The Pied-billed Grebe is described by the Cornell Lab of Ornithology as part bird, and part submarine. They live in sluggish rivers, freshwater ponds, lakes, marshes and estuaries. They are excellent divers and are able to adjust their buoyancy to match their hunting needs. They have chunky bills, and eat a variety of fish and crustaceans, including frogs. See link below to see how a Grebe can swallow a bullfrog in one piece! The bill develops a black band during mating season, accounting for the name "pied." It All images here taken at Sweetwater Wetlands, where this bird is common.
For more on the Pied-billed Grebe, and a sequence of a Grebe swallowing a frog at Sweetwater Wetlands, follow this link to the blog post in January 2016.