Birds come in many varieties and have different behaviors. They search for food like worms and mollusks by poking their beaks in sand or soil. Birds sing to attract mates and mark their territory, combining songs with flight displays. There are many types of birds including backyard, sea, shore, ground, and woodpeckers birds as well as hawks, eagles, vultures, hummingbirds and owls. Examples given include the sanderling, rock-hopper penguin, American coot, yellow-bellied sapsucker and wood stork. The yellow-bellied sapsucker is noted as a favorite due to its red crown and pale yellow underparts.