Woodpeckers Talk, 9 November 2005

This was a fascinating talk by BARRY HUGHES, illustrated with superb photographs. The emphasis was on British species but he made comparisons with other species around the world.

Woodpeckers fall into the order Piciformes, family Picidae. They are widely distributed throughout the world's continents except Australia. The official UK list contains four true woodpeckers and the Wryneck. The four species are the Great Spotted Woodpecker (Dendrocopos major), the Lesser Spotted Woodpecker (Dendrocopos minor), the Green Woodpecker (Picus viridis) and the Yellow-Bellied Sapsucker (Sphryrapicus varius). The latter has only been seen twice in the British Isles, once in Ireland and once in the Scilly Isles. It is a native of North America, migrating southwards for the winter, and must have been blown across the Atlantic by a gale. European woodpeckers do not migrate, as their food supply is not unduly affected by climate. They remain in a relatively small territory, which probably accounts for European species such as the Black Woodpecker and the Middle Spotted Woodpecker, both common on the continent, not crossing the English Channel. Ireland, the Isle of Man and even Anglesey are devoid of woodpeckers. The Wryneck does migrate and is now a relatively rare summer visitor to Britain.

Woodpeckers evolved to exploit a niche in the food environment. They feed mainly on the abundant insects and larvae that hide behind the bark of both living and dead trees. They have developed strong chisel-like beaks, thickened skulls and cushioning behind the beak to soften the blows and to protect the brain. They have strong legs and zygodactyl feet, two toes pointing forwards and two backwards, armed with sharp curved claws. The tail feathers are stiffened and act as a strut or third leg to support the body in a vertical position on a tree trunk. The true woodpeckers and the Wryneck have exceedingly long sticky tongues with a barbed end. The hyoid apparatus at the base of the tongue curves back over the top of the cranium and can project the tongue out four to five times the length of the beak. They drill a hole through the bark of a tree, insert the tongue, and search behind the bark for insects. The Spotted woodpeckers feed mainly in the trees but the Green often feeds on the ground, searching for Leather-Jackets and other insects and invading ants' nests. However, they are not averse to breaking into nest boxes and extracting fledglings if the opportunity arises.

Woodpeckers are dimorphic, males and females having small colour differences. The males usually have additional distinct red patches absent on the female. The Green has a patch of red in the moustache, the Great Spotted has a patch of red on the back of its head and the Lesser Spotted a red patch on the top of its head. This type of red colouring is fairly common among most of the world's woodpeckers. Woodpeckers are more abundant in southern Britain.

Twenty years ago the Green was the most common but forestry management has changed and dead trees are no longer routinely removed. This has increased the insect food supply and has also provided good trees for nest building, favouring the Great Spotted Woodpecker, which now outnumbers the Green. The Lesser Spotted Woodpecker is rarer and spends most of its time in the canopy. It is only about the size of a sparrow and is easily overlooked and thus difficult to count.

All woodpeckers nest in holes excavated by their chisel-like beaks. The nest is usually about 45 cm deep. The eggs are invariably white and laid directly on the wood; they have no need of camouflage and it is thought that, in the dark base of the hole, white eggs are more visible and less likely to be trodden on. It makes a new hole each year to avoid parasite contamination. Wrynecks also nest in holes but they cannot make their own. Other birds such as the Starling also use woodpecker holes and have been known to drive a woodpecker out of its new hole.

Woodpeckers do not feed solely on insects but also eat fruit and nuts. In autumn when they have eaten sufficient they will hide nuts for use during the winter. BARRY showed us an extreme example of the Acorn Woodpecker of North America that had created a larder of acorns in a telegraph pole.

CHRIS BRADING