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Scientists tap into the woodpecker’s world
THE inspiration for many inventions was the world of nature.
Examples include the ability of wasps to manufacture paper – an idea that transformed the world – and the magic of burrs, the seeds of the burdock. They stick to animals’ fur, human clothing and all kinds of hair. This is the plants’ method of spreading their seeds.
In the past, children would play games with burrs, throwing them at one another and scoring points when the seeds clung to clothes, fur or hair.
For them, it was just a game and it required the inventive mind in 1941 of a Swiss engineer, Georges de Mestral, to realise the commercial potential of burrs.
Using the principal of tiny hooks that appear on the burrs, he invented hook and loop fasteners which we now call Velcro. An older name was burr and touch.
In contemplating these examples, we might ask why a woodpecker drilling a hole in a tree or telegraph pole does not suffer from a broken skull, brain damage or merely a headache. For many years this has puzzled scientists and it led to the invention of crash helmets.
Scientists calculated that a woodpecker’s beak strikes wood at about 1,300mph, whereas a motorist’s head that hits a windscreen at 35mph can result in death or severe injury.
Over the years, scientists have tried to understand how woodpeckers achieve their safety. In 1976, an American expert working at the University of California discovered the bird possesses relative sponginess in that part of the skull that has to cope with machine-gun rapid strikes against solid wood.
As recently as last year, Chinese scientists attempted to understand how woodpeckers survive their wood hammering and they were aided by the latest scientific techniques which included synchronous high-speed video cameras.
Their research appears to conclude that the birds do possess that sponginess in the critical part of their skulls, but another factor is that the upper part of the beak is slightly longer than the lower.
Furthermore, they appear to strike their targets at differing angles which are determined by the toughness of the wood.
The research shows that humans can withstand an impact of no more than 18 times the force of gravity while woodpeckers can withstand up to a thousand times such a force.
I am not sure whether this means we should all wear crash helmets with two different lengths of the peak but it does add a new dimension to the old Yorkshire joke that was used when someone appeared to be rather slow thinking – “Put your hat on, there’s a woodpecker about.”
We may expect to see four varieties of woodpecker in this country – the green, the great spotted, the lesser spotted and a curious bird called a wryneck which is not a true woodpecker.
The first three are present in Britain throughout the year but the wryneck is a summer visitor who winters in tropical Africa. It has a strange habit of twisting its neck when startled or alarmed. The neck can even appear to be broken and it also does this when it is courting or handled by a human.
The wryneck, only slightly larger than a house sparrow, has a mottled grey and brown plumage which acts as a good camouflage among trees and bushes. In any case, the chances of seeing one in this part of the country are rare, the south-east coastal areas being the most likely although they do appear in northeast Scotland. They don’t climb or drill holes in the manner of the woodpeckers.
The green woodpecker is unmistakable with its green plumage, red cap, black wing and tail tips, and a prominent yellow rump clearly seen in flight.
The great spotted is also very colourful with black and white markings with a red patch under the tail. The rarer lesser spotted woodpecker is also black and white with a red cap but without a red patch beneath the tail.
Both spotted woodpeckers make drumming sounds by hammering on hollow trees or telegraph poles and this is a means of declaring the boundaries of their territories and warning off possible invaders. The green woodpecker, once our most common species but now rarer, makes a familiar laughing type of call.
In Yorkshire and Durham, this has led to it being known locally as the yaffle, but it has other names such as the green popinjay, rainbird and even hewel meaning hew hole.
It is said that green woodpeckers cannot drink water in the conventional way so they sit beneath leaves during rainfall and catch the drops with open beaks. This is why they laugh so much just before rain is due – hence their name of rainbird.