Bird Anatomy Circulatory System Separate systemic pulmonary circulations

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 (~10 X 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 • 2 X 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 35 X 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 -300 X 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 • 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 • 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?