Grebes are small to medium-large in size, have lobed toes, and are excellent swimmers and divers. However, although they can run for a short distance, they are prone to falling over, since they have their feet placed far back on the body.
Grebes have narrow wings, and some species are reluctant to fly. They respond to danger by diving rather than flying, and are in any case much less wary than ducks. Bills vary from short and thick to long and pointed, depending on the diet, which ranges from fish to freshwater insects and crustaceans. The feet are always large, with broad lobes on the toes and small webs connecting the front three toes.
Grebes make floating nests of plant material concealed among reeds on the surface of the water. The young are precocial, and able to swim from birth.
Cormorants are medium-to-large seabirds. The bill is long, thin, and sharply hooked. Their feet have webbing between all four toes, as in their relatives.
They are coastal rather than oceanic birds, and some have colonised inland waters. All are fish-eaters, dining on small eels, fish, and even water snakes. They dive from the surface, though many species make a characteristic half-jump as they dive, presumably to give themselves a more streamlined entry into the water. Under water they propel themselves with their feet.
Cormorants are colonial nesters, using trees, rocky islets, or cliffs. The eggs are a chalky-blue colour.