Gulls are generally quite widespread and easy to see. However, I rarely see any gulls at Croome. This one is quite common to the general area (you'll see plenty in Worcester), along with the black-headed gull. Herring gulls are similar, but have much paler wings. The greater black-backed gull is only usually found near large bodies of water such as the sea or reservoirs. Lesser black-backed gulls at Croome tend to be with others, in the farm fields behind the Shrubbery, but they are usually just passing through.

The one below was an exception - lurking by the river, probably on the lookout for chicks. You can clearly see the another difference - they have yellow legs (Herring gulls and greater black-backed have pink legs).