The Laughing Gull (Leucophaeus atricilla) is a medium-sized gull of North and South America.
Laughing Gulls take three years to reach adult plumage.
Summer adults have a crisp black hood, white arcs around the eye, and a reddish bill.
In winter, the hood becomes a blurry gray mask on a white head.
The legs are reddish-black to black.
Immatures are much browner and more subtly patterned than adults.
Laughing Gulls are a coastal species and are only occasionally seen very far inland. 
Laughing Gulls eat almost anything, including food they catch or steal, handouts, garbage, and discards from fishing boats.
They often congregate in parking lots, sandy beaches, and mud bars.

Cape Cod, Massachusetts, USA, 10 August 2017