Wednesday, 22 October 2014

Autumn Progress

In early October the first few migrant woodcock begin to arrive.  The vast majority, however, will not be here until November or even later; in an average year birds are still arriving through December. Last week I heard the first reports of migrants seen on the east coast but our satellite-tagged birds are showing little in the way of migratory behaviour.

The GWCT’s Woodcock Watch project tracks the migrations of British wintering woodcock across Europe; over the last three years the project has followed the fates of thirty-nine individuals using state of the art tracking technology.

In February and March, woodcock are caught and fitted with lightweight tags which are able to provide a near real-time relay of their outward spring migration. The devices are equipped with tiny solar-panels, and providing they receive enough sunlight, they should remain charged to track their returning journeys in the autumn and in some cases, in subsequent years. In 2014, we tracked twenty-five woodcock; seventeen of which were caught this spring and eight of which were tagged in previous years but whose transmitters were still active. All but one tag provided useable data and twenty of our birds completed a spring migration.

Eleven of these migrated to breeding sites in Western Russia. There were three woodcock that chose relatively southern locations in the area west of Moscow and east of the Belarussian border, whilst another eight settled in the more northerly region east of Finland. One of these birds, James, was amongst the most northerly breeders Woodcock Watch has tracked, visiting a site close to Arkhangelsk on Russia’s White Sea. Other tagged woodcock this year headed for Finland, Latvia and Norway.

The birds we have been able to track in multiple years have demonstrated that woodcock remain loyal to the same breeding site year on year. Rebecca, in particular, has been a striking case in point and has returned annually to the same wood in Russia since being tagged in February 2012. In just the three years we have monitored her, she has covered a total distance of 15,000 km from Wales to Russia and back two and a half times. We have yet to conclusively prove it, but we believe that birds like Rebecca are returning to breed at sites close to where they hatched as chicks; research suggests this to be so in most other wading bird species.

We are still receiving data from many of the tagged woodcock and transmissions have remained encouragingly frequent this year, but so far most are only showing small scale movements on the summering grounds. Instinctively, the woodcock will be anticipating the long flight ahead of them and are probably busy trying to find sufficient food to reach an optimum physical condition.

The only bird that appears to have begun her autumn migration is Nastasia. She was tagged in County Cork, Ireland, in March 2014. During the first two weeks of April she made her way to Western Russia via Belgium, Germany and Poland, ultimately settling in a site not far from St. Petersburg. Here she remained until early October. On the 18th October her tag sent fresh data showing her to be in Lativa, having flown the first 600 km of her westward migration.

It remains to be seen when the rest of the birds will depart. The weather in Finland and Western Russia is still relatively mild, but this appears to be changing. If the temperature continues to drop, we would expect this to prompt migration in those woodcock that have yet to leave. Typically, the average woodcock migration consists of a long, sustained flight over a relatively short time period, followed by a break of a week to ten days’ rest before the next long flight. Migrating in stages keeps the birds ahead of the oncoming cold weather and gives them an opportunity to feed and recover en route. This could mean it is another month or more before they are back in the UK and Ireland.

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