Download Bird Anatomy

Bird Anatomy
Circulatory System
• Separate systemic,
pulmonary
circulations
• 4-chambered heart
• Same in mammals homeotherms
Hearts
• 1.5-2 X larger than in
comparable mammals
• Maintain higher
metabolism
• Smaller birds have
relatively larger hearts
than larger birds
• Heart size increases with
latitude, altitude for same
species
Heart Beat
• Heart beat slower than
in mammals
• Smaller birds have
faster heartbeats than
larger birds
Blood Pressure
• Slightly higher than
mammals
• Bordering on safety
• Heart, aortic ruptures
can occur
Respiratory System
• Most efficient among
vertebrates
• Unique design
• Complex flow-through
system of sacs &
interconnecting tubes
Respiratory System
• Small lungs (2% of
body volume)
connected to large air
sacs (~10X larger)
• 4 pairs of sacs plus 1
unpaired sac (some
variation)
Respiratory System
• Tiny, inelastic lungs
filled with tubular air
capillaries parabronchi
• Unidirectional
movement of air
through parabronchi
compared to dead-end
structure of
mammalian alveoli
Respiratory System
Respiratory System
• Process - 2-cycle
pump
• 2 inhalation/exhalation
cycles required to
move each breath
totally through
respiratory system
• Posterior air sacs to
lungs to anterior air
sacs
Respiratory System
Respiratory System
• Unidirectional air flow
through lungs
• Oxygenated air during
both inhalation and
exhalation
• Blood flows in
opposite direction
Air Sacs
•
•
•
•
May also aid in:
Cooling
Buoyancy
Defecation/egg-laying
muscle assistance
• Courtship
Accessory Things
• Syrinx - voicebox
• Where trachea splits
into bronchi
• Various types, but
generally are complex
arrangements of
muscles, membranes
Accessory Things
• Sounds (songs)
produced in several
ways
• Vibrating membranes
• Changing size of
openings
• Changing air
movement patterns
Excretion
• Kidneys and salt
glands
• Kidneys similar to
mammal kidneys
• 2X as large (relative)
– More rapid metabolism
• Not as efficient at
removing salt
– Need for salt glands
Excretion
• Kidneys produce
primarily uric acid
rather than urea
• Requires less water
(not as toxic as
urea)
• Holdover from
embryo (egg)
Excretion
• Uric acid works well
in dry climates,
conserves weight
• Water not needed in
large quantities
• Wastes dumped into
cloaca (no urinary
bladder), mixed with
feces, forms white
paste with dark lumps
Excretion
• Salt glands in head
• Concentrate salt 35X that in blood
• Discharge through
nostrils
• Especially active in
marine birds
Reproductive Anatomy - Male
• Paired testes
• Grow during
breeding season,
shrink otherwise
• Up to 200-300X
difference in size
between seasons
Reproductive Anatomy - Male
Reproductive Anatomy - Male
• Left testis slightly
larger than right
• Related to female left side only?
Reproductive Anatomy - Male
• Vas deferens wavy tubes
• Mature sperm
collect until
transferred
• End nearest cloaca
may swell to serve
as storage sac
Reproductive Anatomy - Male
• Copulatory organ - present
in more primitive birds
• E.g., flightless ratites,
Galliformes, ducks &
geese
• Erectile, grooved structure
used to guide sperm into
female’s cloaca during
copulation
• Birds lacking feature just
press cloacal openings
together
Sperm Development
• High body
temperature
causes problems
• Sperm cells can’t
develop at
normal body
temperatures
Sperm Development
• Alternatives:
• Develop at night when
body temperature may
drop
• Delay final
development until
storage in cooler sac
or pouch near cloaca
Sperm Output
• Millions to billions per
copulation
Sperm in Female
• Sperm may be stored
in female temporarily
in lower oviduct
pouch
• Stored sperm may
remain viable for up to
several months before
eggs are laid
– Highly variable
among species
Fertilization
• One to many
copulations may be
required for
fertilization
• Parthenogenesis
possible in some
species (e.g., turkeys)
Reproductive Anatomy - Female
• Left side only
• Ovary, oviduct
• Right ovary, oviduct
whither away
• Weight reduction?
• But paired systems
(abnormal) have been
observed in dozens of
species
Reproductive Anatomy - Female
• Enlarge during
breeding season,
shrink after
Reproductive Anatomy - Female
• Ovary may contain
thousands of ovarian
follicles
• Only few per year
mature into ova
• Rapid growth through
addition of fat, protein
food (yolk) probably
from liver
Reproductive Anatomy - Female
• Oviduct responsible
for adding albumen,
shell membranes,
shell, pigment to ova
• Five regions
Reproductive Anatomy - Female
• Infundibulum funnels, captures
released ova
• 2 ova released
simultaneously
produce “doubleyolked” egg
• Ovum spends ~18 minutes
here in chicken
Reproductive Anatomy - Female
• Magnum - largest
region
• Secretes layers of
albumen (egg-white)
• Moisture and
cushioning
• Ovum spends ~4 hrs
here in chicken
Reproductive Anatomy - Female
• Isthmus
• Produces shell
membranes
• Flexible keratin
• Ovum spends ~1.25
hrs here in chicken
Reproductive Anatomy - Female
• Uterus
• Shell gland produces
the calcium carbonate
shell
• Pigment glands apply
color(s)
• Ovum spends ~18-20
hrs here in chicken
Reproductive Anatomy - Female
• Vagina
• Lined with mucous
glands and muscular
to aid egg-laying
• Ovum spends very
brief time here in
chicken - just passing
through!
Calcium Sources for Eggs
• Diet most important
source for most birds
• Bones serve as a
secondary source
Bird Songs & Calls
• Calls are brief sounds with
simple acoustic structure
• Usually 1 or 2 notes,
rarely 4 or 5
• Used for behavior
coordination
– Non-sexual
– Flocking, feeding,
migration, predator
reaction
• Some innate, others
learned
Bird Songs & Calls
• Songs are complex
sounds
• Groups of notes
separated from one
another by relatively
long pauses
Bird Songs & Calls
• Songs often serve as
substitute for physical
combat (territory
defense)
• Maintaining pair bond
• Stimulate, synchronize
reproduction
• More commonly
modified by learning
than are calls
Bird Songs & Calls
•
•
•
•
Overall functions:
Reproductive
Social
Individual
Calls as Vocabularies
• Many different
birds have different
calls
• Enable members of
a species to “talk”
to one another
• Different calls have
different meanings:
• Assembly
• Alarm
• Distress
• Feeding
• Individual “name”
calls
Cluck-Cluck-Cluck
• Chicken has at least 10 • ¿Como estan ustedes?
different calls for
• Some calls also may
communicating with
be interspecific
others
• Species that often
• Species generally have
flock together have
calls numbering in the
relatively common
teens or twenties
calls that all species
• Songbirds average ~15
can understand
Chink-Chink-Chink
• Used by many
species to indicate
stationary threat
• Low frequency
• Repeated
• Easy to locate
caller
Seeet
• Used to indicate
moving threat
• High frequency
• Singular
• Difficult to locate
caller
Source of Sound
• Syrinx - found only
in birds
• Sounds produced
by vibrations of
vocal membranes in
syrinx, or vibration
of air columns
Source of Sound
• Air in trachea or air
sacs may also
resonate and either
dampen or enhance
vibrations caused
by vocal
membranes
Source of Sound
• Some birds capable of
producing two
unrelated
(harmonically) sounds
simultaneously
• Duplicate membranes
controlled by separate
muscles in each
bronchus
Trachea and Pitch
• Length, diameter of
trachea determines
pitch
• Long & wide - deep
voice
• Short & narrow - high
voice
Trachea and Pitch
• Geese, swans, etc.
have strange method
for lengthening
trachea, deepening
voice
• Some birds compress
trachea to increase
pitch
• Also inflate air sacs to
add resonance, volume
Primary Songs
• Loud
• Courtship and
territory defense
• Adult males mostly
Secondary Songs
• “Subsongs” or
“whisper songs”
• Weak, quiet practice?
• Young males,
males outside of
breeding season,
females
Song Cycles
• Seasonal variation
correlated with
breeding activity,
hormone
production
• Richest, fullest
song in spring
– Territory
establishment,
courtship
Song Cycles
• Decreases after
mating, during
family rearing
• Rarely sing on or
near nest
• Silent during molt,
cold weather
• Testosterone can
induce song out of
season
Song Cycles - Daily
• Most vigorous at
dawn, tapers to
midday, increases into
evening, ceases at
dusk
• Nocturnal species
opposite
• Chief stimulus - light
intensity - minimum to
initiate
– Inverse in nocturnal
species
Innate vs. Learned
• Some species have
entirely inherited
songs
• Complete song
develops in absence of
exposure to adults innate
• Other species’ songs
have both innate,
learned components
Innate Song
• Innate pattern is
rather simple
• Serves as a
“template”
Learned Song
• Learning enhances the
template
• Critical period learners
- learning can only be
done before a certain
age
• Open-ended learners learning can occur at
any time
Open-ended Learning
• Song may be changed
from year to year
• May learn a more
complex song
• May show
“experience” and more
successfully attract a
mate
Song Mimicry
• Many species capable
of mimicking calls,
songs of other species
• Mimidae (catbird,
mockingbird,
thrasher), starling,
crow
• May also imitate other
animals, sounds
Song Mimicry
• Why?
• Ulterior motives?
• Imitated sounds
apparently not used to
keep away those
species
• Better mimic may be
more likely to attract
its own mate
Song Dialects
• Geographic variation
in songs - dialects
• Species members in
one area sing similar
songs, but different
from same species
elsewhere
Song Dialects
• Widely separated birds
may sing such
dissimilar songs that
they may not
recognize each other
as members of same
species
• Young learn dialects
from parents and/or
neighbors
Song Dialects
• Familiar neighbor’s
song may elicit less of
a response than song
of non-neighbor
• Intruder?