Red knots feed on horseshoe crab eggs in spring in Delaware Bay. (Photo: Gregory Breese/USFWS)
As winter eases its grip, migratory birds return from southern wintering areas. National wildlife refuges provide critical habitat for ducks, geese, songbirds and shorebirds on their northward flights. Hungry and tired, migrating birds begin arriving in northern refuges as early as February and continue through May. As the air warms and the ground thaws, many other rites of spring take place in the air, on land and at sea.
Saline shooting stars bloom at J. Clark Salyer National Wildlife Refuge in North Dakota. (Photo: Gary Eslinger/USFWS)