du bois du Ligoures Pointer

Pointer

 Autumn migration about to kick off

Of the million or so migrant woodcock that will spend their winter in the UK, the vast majority will arrive here between mid-November and mid-December. Given that some of these birds will have spent the breeding season as far away as central Russia, we would expect to see the first signs of movement now. We have now had a few reports of small numbers of migrating woodcock being seen in disparate locations across central Europe.

 Monkey and Busy

At least two of our tagged woodcock have already started their migration. Monkey  spent his summer in Siberia, 5,800 km from where we caught him in Cornwall.Our furthest flown bird, he sent data on 15 September showing that he had moved.  His new location put him nearly 2000 km west of his breeding site and it looked as though he was on his way back to the UK. Ten days later and Monkey had not travelled any further. It is common for birds to pause on migration like this; resting at stopover sites to recuperate. Monkey will be trying to maintain an optimum body weight and condition to ensure he is fit for the rest of his long journey.

More recently, we received data from Busy on 14October. This shows him/her near Kaliningrad, Russia. This is approximately 580 km west of the location received on 6 October, near the Belarusian border where Busy spent the summer. These are promising signs, but why have we not seen more movement from the other birds?

 Research data is encouraging

 During August and September woodcock undergo their annual moult, replacing their old feathers with a new set. During this time woodcock may find themselves more vulnerable to predators and may go to greater lengths to remain out of sight. If our tagged birds are doing this, the dense cover in which they have been roosting and feeding may be disrupting the transmission of data.

We had foreseen this issue, but are hoping that once the birds begin migration their tags will start to transmit normally again. The data sent by Busy and Monkey are encouraging because it suggests this is the case. Both these birds had gone through a period of apparent inactivity, only to resume transmission several weeks later.  We are hoping that as the other birds set off we will see them all reappear on our map.

In the meantime, we are able to look at the data that the tags have been sending. During moult, the birds’ tags do transmit, it’s simply that dense vegetation can disrupt this and makes transmissions less accurate. These less accurate data, although not currently displayed on our map, can still be of a sufficient quality to give an idea of where the birds are. Using these data we can piece together what our birds have been doing during these ‘quiet’ periods.