Green woodpecker

The green woodpecker (Picus viridis) is easily the largest of the three species of woodpecker that breed in the United Kingdom. They are not always easy to see, partly because of their green colouring but also because they have a habit of moving out of sight when they become aware of people in the vicinity.

Appearance and anatomy

As the name suggests, the green woodpecker is founds in woods, copses, orchards and parks, but they also often feed outside woodland areas.

The green woodpecker is around 32 centimetres (12-13 inches) long. The body is heavy-looking, the tail short and the bill, as might be expected, short and strong. The male is pale green on the underside and olive green on the back and upper wings. The rump is yellow and the underwings yellowy-green. The head has a red crown and there is a red “moustache” below the eye. Females are similar in appearance apart from their underparts being more brown than green, and the moustache being black rather than red.

An unusual feature of the green woodpecker (although shared with other woodpecker species) is its feet, which have two toes pointing forwards and two back, thus making it easier for the bird to climb trees and grab hold of branches.

Even more unusual is the structure of the head, which again is something shared by other woodpeckers. The action of pecking at a tree trunk, which in some woodpecker species reaches 16 times a second, creates enormous pressures on the bird’s head. It has been estimated that the force can be equivalent to a thousand times that of gravity. The woodpecker therefore has a built-in shock absorber in the form of a cartilage cushion, and muscles that pull the brain case away from the beak at the moment of impact.

Another remarkable feature is the bird’s tongue. Green woodpeckers feed mostly on ants, and they therefore have tongues that resemble those of insect-eating mammals, reptiles and amphibians, being long, barbed and sticky. In the case of the green woodpecker, the tongue is ten centimetres long, and when not in use it folds back into the bird’s head, wrapped around the outside of the skull.

Behaviour and breeding

Green woodpeckers are not actually the most active “drummers” among the woodpecker species, and when they do drum this is done as a means of contacting other birds. They prefer to drill holes in older deciduous trees, especially where the wood is soft or has started to rot. When nesting, the pair will create a pear-shaped cavity inside the trunk that can be up fifty centimetres deep, which will take them about two weeks to achieve. They will also drill a second cavity that is used as a sleeping chamber. A pair will use the same holes for a number of years, or even make use of ready-made holes, such as in brick or stone walls. As woodpeckers go, the green variety likes to make life as easy as possible!

The clutch is usually five to seven eggs, which both birds incubate in turn for up to 17 days. The chicks, which are blind and featherless when they hatch, are fed by the parents on ants and insect larvae.

Feeding

As mentioned above, the main food of green woodpeckers is ants, which the bird prefers to find not so much under tree bark as in anthills. One name also used for the green woodpecker is “yaffle”, which means “to eat greedily” (as well as being an imitation of the bird’s call). A single bird can consume up to 2,000 ants at a time, so the name seems to be well justified. A green woodpecker will sometimes dig tunnels in the ground to reach an ant’s nest, or attack a wooden beehive to take bees, an action which is understandably unpopular with beekeepers!

The green woodpecker is on the “amber” list of threatened species, as designated by the RSPB (Royal Society for the Protection of Birds). This is mainly due to modern farming methods that make it difficult for many ant species to establish themselves in sufficient numbers to provide a reliable food supply. That said, the range of the green woodpecker has expanded in recent years and is now found in upland areas where it would have been absent in the past.

This page ofthe RSPB website contains more information including a recording of the bird’s call.

© John Welford