IT is reputed (Countryside, 12, No. 5, 93 ; 1942) that it is exactly fifty years since flocks of gulls began to winter on the London Thames, in the severe winter of 1892. Most of these birds are black-headed gulls, but whether or not the severe winter of 1892 was the origin of gulls frequenting the Thames embankment in numbers is not accepted by all ornithologists. T. L. Bartlett notes that sixty years ago the occasional appearance of gulls in London caused unusual interest amongst ornithologists, and although there were,occasional records of gulls passing up-river in severe weather, the first winter occupation of central London by black-headed gulls appears to be the severe winter of 1892 at Blackfriars Bridge., where new legislation protected them from gunshot. But the black-headed gull has not really changed its habit: it was always known as an inland as well as coastal bird. The difference in the past fifty years has been its great increase in numbers-which may be from biological reasons-and its protection under the bird laws which give it encouragement to stay on waters where formerly it was persecuted and driven away. Bartlett, however, suggests also that they were encouraged to winter on the Thames after 1892 by the public feeding the gulls with large sprats, and fifty years of embankment feeding with bread have changed its ways to a town gull. The habits of Thames gulls have, however, been given exaggerated importance. Similar changes in the status of the black-headed gull have occurred in the Mersey and other rivers where there was no great public feeding of the gulls, and the flocks became regular winter inhabitants of the park lakes.