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.
Please help us continue our woodcock research