Heermann's gulls, the warm-water gulls of summer and fall, accompany Brown pelicans as they fly north each summer.
Although most feed along the shore or in the ocean, some feed on tide flats. They often steal food from Brown pelicans. They may take fish directly from the pelicans' bills immediately after a dive or claim food that pelicans have located, discarded, or disturbed.
This gull is common on the outer seacoasts, beaches, bays and estuaries. They are strongly associated with outer coasts and adjacent ocean waters, usually within a few miles of shore. A few wander inland during the fall southward retreat.