bird anatomy circulatory system separate systemic, pulmonary circulations 4-chambered heart same in...
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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 are
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 3-
5X 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 “double-yolked” 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 different calls for communicating with others
• Species generally have calls numbering in the teens or twenties
• Songbirds average ~15
• ¿Como estan ustedes?• Some calls also may
be interspecific• Species that often
flock together have relatively common calls that all species 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?