27-1 CHAPTERCHAPTER Birds Birds. Copyright © The McGraw-Hill Companies, Inc. Permission required...

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CHAPTER CHAPTER CHAPTER CHAPTER

BirdsBirds BirdsBirds

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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DiversityDiversity

ProfileProfile Over 9,700 species have been Over 9,700 species have been

described worldwidedescribed worldwide Birds live in all biomesBirds live in all biomes Some live in dark caves, and some dive Some live in dark caves, and some dive

to 45 meters depthto 45 meters depth The “bee” hummingbird is one of the The “bee” hummingbird is one of the

smallest vertebrate endothermssmallest vertebrate endotherms

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.QuickTime™ and a

TIFF (Uncompressed) decompressorare needed to see this picture.


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The The featherfeather is the unique and essential is the unique and essential feature or hallmark of birdsfeature or hallmark of birds Some feathers were also present in some Some feathers were also present in some

dinosaursdinosaurs These feathers were not capable of supporting These feathers were not capable of supporting

flight flight Obviously served in other capacities such as Obviously served in other capacities such as

thermoregulation or mating behaviorthermoregulation or mating behavior

DiversityDiversity


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Uniformity in StructureUniformity in Structure Forelimbs are modified as wings, although not all Forelimbs are modified as wings, although not all

are capable of flightare capable of flight Hindlimbs are adapted for walking, swimming or Hindlimbs are adapted for walking, swimming or

perchingperching All birds have horny, keratinized beaksAll birds have horny, keratinized beaks All birds lay eggsAll birds lay eggs

DiversityDiversity


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Origin and RelationshipsOrigin and Relationships

HistoryHistory Discovery of the fossil of Discovery of the fossil of Archaeopteryx Archaeopteryx

lithographicalithographica in 1861 linked birds and in 1861 linked birds and dinosaursdinosaurs Skull resembled modern birds but had teeth rather Skull resembled modern birds but had teeth rather

than a beakthan a beak Skeleton was reptilian with clawed fingers, Skeleton was reptilian with clawed fingers,

abdominal ribs, and a long bony tailabdominal ribs, and a long bony tail FeathersFeathers were unmistakably imprinted along wings were unmistakably imprinted along wings


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Archaeopteryx - 147 million year old ancestor of bids


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RelationshipsRelationships Modern birds include:Modern birds include:

PaleognathaePaleognathae (Ratite) (Ratite) Large flightless birdsLarge flightless birds with a flat sternum (no keel extension)with a flat sternum (no keel extension)

NeognathaeNeognathae with a keeled sternum (keel is an extension of sternum for high with a keeled sternum (keel is an extension of sternum for high

muscle attachment)muscle attachment) All flying birds…but some non-flyersAll flying birds…but some non-flyers

Original theories were based on ability to flyOriginal theories were based on ability to fly Smaller birds can revert to flightlessness on islands Smaller birds can revert to flightlessness on islands

that lack terrestrial predatorsthat lack terrestrial predators



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Cormorant: FlightlessNeognathae Bird -

(keeled sternum)Lives in GalapagosExcellent Swimmer


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Larger flightless birds such Larger flightless birds such as the ostrich and emu can as the ostrich and emu can outrun predatorsoutrun predators

Flightless birds are free Flightless birds are free from weight restrictions of from weight restrictions of flight and some evolved to flight and some evolved to very large sizesvery large sizes



are needed to see this picture.

Paleognathae Bird


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Structural and Functional Adaptations for FlightStructural and Functional Adaptations for Flight

Feathers Feathers StructureStructure

Hollow quillHollow quill emerges from skin follicle and emerges from skin follicle and continues as a continues as a shaft or rachisshaft or rachis

Rachis bears numerous Rachis bears numerous barbsbarbs Up to several hundred barbs are arranged to form Up to several hundred barbs are arranged to form

a flat, webbed surface, thea flat, webbed surface, the vane vane Each barb resembles a Each barb resembles a miniature featherminiature feather

Numerous Numerous barbulesbarbules spread laterally spread laterally


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A - E: DevelopmentOf Contour FeatherProtective Sheath splits open

when growth is complete.Contour Feathers = Flight Feathers

G: Filoplumes Hairlike, connected to

nervous system (barbs only at top)

H: Down Feather (no hooks, rachis reduced)

Function -Conserve HeatLocated under contour feathers


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Up to Up to 600 barbules in each side600 barbules in each side of a barb of a barb May be May be over one millionover one million in the whole feather in the whole feather

Barbules from two neighboring barbs overlapBarbules from two neighboring barbs overlap ““Zip” together with tinyZip” together with tiny hooks hooks

When separated, they are “zipped” back together When separated, they are “zipped” back together by by preeningpreening

Preening gland (uropygial gland)- secretes oil Preening gland (uropygial gland)- secretes oil (waterproof)(waterproof)



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Molting Molting Fully-grown feather is a dead structureFully-grown feather is a dead structure

Shedding or molting is an orderly processShedding or molting is an orderly process Except in penguins, molting is a gradual process Except in penguins, molting is a gradual process

that avoids leaving bare spotsthat avoids leaving bare spots Flight and tail feathers are lost in pairs,Flight and tail feathers are lost in pairs, one on one on

each side, to maintain balanceeach side, to maintain balance In some species, In some species, replacement is continuousreplacement is continuous

Flight is unimpairedFlight is unimpaired In many water birds,In many water birds, primary feathers are molted primary feathers are molted

all at once all at once Birds are temporarily groundedBirds are temporarily grounded

Most birds Most birds molt once a year,molt once a year, usually in late usually in late summer after the nesting seasonsummer after the nesting season


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Osprey feathers molt in sequence with exact pairs to maintain balance during flight.


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SkeletonSkeleton Bone WeightBone Weight

Modern birds have light, delicate bones laced with Modern birds have light, delicate bones laced with air cavitiesair cavities

Termed pneumatized bonesTermed pneumatized bones Very strongVery strong Total weight of a bird’s feathers may outweigh Total weight of a bird’s feathers may outweigh

skeletonskeleton



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Hollow Wing Bone:(Pneumatized)

Shows Struts andAir Spaces

Strut


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Muscular SystemMuscular System Pectoralis musclesPectoralis muscles

Depress the wing in flight and attached to the Depress the wing in flight and attached to the keelkeel Supracoracoideus muscleSupracoracoideus muscle

Raises the wing, is also attached to the Raises the wing, is also attached to the keelkeel Lays under the pectoralis musclesLays under the pectoralis muscles Pulls the wing up from below by way of a “rope-Pulls the wing up from below by way of a “rope-

and-pulley” type of arrangementand-pulley” type of arrangement



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Flight Muscles:

Contraction of pectoralispulls wing down.

Contraction of Supracoracoideus pulls

wing upward.


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Main leg muscle mass is in thigh with connections by Main leg muscle mass is in thigh with connections by long tendons to feet and toeslong tendons to feet and toes

Toe-locking mechanismToe-locking mechanism prevents a perching bird prevents a perching bird from falling off a branch while asleepfrom falling off a branch while asleep


Tendons automatically

tighten, closingtoes around the

perch


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Food, Feeding and DigestionFood, Feeding and Digestion

Beaks of birdsBeaks of birds often reveal their food often reveal their food habits and vary between seed-eaters, habits and vary between seed-eaters, insect-eaters, etc.insect-eaters, etc.

Woodpecker has a straight, hard, chisel-like Woodpecker has a straight, hard, chisel-like beak to expose insect burrowsbeak to expose insect burrows

Long, flexible, barbed tongue seeks out insects Long, flexible, barbed tongue seeks out insects in wood galleriesin wood galleries

Characteristics of BirdsCharacteristics of Birds


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Different bills of birds

showing adaptationsto different

environments


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Food QuantityFood Quantity Birds are Birds are BIG feeders BIG feeders Have a Have a high metabolic ratehigh metabolic rate

Small birds need even more food per body massSmall birds need even more food per body mass Hummingbirds use oxygen 12 times faster than a Hummingbirds use oxygen 12 times faster than a

pigeon and 25 times that of a chickenpigeon and 25 times that of a chicken Eats 100% of body weight each dayEats 100% of body weight each day Canary about 30% Canary about 30% Chicken about 3.4%Chicken about 3.4%

Have rapid and efficient digestive systems Have rapid and efficient digestive systems A shrike can digest a mouse in 3 hoursA shrike can digest a mouse in 3 hours A thrush will pass berries through the tract in just 30 A thrush will pass berries through the tract in just 30

minutesminutes



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Loggerhead Shrike



Blue-Whistling Thrush


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Because birds Because birds lack teethlack teeth Foods that require grinding are cut apart in the Foods that require grinding are cut apart in the

gizzardgizzard Few taste buds Few taste buds Many have a Many have a crop crop that serves to store food that serves to store food

at lower end of esophagusat lower end of esophagus



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Stomach: 1st Chamber

Stomach’s 2nd chamber: Gizzard

Crop will store food and also regurgitate during nesting time for young.1st chamber of stomach secretes enzymes and acid to help break down food.

Muscular walls of Gizzard move around contents and stones help break down food


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Stomach consists of 2 chambers:Stomach consists of 2 chambers: 1st: Proventriculus1st: Proventriculus

Secretes gastric juice Secretes gastric juice 2nd: Gizzard2nd: Gizzard

Grinds foodGrinds food Birds may Birds may swallow pebbles or gritswallow pebbles or grit to assist to assist

grinding in gizzardgrinding in gizzard Birds of preyBirds of prey such as owls such as owls

Form a Form a pellet pellet of indigestible material in the of indigestible material in the proventriculus and eject itproventriculus and eject it

End of the digestive system is the End of the digestive system is the cloacacloaca Also receives products from genital ducts and uretersAlso receives products from genital ducts and ureters



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Circulatory SystemCirculatory System 4-chambered heart4-chambered heart is large, with strong is large, with strong

ventricular wallsventricular walls Share with mammals:Share with mammals:

complete separation complete separation (oxygenated/deoxygenated)(oxygenated/deoxygenated)



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Larger birds have slower heart rate (Turkey =93 beats/minute)Hummingbird heart rate is over 500 beats/minute


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Respiratory System Respiratory System Differs radically from lungs of reptiles and Differs radically from lungs of reptiles and

mammalsmammals Bird LungsBird Lungs

Air sacs Air sacs Extend into thorax, abdomen, and long bonesExtend into thorax, abdomen, and long bones

Large portion of air bypasses lungs and flows Large portion of air bypasses lungs and flows directly to air sacs on inspirationdirectly to air sacs on inspiration

On expiration, oxygenated air flows through lungsOn expiration, oxygenated air flows through lungs Continuous air flow to anterior air sacs, then exitsContinuous air flow to anterior air sacs, then exits

Takes 2 respiratory Takes 2 respiratory cyclescycles for a single breath of air for a single breath of air to pass through systemto pass through system

Most efficient respiratory system of any vertebrateMost efficient respiratory system of any vertebrate



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One side of lungs and air sacs Showing 2 cycle process of respiratory system


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An air sac system helps An air sac system helps cool bird during cool bird during vigorous exercisevigorous exercise when up to 27 times more when up to 27 times more heat is producedheat is produced

Air sacs extend into bones, legs and wings, Air sacs extend into bones, legs and wings, providing considerable buoyancy providing considerable buoyancy



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Excretory System Excretory System Pair of large Pair of large kidneyskidneys is composed of many is composed of many

thousands of thousands of nephronsnephrons Urine flows through Urine flows through uretersureters to the to the cloacacloaca



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Marine birdsMarine birds excrete larger salt loads due excrete larger salt loads due diet and seawater they drinkdiet and seawater they drink Salt glandsSalt glands located above each eye excrete highly located above each eye excrete highly

concentrated solutionsconcentrated solutions Salt solution runs out the nostrilsSalt solution runs out the nostrils Gulls and other sea birds have a perpetual “runny Gulls and other sea birds have a perpetual “runny

nose”nose”



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Salt Gland of Marine Birds:Salt is secreted into many

radial tubules, then flows intocentral canal that leads to nose,

causing “Runny Nose”


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Nervous and Sensory SystemsNervous and Sensory Systems Have Have good hearing and superb visiongood hearing and superb vision

Best in the animal kingdomBest in the animal kingdom Although Although sense of smell and taste is poorsense of smell and taste is poor in most in most

EarEar is similar to that of mammals is similar to that of mammals External ear canal leads to an eardrumExternal ear canal leads to an eardrum

Eye Eye is similar to mammal eye, but it is larger is similar to mammal eye, but it is larger for a relative to body sizefor a relative to body size Less spherical and almost immobileLess spherical and almost immobile

Bird turns its head rather than eyesBird turns its head rather than eyes Has both rods and conesHas both rods and cones



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Hawk Eye: Pecten nourishes retinaCone cells on Foveae- 1.5 million for hawk, 0.2 million for human

Allows for better vision


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Birds of preyBirds of prey have eyes directed forward have eyes directed forward Provides Provides better depth perceptionbetter depth perception

A hawk has eight times the visual acuity of a A hawk has eight times the visual acuity of a human and can see a rabbit over a kilometer human and can see a rabbit over a kilometer awayaway

An owl’s ability to see in dim light is more An owl’s ability to see in dim light is more than ten times that of a humanthan ten times that of a human



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FlightFlight


Normal Flapping Flight of Strong Flappers: the wings sweep downward and forwardfully extended. To begin upbeat the wing is bent, bringing it upward and backward.

Hummingbirds can change direction instantly or hang motionless.Its hinged at the shoulder by a swivel joint, and powered by flight muscles.


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4 Basic Forms of Bird Wings

A. Slotted wing tipPrevents stalling, and quick maneuvering

B. Long Migration birds High Speeds

C. Soaring, poor Maneuvering,

Strong to handle ocean winds and currents

D. High lift, slow speed, Land Soarers


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Migration and NavigationMigration and Navigation

MigrationMigration About half of all bird species migrateAbout half of all bird species migrate Can exploit seasonal changes in abundance Can exploit seasonal changes in abundance

of insects and avoid predatorsof insects and avoid predators Appearing one time a year Appearing one time a year prevents buildup prevents buildup

of specialized predatorsof specialized predators Migration also expands living spaceMigration also expands living space Migration Migration favors homeostasis,favors homeostasis, allowing birds to allowing birds to

avoid climatic extremes and food shortagesavoid climatic extremes and food shortages


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Migration RoutesMigration Routes Most migratory birds follow Most migratory birds follow established established

north-south routesnorth-south routes Some use different routes in Some use different routes in the fall and the fall and

springspring



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Migration: 14,000 miles


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Stimulus for MigrationStimulus for Migration Long days of late winter and early spring Long days of late winter and early spring

stimulatestimulate Gonadal growth, fat deposition, migration, Gonadal growth, fat deposition, migration,

courtship, mating behavior, and care of youngcourtship, mating behavior, and care of young Gonadotropic hormoneGonadotropic hormone



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Direction Finding in Migration Direction Finding in Migration Experiments suggest birds Experiments suggest birds navigate navigate

chiefly by sightchiefly by sight Birds recognize topographical Birds recognize topographical

landmarks and follow familiar migratory landmarks and follow familiar migratory routesroutes

Research indicates they can navigate by Research indicates they can navigate by the the earth’s magnetic fieldearth’s magnetic field



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Sun OrientationSun Orientation Birds navigate by Birds navigate by sun at daysun at day Use the Use the North StarNorth Star as an axis at night as an axis at night

Natural selection culls individuals that Natural selection culls individuals that make errorsmake errors Only the best navigators leave offspringOnly the best navigators leave offspring



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Bird maintains same relative position to sun when placed in

experimental situation.Birds use sun as a compass.


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Pelicans Feeding:Work together form a

horseshoe to drive fish together. Then

they plunge at same time to scoop-out fish.

Birds are ususally in SOCIAL GROUPS!


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Reproductive SystemReproductive System TestesTestes are very small until the approach of are very small until the approach of

the breeding seasonthe breeding season May then enlarge 300 times May then enlarge 300 times

Before discharge, sperm are stored in a Before discharge, sperm are stored in a greatly enlarged greatly enlarged seminal vesicleseminal vesicle

Males of most species Males of most species lack a penislack a penis Mating involves bringing Mating involves bringing cloacal surfaces cloacal surfaces

in contact in contact In most birds, left ovary and oviduct develop In most birds, left ovary and oviduct develop

and and right ovary and oviduct degenerateright ovary and oviduct degenerate

Social Behavior and ReproductionSocial Behavior and Reproduction


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Albatrosses Mating: Press Cloaca together


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Right Side of reproductive tractdegenerates, leaving only

left side. Fertilization occur in upper oviduct and albumin

and shell membrane are addedseveral hours later in lower

oviduct and uterus


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Mating SystemsMating Systems Over 90% of bird species are Over 90% of bird species are monogamous monogamous

Only mate with one partner each breeding seasonOnly mate with one partner each breeding season In a few species, such as swans and geese, In a few species, such as swans and geese,

partners are partners are chosen for lifechosen for life Recent DNA analysesRecent DNA analyses have shown many have shown many

passerine species frequently are “unfaithful,” passerine species frequently are “unfaithful,” engaging in extra-pair copulationsengaging in extra-pair copulations Nests of many of these species may contain Nests of many of these species may contain 30% 30%

of youngof young with fathers other than attendant male with fathers other than attendant male In monogamous birds, both male and In monogamous birds, both male and

females are females are equally share most aspects of equally share most aspects of parental careparental care



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Some birds areSome birds are polygamous polygamous Individuals mate with two or more partners Individuals mate with two or more partners

each breeding seasoneach breeding season PolygynyPolygyny

Most common form of polygamy Most common form of polygamy One male mates with many femalesOne male mates with many females

Polyandry Polyandry in which a female mates with in which a female mates with several males and the male incubates the several males and the male incubates the eggs, is eggs, is relatively rare in birdsrelatively rare in birds

Spotted sandpiper (on right)Spotted sandpiper (on right)





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Male Grouse: Mates with many females


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Nesting and Care of YoungNesting and Care of Young Nearly all birds lay eggs that must be Nearly all birds lay eggs that must be

incubated incubated by one or both parentsby one or both parents Often the female performs most of the duties Often the female performs most of the duties

of incubationof incubation Rarely the male has equal or sole dutiesRarely the male has equal or sole duties

Cuckoos and cowbirds are Cuckoos and cowbirds are nest parasitenest parasite Lay eggs in other bird’s nestsLay eggs in other bird’s nests



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Anna’s Hummingbird: Mother cares for young aloneHummingbird eggs are size of peas.


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Precocial birdsPrecocial birds are able to feed and run or are able to feed and run or swim as soon as they are hatchedswim as soon as they are hatched

Altricial birdsAltricial birds are naked and helpless at birth are naked and helpless at birth and must be fed in the nest for a week or and must be fed in the nest for a week or moremore Nesting successNesting success in altricial birds is very low in altricial birds is very low

Sometimes barely 20% of nests produce young Sometimes barely 20% of nests produce young Causes of nesting failure include predators, nest Causes of nesting failure include predators, nest

parasites and other factorsparasites and other factors



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Since the dodo went extinct in Since the dodo went extinct in 1695 (flightless bird)1695 (flightless bird) More than More than 80 bird species80 bird species have have

also become extinct due to also become extinct due to human influencehuman influence

Causes of bird extinction Causes of bird extinction include include habitat destruction habitat destruction and huntingand hunting

Songbirds have declined: Songbirds have declined: Habitat destruction, house cats Habitat destruction, house cats

increased, etc.increased, etc.

Bird PopulationsBird Populations



Dodo Bird


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Largest of All Living BirdsAfrican Ostrich


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27-1 CHAPTERCHAPTER Birds Birds. Copyright © The McGraw-Hill Companies, Inc. Permission required...

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