birds chapter 42 table of contents section 1 origin and evolution of birds section 2 characteristics...
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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.
Section 1 Origin and Evolution of BirdsChapter 42
Characteristics
There are seven characteristics all birds share
• Feathers• Wings• Lightweight, rigid skeleton• Endothermic metabolism• Unique respiratory system• Beak• Oviparity
Section 1 Origin and Evolution of BirdsChapter 42
Evolution
There are several similarities between birds and some dinosaurs:
• Flexible S-shaped neck
• Unique ankle joint
• Hollow bones
Section 1 Origin and Evolution of BirdsChapter 42
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
Section 1 Origin and Evolution of BirdsChapter 42
Evolution, continued
Archaeopteryx had characteristics of birds and dinosaurs.
Section 1 Origin and Evolution of BirdsChapter 42
Evolution, continued
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
Section 1 Origin and Evolution of Birds
Chapter 42
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Visual Concept
Adaptations for Flight
Section 1 Origin and Evolution of Birds
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
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Visual Concept
Characteristics of Birds
Section 2 Characteristics of Birds
Section 2 Characteristics of BirdsChapter 42
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.
Section 2 Characteristics of BirdsChapter 42
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
Section 2 Characteristics of BirdsChapter 42
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
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Visual Concept
Parts of a Feather
Section 2 Characteristics of Birds
Chapter 42
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Visual Concept
Preening
Section 2 Characteristics of Birds
Section 2 Characteristics of BirdsChapter 42
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.
Section 2 Characteristics of BirdsChapter 42
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.
Section 2 Characteristics of BirdsChapter 42
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.
Section 2 Characteristics of BirdsChapter 42
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
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Visual Concept
Bird Digestive System
Section 2 Characteristics of Birds
Section 2 Characteristics of BirdsChapter 42
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.
Section 2 Characteristics of BirdsChapter 42
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
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Visual Concept
Bird Lungs
Section 2 Characteristics of Birds
Section 2 Characteristics of BirdsChapter 42
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
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Visual Concept
Bird Heart
Section 2 Characteristics of Birds
Section 2 Characteristics of BirdsChapter 42
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
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Visual Concept
Parts of a Bird Brain
Section 2 Characteristics of Birds
Section 2 Characteristics of BirdsChapter 42
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.
Section 2 Characteristics of BirdsChapter 42
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.
Section 2 Characteristics of BirdsChapter 42
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.
Section 2 Characteristics of BirdsChapter 42
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.
Section 2 Characteristics of BirdsChapter 42
Reproduction, continued
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.
Section 2 Characteristics of BirdsChapter 42
Reproduction, continued
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
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Visual Concept
Anatomy of a Bird
Section 2 Characteristics of Birds
Section 2 Characteristics of BirdsChapter 42
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.
Section 3 ClassificationChapter 42
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
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Visual Concept
Beak Adaptations and Bird Diversity
Section 3 Classification
Chapter 42
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Visual Concept
Foot Adaptations and Bird Diversity
Section 3 Classification
Section 3 ClassificationChapter 42
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
Section 3 ClassificationChapter 42
Diversity, continued
Order Anseriformes
• Includes swans, geese, ducks and other waterfowl
– Webbed feet
– Flattened bill
– Precocial young
Section 3 ClassificationChapter 42
Diversity, continued
Order Strigiformes
• Includes owls
– Nocturnal
– Keen vision with forward facing eyes
– Predators
– Keen hearing
Section 3 ClassificationChapter 42
Diversity, continued
Order Apodiformes
• Includes hummingbirds and swifts
– Small birds with tiny feet
– Fast flying, some can hover
– Insectivores and nectar feeders
Section 3 ClassificationChapter 42
Diversity, continued
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
Section 3 ClassificationChapter 42
Diversity, continued
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
Section 3 ClassificationChapter 42
Diversity, continued
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.
Section 3 ClassificationChapter 42
Diversity, continued
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
Section 3 ClassificationChapter 42
Diversity, continued
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
Section 3 ClassificationChapter 42
Diversity, continued
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
Section 3 ClassificationChapter 42
Diversity, continued
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