Birds
Taxonomy
Kingdom Animalia
Phylum Chordata
Subphylum
Vertebrata
Class Aves
Key Term
The study of birds
is called
Ornithology.
Origin of Birds
 Most scientists agree that birds evolved
from a group of early reptiles.
 Bird fossil records are incomplete due to
lightweight/delicate skeleton.
 Archaeopteryx is the earliest and most
primitive bird ever found – fossil had teeth,
long tail, hind wings, and feathers.
 Archaeopteryx is considered a transitional
fossil between dinosaurs and birds.
Modern Birds
 ~ 9000 species
 Divided among 27 different orders
 Compared to 3 orders of amphibians and 4
orders of reptiles.
Similarities to Reptiles
 1. clawed toes
 2. scales on their feet
 3. internal fertilization
 4. shelled amniotic eggs
Differences from Reptiles
 4-chambered heart
 endothermic – maintains constant body temperature
 respiration – air sac – 75% of air goes into air sac
and 25% goes in to lungs
 no teeth
 have feathers
 have a beak or bill, which is a keratinized extension
of their bony jaw
 feet adapted for swimming, grasping, and perching
Feathers
 A feather is a lightweight, modified scale that
provides 1) insulation and 2) enables flight.
 Also plays role in courtship, incubation, and
waterproofing
 Plumage – the covering of feathers on a bird.
 Preening – process of cleaning and rubbing oil on
the feathers to keep them waterproof and in good
flying condition, also gets rid of parasites.
 Ruffled feathers need smoothing with the bill so barbules
re-connect.
 A preen (oil) gland is usually located above the base of
the tail.
Feathers
 Molting – shedding of a few old feathers
w/the growth of new ones
 flight and tail feathers are usually lost in
pairs as to maintain balance
 do not molt at critical times such as
breeding, migration or food shortage
(drought)
 Different types of feathers
3 Types of Feathers
1.Down feathers
2.Contour feathers
3.Filoplume feathers
1.Down Feather
 Down feathers Insulation &
waterproofing
feathers - common in
young birds; fluffy
w/no barbs (hooks
that interlock their
filaments)
 found underneath the
contour feathers.
2. Contour Feathers
 Contour feathers – most
common; gives body
shape; used for flight;
sleek, streamlined
 Specialized contour
feathers found on wings
and tail; contains
barbules that stay
together and move air.
3. Filoplume Feathers
 Filoplume feathers – long,
thin shafts w/weak barbs
and barbules, found
around beaks.
 They are believed to have
a sensory function,
helping birds keep their
feathers in order.
Parts of a Feather
 Shaft – continuation of
quill, bears numerous
barbs
 Barbs – branch off into
barbules which overlap
w/adjacent
barbs/barbules with the
ends interlocking,
keeping feathers firm
and smooth
 Quill – hollow; emerges
from skin follicle
Color
 Some color is a result of pigments, other
colors called structural colors, result from
irregularities on the surface of the feather
that diffracts white light.
 Color patterns are involved in species
and sex recognition and sexual
attraction, as well as provide camouflage.
Color
 Pigment Colors
 Melanin produces black, brown, and tan
 Carotenoids produce red, orange and yellow
 Structural colors
 blue and green feathers – barb reflects blue
wavelengths of light, other wavelengths pass
through the barb and are absorbed.
 white is the complete light reflection
 iridescence results from interference of light
waves caused by the flattening and twisting of
barbules.
Adaptations for Flight…
 1. have feathers
 2. front appendages modified as wings
 wing shapes vary- some adapted for soaring and
others for short quick flights
 3. endothermic- helps to 1) maintain high energy
levels necessary for flight 2) inhabit a variety of
habitats (tropics to Antarctic)
 4. high metabolic rate – eats large amounts of
food to maintain energy levels
 5. vertebral column modified for flight – long,
flexible neck allows for bill and neck to function
as a third appendage
Adaptations for Flight
 6. air spaces in the bones – sturdy, thin, hollow
bones; strengthened by bony crosspieces with air
spaces;
 7. sternum w/keel – sternum (breastbone)-where flight
muscles are attached
 8. four-chambered heart – rapidly moves oxygenated
blood, bringing needed oxygen to cells quickly
 9. efficient respiration - 2 cycles-when bird exhales,
oxygenated air passes from sacs into lungs – birds
receive oxygenated air when they breathe in and out;
heat also carried away w/water vapor in the air that is
exhaled.
 10. digestive system that is adapted to deal w/large
amounts of food
How Birds Fly
 1. Lift of the wings must overcome bird’s
weight.
 2. Forces that propel bird forward must
overcome drag that bird moving in air
creates.
 Wings provide propulsion.
 Tail provides balance, steering, and
breaking.
Types of Flight
 1. flapping flight
 2. gliding flight – common in seabirds
(albatross)
 3. circling
 4. hovering – common in birds of prey
(falcons)
 5. soaring – use rising air currents over heated
land or beside cliffs; eagle
 6.diving – may be for hunting, mating, warnings
2 Groups of Birds Based on
Ability to Fly
 1. Paleognathae – large flightless
ostrich-like birds, Kiwis – have a flat
sternum with poorly developed pectoral
muscles; descended from flying birds –
evolved to be large because their weight
did not matter.
 2. Neognathae – flying birds that have a
keeled sternum on which powerful flight
muscles attach.
 (Birds can also be grouped by feeding habits)
Feeding
 Birds have no teeth – swallow small
stones that help grind food in the gizzard.
 Lack bony jaw – reduces weight.
 Have a beak/bill that is adapted to their
food source.
 Crop is the storage structure for food,
allows for consumption of large quantities
of food.
Bills
Senses
Acute sense of hearing
and vision.
Birds have large eyes
relative to body size.
Reproduction
 Life cycle – (reproduction usually takes place in
spring) Times vary with species and size of birds
 Example: Warbler

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Nest construction - 4 to 5 days
Egg laying – 5 to 7 days
Incubation – average 11 days (albatross 80 days)
Fledgling – 9 to 12 days (hatchling to departure of
young)
 Lifespan can be 5 years for some warblers, up to 30
years for some species (herring gull). Typically, the
larger the bird, the longer their lifespan.
 Attract mates with colors, songs or calls.
Chick care…
 Altricial - Young
are entirely
dependant on
parents at birth.
 Precocial - Young can care for
themselves at birth. Eyes open
with downy feather covering.
2 Types of Mating
 1. monogamy – 1 partner per breeding
season; 90% of all birds exhibit this
behavior; female needs male to set up
and defend territory, find food, provide
prenatal care; some swan/geese species
have 1 mate for life.
 2. polygamy – 2 or more partners per
breeding season
Migration
 Migration – innate behavior; follow the
food; fly south around September,
triggered by length of daylight hours; return
early spring.
 Migration allows birds to avoid extreme
climate changes and to secure food and
shelter.
 Arctic terns fly up to about 40,000 miles/yr.
Causes of Extinction
 1. habitat destruction
 2. collecting bird parts, such as feathers,
beaks, talons, pet trade
 3. lead poisoning
 4. toxic effects of pesticides, oil spills,
and chemical dumping
 5. competition by introduced species
(cats, rats, mongoose, rabbits and goats)