Download Aves

Aves
Birds
Well adapted to terrestrial, freshwater, and
marine habitats
Bodies adapted for flight
Endothermic- body temperature controlled
by metabolism
Evolution:
Evolved from reptiles
Few fossils due to lack of preservation of feathers or
thin, hollow bones
Archaeopteryx:
1. Possible link between birds & reptiles
2. Lived during Jurassic period
3. Large skull with reptile like teeth
4. Bones not hollow
5. Claws on forelimbs
6. Long tail
7. Strong legs & rounded wings for gliding
8. Feathers
9. Furculum - fused collarbone or wishbone
Archaeopteryx:
Evolution:
Hesperonis:
1. Bird fossils from Cretaceous period
2. Large, flightless bird
3. Had teeth like reptiles
Evolution:
Ichthyornis:
1. Smaller, tern like bird
2. Lived during Cretaceous period
3. Had large flight wings
Similarities between birds and
dinosaurs
1. Flexible S-shaped
neck
2. Unique ankle joint
3. Hollow bones
Dinosaur and Pigeon
Characteristics of Birds:
Body covered with feathers made of
protein called keratin
Thin, hollow bones
Some bones fused for extra strength
Forelimbs modified into wings for flight
Two hind limbs with claws to support
upright body
Scales on legs
Characteristics of Birds:
Toothless, horny beak
Additional air sacs with lungs for more oxygen
Endotherms (40 to 41 degrees Celsius body
temperature)
Four chambered heart with single, right aortic
arch
Amniote egg with calcium carbonate shell
Oviparity with both parents often caring for eggs
Eggs usually incubated within a nest
Feathers:
Modified scales
Function to provide lift for flight & help
conserve body heat
Five kinds of feathers ----- down, contour,
flight, filoplume, & bristles
Down feathers:
1. Soft & fluffy
2. Cover the body of nestlings
3. Provide an undercoat insulating adult birds
Feathers:
Contour Feathers:
1. Give streamline shape to body
2. Provide coloration to adult birds
3. Give additional insulation to body
Flight Feathers:
1. Specialized contour feathers
2. Found on wings & tail
Filoplumes:
1. Called pin feathers
2. Hairlike feathers under contour feathers on
body
Feathers:
Parts of a feather:
Develop from tiny pits in the skin called follicles
Shaft emerges from the follicle
Two vanes develop on either side of shaft
Barbs branch off of each vane & have projections called
barbules
Barbules have microscopic hooks to hold barbules
together
Birds preen their feathers to clean them & coat them
with oil
Preen glands - oil glands located at the base of the tail
Birds shed or molt feathers periodically:
1. Molting usually in late summer between breeding &
migration
2. Flight feathers replaced
3. Some birds molt before courtship
Parts of a feather
Beaks and Feet:
Adapted to habitat & feeding
Hawks & eagles have hooked beaks & talons for
tearing meat
Swifts have tiny beaks that open wide to catch insects
in midair
Flightless birds like ostriches have legs & feet
modified for running & walking
Penguins have wings modified into flippers for
swimming
Ducks & geese with webbed feet
Legs of some birds such as herons & egrets turn vivid
colors to attract mates; caused by hormones
Skeleton and Muscles:
Pelvic & pectoral girdles fused for
strength
Bones thin & hollow so bird lighter
Furculum or wishbone is a fused
collarbone that stabilizes bird in flight
Lighter beak replaces heavy teeth & jaws
Lower vertebrae fused so no heavy
ligaments needed
Skeleton and Muscles:
Enlarged eye sockets reduce skull weight
Keeled sternum for attachment of large flight
muscles
Pygostyle - terminal vertebrae support tail &
aids in flight (lift, steering, & braking)
Two digits in forelimbs lost & other three digits
fused to form wings
Wings shaped like air foils (thicker in front &
tapering to back) so air moves faster on top
causing lift
Skeleton
Skeleton and Muscles:
Powerful muscles make up 50% of body weight
each wing movement uses different set of
muscles
Flight muscles called pectorals & are attached to
wing & keeled sternum
When large pectorals contract, wings move
down
When large pectorals relax & small pectorals
contract, wings move upward
Body Temperature:
Metabolism generates body heat (endothermic)
Enables birds to survive in warm & cold
environments
Rapid breathing & increased air sacs in lungs
bring in more oxygen
Ingest large amounts of food for energy
Fluff out feathers to trap air for insulation
Aquatic birds have thin layer of fat for
insulation
Digestive System:
Fast & efficient digestion (mouse digested
in 3 hours)
No chewing
Crop for temporary food storage
Two part stomach --- proventriculus &
gizzard
Proventriculus is 1st chamber where
digestive juices added
Digestive System:
Gizzard is 2nd part for crushing food
Small stones & gravel eaten by birds aids
grinding in gizzard
Pyloric sphincter valve at lower end of gizzard
controls food movement into intestines
Duodenum - beginning of small intestine where
bile (digests fats) & pancreatic juice are
added & digested food is absorbed
Excretory System:
Paired kidneys filter nitrogen wastes (uric acid)
from blood
No urinary bladder to store liquid wastes
Uric acid travels down ureters to cloaca where
intestinal wastes & reproductive products added
Uric acid secreted in white, semi solid mass
Shorebirds have salt secreting glands above
the eyes & secrete excess salt through their
nostrils
Respiratory System:
Fly at high altitudes where there is less
oxygen so need efficient respiratory
system
High metabolic rate requires large
amount of oxygen
Nine air sacs associated with lungs
increase oxygen level & decrease density
Air sacs connected to air spaces in
hollow bones
One way flow of air in lungs & air sacs so
more oxygen is removed
Respiratory System:
Air pathway:
air enters body through nostrils on
beak trachea (windpipe) syrinx (voice
box) 2 primary bronchi 75% of air into
two posterior air sacs and 25% of air into
lungs air from lungs into other seven air
sacs
When carbon dioxide exhaled, oxygen
from posterior air sacs moves into lungs to
always keep fresh oxygen supply
Circulatory System:
Four chambered heart
Right side of heart pumps deoxygenated blood
from body cells to lungs
Left side of heart receives oxygenated blood
from lungs & pumps it to the body cells
Single aortic arch
Rapid heartbeat (hummingbird 600X/minute &
chickadee 1000X/minute)
Less active birds such as ostrich have slower
heart rates (70X/minute)
Nervous System:
Large brains relative to size of bird
Most highly developed brain areas control
flight
Cerebellum coordinates movement
Cerebrum controls navigation, mating,
nest building, & care of young
Optic lobes receive & interpret visual
stimuli
Keen vision
Have color vision for locating food
Nervous System:
Large eyes located on side of head for wide field of
vision in most birds
Some birds such as owls with eyes on front of head for
binocular vision (depth perception)
No external ears, but have feathers around ear
openings to direct sounds into ear canals
Tympanic membrane or eardrum for picking up sound
vibrations
Semicircular canals in inner ear regulate balance
Poorly developed sense of smell except in ducks &
flightless birds
Sense of taste helps avoid bitter tasting or toxic foods
Reproductive System:
Testes in males produces sperm that travels by the vas
deferens to cloaca
Females have single ovary that makes eggs
Eggs are fertilized in the oviducts
Shell added by shell gland & then egg moves into
In mating, male presses cloaca to female to transfer
sperm (internal fertilization)
Lay an amniote egg:
1. Embryo suspended in fluid called albumen (white of
egg)
2. Chalaza - rope like strands suspending embryo in
albumen
3. Chorion is membrane inside of shell
4. Yolk is stored food surrounded by yolk sac
Bird Egg
Incubation & development of
Egg
Eggs incubated by one or both parents
Brood patch - thickened, featherless patch of skin on
abdomen of bird used to warm eggs
Membranes grow out of embryo's digestive tract &
surround yolk
Membranes make digestive enzymes to dissolve
proteins & lipids in yolk
Yolk sac has blood vessels to carry food to embryo
Wastes from embryo collect in membrane called
allantois
Chorion membrane lines the shell & allows gas
exchange
Young birds may be precocial or altricial
Incubation & development of
Egg
Precocial young:
1. Have longer incubations
2. More eggs laid
3. Active as soon as hatch
4. Nestlings can swim, walk, & feed
themselves
5. Need some parental care
6. Includes chickens, ducks, geese, &
swans
Incubation & development of
Egg
Altricial young:
1.Lay fewer eggs
2. Hatch quickly
3. Hatchlings are blind, naked, & helpless
4. Depend on parents for warmth & food
for several weeks
5. Includes songbirds, woodpeckers,
hawks, pigeons, doves, raptors
Behavior:
Longer parental care allows more complex learning
(courtship, nesting, migration, etc.)
Territoriality allows males to establish & defend
breeding areas
Courtship behaviors are used by males to attract
mates:
1. Brightly colored feathers
2. Flight displays
3. Songs
Nest building holds eggs, conceals & shelters young
birds, may help attract mates
Nests are built in sheltered, well-hidden spots in trees,
on the ground, etc. & are made of twigs, mud, grass,
feathers...
Behavior:
Migration to new areas is triggered by
dropping temperatures & dwindling food
supplies
Birds use migration clues including:
1. Position of sun & stars
2. Topographical landmarks
3. Magnetic clues
4. Air pressure changes
5. Low frequency sounds
Classification:
Class Aves
27 orders
Gaviiformes - loons
Pelecaniformes - pelicans & cormorants
Ciconiiformes - wading birds like ibises & herons
Anseriformes - ducks, geese, & swans
Falconiformes - falcons, eagles, hawks, vultures
Galliformes - turkey, quail, pheasants
Gruiformes - cranes, coots, & rails
Charadriiformes - snipes, sandpipers, gulls, terns
Columbiformes - pigeons & doves
Psittaciformes - parrots, parakeets, & macaws
Cucluiformes - cuckoos & roadrunners
Strigiformes - owls
Caprimulgiformes - whippoorwill & nighthawk
Apodiformes - hummingbird & swifts
Coraciiformes - kingfishers
Piciformes - woodpeckers, sapsuckers, & flickers
Passeriformes - perching birds like robins, cardinals, blue jays
Food & Habitat Adaptations:
Anseriformes (ducks, geese, & swans) have webbed
feet for swimming & flattened bills; young are precocial
but need some parental care
Strigiformes (owls) have sharp, hooked beaks &
talons (claws) for meat eating, keen hearing & eyesight,
& forward facing eyes
Apodiformes (hummingbirds) are small, fast-flying
birds with tiny feet & long tongues for drinking nectar;
found only in western hemisphere
Psittaciformes (parrots, cockatoos, parakeets...)
have a strong, hooked beak for seed opening & two
forward & two rear facing toes for perching & climbing
Piciformes (woodpeckers, toucans, & flickers) have
two rear facing toes for dwelling in tree cavities &
sharp, chisel like bills for drilling into trees
Falconiformes or raptors ( hawks, eagles, vultures)
have hooked beaks & talons & keen vision for seeing
prey
Food & Habitat Adaptations:
Passeriformes or songbirds (blue jays, cardinals,
sparrows, robins ...) have enlarged rear facing toe to grip
branches, a syrinx or voice box in males to produce songs, &
a variety of beak shapes to feed on seeds, nectar, fruits, &
insects; known as passerines or perching birds
Columbiformes (pigeons & doves) have small heads &
bills, a crop that makes "pigeon's milk" for feeding young,
short incubation period (2 weeks)
Ciconiiformes (herons, ibises, & egrets) have long legs for
wading & sharp pointed bills for piercing frogs & fish
Galliformes (turkeys, quail, pheasants, & chickens) have
plump bodies with limited flying & a large gizzard for
grinding grains
Sphenisciformes (penguins) have wings modified into
flippers, an extra layer of body fat for insulation, & webbed
feet for swimming
Struthioniformes (ostrich) are the largest birds that can't fly
but have long legs with only two toes adapted for fast
running