Few gamebirds are held in higher esteem than the woodcock; its appeal no doubt derives from its challenge as a sporting bird, as well its enigmatic nature and beautifully cryptic plumage. But if there is one reason we should really revere these captivating birds, it is the great feats of migration they perform that deserve the most respect. It is believed that over one million woodcock can visit the UK each year, some of which may have travelled nearly four thousand miles to reach our shores. The Woodcock Watch project is run by the Game & Wildlife Conservation Trust (GWCT) to increase our understanding of migratory woodcock and reveal the finer details of their impressive journeys.
Our new insight into woodcock migration is made possible by the constant improvement of tracking technology. As biologists we have a greater array of compact, lightweight and accurate transmitters at our disposal than ever before. The recent availability of a 9.5g satellite-transmitter, small and light enough to be mounted on a woodcockâ€™s back, has made it possible to track the movements of these birds in near real time. To date we have tagged 26 woodcock over two successive winters including individuals from a range of wintering sites (Cornwall, Norfolk, Northern England, Scotland, Wales, and Western Ireland) as well as a mixture of juvenile and adult birds.
The data we have collected is leading us towards some interesting conclusions; some complementing and others contradicting traditional beliefs about woodcock migration. It was typically agreed that most birds wintering in Britain originated in Scandinavia, Western Russia and the Balkan states, a fact that was echoed by the results of the satellite-tracking. Nonetheless, it was fascinating to see the range of countries our birds returned to in the spring; from our sample of just 26 birds, we had woodcock return to breeding sites in seven different countries.
Most remarkable was the migration of an individual named Monkey, who in Spring 2012, flew close to four thousand miles from his wintering site in Cornwall to breed in the birch forests of western Siberia. This was topped in Spring 2013; not only did Monkey return to exactly the same site in Siberia for a second summer, but two other birds, one from Cornwall, the other from Norfolk, made journeys of a similar scale to breeding sites close to Monkeyâ€™s.
We have discovered through our satellite tracking that birds of different European origins do not necessarily favour different wintering grounds; rather a single wintering site can hold birds from all over Europe and Russia. This mixing is most clearly demonstrated by our Cornish birds; of the eight Cornish birds that have returned to their breeding sites, we have had two in Central Russia, three in Western Russia, two in Sweden and one in Belarus.
The project is not without its difficulties. Low light intensities in winter, combined with the woodcockâ€™s secretive and nocturnal behaviour, have meant that the solar-powered satellite tags have not always received sufficient sunlight to charge their batteries. This has led to more sporadic data in the autumn, although we feel the quality of the spring data has more than made up for this. Thankfully some of our woodcock do continue to transmit well in the autumn and winter and this January in particular has seen some surprising results in what has been an interesting, albeit unusual, year.
Olwen is a woodcock that was caught in Wales in February 2013, who flew to western Russia to breed. In December, after a short spell of silence, Olwen started sending data from a farm in East Yorkshire which we expected to be a stopover point on a journey that would ultimately lead Olwen back to Wales. Surprisingly this was not the case; instead Olwen has remained in East Yorkshire for the duration of the winter. Weâ€™ve seen similar behaviour from a second bird, Wensum, who was tagged in Norfolk in early 2013 and spent her winter in Germany and the Netherlands rather than making the return flight to East Anglia. These observations present a significant departure from what we believe to be the norm; Woodcock are usually thought to show a high degree of fidelity to a specific wintering site. Indeed this was the case with the 2012 batch of birds; all of those that we received autumn/winter data from returned to the sites at which they were caught. This site faithfulness is also seen when analysing the recovery of birds marked with metal leg rings â€“ one of the few ways that this kind of study was possible prior to the advent of our modern tracking technology.
The migration of one of this yearâ€™s Irish birds, Amy, also goes against the grain. Unlike Olwen and Wensum, Amy did eventually return to within less than a mile of her capture site in Western Ireland, demonstrating impeccably the site faithfulness we would normally expect to see. Data from Amy was scant over the majority of the winter, but we had a transmission on the 6th Feb showing her to be in Country Kildare in the east of Ireland. She only made her final movement to County Galway in the west between the 6th and the 11th Feb. Because data earlier in the winter is unavailable, we are unsure whether Amy spent December and January in Eastern Ireland, Britain or continental Europe, but what is clear is that she was still making large migratory movements as late as mid-February. Anyone familiar with woodcock will know of the eponymous â€˜woodcock moonâ€™ which accompanies the arrival of autumn migrants, yet here we have a bird migrating, not in October or November as expected, but towards the very end of our winter.
Both of these apparent anomalies, the shorter than expected migration and the later arrival date, may be more common than we appreciate. It appears to show an interesting amount of adaptability and flexibility in the birdâ€™s migration strategies, rather than following a hard-wired instinct to perform the same migration year-on-year the birds are able to react to annual variations in the winter weather. In harsh winters, when the weather is particularly cold and the ground permanently frozen elsewhere, the numbers of migrants visiting the South-West (Pembrokeshire, Devon, Cornwall) are observed to increase significantly â€“ the weather here remains milder than the rest of the UK and the woodcock are driven here as conditions elsewhere become intolerable. Although this winter has been wet and windy, it has been comparatively mild, and it seems as though the opposite has happened.Â Many birds appear not to have flown further than necessary and birds such as Olwen have only performed part of their migration. Similarly, birds like Amy have not been forced into the extreme south and west of Britain and Ireland in autumn by frozen ground and heavy snowfall on the continent.
These more recent discoveries emphasise what is important about our Woodcock Watch project. On the face of it a satellite-tracking study of this type may simply seem a question of â€˜where do these birds go?â€™ but in truth, there is more to learn from these data; just as interesting and often more surprising are the details of the journey; the routes, the stop-offs, the timing of departure and arrival, and how migration is affected by the age, sex or origin of the bird as well as variations in weather between and within winters.
We are deploying more tags in February and March 2014. Repetition in successive years helps us study migration across the full gamut of winter weather and the increased sample size means we can account for variability between individuals. The progress of these new birds will be published on the Woodcock Watch website at www.woodcockwatch.com from April onwards. The website also provides details for those who may wish to sponsor a bird; it costs as little as Â£3 a month and helps fund this pioneering project.