Outdoors: New technology sheds light on what Scotland’s woodcocks are up to

By KEITH BROOMFIELD
Published on 06/01/2013 14:34

THE “WOODCOCK moon” is when during the first full moon of November, huge influxes of woodcock begin to descend upon our shores from their breeding quarters in Scandinavia and Russia, supplementing our own native population by as many as a million birds.

The mysterious movements of the woodcock have long been a source of debate and conjecture, and at one time it was even believed that woodcocks went to the moon in winter, as highlighted by John Gay, the 18th-century poet, who wrote: Some think to northern coasts their flight they tend, Or to the moon in midnight hours ascend.

But now new research by the Game & Wildlife Conservation Trust (GWCT) is providing a fascinating insight into the migratory movements of woodcock. It is by nature one of our most intriguing birds; a nocturnal wader that lives in woods rather than by the shore. During the day, the woodcock sits motionless on the woodland floor, relying on its cryptic brown plumage for camouflage, with its large eyes on the side of its head providing almost 360 degrees peripheral vision for the detection of predators. Curiously, the way in which the eyes are set on the head means it can’t see the tip of its long bill.

It has long been known from ringing studies that many woodcocks arrive in the UK from Scandinavia and Russia each autumn and early winter. But knowledge on the extent and detail of these migratory movements was scant, given the relatively small number of marked birds recovered. In the last three years, however, GWCT has employed the innovative technique of analysing the chemical composition of woodcock feathers as an alternative approach to ringing. Birds from different areas have their own distinctive geographical signature and the stable isotope analysis of recovered feathers from moulting locations in late summer can give a good indication of the migratory movements of woodcock.

In 2010, this stable isotope analysis by GWCT was complemented by the marking of some woodcock caught in winter in the UK with geolocators and, more recently, with satellite tags providing real-time information on their movements.

According to Dr Andrew Hoodless of GWCT, who has studied the woodcock intensively for more than 20 years, this research has revealed that woodcock from Russia and the Baltic states travel to Britain across a relatively wide front, whereas Scandinavian birds appear more restricted to Scotland, Wales and Ireland, with a lower portion reaching southern England. There is also evidence that they often migrate in groups.

“It seems that Scandinavian and Russian/Baltic states birds follow parallel migration routes, with most Scottish migrant arrivals being from Norway and Sweden, while the Russian birds tend to concentrate in central and southern England,” says Andrew. “It is also apparent that individual birds generally follow the same migration path each year from their wintering location to their breeding grounds, and vice versa. This is a strategy that makes eminent sense as it means each individual bird will know its breeding and wintering location intimately, including the best places for feeding and shelter.”

The satellite telemetry has also shown the vulnerability of birds to the vagaries of the weather during migration. One bird tagged near Beauly last February spent the summer in northern Norway, but on its way back to Scotland was blown off course to Denmark.

As well as its ecological significance, the woodcock is also valuable economically as a much-favoured game quarry, underlining the importance of the GWCT research in shedding light on the factors affecting woodcock numbers and its favoured breeding, wintering and migration stop-off places. “We think the breeding population in the UK is in decline,” says Andrew. “There is some evidence that the Russian population may be stable, although heavy logging operations in the country are bound to be having an impact. By building up an accurate picture of woodcock movements we can determine any long-term trends caused by climate change, habitat loss and changes in hunting pressure.

“By using radio trackers we hope to see what habitats woodcock use in summer to rear their chicks, identify forest areas that may be important during migration, and in winter to provide food and cover in bad weather.

“This can help in the formulation of international conservation policies and can also be used to encourage hunters to provide ideal habitats for their quarry species, which in turn will benefit other fauna and flora.”