Laughing gull

The number of black-headed gulls along the Stratford stretch of the Avon has plummeted over the last couple of weeks, as birds take themselves off to their breeding grounds. The RSPB estimate a breeding population in the UK of around 140,000 pairs, but in winter our population rises to over two million, as birds immigrate from mainland Europe, Iceland and Russia to take advantage of our relatively mild winter weather.

Solitary nests aren't unknown, but this species mainly breeds in colonies, which can number several thousand birds in suitable territory. For resident birds, these colonies mostly occur in coastal or inland wetlands and marshes, with favoured inland sites including lakes, reservoirs, sewage works and flooded gravel pits. Breeding birds leave their colonies in late summer and spread out to winter feeding grounds, leaving again in March and April, which is when the breeding season begins. This individual has almost completed its partial moult into breeding plumage, so I assume it won't stay in Stratford much longer.

One of the strangest facts I know about the black-headed gull is that its eggs are regarded by some people as a huge delicacy. Exploitation of gull meat and eggs used to be commonplace - according to the BTO 300,000 eggs per year were sold through Leadenhall Market in London alone during the 1930s - but these days the trade in eggs is strictly regulated. They can only be taken by a few licensed collectors at six sites (four in Hampshire, one in North Yorkshire and one in County Durham) between 1st April and 15th May each year, and only one egg can be taken from each nest. The eggs are only legally available from certain (expensive) licensed fishmongers and restaurants, and cannot be sold after 30th June. When this article was published in Country Life, seven years ago, they gave the cost of the eggs as between £4 and £10 each; this supplier is listing them today at £7.95 each, though (of course) currently unavailable.

Advocates of eating black-headed gulls' eggs assert that under these strict conditions the trade poses no threat to the species, but conservation organisations disagree, and given that a falling winter population over the past few years has led to this gull being placed on the UK Birds of Conservation Concern Amber List, its continuation is uncertain. I can't help thinking that it would be more controversial if more people were aware that it happens.