Black Skimmers are medium-sized ternlike seabirds with very long wings and an outsized bill in which the lower mandible is much longer than the upper. At hatching, the upper and lower bill of a young Black Skimmer are equal in length, but by fledging at four weeks, the lower mandible is already nearly a half-inch longer than the upper.
Skimmers feed by opening the bill and dropping the long, narrow lower mandible into the water, skimming along until they feel a fish. Then they relax the neck, quickly closing their jaws and whipping the fish out of the water. Because they feed by essentially by touch, they can even forage at night.