrocopos maculatus) spotted by KdonGalay in the Philippines
White-naped woodpecker (Chrysocolaptes festivus) seen by Nishant in India
Great spotted woodpecker (Dendrocopos major) spotted by Jeannette in Denmark
Golden-naped woodpecker (Melanerpes chrysauchen) photographed by jmunozcr in Costa Rica
The smallest known woodpecker is the bar-breasted piculet, which measures about 3.25 inches (8 cm); the largest was the imperial woodpecker, which measured 23 inches (58 cm). Of the surviving known species, the largest is now the great slaty woodpecker, a bird seen in Southeast Asia that measures about 20 inches (50 cm). Woodpeckers have two forward-facing and two backward-facing toes which help them walk vertically up tree trunks, giving them “zygodactyl feet” (an interesting trivia question!).
Yellow-fronted woodpecker (Melanerpes flavifrons) spotted by Aisse Gaertner in Brazil
Woodpecker species are important to their ecosystems. Woodpeckers not only help control insect populations; their nest cavities are also used by birds and animals (deer mice, raccoons, flying squirrels) that cannot create cavities themselves. Woodpecker species that use their bills for probing soil rather than regular pecking often have longer and more decurved beaks. Their long sticky tongues have bristles that help them grab insects. Some species also drink tree sap and eat fruit, nuts, acorns, seeds and suet. There are three species of woodpeckers that live on the ground, the Andean flicker (Colaptes rupicola) and campo flicker (Colaptes campestris) of South America and Africa’s ground woodpecker (Geocolaptes olivaceus).
Ground woodpecker (Geocolaptes olivaceus) seen by Adam Riley in South Africa
Some woodpecker species are solitary, while others live in groups; the collective name for a group of woodpeckers is a “descent”. Woodpeckers’ strong beaks enable them to bore holes into trees – and other structures! – for their nests. In most species, the nest excavation is done by the male, who also helps incubate the eggs for about 11-14 days. Nestlings fledge after 18-30 days. A few species are known to use nest boxes which are built with the proper specifications; a downy woodpecker used a bluebird box in my yard as its night-time refuge over the past winter.
Downy woodpecker (Picoides pubescens) spending a winter night in bluebird box; spotted by Maria de Bruyn
This pileated woodpecker (Dryocopus pileatus) bored through the wall of an office building in Florida to excavate a nest; spotted by Mick G
Adult woodpeckers, nestlings and eggs fall prey to a variety of predators, including hawks, owls, starlings, snakes and raccoons. Threats to woodpeckers around the world include habitat loss, habitat fragmentation, forest fires that eliminate dead wood, and insecticides that decrease their food sources. Where deadwood increases in forests, however, species may proliferate as shown for the white-backed woodpecker (Dendrocopos leucotos) in Switzerland.
Maria de Bruyn
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