In flight this species' affinity to Gulls is more pronounced than the link thru a heavy bill. On the rare occasions I have seen them I invariably thot of Bonaparte's Gull. They seem to be receding into the tropics and are no longer found in northern parts of their range where once fairly common.
Their "chattering laugh" on the breeding grounds has been translated into katydid, katydid or heywek, heywek.
From Gulf States' coasts southward over a large part of the world.