BIRDS WHAT IS A BIRD Birds can maintain

BIRDS

WHAT IS A BIRD? Birds can maintain a constant internal body temperature. They have feathers, two legs covered with scales used for walking or perching. They have front limbs modified into wings. Feathers are made of protein and develop in the birds’ skin. Feathers are important for flight and to keep the bird warm. There are 2 types of feathers: contour and down feathers.

FORM, FUNCTION, AND FLIGHT Birds have many different things that allow them to fly: they have a highly efficient digestive, respiratory, and circulatory system; aerodynamic feathers and wings; strong, lightweight bones; and strong chest muscles.

BODY TEMPERATURE CONTROL Birds are endotherms. That means they can generate their own body temperature. Birds, mammals, and a few other animals have a high rate of metabolism. Metabolism are all of the chemical reactions inside an animal. This process produces heat. A bird’s feathers insulate its body enough to conserve its metabolic energy keeping the bird warm.

FEEDING The more food a bird eats, the more heat energy its metabolism can generate. Small birds have to eat more than large birds because they lose heat faster. Birds will have different beaks based on what they eat. Insect eaters have short, fine bills. Seed eaters have short, thick bills. Carnivorous birds have strong hooked bills. Nectar eaters have long, thin bills. Fruit eaters have large, long bills. Fish eaters have long, flat bills.

Birds do not have teeth. Birds have a crop – food is stored and moistened in the crop. After the crop food moves to the stomach. Birds that eat insects and seeds have a gizzard to help them grind food down. Food moves from the stomach to the small intestine.

RESPIRATION When a bird inhales the air will enter large air sacs. Birds have a very effective respiratory system. The respiratory system helps them to keep a high metabolic rate and maintain body temperature. A good respiratory system is also important for flight.

CIRCULATION Birds have a 4 chambered heart with 2 separate loops. They keep oxygen-rich and oxygenpoor blood completely separate.

RESPONSE Birds have a well-developed sense system to help them with flight. Birds have well developed eyes and see color very well. Most birds can also hear well. Taste and smell is not well-developed in birds.

MOVEMENT Some birds cannot fly but they get around by walking or running. Most birds can fly. They have bones that are fused together to make a rigid skeleton to help fly. Bird bones are lightweight. They have large chest muscles.

REPRODUCTION Birds lay amniotic eggs like reptiles but they have a hard outer shell. Most birds will incubate their eggs until they hatch.

GROUPS OF BIRDS There a large variety of birds. The largest order of birds are passerines or perching birds. Pelicans and their relatives – found in aquatic ecosystems. All have 4 toes connected by a web. Parrots – colorful, noisy, use feet to hold food. Birds of prey – good predators with hooked bills, large wingspans, and sharp talons. Cavity-nesting birds – these birds live in holes they make in trees, mounds, or underground tunnels Herons and relatives – adapted to wade in water. Ostriches and relatives – flightless birds that must move by running or swimming.

ECOLOGY OF BIRDS Some birds are important for pollinating – like a hummingbird. Some birds are important for seed dispersal – they will eat seeds but not digest them so the seeds come out in the droppings. They can control insect populations. Many birds migrate. They can help indicate if there is a problem in the environment.