1. KEY CONCEPT Birds have many adaptations for flight.

2. Birds evolved from theropod dinosaurs.
Birds and many theropods share anatomical features.
hollow bones
fused collarbones that form V-shaped wishbone
rearranged muscles in the hips and legs
“hands” that have lost their fourth and fifth fingers
feathers

3. The oldest undisputed fossilized bird is Archaeopteryx.
Unlike all living birds, Archaeopteryx had a full set of teeth, a rather flat sternum ("breastbone"), a long, bony tail, gastralia ("belly ribs"), and three claws on the wing which could have still been used to grasp prey (or maybe trees). However, its feathers, wings, furcula ("wishbone") and reduced fingers are all characteristics of modern birds.

4. A bird’s body is specialized for flight.
Birds have several unique features that allow them to fly.
wings to produce flight
strong flight muscles to move the wings
active metabolism that provides energy to the muscles
hollow bone structure to minimize weight
gonads active during only part of year
small
intestine
large
lung
gizzard
kidney
cloaca
crop
sternum (keel)
heart
liver
pectoral muscle

5. Wings are structures that enable birds to fly.
airfoil shape
covered with feathers

6. Air sacs help a bird meet its oxygen demand during flight.

7. Birds have spread to many ecological niches.
The shape of a bird’s wing reflects the way it flies.
short and broad
long and narrow

8. The shape of a bird’s wing reflects the way it flies. wide and broad
small
intestine
large
lung
gizzard
kidney
cloaca
crop
sternum (keel)
heart
liver
pectoral muscle
stout and tapered

9. Differences in the shape of a bird’s beak reflects how it eats.
spearlike
hooked
chisel-shaped
blue-footed booby
Bald eagle
green woodpecker

10. Birds show great diversity in their foot shape. webbed heavy claws
different toe location
blue-footed booby
bald eagle
green woodpecker

11. Feathers: Anatomy

12. Feather Types

13. Flight Feathers

14. Flight feathers and the Wing
Primaries
Attached to hand
Asymmetrical vanes
Owls have silent flight because of barbs on front of vane
Generate thrust (forward motion)
Secondaries
Attached to ulna
Generate lift
Tail feathers
Function in steering and braking

15. Wing shapes
Great once in the air, but first need to get launched!
- Mastery of Flight beginning of video

16. Birds preen up to once an hour!
Feather care
Birds preen up to once an hour!
Some preening glands have lipids which resist keratin eating fungi and bacteria
Preening is the process by which birds groom and care for their feathers. When a bird is preening, she uses her beak to pick through her feathers -- removing any debris, arranging feathers that are out of place, and distributing a special oil that is secreted from a gland at the base of the tail.

17. Adaptations for flight: Anatomical
Feathers
Wing
Reproduction (internal, eggs)
Bones

18. Anatomical adaptations: Bones (already mentioned)
Lightweight, strutted or hollow
No teeth
Modified forelimb
Fused bones provide rigidity and strenth. Uncinate processes overlap ribs for strengthening thorax; furcula prevents lateral compression of chest

19. Anatomical adaptations: Bones
Fused bones of pelvis, feet, hands, head
Uncinate processes on ribs
Furcula (wishbone)
Fused bones provide rigidity and strenth. Uncinate processes overlap ribs for strengthening thorax; furcula prevents lateral compression of chest

20. Flight Adaptations: Physiological adaptations
Endothermic
Separate red and white muscle fibers

21. Flight Adaptations: Red versus White fibers
Red fibers = sustained work, ability to produce heat by shivering
White fibers – powerful stroke but cannot be sustained
Pigeon wing and breast?
Grouse or turkey wing and breast?
Bird leg?
Humming bird wing and breast?

22. Flight Adaptations: Circulatory System
High metabolic demands require rapid circulation of high volumes of blood.
Four chambered heart
Double circulatory system (pulmonary and systemic)
Large heart % larger and more powerful than mammals of the same size.

23. Flight Adaptations: Respiratory System
Mammals: simple but inefficient. 20% of air never contacts a respiratory surface for exchange
Birds require 2 full breaths to move air completely through system. More efficient w/ help of air sacs
In addition to lungs, th ey have ~9 air sacks extending into abdomen, land toward wings
Average 9 ranges 6-14.

24. Flight Adaptations: Urinary system
How often do you see a bird drink?
Sources:
High metabolism = high metabolic water production (up to 80% of requirements)
Food: particularly birds of prey and insectivores.
Seed eaters need the most water
Free water – streams, watering hole, raindrops, snow

25. Flight Adaptations: Urinary system
Water conservation
Excrete uric acid – a semi-solid with 2x the nitrogen per molecule. Concentrated in cloaca up to 3000x the acid level as in blood
Mammals excrete a lot of water to flush and dilute the nitrogenous wastes (urea)

26. Flight Adaptations: No teeth…Digestive system impact?
Crop
Proventriculus (stomach)
Ventriculus (Gizzard)
Intestines
Caecae
If a nectar eater, is a gizzard important?
What size caecae would a goose have?
What other feeding adaptations do birds have?

27. Bird Adaptations: Bill Shape
So important that this is one way birds are classified. Twenty different orders of birds are recognized
Why are there so many different types of birds?

28. Evolutionary Arms Race
Over evolutionary time, we expect natural selection increases the efficiency with which predators detect/capture prey AND also we expect selection to increase prey ability to avoid detection and to escape!
Who wins?

29. Evolutionary Arms Race
Predator adaptation
Prey Counter-Adaptation
Improved visual acuity
Search image
Limit search to abundant areas
learning
Crypsis
Polymorphism
Space out
mimicry
Winners? No. Life versus dinner principle. Stronger selection on prey. Predators adapting to a variety of prey species and cannot specialize.

30. Bird Adaptations: Reproductive System
Bird Egg
One functional ovary (less weight)
Nest structure and bird behavior create microclimate for embryo
Laying/incubating eggs is dangerous. Need to avoid predators!
Site choice
Nest structure
Adult behavior