Avian Bio: Organ Systems and Physiology

Nares

Nostrils

Cere

fleshy skin/keratin around nostrils

Specializations: tubenoses

group of seabirds that have tubular nostrils on top of the bill. Associated with salt glands that help seabirds remove excess salt from their bodies. (ex. albetrosses)

Specializations: baffles

Structures that guide or redirect airflow, helping regulate the movement of air. (ex. falcons)

Trachea

Black line. Main respiratory tube.

Syrinx

unique to birds. Sound producing organ located at the split between trachea and bronchi.

Lungs

Dont inflate. Trachea → Bronchi → 2 Bronchi → Parabronchi

Parabronchi

Fundamental sire of gas exchange, these are the traditional “lungs”

Anterior air sacs

Interclavicular (red line) and cranial thoracic (green line). They are located in the front.

Posterior air sacs

Abdominal (teal line) and caudal thoracic (purple line). They are located in the back.

Unidirectional lung ventilation

Happens by movement of the rib cage by uncinate (small, hook-shaped projections on the ribs of birds) processes. Air flows through the lungs one way. Mixing oxygen and carbon to blood so they always encounter a fresh oxygen supply.

Tongue

Important for accessing and manipulating food, has few tastebuds.

Alimentary canal: Crop

red line. Extension of the esophagus for food storage.

Alimentary canal: Stomach, Proventriculus

Glandular portion of stomach that produces enzyme for digestion.

Alimentary canal: Stomach, Gizzard

yellow line. Muscular portion of stomach. Site of mechanical digestion - blue line (breaking down hard foods, seeds).

Alimentary canal: Small intestine- duodenum, jejunum, ileum

purple line

Alimentary canal: Pancreas

pink line

Alimentary canal: Liver

green line

Alimentary canal: Large intestine

blue line

Urogenital system

Uro: urinary system. Genital: reproductive system

Gonads: gender

females = ZW (determine sex of baby). males = ZZ

Gonads: organs

Females- single (left) functional ovary

Males- testes; cloacal phallus (very rare, ostriches and ducks) in some.

Cloaca

Common site of output of digestive + urinary system

Brain size

brain size varies with body size. Larger size = larger brain.

Hippocampus

Perception and memory space. Well developed on caching species (jays and crows)

Bill tip organ

Clusters of mechanoreceptors (sensory receptors that detect physical forces) along bill. Best developed in kiwis, shorebirds, and parrots.

Nictitating membrane

3rd eyelid for added protection

Rods

monochromatic

Cones

4 types: red, green, blue, and Ultra Violet light

Central fovea

monocular vision

Temporal fovea

Binocular vision

Fovea

area of highly concentrated cones

Motion parallax

Stereoptical effects through head-bobbing. Closer objects appear to move faster

Hearing: Barn owls

They have asymmetrical ear positions that help triangulate the location of sound (prey)

Olfaction

Sense of smell that is well developed in tubenose seabirds (finding prey and their own nesting burrows), vultures (carrion), and kiwis (foraging).

Metabolic waste

Uric acid: Produced in liver. Water conserving but requires more energy to produce.