BirdsBirds

Characteristics of BirdsCharacteristics of Birds

The following characteristics The following characteristics distinguish birds from other distinguish birds from other Vertebrates: Vertebrates: Forelimbs modified into wingsForelimbs modified into wings FeathersFeathers Hollow, lightweight bonesHollow, lightweight bones EndothermicEndothermic Efficient respirationEfficient respiration

Characteristics of Birds Characteristics of Birds cont.cont.

4 chambered heart4 chambered heart The two hind limbs, with clawed The two hind limbs, with clawed

toes support body and scaly feettoes support body and scaly feet A toothless, horny break in presentA toothless, horny break in present Amniote eggs are encased in hard, Amniote eggs are encased in hard,

calcium-containing shells.calcium-containing shells. Furculum (wishbone)Furculum (wishbone)

Class Aves – BirdsClass Aves – Birds

Ornithology – Ornithology – study of birdsstudy of birds

Feathers!Feathers! Soft, fluffy down feathers Soft, fluffy down feathers

cover body of nestling cover body of nestling birds and provide and birds and provide and insulating undercoat for insulating undercoat for adults.adults.

Contour feathers cover the Contour feathers cover the head and body and head and body and provide coloration provide coloration

Flight feathers are Flight feathers are specialized contour specialized contour feathers on the wings and feathers on the wings and tails and they provide lifttails and they provide lift

Feathers ContinuedFeathers Continued

At maturity each vane At maturity each vane (branch of feather) has many (branch of feather) has many barbules that are equipped barbules that are equipped with microscopic hooks to keep with microscopic hooks to keep feathers togetherfeathers together

Birds preen, or comb through Birds preen, or comb through their feathers spreading oils to their feathers spreading oils to keep them waterproof and keep them waterproof and repairing vanesrepairing vanes Oil is secreted from a preen glandOil is secreted from a preen gland

FeathersFeathers

Most birds go through a major Most birds go through a major molt, during which the birds molt, during which the birds replaces its flight feathers replaces its flight feathers This occurs in the late summer This occurs in the late summer

between breeding and migration.between breeding and migration.

EndothermsEndotherms

Generate and regulate body heat Generate and regulate body heat internallyinternally

Enables birds to inhabit both cold Enables birds to inhabit both cold and hot climatesand hot climates

Body temperature ranges from 40-Body temperature ranges from 40-46 degrees Celsius. 46 degrees Celsius.

To help conserve body heat, birds To help conserve body heat, birds fluff out their feathers to insulation.fluff out their feathers to insulation.

Beaks and feetBeaks and feet Hawks and eagles have Hawks and eagles have

powerful break and powerful break and clawed talons that help clawed talons that help them capture and then rip them capture and then rip their prey.their prey.

Swifts have a tiny breaks Swifts have a tiny breaks that opens wide like a that opens wide like a catchercatcher’’s mitt to share s mitt to share insects in midair.insects in midair.

The feet of flightless The feet of flightless birds, on the other hand birds, on the other hand are modified for walking are modified for walking and runningand running

BeaksBeaks

Short and thick - seed cracking (robin) Long and thin, slightly curved - eating nectar

(hummingbird) Strong, chisel like - drilling (woodpecker) Sharp, curved and pointed - tearing flesh

(hawk) Long and flattened - straining algae and plants

(ducks) Spear shaped - spearing fish (heron)

FeetFeet

3 toes in front, 1 behind - perching (robin) 2 toes in front, 2 behind - climbing (parrot) Powerful curved talons - grasping prey

(hawk) Webbed - swimming (duck) Long and thin - wading (heron) Thick and stout - running (ostrich)

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Skeletons and MusclesSkeletons and Muscles

Combine lightness and strengthCombine lightness and strength Bones are thin and hollow Bones are thin and hollow

(internal struts to add strength)(internal struts to add strength) Many large bones are fused:Many large bones are fused:

Collar bone into wishboneCollar bone into wishbone Pelvic girdlePelvic girdle Parts of the vertebraParts of the vertebra

Fusion of bones helps provide a Fusion of bones helps provide a rigid frame for flightrigid frame for flight

Have very large pectoral muscles Have very large pectoral muscles and sternum modified into keeland sternum modified into keel

Digestive SystemDigestive System Food passes from the mouth Food passes from the mouth

cavity straight to the cavity straight to the esophagus.esophagus.

Enlargement of the Enlargement of the esophagus called the crop esophagus called the crop stores and moistens food.stores and moistens food.

In the first chamber of the In the first chamber of the stomach, gastric fluids begin stomach, gastric fluids begin breaking down the food.breaking down the food.

Then food passes through Then food passes through the gizzard, a muscular the gizzard, a muscular organ that kneads and organ that kneads and crushes the foodcrushes the food

Excretory SystemExcretory System

The avian excretory system is also The avian excretory system is also efficient and light weight efficient and light weight

The two kidneys filter a nitrogenous waste The two kidneys filter a nitrogenous waste called uric acid from the bloodcalled uric acid from the blood

highly concentrated uric acid travels by highly concentrated uric acid travels by ducts called ureters to the cloaca, where ducts called ureters to the cloaca, where along with undigested matter from the along with undigested matter from the intestines, it is excreted in a semisolid, intestines, it is excreted in a semisolid, usually white massusually white mass

Respiratory SystemRespiratory System Air enters through Air enters through

paired nostrils at base paired nostrils at base of beakof beak

When bird exhales the When bird exhales the carbon dioxide-rich air carbon dioxide-rich air from the lungs, oxygen from the lungs, oxygen rich air is forced out of rich air is forced out of the posterior air sacs the posterior air sacs into lungs via small air into lungs via small air tubestubes

Circulatory SystemCirculatory System 4 chambered heart4 chambered heart Right and left sides completely separatedRight and left sides completely separated Right side receives deoxygenated blood from Right side receives deoxygenated blood from

the body and pumps it to the lungsthe body and pumps it to the lungs Left side receives oxygenated blood from the Left side receives oxygenated blood from the

lungs and pumps it to the rest of the bodylungs and pumps it to the rest of the body Has a single aortic archHas a single aortic arch Most birds have a rapid heart beat compared Most birds have a rapid heart beat compared

to other vertebrates – Hummingbird (600 to other vertebrates – Hummingbird (600 times a minute)times a minute)

Nervous SystemNervous System Birds have a large brains, relative to their sizeBirds have a large brains, relative to their size Cerebellum coordinates movementCerebellum coordinates movement Cerebrum controls complex behavior patterns such as Cerebrum controls complex behavior patterns such as

navigation, mating, and nest buildingnavigation, mating, and nest building Optic lobe receives and interpret visual stimuli Optic lobe receives and interpret visual stimuli Keen vision is necessary for taking off, landing, Keen vision is necessary for taking off, landing,

spotting landmarks, hunting and feedingspotting landmarks, hunting and feeding Have good color visionHave good color vision Birds large eyes are located near the sides of its head, Birds large eyes are located near the sides of its head,

giving a bird a wide field of visiongiving a bird a wide field of vision

Nervous systemNervous system Birds large eyes are located near the sides of its head, Birds large eyes are located near the sides of its head,

giving a bird a wide field of visiongiving a bird a wide field of vision Birds with eyes near the front of the head have better Birds with eyes near the front of the head have better

binocular visionbinocular vision Hearing important to nocturnal species that rely on Hearing important to nocturnal species that rely on

sounds to help them locate preysounds to help them locate prey Birds lack internal ears-ear canal leads to a tympanic Birds lack internal ears-ear canal leads to a tympanic

membrane, called an eardrummembrane, called an eardrum Sense of smell is poorly developed except in ducks Sense of smell is poorly developed except in ducks

and flightless birdsand flightless birds Sense of taste helps birds avoid bitter-tasting or toxic Sense of taste helps birds avoid bitter-tasting or toxic

foodsfoods

Reproductive System Reproductive System Bird sperm is produced in two Bird sperm is produced in two

testes that lie beneath the testes that lie beneath the kidneyskidneys

Sperm passes through small Sperm passes through small tubes called the vas deferens tubes called the vas deferens into the male’s cloacainto the male’s cloaca

During mating the male presses During mating the male presses his cloaca to the females and his cloaca to the females and releases spermreleases sperm

Females single ovary releases Females single ovary releases eggs into a long, funnel-shaped eggs into a long, funnel-shaped oviduct where they are fertilized oviduct where they are fertilized by spermby sperm

Reproductive SystemReproductive System Fertilized eggs move down the oviduct, where Fertilized eggs move down the oviduct, where

they receive protective covering and a shellthey receive protective covering and a shell Unfertilized egg consists of a nucleus, cytoplasm, Unfertilized egg consists of a nucleus, cytoplasm,

and a yolkand a yolk When fertilized, the embryo is suspended in When fertilized, the embryo is suspended in

albumen, the egg whitealbumen, the egg white The liquid medium is supported by ropelike The liquid medium is supported by ropelike

strands of material called chalaza that are strands of material called chalaza that are attached to the shell membraneattached to the shell membrane

Female has a shell gland that secretes a protective Female has a shell gland that secretes a protective calcium carbonate shell to surround the eggcalcium carbonate shell to surround the egg

Incubation and Incubation and DevelopmentDevelopment A female bird usually lays A female bird usually lays

eggs in the nest. One or both eggs in the nest. One or both parents will incubate or warm parents will incubate or warm the eggs by sitting on them.the eggs by sitting on them.

They cover them with a thick, They cover them with a thick, featherless patch of skin on featherless patch of skin on their abdomen called a brood their abdomen called a brood patch.patch.

In penguins the male emperor In penguins the male emperor heats the egg by placing it on heats the egg by placing it on his webbed feet and enfolding his webbed feet and enfolding it with his warm abdomen.it with his warm abdomen.

Incubation and Incubation and DevelopmentDevelopment

Embryo development Embryo development begins when the zygote begins when the zygote forms a plate of cells forms a plate of cells on the surface of the on the surface of the yolk.yolk.

This plate begins to This plate begins to form the tissues and form the tissues and organsorgans

The membrane The membrane produces digestive produces digestive enzymes that dissolve enzymes that dissolve proteins and lipids in proteins and lipids in the yolk.the yolk.

Incubation and Incubation and DevelopmentDevelopment

Blood vessels in the yolk sac Blood vessels in the yolk sac membrane carry the nutrients to the membrane carry the nutrients to the embryo.embryo.

When hatching begins the embryo When hatching begins the embryo makes a star-shaped crack in the shell makes a star-shaped crack in the shell with a scale-like egg tooth.with a scale-like egg tooth.

The chick presses and scrapes the The chick presses and scrapes the shell until the crack widens enough for shell until the crack widens enough for the chick to emerge.the chick to emerge.

The egg tooth falls off soon after the The egg tooth falls off soon after the chick hatches.chick hatches.

Incubation and Incubation and DevelopmentDevelopment

Bird have two contrasting Bird have two contrasting methods for rearing methods for rearing young:young: Those that lay many eggs Those that lay many eggs

and incubate them for long and incubate them for long periods hatch precocial periods hatch precocial young.young.

These birds are active as These birds are active as soon as they hatch, they soon as they hatch, they can walk, swim, and feed can walk, swim, and feed themselves. For examples themselves. For examples ducks and quail.ducks and quail.

Incubation and Incubation and DevelopmentDevelopment

Birds that lay only a few eggs and Birds that lay only a few eggs and hatch quickly produce altrical hatch quickly produce altrical young.young. They depend on both parents for They depend on both parents for

several weeks. several weeks. For ex. Woodpeckers, hawks, pigeons For ex. Woodpeckers, hawks, pigeons

parrots.parrots.

BehaviorBehavior The long periods of parental The long periods of parental

care may enable birds to learn care may enable birds to learn such complex behaviors as such complex behaviors as courtship, nesting, and courtship, nesting, and migration.migration.

Young birds need protection Young birds need protection until they develop the strength until they develop the strength to fly and obtain foodto fly and obtain food

Territoriality and CourtshipTerritoriality and Courtship During the breeding season many male birds During the breeding season many male birds

establish an area that they defend against other establish an area that they defend against other males of their species – territorialmales of their species – territorial

The male then attempts to attract a female to The male then attempts to attract a female to share this territory.share this territory.

Once a territory is established most birds engage Once a territory is established most birds engage in a period of courtship, behavior that is in a period of courtship, behavior that is designed to attract a mate.designed to attract a mate.

Many males attract females by means of their Many males attract females by means of their brightly colored feathers.brightly colored feathers.

Some males combine song with flight displays.Some males combine song with flight displays.

Nest BuildingNest Building Nests hold eggs, conceal young birds Nests hold eggs, conceal young birds

from predators, provide shelter from from predators, provide shelter from the elements, and sometimes even the elements, and sometimes even serve to attract a mate.serve to attract a mate.

Most birds build nests in sheltered, Most birds build nests in sheltered, well-hidden spots- from holes in the well-hidden spots- from holes in the ground to treetops.ground to treetops.

As a further adaptation to their As a further adaptation to their environment, birds construct their environment, birds construct their nests of almost any material available.nests of almost any material available.

Twigs, grasses, feathers, and mud are Twigs, grasses, feathers, and mud are the most common materials used.the most common materials used.

MigrationMigration When temperatures drop When temperatures drop

and the food supply and the food supply dwindles, many birds dwindles, many birds migrate to warmer climates.migrate to warmer climates.

Birds rely on a variety of Birds rely on a variety of cues to help them navigate.cues to help them navigate.

Some species monitor the Some species monitor the position of the stars or the position of the stars or the sun.sun.

Others rely on topographical Others rely on topographical landmarks, such as landmarks, such as mountains.mountains.

MigrationMigration

Magnetic cues, changes in air Magnetic cues, changes in air pressure, and low –frequency pressure, and low –frequency sounds may also provide sounds may also provide information to migrating birds.information to migrating birds.

The ability of birds to read these The ability of birds to read these cues, along with their many cues, along with their many adaptations for flight, enables adaptations for flight, enables them to migrate to and inhibit them to migrate to and inhibit virtually any environmentvirtually any environment..

Evolution and Evolution and ClassificationClassification

Almost every feature of their reptilian Almost every feature of their reptilian anatomy has undergone modification in anatomy has undergone modification in their adaptation to flight.their adaptation to flight.

Becoming endotherms has Becoming endotherms has enabled birds to survive in enabled birds to survive in virtually every known virtually every known environmentenvironment

Class Aves – BirdsClass Aves – Birds

Birds are found in most every habitat Birds are found in most every habitat from forests to deserts, even in caves. from forests to deserts, even in caves. Some birds dive in the ocean to 45 m to Some birds dive in the ocean to 45 m to

catch prey.catch prey. Birds live at both the North & South poles.Birds live at both the North & South poles. The bee hummingbird of Cuba weighs 1.8g The bee hummingbird of Cuba weighs 1.8g

and is one of the smallest vertebrate and is one of the smallest vertebrate endotherms.endotherms.

Origin and Early EvolutionOrigin and Early Evolution

Evidence from fossils Evidence from fossils and from studies of and from studies of comparative anatomy comparative anatomy indicates that birds indicates that birds evolved from reptilesevolved from reptiles

Their features and Their features and their fragile hollow their fragile hollow bones do not bones do not preserve well preserve well not not very many fossilsvery many fossils

ClassificationClassification

Most taxonomists Most taxonomists classify the nearly classify the nearly 9,000 species of Class 9,000 species of Class Aves into 27 ordersAves into 27 orders

Birds are classified by Birds are classified by their beaks and feettheir beaks and feet

Bird GroupsBird Groups Bird species are often categorized Bird species are often categorized

into six groups based on the birdinto six groups based on the bird’’s s lifestylelifestyle Perching birds Perching birds Birds of prey Birds of prey Flightless birdsFlightless birds Water birdsWater birds Wading birdsWading birds Diving birdsDiving birds

Terrestrial (land) BirdsTerrestrial (land) Birds

Most Most perching birds, birds of perching birds, birds of prey, prey, and and flightless birds flightless birds are are terrestrial birdsterrestrial birds They live mainly on dry landThey live mainly on dry land

Terrestrial birds have feet adapted Terrestrial birds have feet adapted to running, perching, or hunting to running, perching, or hunting and beaks adapted to eating fruits, and beaks adapted to eating fruits, seed, insects, or small animals seed, insects, or small animals

Perching BirdsPerching Birds Are the most common group of birds Are the most common group of birds In order to perch and grip onto In order to perch and grip onto

branches:branches: One toe points backwardsOne toe points backwards All other toes point forwardsAll other toes point forwards

The beaks of perching birds are:The beaks of perching birds are: Strong for cracking open seeds and nutsStrong for cracking open seeds and nuts

Ex. GoldfinchesEx. Goldfinches Long thin beaks for catching insects in the Long thin beaks for catching insects in the

air or digging them out of the ground or air or digging them out of the ground or tree trunkstree trunks

Ex. WarblerEx. Warbler

Birds of PreyBirds of Prey

Most Most Birds of prey Birds of prey are hunters with are hunters with keen vision keen vision

Eagles, hawks, and smaller birds of Eagles, hawks, and smaller birds of prey hunt during the day prey hunt during the day

Owls have huge eyes and hunt for Owls have huge eyes and hunt for small prey during the night small prey during the night

Some birds do not use vision to huntSome birds do not use vision to hunt Vultures rely on their incredible Vultures rely on their incredible sense of smell to find dead animalssense of smell to find dead animals

Birds of PreyBirds of Prey

Most birds of prey have sharp Most birds of prey have sharp talons talons and curved beaksand curved beaks Talons Talons are used to grasp preyare used to grasp prey Curved beaks are used for tearing flesh Curved beaks are used for tearing flesh

Most birds of prey hunt aloneMost birds of prey hunt alone However, some birds of prey hunt in However, some birds of prey hunt in

groups and flush prey towards their groups and flush prey towards their waiting partners waiting partners

Flightless BirdsFlightless Birds

Flightless birds are the largest Flightless birds are the largest

birdsbirds The biggest flightless birds are ostriches, The biggest flightless birds are ostriches,

emus, rheas, and cassowaries emus, rheas, and cassowaries There are some small flightless birdsThere are some small flightless birds

Example: Flightless Kiwi is the size of Example: Flightless Kiwi is the size of

a chicken a chicken

They have small wings and areThey have small wings and are

built to run on land built to run on land Ostriches can run up to 55 km/h Ostriches can run up to 55 km/h

Flightless Bird LegsFlightless Bird Legs

Many flightless birds have long, Many flightless birds have long, strong legsstrong legs Ostriches have two large, clawed toes Ostriches have two large, clawed toes

on each foot on each foot

Aquatic BirdsAquatic Birds

Diving birds, water birds, Diving birds, water birds, and and wading birds wading birds are aquatic birds are aquatic birds Live mainly in waterLive mainly in water

Aquatic birds have feet adapted to Aquatic birds have feet adapted to paddling and wading paddling and wading

Aquatic birds have beaks adapted Aquatic birds have beaks adapted to eating aquatic organisms to eating aquatic organisms

Diving BirdsDiving Birds Not all flightless birds live on landNot all flightless birds live on land

Penguins are flightless, and their wings Penguins are flightless, and their wings and feet have been adapted for swimming and feet have been adapted for swimming

All 17 species of penguins live in the All 17 species of penguins live in the Southern Hemisphere Southern Hemisphere

Some diving birds are found in the Some diving birds are found in the Northern HemisphereNorthern Hemisphere Their wings can still be used for flight, so Their wings can still be used for flight, so

they CANNOT dive as well as penguins can they CANNOT dive as well as penguins can

Diving Birds – Penguins Diving Birds – Penguins

Their wedge-shaped wings work as Their wedge-shaped wings work as flippersflippers

Webbed feet can be used as paddles Webbed feet can be used as paddles Have a thick coat of feathers and a Have a thick coat of feathers and a

layer of fat beneath their skin that layer of fat beneath their skin that allows them to live in freezing allows them to live in freezing temperaturestemperatures A rich diet of krill and fish help penguins A rich diet of krill and fish help penguins

maintain the fat layer maintain the fat layer

Water BirdsWater Birds Swan, Geese, and Ducks are Swan, Geese, and Ducks are

water birds, or birds found in or water birds, or birds found in or near the water near the water

Water birds have webbed feet Water birds have webbed feet for paddling for paddling

Have long, flattened beaks with Have long, flattened beaks with rounded tips rounded tips Beaks are ideal for a variety of Beaks are ideal for a variety of

food such as small insects, fish, food such as small insects, fish, and grassand grass

SeabirdsSeabirds

SeabirdsSeabirds are an unrelated group of are an unrelated group of birds that also live near open waters, birds that also live near open waters, but they are found around oceans but they are found around oceans

They have webbed feet like water They have webbed feet like water birdsbirds

However, their beaks are longerHowever, their beaks are longer Beaks are made for catching their Beaks are made for catching their

typical meal of fish or squid typical meal of fish or squid

Wading BirdsWading Birds

Herons, storks, flamingos, and egrets Herons, storks, flamingos, and egrets are wading birds are wading birds

Wading birds feed in shallow waters Wading birds feed in shallow waters that are rich with fish and that are rich with fish and invertebrates invertebrates

Wading birds have long, slender Wading birds have long, slender

legs to feed in a range of depths legs to feed in a range of depths Have long toes to keep them from Have long toes to keep them from

sinking into the mud sinking into the mud

Wading BirdsWading Birds

Many wading birds have spear-shaped Many wading birds have spear-shaped beaks for fishingbeaks for fishing Fishing waders stand motionless as they Fishing waders stand motionless as they

wait for fishwait for fish When they see a fish they quickly snatch it When they see a fish they quickly snatch it

in their beak or may even spear it in their beak or may even spear it Waders that feed on invertebrates in Waders that feed on invertebrates in

the mud may have beaks that are built the mud may have beaks that are built for stabbing into the mud to find preyfor stabbing into the mud to find prey