Transcript Birds
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
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)