The great black-backed gull is the largest gull that is found in the Chesapeake Bay watershed. Adult birds have a white head (in summer), dark back, and red spot on the bill.
Great black-backed gulls tend to stand out whenever they flock together with other aquatic birds. The species is easily distinguishable not only by its size and dark back, but also by its dominant behavior towards other gulls.
The great black-backed gull is similar in appearance to the American herring gull, but larger and darker above.