 In large birds, they are one to two inches long, and in songbirds, about half an inch.Many other species produce pellets, including grebes, herons, cormorants, gulls, terns, kingfishers, crows, jays, dippers, shrikes, swallows, and most shorebirds.Ornithologists examining pellets have discovered unusual items in them—even bird bands that were once attached to a smaller species that was consumed by the predator bird.