NOTES PRESENTATION TANNON YU JACOB BREAUX KHALID YUSUF Chapter 31-2: Birds

What Is a Bird? KEY CONCEPT: Birds are reptilelike animals that maintain a constant internal temperature. Key features include wings, two legs, and feathers. Minor Details: Feathers are mostly made of protein. There are two types of feathers: contour and down.  Contour feathers provide the lifting force and balance for flight.  Down feathers provide warmth.  Some birds that live in water have powder down feathers, which release a fine powder to repel water. The legs are covered with scales.

Evolution of Birds KEY CONCEPT: Paleontologists agree birds evolved from extinct reptiles. Most believe they evolved directly from dinosaurs through the Archaeopteryx (  pictured to the left), an animal that appears to be a transitional species, sharing characteristics of both dinosaurs and birds. Others insist birds and dinosaurs both evolved from an earlier common ancestor and are not directly related.

Form, Function, and Flight KEY CONCEPT: Highly effective digestive, respiratory, and circulatory systems along with aerodynamic feathers and wings, strong lightweight bones, and strong chest muscles enable birds to fly.

BODY TEMPERATURE CONTROL ENDOTHERMS Animals that can generate their own body heat. METABOLISM The sum of chemical and physical processes that go on inside the body. Unlike reptiles, birds are endotherms (  definition to the left). To maintain a constant internal body temperature, birds have a high metabolism (  definition to the left) rate, which produces heat.

FEEDING CROP Moistens and stores food. Produces a substance rich in fat and protein during nesting season, which is regurgitated by the parents and feed to the young birds. GIZZARD Mechanically breaks down food by grinding. OBTAINING NUTRITION: 1. Food enters mouth. 2. Food travels down esophagus and stored in the crop (  definition to the left). 3. Moistened food travels into the first chamber of a two-chamber stomach. There, the first chamber secretes acid and enzymes to partially digest the food. 4. Partially digested food then goes to the gizzard (  definition to the left), where the food is squeezed while being grinded. 5. Digestion continues through the intestines. 6. Undigested food is expelled through the cloaca.

FEEDING continued… Bird beaks (bills) are often adapted to the type of food they eat.  Insect-eating birds have short, fine bills (  pictured to the left).  Seed-eating birds have short, thick bills.  Carnivorous birds have strong hooked bills.  Large, flat bills are used to eat fish.  Large, long bills are used to eat fruit.

RESPIRATION When a bird inhales, most air enters large posterior air sacs in the body cavity and bones. It then flows through the lungs in a series of small tubes. Birds’ respiratory system flows in one direction. The one-way flow constantly exposes the lungs to oxygen-rich air.

CIRCULATION Birds have a double-loop circulatory system and a four-chambered heart.

EXCRETION Nitrogenous wastes are removed from the blood by kidneys, converted to uric acid, and deposited in the cloaca. Uric acid, combined with water, is expelled through the cloaca as bird droppings.

RESPONSE Birds have highly developed nervous systems. Minor Details: Their brains are rather large in relation to their body size. They can perceive color extremely well, sometimes even better than humans. Their sense of taste and smell are poor though…

Bird Brain Diagram

MOVEMENT The vast majority of birds move by flight. Those that cannot fly move by walking/running, or swimming.

REPRODUCTION Both male and female reproductive tracts open in the cloaca. Birds reproduce by internal fertilization. Minor Details: When it is not breeding season, the reproductive organs often shrink in size. When birds prepare to mate, the ovaries and testes enlarge until they reach functioning size. Cloacas are then pressed together to transfer sperm. Some male birds may have a penis. Bird eggs are amniotic.

Groups of Birds KEY CONCEPT: There are nearly 30 different orders of birds. The largest of which are the passerines, or perching birds. There are over 5,000 species of passerines.

The Most Awesomest Birds

Diversity in Birds Pelicans Ostriches Perching birds Parrots Herons Birds of prey

ECOLOGY OF BIRDS Birds also serve as important indicators of environmental health. Birds are often killed in horrific accidents involving vehicles, such as planes and cars. These are known as bird strikes.