Class Aves Birds Class Aves Birds n Ornithologist
Class Aves (Birds)
Class Aves (Birds) n Ornithologist – Zoologists that study birds
Characteristics of Birds Vertebrate n Feathers n Wings (but not all fly) n Scale-covered legs n Homoeothermic (Keeps their body temperature at one temperature) n Endothermic (Warm blooded) n
Designed For Flight. The following characteristics equip birds for flying: n Compact, lightweight, and very strong skeleton
Designed For Flight. n Lightweight beaks and skulls.
Designed For Flight. n A nearly rigid backbone that gives a solid support for the strenuous muscle activity required for flying
Designed For Flight. n Hollow spaces in the skeleton that provide room for air sacs, which contribute to the efficiency of the respiratory system and make the bird lighter.
Designed For Flight. n Bipedal (“twofooted”) anatomy, which leaves the wings free for flying.
Designed For Flight. n A prominent ridge, or keel, on the breastbone to allow for the attachment of flight muscles by strong tendons.
Designed For Flight. n Three bones in the shoulder to support each wing.
Designed For Flight. n An efficient circulatory system, including a four-chambered heart.
Designed For Flight. n Powerful muscles to power the wings during flight.
Perching Birds – Three toes pointing forward and one toe pointing backward. n Leg has a special design that allows the bird to stay on their perch even if they are sleeping. n
Diagram of Perching Bird’s Leg
Birds of Prey Especially acute eyesight n Sharp, Powerful talons (grasping and killing their prey) n Hooked Beak n
Swimming and Wading Birds – Many have water repellent feathers n Webbed or Lobed feet for swimming n Some Birds have very long legs designed for wading n
Game Birds – Have been hunted for food and sport n Large flight muscles (Breast meat) allow them to burst into flight n
Tropical Birds – Live in the world’s tropical forests n Brightly colored n Many have large unusual beaks n
Flightless Birds Have wings or wing-like structures n Usually equipped with powerful legs for running n
Extinct Birds Some became extinct because of the pressures put on their habitat n Some have been extinct for thousands of years n
Avian Anatomy and Physiology
Function of Feathers n Lightweight body covering that is an excellent insulator n Smoothly tapered, streamlined shape n Broad surface area of wings allow for lift
Types of Feathers n Contour Feather – Strong feathers found on the bird’s body, wings, and tail
Types of Feathers n Flight Feather – A special contour feather that provides the necessary wing shape for flight
Types of Feathers n Down Feather – Soft fluffy feathers close to the birds body to provide great insulation without adding much weight
Types of Feathers n All feathers are pointed to the bird’s tail to aid in streamlining
Parts of the Feather n Calamus – The shaft in the middle of the feather that attaches to the bird.
Parts of the Feather n Rachis – The long shaft in the middle of the feather that the barbs attach to.
Parts of the Feather n Barbs – Small projections coming off the rachis which have barbules with hooks or flanges coming off of them
Parts of the Feather n Barbules – Small projections coming off the barb that hook together with the barbules of the next barb
Parts of the Feather n Vane – All of the Barbs on one side of the rachis
The Incredible Feather n By design, a feather can change shape during flight in response to different pressures in the air
The Incredible Feather Most of the feathers are designed to give lift n Some feathers are designed as ailerons and flaps to control direction and give extra lift. n
The Incredible Feather n The tail feathers serve as a rudder and elevator to control flight direction.
The Incredible Feather n There are nerve endings near the end of each feather that turn the feathers into sensory receptors
Flight Patterns n Powered Flight – Flap with a downward stroke of the wings to produce lift
Flight Patterns n Gliding – Use of the air movement to “fall” slowly and gracefully
Flight Patterns n Soaring – Use of thermal up-currents to rise in a circular pattern. Birds can dive and start climbing again
Flight Patterns n Special Flight Patterns – Complicated motion of the wings produce a vertical, reverse or hovering flight. (Hummingbird and Skylark)
Specially Designed Skeletal System n Many bones are hollow and filled with air instead of marrow
Specially Designed Skeletal System n The hollow bones are strengthened with internal cross bracing
Specially Designed Skeletal System n Birds have a blade-like sternum or breastbone that the large muscles responsible for flight attach to
Specially Designed Muscular System n Very large pectoralis major muscle powers the downward stroke that gives the bird lift
Specially Designed Nervous System n Usually have a poor sense of taste and smell
Specially Designed Nervous System Their sense of hearing is very good. n Because of the need to distinguish between the differences of different bird calls the bird needs to be able to distinguish differences in intensity and rapid fluctuations in pitch n
Specially Designed Nervous System Most birds have very good eyesight n Instead of moving their eyes in their head they will move their whole head n
Specially Designed Nervous System n They have a third eyelid called a nictitating membrane that is transparent and allows the bird to blink to moisten its eyes in flight.
Specially Designed Nervous System n Nocturnal birds have extraordinary night vision.
Specially Designed Digestive System n Relative small size and great activity requires a great deal of fuel
Specially Designed Digestive System n Birds absorb a very high percentage of the food they eat.
Specially Designed Digestive System n Different birds have different bills designed for what they eat
Specially Designed Digestive System n Birds are able to eat and digest their food quickly
Special Parts of the Digestive System n Crop – Many birds have a special sac in their esophagus that serves as a storage chamber.
Special Parts of the Digestive System n Gizzard – A chamber of the digestive system found after the stomach that is muscular, has horny plates, and sometimes contains grit to help grind the food up.
Special Parts of the Digestive System n Cloaca – Area of the digestive system where the waste is expelled. Also where the sperm is received for reproduction, where the eggs are released and where the wastes from the kidneys are released.
Specially Designed Excretory System n Birds produce uric acid instead of urea. This does not have to be dissolved in water and keeps water in the bird.
Specially Designed Excretory System n Birds release their uric acid through the cloaca
Specially Designed Excretory System n Some birds have a salt gland, which takes salt out of their body and puts it into a salty solution that runs through a duct in the nostril.
Specially Designed Excretory System n The salt gland allows marine birds to get the water they need by drinking seawater
Specially Designed Circulatory System Have a four-chambered heart n Have a high metabolism to keep the body at a constant temperature, so they have a rapid heartbeat n
Specially Designed Respiratory System n The respiratory system is completely different from every other living vertebrate.
Specially Designed Respiratory System n Breathes “through” their lungs instead of “into” their lungs n Lungs do not expand or contract
Specially Designed Respiratory System n With this different way of breathing, birds are able to take more oxygen out of the air
Specially Designed Respiratory System n Respiratory system allows birds to fly at high altitudes and have enough oxygen
Specially Designed Respiratory System n The air sacs of birds are used to cool the body during flight.
Specially Designed Respiratory System n The bird’s “voice box” (syrinx) has a membrane that vibrates when air passes over it.
Family Life of Birds
Migration n Migration – the annual movement to a different region
What we know about Migration 1. Migrating birds follow the same route each year (These are called Flyways)
What we know about Migration 2. A keen sense of direction and recognition of landmarks seems to be involved
What we know about Migration 3. The position of stars and constellations guide many migrating birds.
What we know about Migration 4. The earth’s magnetic field helps guide certain birds
What we know about Migration 5. The length of the day has a bearing on the migratory instinct
What we know about Migration 6. The urge to migrate may be related to breeding and development of sex organs
What we know about Migration 7. Migration generally occurs in the spring and fall
What we know about Migration 8. Most migration is north and south
North American Blue Grouse n Migrates about 300 miles, one of the shortest
Arctic Tern n Migrates 11, 000 miles each time from Antarctica to the Arctic
Courtship n Depending on the species, males display some form of behavior that attracts the female.
Color (Frigate Bird)
Plumage (Superb Bird of Paradise)
Nesting Most birds build a new nest for every new brood n There about as many different nests as there are species of birds n
Robin nest n Made of twigs and grass
Barn Swallow nest n Made of mud
Killdeer nest n Made of stones
Oriole nest n Nest hangs from branches
Osprey nest n High, built near water
Nesting (Sparrow Eggs) n Nesting is done for the protection of eggs
Parts of the Egg Yolk – A food source rich in fat n Embryo – Living part of the egg n Germinal Spot – Special area where the embryo develops n
Parts of the Egg n Shell – Protective covering of the egg with tiny pores that allow for diffusion of oxygen, water vapor, and carbon dioxide.
Parts of the Egg n Chalaza – Twisted cord that supports the yolk and makes sure that the germination spot is always facing up.
Parts of the Egg Albumen – Egg white. Surrounds the yolk. n Air Chamber – Small amount of air inside the shell n
Diagram of an Egg
Diagram of an Egg
Incubation n Incubation –keeps eggs warm so the young will develop properly
Incubation n Brood Patch – a patch of skin where an adult loses feathers on its belly to transfer heat to the egg
Incubation n The bird instinctively senses the temperature within the egg and adjusts it accordingly
Emperor Penguin n Emperor penguin keeps the egg at 93 degrees for 8 -9 weeks with air temperatures at 77 below 0
Hatching n Altricial – Birds are naked and helpless at birth (Robins, Blue Jays, Cardinals)
Hatching n Precocial – Birds that are covered with down and are able to run or swim immediately after hatching (Ducks, Geese, Killdeer)
Feeding n Some birds will wait with their mouths open.
Feeding n Parents will store food in their crop and “regurgitate” it for the birds
Feeding n Some young birds reach into their parent’s mouth to eat
Feeding Doves and pigeons produce crop milk rich in protein and fat n The flamingo produces an oily fluid in their digestive tracts to feed their young n
Flamingo about to receive crop milk