Tuesday, 16 December 2014

Why aren't we seeing much new location data?

Many woodcock sponsors have noticed a recent lack of activity from the tagged birds, and would be forgiven for thinking that there is a problem with the Woodcock Watch website. We can assure that this is not the case; it’s simply that no data is being transmitted at present.

We currently believe that the problem relates to the tags’ batteries. The tags are solar-powered and need to be recharged by the sun. To fully recharge a battery from flat will take about 4 hours of bright sunlight. It seems that the tags are not receiving this. Day length is short and sunlight intensity low in the northern locations where the birds have spent the autumn. Light intensity on a sunny winter’s day is only one ninth of that experienced on a day in June. On top of this, the woodcock’s nocturnal, secretive nature means that it spends most of the day hidden beneath dense vegetation. This does not mean the tags are permanently out of action though; assuming that some of the birds are still alive, their tags will begin to transmit again as soon as they recharge. This point has been proven by Olwen, who has transmitted good-quality data this week despite having been out of touch for over two months. He has now reappeared in Lincolnshire, where he is alive and well, having made his way from Western Russia.

Olwen's journey
It’s important to remember that this research is not tried and tested; this is new technology which has not been trialled on woodcock. Most current satellite tagging studies performed in the UK relate to diurnal summer visitors migrating between Britain and Africa. This is a far cry from the nocturnal woodcock which is migrating north to Russia and Scandinavia. Because this is such a new area of research there will undoubtedly be surprises and unforeseen problems. Whilst this may seem a disappointment, we must keep in mind the quality of the revelatory spring data we have gathered using these tags which more than make up for the problems we experience in autumn.

Please help us continue our woodcock research

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