bird, Any of the warm-blooded, beaked vertebrates of the class Aves, including more than 9,600 living species. A covering of feathers distinguishes birds from all other animals. Birds have a …

2025年3月18日 · Bird - Anatomy, Flight, Migration: The structures associated with flight distinguish birds from other animals. Feathers are made of keratin; contour feathers are shed …

Birds have been significant to human society in many ways. Birds and their eggs have been sources of food for humans since their origin and still are in most societies. The eggs of some …

From pigeons in big cities to penguins in Antarctica, all birds have similar features. They all have wings, though they cannot all fly. All birds also have feathers. In fact, birds are the only living …

2025年3月18日 · 66 species in 6 families worldwide, including cormorants, boobies, gannets, tropic birds, and frigate birds. Water birds with all 4 toes webbed; bill hooked or straight and …

2025年2月6日 · Parrot, term applied to a large group of gaudy, raucous birds of the family Psittacidae. They have been kept as cage birds since ancient times, and they have always …

2025年3月18日 · Bird - Muscles, Organs, Flight: Birds have a complete separation between pulmonary and systemic circulation, hearts that are large for their body weight, lungs …

Birdsong, certain vocalizations of birds, characteristic of males during the breeding season, for the attraction of a mate and for territorial defense. Songs tend to be more complex and longer than …

For centuries people have wistfully watched birds take wing and felt a bit jealous. But what about birds that don’t fly? You’d think they’d hold a grudge against their freewheeling cousins, but …

Beak, stiff, projecting oral structure of certain animals. Beaks are present in a few invertebrates (e.g., cephalopods and some insects), some fishes and mammals, and all birds and turtles. …