Characteristic of Birds

Birds are an endothermic vertebrate that have feathers, four-chambered heart and they have hollow bones. Most birds are adapted fir flight, feathers help birds fly, many of a bird’s bines are nearly hollow which can make their body lightweight. A contour feather is one of the large feathers that give shape to a bird’s body. The long contour feathers that extend beyond the body on the wings and tail are called flight feathers. When a bird flies, these feathers help it balance and steer. Birds also have short, fluffy down feathers that are specialized to trap heat and keep the bird warm.
Like reptiles, birds have internal fertilization and lay eggs. Bird eggs are hard-shelled. The hard shell keeps an egg from drying out and allows parents to sit on the eggs during incubation. Even though bird eggs are hard-shelled, they have microscopic pores which allow oxygen to pass into and carbon dioxide to exit the shell.