The books suggest that Curlews generally spend the breeding season in upland areas and then head for the coast in the winter.  This makes sense, since they seem to appear on our local moors around early March and disappear around October time.  When I used to live near the coast in Cornwall, they would appear around October time and disappear around Feb / March.

I was wondering if anyone knows whether any specific ringing studies have been done on Curlews which breed in this area, and if anyone has figured out where "our local Curlews" go for the winter ?

It's probably wishful thinking, but I can't help wondering if a few of the birds I used to see in Cornwall in winter might have been the same ones which I've subsequently seen in summer in Yorkshire.

Many thanks for your comments David.  After some searching I found a paper on the subject of Curlew migration dating back to 1978, based on ringing studies.  This seemed to confirm, as you suggested, that the Curlews which breed in Northern England generally head west or south west for the winter.  One interesting finding, however, was that there were a number of recoveries in Cornwall of Curlews ringed in the Netherlands, so I guess I'll never know for sure if the Curlews from my days in Cornwall were from Yorkshire or simply Dutch!