1. Birds

2. Characteristics of Birds
The following characteristics distinguish birds from other Vertebrates:
Forelimbs modified into wings
Feathers
Hollow, lightweight bones
Endothermic
Efficient respiration

3. Characteristics of Birds cont.
4 chambered heart
The two hind limbs, with clawed toes support body and scaly feet
A toothless, horny break in present
Amniote eggs are encased in hard, calcium-containing shells.
Furculum (wishbone)

4. Class Aves – Birds
Ornithology – study of birds

5. Feathers!
Soft, fluffy down feathers cover body of nestling birds and provide and insulating undercoat for adults.
Contour feathers cover the head and body and provide coloration
Flight feathers are specialized contour feathers on the wings and tails and they provide lift

6. Feathers Continued
At maturity each vane (branch of feather) has many barbules that are equipped with microscopic hooks to keep feathers together
Birds preen, or comb through their feathers spreading oils to keep them waterproof and repairing vanes
Oil is secreted from a preen gland

7. Feathers
Most birds go through a major molt, during which the birds replaces its flight feathers
This occurs in the late summer between breeding and migration.

8. Endotherms Generate and regulate body heat internally
Enables birds to inhabit both cold and hot climates
Body temperature ranges from degrees Celsius.
To help conserve body heat, birds fluff out their feathers to insulation.

9. Beaks and feet
Hawks and eagles have powerful break and clawed talons that help them capture and then rip their prey.
Swifts have a tiny breaks that opens wide like a catcher’s mitt to share insects in midair.
The feet of flightless birds, on the other hand are modified for walking and running

10. Beaks Short and thick - seed cracking (robin)
Long and thin, slightly curved - eating nectar (hummingbird)
Strong, chisel like - drilling (woodpecker)
Sharp, curved and pointed - tearing flesh (hawk)
Long and flattened - straining algae and plants (ducks)
Spear shaped - spearing fish (heron)

11. copyright cmassengale
Feet
3 toes in front, 1 behind - perching (robin)
2 toes in front, 2 behind - climbing (parrot)
Powerful curved talons - grasping prey (hawk)
Webbed - swimming (duck)
Long and thin - wading (heron)
Thick and stout - running (ostrich)
copyright cmassengale

12. Skeletons and Muscles Combine lightness and strength
Bones are thin and hollow (internal struts to add strength)
Many large bones are fused:
Collar bone into wishbone
Pelvic girdle
Parts of the vertebra
Fusion of bones helps provide a rigid frame for flight
Have very large pectoral muscles and sternum modified into keel

13. Digestive System
Food passes from the mouth cavity straight to the esophagus.
Enlargement of the esophagus called the crop stores and moistens food.
In the first chamber of the stomach, gastric fluids begin breaking down the food.
Then food passes through the gizzard, a muscular organ that kneads and crushes the food

14. Excretory System
The avian excretory system is also efficient and light weight
The two kidneys filter a nitrogenous waste called uric acid from the blood
highly concentrated uric acid travels by ducts called ureters to the cloaca, where along with undigested matter from the intestines, it is excreted in a semisolid, usually white mass

15. Respiratory System Air enters through paired nostrils at base of beak
When bird exhales the carbon dioxide-rich air from the lungs, oxygen rich air is forced out of the posterior air sacs into lungs via small air tubes

16. Circulatory System 4 chambered heart
Right and left sides completely separated
Right side receives deoxygenated blood from the body and pumps it to the lungs
Left side receives oxygenated blood from the lungs and pumps it to the rest of the body
Has a single aortic arch
Most birds have a rapid heart beat compared to other vertebrates – Hummingbird (600 times a minute)
Chickadee

17. Nervous System Birds have a large brains, relative to their size
Cerebellum coordinates movement
Cerebrum controls complex behavior patterns such as navigation, mating, and nest building
Optic lobe receives and interpret visual stimuli
Keen vision is necessary for taking off, landing, spotting landmarks, hunting and feeding
Have good color vision
Birds large eyes are located near the sides of its head, giving a bird a wide field of vision

18. Nervous system
Birds large eyes are located near the sides of its head, giving a bird a wide field of vision
Birds with eyes near the front of the head have better binocular vision
Hearing important to nocturnal species that rely on sounds to help them locate prey
Birds lack internal ears-ear canal leads to a tympanic membrane, called an eardrum
Sense of smell is poorly developed except in ducks and flightless birds
Sense of taste helps birds avoid bitter-tasting or toxic foods

19. Reproductive System
Bird sperm is produced in two testes that lie beneath the kidneys
Sperm passes through small tubes called the vas deferens into the male’s cloaca
During mating the male presses his cloaca to the females and releases sperm
Females single ovary releases eggs into a long, funnel-shaped oviduct where they are fertilized by sperm

20. Reproductive System
Fertilized eggs move down the oviduct, where they receive protective covering and a shell
Unfertilized egg consists of a nucleus, cytoplasm, and a yolk
When fertilized, the embryo is suspended in albumen, the egg white
The liquid medium is supported by ropelike strands of material called chalaza that are attached to the shell membrane
Female has a shell gland that secretes a protective calcium carbonate shell to surround the egg

22. Incubation and Development
A female bird usually lays eggs in the nest. One or both parents will incubate or warm the eggs by sitting on them.
They cover them with a thick, featherless patch of skin on their abdomen called a brood patch.
In penguins the male emperor heats the egg by placing it on his webbed feet and enfolding it with his warm abdomen.

23. Incubation and Development
Embryo development begins when the zygote forms a plate of cells on the surface of the yolk.
This plate begins to form the tissues and organs
The membrane produces digestive enzymes that dissolve proteins and lipids in the yolk.

24. Incubation and Development
Blood vessels in the yolk sac membrane carry the nutrients to the embryo.
When hatching begins the embryo makes a star-shaped crack in the shell with a scale-like egg tooth.
The chick presses and scrapes the shell until the crack widens enough for the chick to emerge.
The egg tooth falls off soon after the chick hatches.

25. Incubation and Development
Bird have two contrasting methods for rearing young:
Those that lay many eggs and incubate them for long periods hatch precocial young.
These birds are active as soon as they hatch, they can walk, swim, and feed themselves. For examples ducks and quail.

26. Incubation and Development
Birds that lay only a few eggs and hatch quickly produce altrical young.
They depend on both parents for several weeks.
For ex. Woodpeckers, hawks, pigeons parrots.

27. Behavior
The long periods of parental care may enable birds to learn such complex behaviors as courtship, nesting, and migration.
Young birds need protection until they develop the strength to fly and obtain food

28. Territoriality and Courtship
During the breeding season many male birds establish an area that they defend against other males of their species – territorial
The male then attempts to attract a female to share this territory.
Once a territory is established most birds engage in a period of courtship, behavior that is designed to attract a mate.
Many males attract females by means of their brightly colored feathers.
Some males combine song with flight displays.

29. Nest Building
Nests hold eggs, conceal young birds from predators, provide shelter from the elements, and sometimes even serve to attract a mate.
Most birds build nests in sheltered, well-hidden spots- from holes in the ground to treetops.
As a further adaptation to their environment, birds construct their nests of almost any material available.
Twigs, grasses, feathers, and mud are the most common materials used.

30. Migration
When temperatures drop and the food supply dwindles, many birds migrate to warmer climates.
Birds rely on a variety of cues to help them navigate.
Some species monitor the position of the stars or the sun.
Others rely on topographical landmarks, such as mountains.

31. Migration
Magnetic cues, changes in air pressure, and low –frequency sounds may also provide information to migrating birds.
The ability of birds to read these cues, along with their many adaptations for flight, enables them to migrate to and inhibit virtually any environment.

32. Evolution and Classification
Almost every feature of their reptilian anatomy has undergone modification in their adaptation to flight.
Becoming endotherms has enabled birds to survive in virtually every known environment

33. Class Aves – Birds
Birds are found in most every habitat from forests to deserts, even in caves.
Some birds dive in the ocean to 45 m to catch prey.
Birds live at both the North & South poles.
The bee hummingbird of Cuba weighs 1.8g and is one of the smallest vertebrate endotherms.

34. Origin and Early Evolution
Evidence from fossils and from studies of comparative anatomy indicates that birds evolved from reptiles
Their features and their fragile hollow bones do not preserve well  not very many fossils

35. Classification
Most taxonomists classify the nearly 9,000 species of Class Aves into 27 orders
Birds are classified by their beaks and feet

36. Bird Groups
Bird species are often categorized into six groups based on the bird’s lifestyle
Perching birds
Birds of prey
Flightless birds
Water birds
Wading birds
Diving birds

37. Terrestrial (land) Birds
Most perching birds, birds of prey, and flightless birds are terrestrial birds
They live mainly on dry land
Terrestrial birds have feet adapted to running, perching, or hunting and beaks adapted to eating fruits, seed, insects, or small animals

38. Perching Birds Are the most common group of birds
In order to perch and grip onto branches:
One toe points backwards
All other toes point forwards
The beaks of perching birds are:
Strong for cracking open seeds and nuts
Ex. Goldfinches
Long thin beaks for catching insects in the air or digging them out of the ground or tree trunks
Ex. Warbler

39. Birds of Prey Most Birds of prey are hunters with keen vision
Eagles, hawks, and smaller birds of prey hunt during the day
Owls have huge eyes and hunt for small prey during the night
Some birds do not use vision to hunt
Vultures rely on their incredible
sense of smell to find dead animals

40. Birds of Prey Most birds of prey have sharp talons and curved beaks
Talons are used to grasp prey
Curved beaks are used for tearing flesh
Most birds of prey hunt alone
However, some birds of prey hunt in groups and flush prey towards their waiting partners

41. Flightless Birds Flightless birds are the largest birds
The biggest flightless birds are ostriches, emus, rheas, and cassowaries
There are some small flightless birds
Example: Flightless Kiwi is the size of
a chicken
They have small wings and are
built to run on land
Ostriches can run up to 55 km/h

42. Flightless Bird Legs Many flightless birds have long, strong legs
Ostriches have two large, clawed toes on each foot

43. Aquatic Birds
Diving birds, water birds, and wading birds are aquatic birds
Live mainly in water
Aquatic birds have feet adapted to paddling and wading
Aquatic birds have beaks adapted to eating aquatic organisms

44. Diving Birds Not all flightless birds live on land
Penguins are flightless, and their wings and feet have been adapted for swimming
All 17 species of penguins live in the Southern Hemisphere
Some diving birds are found in the Northern Hemisphere
Their wings can still be used for flight, so they CANNOT dive as well as penguins can

45. Diving Birds – Penguins
Their wedge-shaped wings work as flippers
Webbed feet can be used as paddles
Have a thick coat of feathers and a layer of fat beneath their skin that allows them to live in freezing temperatures
A rich diet of krill and fish help penguins maintain the fat layer

46. Water Birds
Swan, Geese, and Ducks are water birds, or birds found in or near the water
Water birds have webbed feet for paddling
Have long, flattened beaks with rounded tips
Beaks are ideal for a variety of food such as small insects, fish, and grass

47. Seabirds
Seabirds are an unrelated group of birds that also live near open waters, but they are found around oceans
They have webbed feet like water birds
However, their beaks are longer
Beaks are made for catching their typical meal of fish or squid

48. Wading Birds Herons, storks, flamingos, and egrets are wading birds
Wading birds feed in shallow waters that are rich with fish and invertebrates
Wading birds have long, slender
legs to feed in a range of depths
Have long toes to keep them from sinking into the mud

49. Wading Birds Many wading birds have spear-shaped beaks for fishing
Fishing waders stand motionless as they wait for fish
When they see a fish they quickly snatch it in their beak or may even spear it
Waders that feed on invertebrates in the mud may have beaks that are built for stabbing into the mud to find prey