Birds Chapter 42 Table of Contents Section 1 Origin and Evolution of Birds Section 2 Characteristics of Birds Section 3 Classification.

BirdsChapter 42

Table of Contents

Section 1 Origin and Evolution of Birds

Section 2 Characteristics of Birds

Section 3 Classification

Section 1 Origin and Evolution of BirdsChapter 42

Objectives

• Identify and describe seven major characteristics of birds.

• List three similarities between birds and dinosaurs.

• Describe the characteristics of Archaeopteryx.

• Summarize the two main hypotheses for the evolution of flight.


Characteristics

There are seven characteristics all birds share

• Feathers• Wings• Lightweight, rigid skeleton• Endothermic metabolism• Unique respiratory system• Beak• Oviparity

Chapter 42

Characteristics of Birds



Evolution

There are several similarities between birds and some dinosaurs:

• Flexible S-shaped neck

• Unique ankle joint

• Hollow bones


Evolution, continued

The oldest known bird fossils are in the genus Archaeopteryx, which date from the late Jurassic

Characteristics of Archaeopteryx

• Feathers on forelimbs, body and tail• Hollow bones and a furcula (fused collarbones

also called a wishbone)• Teeth• Claws on forelimbs• Long, bony tail



Archaeopteryx had characteristics of birds and dinosaurs.



Origin of Flight

• One hypothesis proposes that the ancestors of birds were tree dwellers that developed the ability to glide between trees.

• Another hypothesis suggests that the ancestors of birds were ground-dwelling and first used feathers to stabilize them when they leapt after prey.

Chapter 42

Phylogenetic Diagram of Birds, Reptiles, and Mammals


Chapter 42

Click below to watch the Visual Concept.

Visual Concept

Adaptations for Flight


Section 2 Characteristics of BirdsChapter 42

Objectives

• Describe the structure of a contour feather.

• Identify two modifications for flight seen in a bird’s skeletal system.

• Contrast the function of the gizzard with that of the crop.

• Trace the movement of air through the respiratory system of a bird.

• Explain the differences between altricial and precocial young.

Chapter 42


Visual Concept

Characteristics of Birds



Feathers

Feathers are modified scales that serve two primary functions: providing lift for flight and conserving body heat.

• Feathers develop from tiny pits in the skin called follicles.• Feathers have a shaft, two vanes, barbs and barbules.


Feathers, continued

There are three basic types of feathers:

• Down feathers - soft, fluffy feathers that cover young birds and provide an insulating undercoat in adults

• Contour feathers - smooth feathers that give adult birds’ bodies a streamlined shape and provide insulation

• Flight feathers - specialized contour feathers located on the wings and tail that are long and rigid


Feathers, continued

Feathers are cared for by a process called preening.

• Preening occurs when birds use their beaks to rub their feathers with oil.

• The preen gland is located at the base of the tail and secretes oils that keep feathers healthy and waterproof.

• Birds periodically shed and regrow their feathers in a process called molting.

Chapter 42

Contour Feather Structure


Chapter 42


Visual Concept

Parts of a Feather


Chapter 42


Visual Concept

Preening


Chapter 42

External Structure of Birds—Bald Eagle



Skeleton and Muscles

• The avian skeleton is light and strong.

• Bones are thin and hollow.

• Many bones are fused, which makes the skeleton more rigid than that of a reptile or mammal.

• A large keel-shaped sternum allows attachment of large flight muscles.

• The pygostyle, fused terminal vertebrae, supports the tail feathers.

Chapter 42

Avian Skeleton



Skeleton and Muscles, continued

• Flight involves complex wing movements. Each movement uses a different set of muscles.

• Birds have large, powerful flight muscles in the breast and wings.

• In some birds, flight muscles account for up to 50% of the body weight.


Metabolism

• Birds are endothermic.

• Birds have a very high metabolic rate.

• Rapid breathing and digestion of large quantities of food support this high metabolic rate.

• Birds’ digestive and respiratory systems have evolved to support a high metabolism.


Digestive and Excretory Systems

The avian digestive system consists of:

• Beak - breaks open or tears apart food• Esophagus - passage from the mouth to the crop• Crop - stores and moistens food• Stomach - consists of two parts

– proventriculus - acids and digestive enzymes begin breaking down food

– gizzard - kneads and crushes food aided by stones which the bird swallows

• Small intestine - absorbs nutrients• Large intestine - absorbs water• Cloaca - eliminates wastes from the body

Chapter 42


Visual Concept

Bird Digestive System



Digestive and Excretory Systems, continued

The avian excretory system is efficient and lightweight.

• Birds have two kidneys that filter nitrogenous wastes.

• Birds do not have a urinary bladder.

• Birds excrete concentrated uric acid, which conserves water.

• Uric acid mixes with feces and is excreted through the cloaca.


Respiratory System

• The avian respiratory system is highly efficient and allows birds to maintain a high metabolic rate.

• Air sacs connected to the lungs provide a constant flow of oxygenated air to the lungs.

• This also allows birds to function at high altitudes.

Chapter 42

Avian Lung Structure


Chapter 42


Visual Concept

Bird Lungs



Circulatory System

The avian circulatory system is similar to that of both crocodiles and mammals.

• Birds have a four chambered heart.• Deoxygenated blood is completely separated

from oxygenated blood in the heart.• Birds have a relatively rapid heartbeat.• Unlike mammals, avian red blood cells have

nuclei.

Chapter 42

Avian Heart Structure


Chapter 42


Visual Concept

Bird Heart



Nervous System and Sense Organs

• Birds have large brains relative to their body size.

• The cerebellum, which controls flight related functions, is large.

• The cerebrum, which controls complex behavior, is also well developed.

• The optic lobes are also very large.

Chapter 42


Visual Concept

Parts of a Bird Brain



Nervous System and Sense Organs, continued

Birds have very good vision.

• Vision is important for flight and feeding.

• Most birds have strong color vision.

• Some birds have eyes located near the sides of the head, which provide a wide field of vision.

• Predatory birds have eyes that are more forward-facing, which provides depth perception.


Nervous System and Sense Organs, continued

Birds have good hearing.

• Hearing is important for songbirds and nocturnal birds.

• Nocturnal predators rely on hearing to locate prey.

• Birds lack external ears.

• Owls have feathers around their ear openings that direct sound into the ear.


Reproduction

Male:• Sperm is produced in two testes, located anterior

to the kidneys.• Sperm passes through small tubes called vasa

deferentia (singular vas deferens).• Sperm exits through the cloaca.


Reproduction, continued

Female:• Eggs are produced in a single ovary, located on

the left side of the body.• Eggs are released by the ovary and pass into a

funnel shaped tube called the oviduct.• Eggs are fertilized in the oviduct.• In the oviduct, eggs are encased in a protective

covering and a shell.• Eggs are released through the cloaca.



Nest building and parental care

• Birds usually lay their eggs in a nest.• One or both parents warm (incubate) the eggs

and guard the nest.• Birds sit on their eggs and cover them with a

thickened featherless patch of skin called the brood patch.

• Birds usually provide extensive parental care.



Birds have two general patterns for rearing young

• Precocial: Young incubate for long periods. Young can walk, swim, and feed as soon as they hatch. This pattern is most often seen in ground-nesting birds.

• Altricial: Eggs hatch quickly. Young hatch blind, featherless, and helpless and require extensive parental care. This pattern is most often seen in birds that nest above ground.

Chapter 42

Internal Structure of Birds—Bald Eagle


Chapter 42


Visual Concept

Anatomy of a Bird



Migration

Migration is the seasonal movement of animals from one habitat to another habitat.

• Many birds nest in temperate regions, and spend winters in tropical regions.

• Bird migration patterns are studied by ornithologists - biologists who study birds.

• Birds may use landmarks, star position, sun position, Earth’s magnetic field, changes in air pressure, or low-frequency sounds to navigate during migration.

• Many species rely on fat reserves for energy during migration. Some species gather and feed along the migration route at places called staging sites.

Section 3 ClassificationChapter 42

Objectives

• Describe the relationship between beak shape and diet in birds.

• List 10 major orders of living birds, and name an example of each order.

• Describe the function of the syrinx.


Diversity

Beak and foot adaptation reveal information about a bird’s habitat and diet, for example:

• Predators: powerful, hooked beaks and sharp talons (claws)

• Seed eaters: strong wide beaks, small feet for perching

• Nectar feeders: long thin beaks • Flightless birds: strong legs for walking and

running

Chapter 42

Avian Adaptations


Chapter 42


Visual Concept

Beak Adaptations and Bird Diversity


Chapter 42


Visual Concept

Foot Adaptations and Bird Diversity



Diversity, continued

• Taxonomists divide birds into about 23 orders.• Morphology (body form), protein sequences, DNA

sequence, and other evidence are used to classify birds.• Ten of the most familiar orders are listed below.

» Anseriformes» Strigiformes» Apodiformes» Poittaciformes» Piciformes» Passeriformes» Columbiformes» Ciconiiformes» Galliformes» Struthioniformes



Order Anseriformes

• Includes swans, geese, ducks and other waterfowl

– Webbed feet

– Flattened bill

– Precocial young



Order Strigiformes

• Includes owls

– Nocturnal

– Keen vision with forward facing eyes

– Predators

– Keen hearing



Order Apodiformes

• Includes hummingbirds and swifts

– Small birds with tiny feet

– Fast flying, some can hover

– Insectivores and nectar feeders



Order Psittaciformes

• Includes parrots, parakeets, macaws, cockatoos, cockatiels and their relatives

– Seed and fruit eaters

– Strong hooked beaks for opening seeds

– Two forward facing and two backward facing toes, for climbing and perching

– Vocal birds, some can mimic human speech



Order Piciformes

• Includes tree dwelling birds such as woodpeckers, honeyguides and toucans.

– All nest in tree cavities

– Two forward and two backward facing toes

– Woodpeckers have sharp, chisel-like bills

– Toucans are fruit eaters and have large bills



Order Passeriformes

• Includes robins, warblers, blue jays, wrens, and other common North American birds

– Perching birds with three toes forward and one backward, with enlarged rear toe for grip

– Seed, fruit, insect, and nectar feeders

– Many are songbirds. Males use elaborate songs to attract females. The song is produced in a structure called the syrinx.



Order Columbiformes

• Includes pigeons and doves

– Large breasts and small heads

– Fruit or grain eaters with small beaks and short legs

– Both sexes feed young with nutritious fluid produced in the crop, called crop milk



Order Ciconiiformes

• Includes herons, storks, ibises, egrets, raptors, vultures and penguins

– Highly diverse group

– Many are wading birds that eat fish and frogs, with long legs, long neck, and long bill

– All are carnivorous



Order Galliformes

• Includes turkeys, chickens, pheasants, grouse, and quails

– Commonly called fowl

– Usually plump bodies, may be poor fliers

– Grain and insect eaters

– Precocial young



Order Struthioniformes

• Includes ostriches, emus, rheas, and cassowaries

– Includes the worlds largest birds

– Fightless birds with small wings and long powerful legs for running

– Ostriches can reach speeds of 55 mph

– Ostriches have two toes per foot

Chapter 42


Visual Concept

Types of Birds


Birds Chapter 42 Table of Contents Section 1 Origin and Evolution of Birds Section 2 Characteristics of Birds Section 3 Classification.

Documents

evolution of birds section

evolution of birds chapter

feathers feathers

young birds

ancestors of birds

adult birds

major characteristics

birds skeletal system