Chapter 31.2 - Birds

Birds are reptile-like animals that maintain a constant internal body temperature.

Pictures of Birds

Characteristics of Birds Class Aves Feathers, wings and thin

hollow bones which allow for flight Keel shaped sternum

4 chambered heart Respiratory systems consist of: lungs,

anterior and posterior air sacs Endotherms (warm blooded)

Able to regulate their internal body temperature

Characteristics of Birds Internal fertilization (sexual)

Amniotic eggs w/ hard shell Incubate their eggs (keep at a consistent

temperature) Adaptations of birds

Feathered legs and feet of ptarmigans Modified wings and feet of penguins Large eyes, acute sense of hearing and

sharp claws of owls Long beaks of hummingbirds

What is a Bird?

Class Aves Feathers,

modified scales that provide insulation & flight

Wings, power provided by muscles attached to sternum (breastbone)

Feathers are made mostly of protein and develop from pits in the birds' skin. Feathers help birds fly and also keep them warm. The two main types of feathers are contour and down.

FeathersFeathers

What is a Bird?

Other adaptations for flight include hollow bones, high metabolism maintained by 4 chambered heart & air sacs

Endotherm, maintains a nearly constant body temperature that does not depend on environment

Skeletal System of a Bird

• Bones are strengthened by struts.

• Air spaces make bones lightweight.

Form, Function, and Flight

Birds are endotherms (animals that can generate their own body heat) They have a high rate of metabolism

compared to ectotherms (metabolism produces heat)

A bird’s feathers insulate its body enough to conserve most of its metabolic energy

Body Temperature Control

Bird Feeding

The more food a bird eats, the more heat energy its metabolism can generate For this reason, the phrase “eats like

a bird” is quite misleading – birds are voracious eaters

A bird’s beak, or bill, is adapted to the type of food they eat

Bird Digestion

Bird Respiration When a bird inhales, most air first enters

large posterior air sacs in the body cavity and bones

The inhaled air then flows through the lungs in a series of small tubes A complex system of air sacs and breathing

tubes ensures that air flows into the air sacs and out through the lungs in a single direction

This constant, one way flow of oxygen-rich air helps birds maintain their high metabolic rate and generates enough energy for flight

Circulation 4 chambered hearts and two

separate circulatory loops

Bird Circulation

Right atrium

Left atrium

Complete division

Heart

Domestic pigeon

Left ventricle

Right ventricle

Structure of Bird’s Heart

Excretion Similar to those of reptiles – white,

pasty uric acid droppings

Bird Excretion

Response Well developed sense organs Well developed eyes that can see

color Excellent hearing

Bird Response

Reproduction in Birds Bird eggs are amniotic eggs

They have hard outer shells Most birds incubate their eggs until

they hatch

Diversity of Birds

A bird’s lifestyle is determined by its type of beak and feet.

Diversity of Birds

Diversity of Birds