Phylum chordata

class Aves

-ornithology
- feather
-more power less weight
-why do birds migrate?
1.Abundant sources of food
2.Long days in far north
3.predators not abundant in far north
4.Increase space for breeding
5.favors homeostasis
-diapsid amniotes
-their closest relatives are the crocodilians
-they are Endothermic
-excellent vision and neuromuscular coordination
-birds are the most species on earth. (vertebrae)
-fishes are the most species in the water (vertebrae)
-more fishes than birds
-smallest vertebrae are hummingbird
1.8 gm.
-forelimbs modified to wings
-hindlimbs for walking, swimming, or perching
-All have horny beaks no teeth
-all lay eggs
-not very diverse group like mammals, whales, bat, giraffe, porcupine, etc.
-respiratory system
-they all have head, neck, trunk
-one occipital condyle
-skeleton has air in it
-sternum with neck or no neck
-single bone in middle ear
-12 pairs of cranial nerves
-heart four chambers R.B.C. nucleated
-voice box called syrinx
-ureters open into cloaca, no bladder uric acid is the waste
-pairs of testes, open to cloaca
-female one ovary and oviduct
-internal fertilization
-external incubation
-precoical young
-altricial young
- females are heterogametic

Feathers:

- contour or vaned feather
-other types are after shaft, filoplumes (hair like) and power-down feather, found in hawks and parrots
-feather came from epidermis
-feather is dead structure like hair in mammals
-it molts at least once a year usually in late summer, after nesting
-in penguins it molt all at once
-feather are molted in sequence that balance is maintained
-parts of feather:
A. quil
B. shaft
C. vane
a. barb
b. barbule

Muscular skeleton system:

-bones are pneumatized
-beak is horny (keratinous)
-most birds have kinetic skull
-ribs are mostly fused with vertebrae
-sternum was missing in Archaeopteryx but some of modern birds sternums have keel
-Archaeopteryx had wishbone
-pectoralis muscles attached to wings
-wishbone is Furcula the fused clavicle
-pectoralis antagonist to supracoracoideus
-this muscle is located under pectoralis on the breast
- both are anchored to keel
-thigh muscle around femur smaller set around tibiotarsus
-feet usually don't have any muscles
-this type of arrangement put most of muscles in near center for center of gravity
-no tail bone unlike Archaeopteryx , but feathers are attached to pincushion-like muscles

Food, feeding and digestion:


-early birds were carnivorous, fed on insects
-Nowadays there is a bird to hunt every insect
-others feed on other invertebrates as well as other birds and small mammals
-there are omnivores birds too
-birds eat a lot
-a 3 gm of humming bird eats 100% of its body weight 3 gm.
- utilize high percentage of food they eat
-pharynx esophagus stomach crop (storage) gizzard intestine
rectum
-some birds crops produce milk, eg. Pigeons, doves, parrots
- higher fat content than cows milk
-bile duct release bile from gallbladder or liver to duodenum
-large liver and it is bilobed
-cloaca is last part of digestive system
-dorsal wall of cloaca has the bursa of fabricius

Circulatory system:

-same as mammals
-heart has four chambers
-brachial and pectoral arteries lead to wings and breast
-jugular veins
-heartbeat in turkey is 73/min.
chicken is 250/min.
black-capped chickadee is 500/min. when sleep; 1000/min. during exercise
-However blood pressure is similar to mammals of same size
-RBC is biconvex and nucleated
-very active phagocytes

Respiratory system:

-nine interconnecting air sacs
-air sacs connect to lung
-about 75% of inspired air bypassed the lung
-air directly end up in posterior air sacs as a reservoir


Advantages of this system:
A.lung receives fresh air at all time during both inspiration and expiration
B.Continous oxygenated blood
C.air sac system cools the bird

Excretory system:

-kidney has many nephneus
-urine passes by ureters to cloaca
-no urinary bladder
-In shelled egg all excretory products must remain in the eggshell with the growing embryo
-cloaca concentrate uric acid
-some have salt gland on each side of eye








Nervous and Sensory System:

-intelligent birds large cerebral hemisphere
-cerebellum the coordinating center
-optic lobes
Ear has three parts like mammals
1.external ear: sound-conducting canal extending to eardum
2.middle ear: has a rodlike columella that transmit vibration
3.inner ear: organ of hearing, the cochlea is located
-Instead of turning their eyes they turn their head
- eye retina
-Position of eye
A.vegetarians
B.carnivorous
-fovea
-Many birds have two fovea
-Many birds can see into ultra violet light



How do birds fly?

-origin of flight was selective pressures
-Two theory how birds began flying:
1.Climbing to high places and glide down
*2."ground up" flapping their wing into air
-One thing for sure feathers were formed before they can fly.
-Some birds have alula: group of small feather on thumb
There are usually four types of wings:
1.Elliptical wings: low aspect ratio. Ratio of length to average width.
highly maneuverable
2.High-speed wings:
high aspect ratio
3.Soaring wings: oceanic soaring birds like sailplanes
- high aspect ratio
4.High-lift wings: vultures, hawks, eagles, owls, and ospreys
- low aspect ratio


Migration:

-not all birds migrate
-aquatic birds migrate very rapidly
-other take a long time warblers 50 to 60 days
-many small birds migrate at night and feed during day
-some do both
-Internal changes of birds cause migration:
1.development of gonads during spring
2.accumulation of fat
3.length of the day (long days) stimulate anterior pituitary release gonadotropic hormones
How do birds fined where they need to go?
sun-azimuth orientation

Reproduction in Birds

-In male testes vas deferentia Cloaca
-sperm is stored in seminal vesicle
-ducks and geese have well developed copulatory organ, penis
-some swift copulate in flight
-eggs from ovary go to oviduct, to cloaca
-while going thru oviduct albumin, egg white is added
-further down in oviduct the shell is formed
-monogamy = one partner for each mating season
-Polygamy = two or more partner each breeding season
-swans and geese partners for life
-Seasonal monogamy is common
-Polygyny = "many female"
-Polyandry = "many male"
-Nest parasites such as brown-headed cowbird and the European Cuckoo

Bird Population:

-it is varied from year to year
-depend on predator and food resources cyclical
-most abundant birds on earth are Starlings and house sparrow
-lead poisoning
-In 1991 band of lead gun-shots
-decline of songbirds:
1.intensification of agriculture i.e. use of herbicides, pesticides, fertilizers
2.deprive of ground nesting
3.fragmentation of forests

Evolution, Comparison, and Summary:

-Archaeopteryx lithographica = German, "ancient wing inscribed in stone"
-this fossile record was same size of crow
-jaws had small bony teeth like reptiles
-long tail like reptiles
-imprints of feather
Birds and reptilesMammals
 -occipital condyle opening-2 opening
-single middle ear bone-3 bones
-lower jaw composed of 5 -lower jaw 1
or 6 bones bone mandibular
-uric acid as nitrogenous -urea nitrogenous waste waste
-similar yolk eggs-no egg formation

-living birds (Neornithes) are two types
1.ratite: large flightless, ostrich like, have flat sternum, poor pectoral muscles
2.carinate: flying birds have keeled sternum which powerful flight muscles are located