The herring gull is a very common sea bird in both Europe and Northern America, however on Iceland it is a relatively new species, where it started to colonise in the 1920s. It is very closely related to the glaucus gull and hybridisation between the two species occurs occasionally throughout Europe. They are large gulls with hefty bills and robust bodies. They tend to rally around fishing boats or refuse dumps and are loud and competitive scavengers. Despite their name, they have no preference for herrings. In fact, studies have shown that echinoderms and crustaceans comprise a greater portion of their diet than fish.