Comparative
Anatomy
Avian-Integument

Keratin-needed to produce scales, feathers and
beaks and claws.
– Dermis very thin-slow to heal.
– Best sites of subQ-wing folds and dorsal trunk and neck

“fluffed birds”-erector muscle of the dermis raise
feathers to trap body heat
– Fluffed and at the bottom of the cage-Not GOOD!!

Glands-no sweat glands
– Uropygial or preen gland


Dorsal aspect of tail
Helps clean and waterproof feathers
Avian-Integument
 Beak/Bill-upper
and lower mandible;
equivalent of mammalian lips
– Tearing food
– Capture food
– Preening
– Picking up material-nesting
 Claws-specialized
scales
– Beaks and Claws grow continually
Avian Integument
 Combs,
Wattles and Snood
– Specialized adaptation
– Can be trimmed off to prevent damage
in commercial operations
– Chickens below showing signs of Avian
Influenza
Snood
Normal Comb-right
Swollen Wattles
Avian Integument

Cere=fleshy membrane at the base of the
beak, location of nares
– Budgerigars-helps sex mature budgies??
Blue-male
Brown-female
– White ring around nares-female?? DNA
testing??
Male or Female??
Avian-Integument
 Feathers
– Functions: flight, protection,
thermoregulation, camouflage,
behaviors (courtship, defense,
recognition)
Avian- Integument
 Feather
Anatomy
– Inferior Umbilicus-vessels
– Superior Umbilicus- small
hole-start of the webbed
portion
– Calamus-quill; between
IU and SU
– Rachis-main feather shaft
– Vane-weblike, flattened
part of feather
Avian Integument
Vane is made up of
barbs, barbules and
hooklets (interlock)
 Looser feather weave

– Feels softer
– Allows air to pass
through-creating silent
flight
Avian Integument
 Types
of Feathers
– Contour-main feather that covers the
birds body; flight feathers, tail feathers
Avian Integument
 Types
of Feathers
– Semiplume- located under contour
feathers, on sides of the abdomen,
along neck and back
 Lack
barbules and hooklets
 Insulation and Buoyancy
– Down-lack a true shaft,
barbules and hooklets
 Insulation
Semiplume
Avian Integument
 Types
of feathers
– Filoplume- bare shaft with no barbs
except at the tip
 Dorsal
back/neck
 Sensory role –pressure and vibration sense
– Bristle Sense
of touch
 Around eyes, nostrils, mouth, and toes
Avian Integument

Feather types
– Powder Down Feather
 Continually
growing
 Produce a waxy powder
for cleaning and
waterproofing feathers.
 Birds without preen gland
- Herons
Avian Integument
 Feather
Damage
– Chewing, mites
– Stress bars-stress during growth phase
of feather; weakened vane and barbs
lack barbules—Nutritional stress
Avian Integument
 Molting=the
replacement
process of feather
– Species variation
– Influenced by season, temperature,
nutrition, egg laying, species and sex
– Generally symmetrical and gradual
replacement of flight feathers
– Waterfowl-molt all their flight feathers
at once right after breeding seasonPostnuptial
Avian Integument
 Molting
– Requires good quality nutrition
– 4-12% body weight is feathers!
– Germinal cells in dermal papilla
activated by:
 Increasing
day length
– Stimulates pituitary and thyroid gland to produce
hormone
– Sex hormones also play a role
– Blood feather=growing feather
Feather Development
Avian-wing trim
 Blood
feathers?
 “They still fly”
– We aren’t
preventing flight,
but preventing
them from
reaching great
heights!
– Glide quite well!!
Avian Musculoskeletal System
 Birds-175-200
 Skeletal
paired muscles
muscle-White or Red muscle
– White fibers-low blood flow, little
myoglobin
 Uses
stored glycogen for contraction
 Flight muscles of short distance fliers
– Red fibers-thinner, rich blood supply,
fat, myoglobin and mitochondria
 Flight
muscle of long distance fliers
Avian Musculoskeletal System
 Major
flight muscles
– Pectoral mm-Adducts and depresses
wing
– Suprocoracoideus mm-Abducts and
elevates the wing
Avian M/S system
 Skeleton-adaptation
to allow flight
– Reduce number of bones
– Fuse bones to form plates to provide
strength
– Reduce density of bones
– Lose internal bone matrix-filled with air
spaces
– Air sacs extend into bones proximal
extremities
 i.e.
fractions/infections
Avian Skeleton
Avian - Vision
Vision and Hearing-control centers
in the brain much larger than taste,
touch, and smell
 Proportionally larger eyes
 Binocular vision-species variation
 Excellent accommodation
 Two fovea-central and lateral
 Pectin-supplies nutrients and
oxygen to vitreous cavity

Comparative Retina

Color Vision
 Wide
spectrum of light wave
lengths
 Diurnal birds (hawks, parrots,
hummingbirds, etc.)- can also see
UV light
– American Kestrels can locate mice by
the UV reflection off the urine of the
mouse!!
– Distinguish ripe vs. unripe fruit
– Male vs. Female when plumage is
similar!
Avian Digestive System
 Beak-based
on what they eat
Avian Digestive System

Esophagus-right side of
the neck
– Mucous glands-lubricates

Crop-expansion of
esophagus-storage
– Larger crop-need less
meals per day
– Mucosal liningcrop milk
(pigeons, doves)
– Protection for insectivores
Avian Digestive System

Stomach
– Glandular Stomach
=Proventriculus
 Chemical
digestion
– Muscular Stomach
=Gizzard
 Striated
muscles to
grind food (bone,
scales, nuts)
 Produces pellets to be
regurgitated (owls,
hawks, herons, etc)
Avian Digestive
System
 Cloaca-termination
of tracts
– Coprodeum-from intestines
– Urodeum-from kidneys and genitals
– Proctodeum-site of sperm storage prior
to “cloacal kiss”, stores other
excrement.
– Mute= waste product
 Dark
fecal center with ring of urates
Avian Circulatory System
Heart-similar to mammalian
 Vessel differences:

– Pectoral and brachial arteries-larger
– Renal Portal System-veins from extremities
travel through kidneys to remove metabolic
waste
– Countercurrent system of heat exchange
– Resting HR estimate (beats/sec)
=12 X (4X weight in gm)
Renal Portal System
Avian Circulatory System
 Blood
– RBC-oval, nucleated and larger than
mammals
– WBC
 Young-produced
by spleen, liver, kidneys,
pancreas and bursa of Fabricius (dorsal wall
of proctodeum)
 Adult-produced by spleen
 Heterophils=mammalian neutrophils
– Thrombocytes=platelets
Avian Blood

Avian Respiratory System
 Due
to extremely high metabolic
rate, respiratory tract must be highly
specialized to quickly and efficiently
deliver Oxygen and remove CO2
Avian Respiratory System
 Choanae-internal
nares
that opens from the
nasal cavity onto the
roof of the mouth
 Larynx structures
surrounding the glottis
(opening into the
trachea)
– No vocal folds!!
Avian Respiratory
System
 Syrinx-Enlargement
above the sternum
of the trachea
– Voice box of the bird
– Number of muscle>>complex
vocalization
 Songbirds-7
pair
 Parrots-3 pair
 Ostrich, strokes, vultures-no pairs of
muscles
Avian Respiratory System
 Trachea
branches into bronchi
 Bronchi enter the lungs, lose
cartilaginous
protection>>Mesobronchi
 Mesobronchi branch into 4-6
ventrobronchi>>parabronchi
 Parabronchi connect to air capillaries
for gas exchange
Avian Respiratory System

Avian Respiratory System
 Air
Sacs
– Paired air sacs
 Cranial
Thoracic
 Caudal Thoracic
 Cervical
 Abdominal
– Unpaired air sac
 Interclavicular
air sac
Avian Respiratory System
 Air
Sac function
– Reservoir for air
– Warmth and moisture to improve
diffusion of air through lung capillaries
– Thermoregulation-internal evaporation
of water>> cools
– Buoyancy
Avian Respiratory System
 Lungs
– Very small
– Attached to thoracic vertebrae and ribs
– Highly vascular
– Inelastic
– House air and blood capillaries for gas
exchange
Avian Respiratory System
 First
inhalation-expand
thoracoabdominal space-creating a
pressure gradient
– Air moves into posterior air sacs to
warm and humidify
 First
Expiration-air is pushed into the
lungs for gas exchange
Avian Respiratory System
 Second
Inspiration-
– Air moves out of lungs into the anterior
parts of the air sacs
 Second
Expiration-
– Air leaves the body via trachea
 No
mixing of inspired and expired
air!!
– 21% oxygen
Demo
Avian Breathing
Avian Urogenital System
 Kidneys
– 3 divisions-each containing cortex and
medulla
– Lack a renal pelvis
– Each nephron:
 Glomerulus
 Renal
tubules surround
a Central vein
Avian Urogenital System

Urine Composition
– 75% Uric acid (nitrogenous waste)
– 10-15% ammonia
– 2-10% urea
*Uric acid is more efficient removal of
nitrogenous waste (2 Nitrogen)
*Uses less water to eliminate
Becomes important in the egg-waste is stored
in the egg throughout development
Avian Reproductive System
 Gonads
grow in size during breeding
season-special adaptation
 L. gonad larger than the right (male
and female)-sexing
– Sex reversal?? (rt. Ovitestes)
Avian Reproductive System
 Male
Reproductive System
– Spermatozoa produced in similar
manner
– No accessory glands-seminal fluid
produced by tubules within the testes
– Epididymus-no divisions
– Vas deferens connects with a storage
pouch for spermatozoa-Seminal Vesicle
 Cooler
temp than core
Seasonal Testes Size

Avian Reproductive System
 Copulation
– Ducks, geese, storks, flamingos-erectile
penis stored in the cloaca
– Most other species of birds-sperm
transfer by bringing male and female
cloaca in close proximity
 “Cloacal
Kiss”
Avian Reproductive System
 Female
Reproductive System
– Ova forms from follicles in the ovary
– Ovulation>>ova to the oviduct
– Oviduct:
 Infundibulum-+/-
fertilization
 Magnum-secretes layers of albumin (egg
whites)
 Isthmus-Deposits keratin shell membrane
 Uterus-shell gland-watery albumin
shell/pigmentation (calcium carbonate)
 Vagina-secretes mucus to assist in laying
the egg. Can store sperm for hours to days!
Avian Female Reproductive Tract
Avian Reproductive
System
 Clutch=Number
of eggs that a
female lays and incubates
– Determinate layers-specific number of
follicles develop. Once eggs are laid,
clutch is complete.
– Indeterminate layers-produce more
eggs than their clutch; will continue to
produce eggs if they disappear
 Endangered
species
Avian Reproductive System
Incubation-keeping the eggs
warm and humidified
 Prolactin levels are high,
suppress LH and FSH
 Brood patch-area of skin on
lower abdomen-where heat
is transferred

– Hen plucks feathers in this
region
Avian Reproductive System
 Hatching-
– Egg tooth-specialized
tooth inside the chick’s bill.
 Disappears
after birth
– Sex Determination
 Z=female,
dominant
 W=male, recessive
 Females can lay ZW, or ZZ
Things to Remember When
Working with Birds

Heart rates vary with the size of the bird.
– 25 grams 275 BPM (resting) – 400-600 BPM
(restrained)
– 1000 grams 130 BPM (resting) – 150-350 BPM
(restrained)
When working with eagles and waterfowl,
always test blood lead levels!
 Jugular - The right jugular vein is used
because it is fairly prominent (many bird
species lack a left jugular vein).

Venipuncture
 Alar
vein - located running across the
ventral surface of the humeralradial-ulnar joint (elbow) directly
beneath the skin.
 Medial Metatarsal Vein – located on
the medial side of the lower leg.
When available, this vein is typically
the site of choice for blood sampling
in birds.
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