Pelicans are social and gregarious. Males and females, juveniles and adults, congregate in large flocks for much of the year. Pelicans are primarily fish eaters, and require up to 4 pounds of fish a day. This includes menhaden, herring, sheepshead, pigfish, mullet, grass minnows, top minnows, and silversides. Brown pelicans have also been known to eat some crustaceans, usually prawns.
Brown pelicans have extremely keen eyesight.
As they fly over the ocean, sometimes at heights of 60 to 70 feet, they can spot a school of small fish, or even a single fish. Diving steeply into the water, they may submerge completely or only partly depending on the height of the dive, and come up with a mouthful of fish. Air sacs beneath the pelican's skin cushion the impact and help it surface. Brown pelicans nest in large colonies on the ground, in bushes, or in the tops of trees. On the ground, a nest may be a shallow depression lined with a few feathers and a rim of soil built up 4 to 10 inches above ground, or it may be a large mound of soil and debris with a cavity in the top.