The Gabriel Foundation

Beyond the Birdie Basics

Anatomy

Avian Anatomy

Avian Anatomy is similar to mammals and other vertebrates, however there are some notable differences.

• Avian bones are adapted to flying, are filled with air and are part of the respiratory system.

• Bones are light and thin walled.

• The sternum or breastbone of birds is massive and supports the powerful pectoral muscles. These muscles comprise 20% of the bird’s body weight.

• Both the spine and the skull bones are fused, which gives added strength and power to the bird beak.

• Birds have an extremely long and flexible neck; the head can rotate 180 degrees.

• Feet – In Passerines (song birds) three toes point forward and one points back. Parrots have zygodactyl toes, two toes point forward and two point back creating an opposable hand-like appendage.

Avian Skeletal System

Avian Muscular System

• Birds have red and white muscles.

• Red fibers use fat as an energy source.

• White fibers use carbohydrates as an energy

source.

• Red meat vs. white meat!

• Mammals just have red muscle fibers.

Avian Cardiac System

• Heart and blood vessels are similar to that of mammals.

• Heart is large with a very fast heartbeat. – Human Human’s heart beats 60-80x a minute

– Canary Canary’s heart beats 500-1000x a minute

– Large parrot beats 150-300x a minute

• Cardiac output (amount of blood moved) is seven times greater in a flying budgie than in an exercising human!

• Enables bird to utilize tremendous amounts of energy very efficiently.

Avian Respiratory System

• Nares - nostrils

• Choana - Slit like opening at the roof of the mouth that filters,

humidifies and heats air.

• Syrinx - voice box

• Air sacs - hollow spaces located in the body cavity and some bones, that fill with air during respiration.

• Birds do not have a diaphragm – their chest muscles act like a bellows to pull and push air out of the body.

• Birds circulate air every 2 breaths throughout their body.

• Canaries take 60-100 breaths per minute.

• Large parrots take 25-40 breaths per minute.

• Humans take 12-16 breaths per minute.

• Birds are very susceptible to respiratory irritants and diseases.

Avian Respiratory System

Avian Digestive System

• Small birds eat 20% of their body weight in food a day.

• Birds use their beak and tongue to prepare food for swallowing.

• Crop - An enlargement at the base of the esophagus - food is stored here for gradual release to the stomach.

• Enables bird to eat a lot at one sitting and then digest slowly.

• Stomach - divided into two sections

• Proventriculus – adds digestive juices to the food

• Gizzard – muscular and pulverizes the food

• Small and large intestine – where food is absorbed into the bloodstream

• Cloaca – the common chamber where fecal, urinary and reproductive elements pass before expulsion from the body.

• Vent – the opening of the cloaca on the outside of the bird’s body.

Avian Digestive System

Avian Urinary System

• Kidneys filter the blood and remove waste products.

• Kidneys regulate the water and electrolytes in the body.

• Birds do not have a bladder or urethra.

• Urine goes directly from the kidneys through the ureters into the cloaca.

• Urine, urates and feces are eliminated together.

• Urates are the white, pasty material made of uric acid.

• Birds must urinate frequently because they don’t have a bladder.

• Blood flow through the lower half of the body travels through the kidneys before going into circulation and waste is filtered out.

• Medications cannot be given below the kidneys or it will be filtered out immediately.

• An infection in the lower half of the bird’s body may cause kidney infection.

Avian Reproductive System

Female Reproductive System

• Left ovary and oviduct develop, but the right ovary and oviduct remain undeveloped.

• Female birds determine the sex of the offspring.

• Reproductive system changes shape and size during breeding season.

• Oviduct – where fertilization and growth of the egg occur

• Uterus – produces the calcified shell around the egg

• Vagina – pushes the egg through the cloaca and to the outside

• Whole process from fertilization to laying takes 25 hours.

Avian Reproductive System

• Eggs can be laid spontaneously, without

fertilization or another bird present; simply

ovulating.

• Cockatiels and lovebirds are known to be very

prolific layers.

• Infertile eggs are clear when light is shined

through them.

Avian Reproductive System

• Paired testes, epididymis and ductus deferens

• No prostate gland

• Testosterone is the primary male hormone.

• Parrots don’t have a penis.

• Semen is transmitted through the joining of the male and female cloacas.

• Parrot semen is fertile for many days or weeks.

• During breeding season, the bird’s testes become extremely enlarged.

Avian Senses

Vision

• Birds have very large, well developed eyes

• They see detail better than mammals

• Each eye operates independently

• Birds can see into the ultraviolet spectrum

• Birds have almost 360 degrees of vision because of the placement of their eyes on the sides of their head, and their ability to swivel their long necks

• Birds have three eyelids – an upper, a lower and a nictitating membrane that is very thin and flicks across the eyeball when the bird blinks

Avian Senses

Hearing

• Birds’ ears are hidden behind feathers below the eye.

• Birds are less sensitive to high and low tones than humans are.

• Birds can differentiate different sounds ten times

faster than humans.

• A canary’s song would have to be slowed down 10 times before the human ear could catch all the notes.

Avian Senses

Taste & Smell

• Birds have a poor sense of smell.

• Birds have a poor sense of taste.

• They have much fewer taste buds than mammals.

• In a study, birds were not able to distinguish among different tastes.

• In this study, the birds disliked bitter and salty flavors, accepted sour flavors, and sometimes liked sweet flavors.

Feathers & Skin

Skin

• Avian skin is very thin and delicate.

• During nesting, the lower chest area of some bird species loses feathers and forms a thickened area with a rich blood supply called a brood patch which provides more warmth for the eggs.

• Uropygial gland – aka preen gland, located at the base of the tail and produces oil which waterproofs and increases feather durability (Amazons don’t have this gland).

• Birds do not have sweat glands.

Feathers & Skin

• Similar to mammalian hair

• A budgie has between 2000 -3000 feathers!

• Insulate and maintain a high body temperature

• Grow in tracts or rows which are called pterylaepterylae.

• Bare areas between rows are called apterylaeapterylae.

• 3 Feather types:

• Contour cover the outline of the body including the wings and tail – 10 Primary flight feathers -longest feathers at the end of the wing

– 10 Secondary flight feather - feathers on the wing near the body

– Coverts - body feathers

• Semiplume - bristle like feathers that appear at the edge of feather tracts ––they may have a sensory function

• Down feathers - fluffy feathers that form an undercoat and provide insulation

Feathers & Skin

Feather Growth

• The old feather falls out.

• A thickened projection of skin grows out.

• A pin or blood feather emerges wrapped in a keratin sheath. – Each new feather contains its own artery and vein.

– If broken, bleeding will occur; however, most birds will NOT bleed to death if the feather breaks off.

– The feather grows in completely and the blood supply dries up.

• If a feather is pulled out, a new feather will begin to grow.

• If a feather is cut off, the new feather will not grow until the bird molts the old feather.

• Molting is the yearly (or more often) cycle of losing feathers and replacing them, takes about 6 weeks.

• Molting can be very stressful to the bird.

• Bird needs to be on a good diet to successfully molt.

Feathers & Skin

Feather Health

• Condition and appearance of the feathers can be an excellent window to the bird’s health.

• Should be shiny and glossy

• Broken, dull, off-colored feathers could indicate a health problem.

• Birds preen their feathers constantly, which helps maintain their beauty and function.

• Preening cleans the feathers of dust and dirt, untangles them and puts them in their proper position.

Beaks

• Birds use their beaks for practically everything!

• It is comprised of hollow bone with sinuses on the inside.

• The outside is covered with keratin.

• The beak grows from the top out from the center line.

• As the beak grows, the keratin covering will flake and peel; this is normal.