Birds are feathered flying vertebrates and are quite diverse, including around 10,000 species, with more than half being small perching birds. Because birds are widespread and abundant, they are important for almost all cultures, but particularly those larger sized birds like waterfowl, upland fowl, shorebirds, and seabirds.
Birds are warm-blooded, feathered vertebrates represented by approximately 10,000 species worldwide. Bird flight adaptations include light, air-filled bones, forelimbs that are modified into wings of various sizes and shapes, and feathers that provide both lift and insulation. Birds are very diversified, including small groups with few species, like loons and grebes, and groups with a few hundred species, like waterfowl, upland fowl, shorebirds and seabirds. But the dominant group of birds is by far the perching birds, which includes a vast array of small-sized birds, including jays, sparrows, and warblers.
Reference
Hickman CP, Roberts LS, Larson A: Animal Diversity. Boston: McGraw-Hill; 2000.