Download Chapter 42.2- characteristics of birds

Chapter 42
Birds
Section 2
Characteristics of
Birds
Feathers
• Modified scales
• 2 functions: conserve body heat &
provide lift for flight
• Down feathers- provide insulation
• Contour feathers- give adults
streamlined shape
• Flight feathers- specialized on
wing & tail
Feathers- made of keratin
• Feathers develop from tiny pits in
the skin called follicles.
• Shaft- emerges from the follicle &
two vanes-develop on opposite
sides of the shaft
• Maturity- vane has many
branches- barbs- many projects
from barbs = barbules
Feathers
• Preening- care for feathers- birds
rub feathers with beak and secrete
oil by a preen gland- located at
base of tail
• Birds molt, or shed to re-grow
feathers
Skeleton and Muscles
• Bones are thin and hollow
• Bones are fused so they are more
rigid- provides stability during flight
• Sternum- breastbone- attachment
point for flight muscles
• Pygostyle- supports tail feathers
Metabolism
• Endothermic- produce body heat
• Have to eat often- high energy
users
• Conserve body heat- fluff up
feathers
• Aquatic birds have a layer of fat
and oil on feathers to keep water
from body
Digestive & Excretory
System
• Esophagus  crop- stores &
moistens food  proventriculusacid and digestive enzymes begin
breaking down food  gizzardcrushes food  small intestines 
cloaca
• Uric acid- waste--- no urine (too
heavy)
Respiratory System
• High metabolic rate = high oxygen
use of birds
• Air sacs- redirect air to lungs
• Efficient breathing
Circulatory System
• Four-chambered heart
Nervous System & Sense Organs
• Complex brain, keen eyesight,
good hearing
Reproduction
• Vasa deferentia- sperm pass
through small tubes
• During mating, birds press cloacas
together
• Ovary released to oviduct- egg
fertilized by sperm
• Egg passes from oviduct- out
cloaca
Nest Building & Parental Care
• Birds lay eggs in nest---why a
nest?
• Brood patch- parents incubate
eggs with a thickened, featherless
patch of skin on abdomen
Nest Building & Parental Care
• Two patterns of rearing young
• Precocial- young can swim, walk,
feed as soon as they hatch
(ducks, chickens, etc)
• Atricial- young are born blind,
naked, and helpless (hawks,
parrots, warblers, etc)
Migration
• Migration- seasonal movement
• Ornithologists- study birds
• Earth’s magnetic field changes
and gives cues on when to
migrate- some monitor position of
stars or sun
• Birds eat double before they
migrate
REVIEW!!!
• In what ways does the gizzard
compensate for the lack of teeth in
birds?
• Identify the cues birds use to help
them navigate during a migration.