Wednesday, 22 January 2014

A Finnish Woodcock, Caught in Norfolk, Wintering in Germany

Until today, we had not heard from Wensum since the 26th October. Back then, she was recorded spending time in southern Sweden, assumedly on her way back from her summer home in Finland to Norfolk where she was tagged last winter. But new data received today place Wensum in northern Germany on the 19th January 2014.

We had expected to see most of the woodcock returning to the same winter sites year on year. This is certainly the pattern shown by other woodcock that we have studied with satellite-tags or geolocators in the past. Yet Wensum has not conformed to this pattern.

Olwen is the only other bird we are hearing from regularly at the moment. Just like Wensum (s)he has bucked the trend and instead of returning to her tagging site in Wales has only made it as far back as East Yorkshire. So why are this year’s birds not choosing not returning to their 12/13 wintering grounds?

It seems likely that the milder winter weather has a lot to do with it. In extremely cold conditions more birds are pushed into the UK, particularly the South and West, where temperatures are kept comparatively clement by the warm gulf stream. In a mild winter, like this one, the pressure to perform such long migrations is lessened; without the push of cold conditions it makes little sense to fly any further than necessary. Until recently the temperature in northern Germany where Wensum is currently wintering has hovered above the 0°C mark meaning it is warm enough for woodcock to feed in unfrozen soil.

This does beg the question though: does Wensum usually winter in Germany, but happened to be in Norfolk last year due to an unusually cold February 2013? Or does she usually winter in Norfolk, but has stayed in Germany this year due to a mild winter 13/14?

Interestingly the weather has just taken a turn for the worse in Germany, and forecasts seem to predict that it will get colder still in the coming months. This may mean that Wensum is forced to move further; but will it be to Norfolk?

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