They can crack open shellfish on hard surfaces. They often attend breeding colonies of birds and seals, cleaning up the scraps or attacking the young or injured. In cities they have adapted well enough to raise their young on rooftops while feeding them on garbage scavenged at dumps. Out on the Bank, gulls can be one of the most obvious indicators seasonal and environmental change. Gulls go through plumage changes throughout the year and their seasonal movements mean that different gulls use the Bank in different ways at different times.
Terns are quite different.
These slim, fragile looking birds are quite specialized. Their long wings and forked tails give them flying abilities unmatched on Stellwagen. These are summer residents of the area, moving north in summer to take advantage of fish populations to feed their young in protected colonies. After hovering over schooling fish, terns make a fast, shallow dive into the school, picking off an individual with their tweezer-like bills. . . Their crisp black and white plumage and sheer size distinguish them from all other birds on Stellwagen.