BIRDS
Class Aves
External Anatomy
•Feathers – insulation and flight
•1. Modified scales that help regulate
body temperature.
•2. Structure and variety varies from
bird to bird.
Structure Types
•Contour – Covers the body, wings and tail
•function: Gives shape to bird and used
for flight
•Consists of a :
a. Quill (calamus)
• b. shaft (rachis)
• c. barbs and barbules
• d. hook – attaches to barbules
•Down – Soft feathers under the
contour and on young chicks
•function: Insulation
More structure parts
•Filoplume – Hairlike feather
with a few barbs and barbules
at end
•function: Sensory
• 4. Birds must molt: shed and replace
feathers.
Some do this all at once, some molt
once or twice a year.
Types of Birds: (with regards to feathers)
Precocial – Born with feathers
Ex.chickens
•. Altricial – Born without feathers
Ex. Robins
•.
Uropygial Gland 11/19
•Function– Secretes oil for feathers.
•location: at base of tail
•function: keeps plumage water
repellent and supple and prevents
chafing on legs and bill
•Feathers eventually become
_dead_____and
•keratinized______structures in a
feather follicle because
•_the blood supply is cut off.
Bill
•Bill (no teeth)
•Uses
•a. Get food
•b. Protection
•c. Preen feathers: clean plumage by
rubbing bill over feathers.
•d. Swimming
•Tail: acts as a rudder during flight or
swimming
Feet with Scales
Uses in addition to walking
•a. Get food
•b. Protection
•c. Perching
•d. Swimming
. Cere: Protective stucture for eyes .
•
1. location: __behind the
bill___.
•E
Internal Anatomy
•Skeleton - __Bones are hollow
(pneumatic)_____________
•Furcula – fused clavical (wishbones)
•Synsacrum – fused vertebrae
•attached to __pelvis___
•function: maintain proper flight
posture; supports hind appendages
during landing, hopping, walking
•Pygostyle – fused vertebrae
•function: supports tail; important in
steering
•Single occipital condyle – birds share
this with reptiles
•first cervical vertebra: has a single
point of articulation
•Keel- ridge of the sternum
•function: attachment of flight
muscles
Digestive system
•Crop – past esophagus
•a. Stores and moistens food
•Stomach
•Proventriculus- secretes gastric juices
•Ventriculus (_gizzard__)- muscular;
grinds food
Excretory system
•a. No _urinary___ _bladder____
•b. Like reptiles in that they excrete
uric acid (nitrogenous waste) into
the cloaca with the urine as a semisolid whitish paste.
Supraorbital
•Salt glands
•function: drains excess NaCl through
nasal opening
•Important in _marine___
_birds_____.
Circulatory System Stop here!
•Heart: 4 chambers (rt. &lt. atria, rt.
&lt. Ventricles)
•Beat of heart: Very rapid
Reproductive System
•Oviparous: internal fertilization; eggs
laid and develop outside of the body.
•Male – paired testes, No
_copulatory__ _organs__.
•Sperm passes from male cloaca to
female cloaca__.
Female
•Female – only left_ ovary functions – right
ovary is _vestigial___.
•Egg development: Ovary releases eggs into
oviduct.
•a. Egg fertilized in upper portion of oviduct
•A gland in lower oviduct adds a shell
•Oviduct opens into the cloaca
•A group of eggs laid and chicks produced is
called a _clutch_
Hatchlings
•altricial: entirely dependent on
parent; born naked
•Ex. American robin
•precocial: born alert and lively with
feathers, needs one parent for food
and shelter
•Ex. Chickens
Respiratory System
•most efficient of all vertebrates
•Syrinx: produces sound
•Tracheal- ducks, pigeons – most simple
•Bronchotracheal- most birds – most
common
•Bronchial- Wood thrush – two sounds at
once
•Males produce more sound than female:
controlled by nerves and hormones
Air passage- Unique because…….
•a. helps in flight – lighter in
weight/volume
•b. helps in water fowl to float
•c. holds more oxygen for rapid
metabolism
•d. air sacs cool body internally
(ventilation
Continued respiratory system•Breathing – Controlled by the medulla of
brain
•a. Lungs composed of parabranchi_,
small air tubes.
•b.Air moves continuously: unidirectional
flow (blood opposite.)
• c.Interclavicular air sac:furnishes air
for syrinx and bones
•Behavior
Behavior
•Migration
•Advantages:
•a. more food available
•b. less competition when breeding
•c. cooler climate for raising young
•d. fewer parasites in North
Disadvantage of Migration
•a. natural disasters - storms
•b. bird uses a lot of energy
•c. loss of many birds (of a species)
•d. man- made obstacles (buildings, cars,
houses (windows)
•Migration depends on environmental
factors and innate genetic clock.
Photoperiod
•migratory cue for migration
•Changes in the length of day initiates seasonal
changes in gonadal development. Serves as a
migratory stimuli. Decreasing day length =
gonad regression; Increasing day length =
gonad development
•Increase in body fat: used as energy reserve.
Territorialism
• Territory- any area of land which is defended by a bird from other
birds of the same species.
• 1. Territorialism: any area of land defended by a bird from other
birds of the same species
• 2. Male: territory determiner – defends against other males of
same species
• 3. Defense displays various behaviors:
• a. Song
• b. feathers (threat display)
• c. physical encounters (last resort)
• d. flight pursuits
Use Defense displays during:
• a. nest building
• b. egg laying
• c. incubation
• d. care of young
• Functions of territory:
• a. Protection of nest, young, mate against other
males
• b. Guarantee of enough food
• c. Sexual bond between male and female from year
to year
• d. Natural selection – limits population size
Courtship • – display of male or female attention
• Fighting: now thought to be a part of
territorialism
• Various courtship displays
• Dances Ex. Argus Pheasant
• Display of feathers Ex. Peacock
• Feeding Ex. Terns
• Mouth color Ex. Frigate, Cassaway
• Beak to beak “kissing”
• 90% of bird species are _monogomous__.