Martyn Priestley found a ringed Black-headed Gull at Harold Park Lake Low Moor on the 23/1/2017 and 25/1/2017.
He did some some research and found that the bird was first ringed at Stavanger Norway on the 22/4/2016 and was aged as a 3cy bird. It remained in and around the area of Stavanger and was sighted twice once on the 30/6/2016 and again on the 9/7/2016. It was not recorded again until the 23/1/at Low Moor.
To me this suggests the bird (given it's age ) may be moving south in autumn to the UK and possibly returning to breed in Norway..