Birds
Class: Aves
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29 Orders
8,600 species
Thought to have come from reptiles because
they:
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1. Lay amniotic eggs
2. Have scales on legs
General Characteristics
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Endotherms-heat comes from within the body
Feathers help with insulation
4 chambered heart
Must have good senses
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Vision: most birds have good eyesight
Visual and motor areas of the brain are well
developed
What is a bird?
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Reptile like
Maintain a constant body
temperature
Have feathers
Have 2 legs that are covered
with scales
The majority of birds can fly,
but those that can’t move by
walking, running, or swimming.
Ratites-birds that don’t fly
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keel is subtle or absent and
lacks muscles to fly
Carinates-have a keel and can
fly
Feathers
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Made mostly of protein called keratin, and
develop from pits in the bird’s skin.
Help with flight and insulation
3 Types of feathers:
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Contour
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Down
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Provide lift and balance needed for flight
Trap air close to body for insulation
Powder down (in birds that are around water)
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Powder repels water
1. Vane
2. Rachis
3. Barb
4. Afterfeather
5. Hollow Shaft
Evolution of Birds
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Thought to have come
from extinct reptiles
Archaeopteryx: First
birdlike fossil
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From Jurassic Period
(150 mya)
Looked like a small
running dinosaur except
it had feathers
Unlike birds, it had teeth
in it’s beak, a bony tail,
and toes and claws on
it’s wings
Comparison of Reptiles and Birds
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Embryos develop in amniotic eggs
Excrete waste in the form of uric acid
Bones in front and hind limbs are very similar
Bodies are Modified for Flight
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Bones:
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Organs:
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Honeycombed (hollow) inside
Makes the bird lighter
Missing some to make bird lighter
Only 1 ovary
No teeth (food is ground up in the gizzard)
Crop (part of the digestive system used to store food)
Beak:
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Make of keratin (lighter than bone)
Different shapes for different diets and is also aerodynamic
Flying
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Requires good coordination and
lots of energy
Flap wings using large pectoral
muscles (breast) anchored to a
keel on the sternum
Some have wings adapted for
soaring and only have to flap
occasionally
Others have to flap continuously to
stay in flight (hummingbird)
Wings work using Bernoulli’s
principal
Video on Pectoral Muscles
Advantages of Flight
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Hunting and scavenging
Catch insects (good source of nutrition)
Escape predators
Can migrate farther
Digestion
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Birds don’t have teeth, so they have to break
down food using a crop
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At the end of the esophagus, it stores and
moistens food before it enters the stomach
In some birds, during nesting season, the crop
produces a protein rich substance that they
regurgitate to their young
Beaks
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Adapted to the food they
eat
Insect eating: short, fine
bills
Seed eating: short, thick
bills
Carnivores: strong, sharp,
hooked bills
Nectar eating: long, thin
bills
Fish eating: large, long bills
Digestion
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Birds that eat insects or seeds have a gizzard
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Forms part of the stomach
Birds swallow stones or small pebbles to help
grind up the food
Waste leaves through the cloaca
Respiration
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When birds inhale, the air
passes into air sacs in the
body cavity and in the
bones.
It then passes through the
lungs on the way out of the
body.
While in the lungs, oxygen
is absorbed into the blood
stream.
This is a one way flow of
oxygen rich blood.
Helps birds fly at high
altitudes where air is thin. http://bcs.whfreeman.com/thelifewire/conte
nt/chp48/4802001.html
Circulation
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Have a 4 chambered
heart.
Oxygen rich blood is
separate from oxygen
poor blood.
Response
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Have well adapted sense organs.
The brain is relatively large for the body size.
Have highly developed eyes that see color
very well.
Taste and smell are not as developed.
Reproduction
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Reproductive tracts open into the cloaca in both
male and female birds.
Sex organs sometimes shrink when not mating.
Mating birds press their cloaca together to pass
sperm into the female (not all birds have a penis)
Birds incubate their amniotic eggs until they hatch.
Chicks use a small tooth on their bill to crack the
egg.
After exiting the egg, it rests and allows the feathers
to dry.
Groups of Birds
Loons and Grebes
Loons
•There are about 5 species of loons
•4 can be found in the US
•Gather food by diving and chasing fish
Grebes
•27 species worldwide
•7 can be found in the US
•Food gathering similar to the loon
•Found in more diverse habitats than loons
Groups of Birds
The Pelagics
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Albatross
 14 species worldwide
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Petrels
 20 species worldwide
Shearwater
 70 species worldwide
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Groups of Birds
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Pelicans and relatives (ex.
Cormorants, boobies, and
frigatebirds)
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Found in all aquatic
ecosystems
Have 4 toes connected by a
web
Groups of Birds
Parrots (Macaws, lovebirds, and
cockatoos)
•Colorful and noisy
•Use feet to hold food
•Most typically mate for life
•Beaks can crack open seeds, nuts
•Tongues have a bone that can help
them tap into fruit
•Very social
Groups of Birds
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Perching Birds (ex.
Sparrows, crows,
mockingbirds, and
cardinals)
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Called passerines
Largest order of birds
Many are songbirds
Herons and relatives (ex.
Storks, ibises, spoonbills,
herons, and cranes)
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Adapted to wading in
aquatic habitats
Groups of Birds
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Ostriches and relatives (ex.
Emus, rheas, cassowaries,
and kiwis)
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Flightless
Must move by running or
swimming
Cavity Nesting Birds (ex.
Barbets, toucans, and
woodpeckers)
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Multicolored
Live in holes in trees,
mounds, or underground
tunnels
Groups of Birds
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Birds of Prey (ex.
Condors, hawks, owls,
eagles, and falcons)
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Also known as raptors
Fierce predators with
hooked bills
Large wingspans
Sharp talons
Ecology of Birds
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Can pollinate flowers (mockingbirds), seed
dispersal, and control insect populations.
Migration
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Usually seasonal
Some species use stars to navigate others use
landmarks or the earth’s magnetic field
Indicators for environmental health
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Songbird eggs became very fragile because of the
pesticide DDT and their population was nearly
extinct
Common Birds around here
Common Birds around here
Common Birds around here
Common Birds around here
Common Birds around here
Common Birds around here
Common Birds around here
Common Birds around here
Common Birds around here
Common Birds around here
Common Birds around here
Common Birds around here