Ornithology Exam 1

Characteristics of Birds

Bipedal

Feathers

Beak

Gizzard

Endothermic

Pygostyle and Uncinate processes

Lay eggs

Evolution

Change in alleles freqs in population over time

Natural Selection

Mechanism of evolution

Avg survival/repro of individuals of different phenotypes

Adaptive Radiation

One taxa diverging into different species due to varying niches

Ex. Finches on Galapagos

Convergent Evolution

Similar adaptations that have evolved in distantly related organisms due to similar environments

Ex. Toucans and Hornbills

6 main biogeographical areas

Avifauna

Regional assemblages of bird species

Differences and similarities between Archaeopteryx and modern birds

Similarities: Furcula and veined feathers

Differences: Long tail, multiple digits, no keeled sternum, and TEETH

Confuciusornis

First birds with true beak and a pygostyle

Enantiornithines

Sister to true birds; lacked uncinate processes and had teeth

Ornithothoraces

True birds

Has feathers, pygostyle

Fused hand bones and pneumatic bones

Furcula and uncinate processes

Keeled sternum

Why did birds evolve feathers?

For temperature regulation

First 4 times flight was evolved?

First, BUGS

Second, Pterosaurs

Third, dinosaurs => now BIRDS

Finally, mammals => BATS

Theories of flight

Arboreal: Glide to flight

Cursorial: Small dinos w/ elongated wings were better at jumping and catching prey => flight

Wing-assisted incline running: Wing strokes came from flapping to climb trees

What are feathers?

Unique to theropods and made of beta-keratin

Different parts of a feather

Importance of feathers

Insulation

Waterproofing

Sexual selection

Flight

What are contour feathers?

Vaned feathers that cover entire body of birds

Fluffy/downy plumulaceous base

Creates smooth surface over body

What are flight feathers?

Feathers used for flight

Remiges (wing feathers) attach to hand bones and ulna; generates LIFT

Rectrices (tail feathers) attach to pygostyle; FLIGHT CONTROL

What are down feathers used for?

Trap and keep warm air next to bird body.

What are bristiles?

Consist of only rachis and basal barbs; found on head

Help feel and trap insects (sensory)

What are filoplumes?

fine hairlike feather with few short barbs at the tip, used for sensory and detech adjacent veined feathers

8-12 on each flight feather

How do feathers develop?

Bulb => barb and barbule develop => Rachis fusion => sheath degenerates => sheath falls off

How do birds care for their feathers?

Preening

Allopreening

Use oil from uropygial gland

What is molting?

Replacement of feathers, typically once a year (twice a year for birds with alternative plumage)

Molting begin at middle most feathers until whole wing/tail is complete

When do birds molt?

Resident species molt at anytime

Short distance migrators molt prior to migration

Long distance migrators begin molting prior but complete at destination

What are the 4 major classes of pigments

Melanins

Carotenoids

Psittacofulvins

Porphyrins

What subgroups make up melanins?

Eumelanin which covers black and grays; increase structural integrity

Pheomelanin which covers reds, browns, rufous, and buff tans

Seen in all birds!

What are carotenoids?

Red and yellow pigments

Acquired through diet => honest signal of health/fitness

What are psittacofulvins?

Responsible for the coloration on ONLY parrots

NOT due to diet

What are porphyrins?

Pigment containing metal

Fluorescent under UV light

NOT due to diet

What are structural colors?

Colors that come from interaction b/w light and nanostructure on feathers

Blues, most greens, and iridescence

What is constructive/destructive interference?

When the light waves bounces in-phase, it is constructive and colors are seen

When light waves bounce out-phase, it is destructive and no colors are seen

What is iridescence?

Change in hue with angle of observation

Due to melanin granules in feather barbs

What are the 4 major components of flight?

Take-off

Maneuvering

Stabilizing

Landing

What are the 4 major forces acting on flight?

Gravity

Lift

Drag

Thrust

What is the Bernoulli effect?

States that air must travel further OVER the wing than under it, which causes reduction in air pressure

Seen in consistent flight

What is the angle of attack?

The angle at which birds use to take-off

What is the purpose of the alula?

Maintain lift at lower speeds, similar to slats on an airplane

What are the two main forms of flight?

Soaring and gliding

What are the two main forms of soaring?

Thermal soaring, often used by hawks and vultures

Dynamic soaring, often used by seabirds

What is flapping flight?

When bird actively adds thrust to flight

Forward thrust created on downstroke of wing

Often seen in small birds

What is hummingbird flight?

Lift generated on upstroke and downstroke of wing

Creates hovering movement

How are gliding and bounding flight different from each other?

In gliding, wings are open; In bounding, wings are folded

Flap gliding is efficient at slower speeds; Flap bounding is efficient at higher speeds

What is formation flying?

When birds fly in formation to conserve energy (50%) by using the rising vertex of the bird in front of them

What are the muscles for flight?

Pecturalis, used in downstroke of flight (Large and directly attached to humerus)

Supracorracoideus, used in upstroke of flight (Smaller and indirectly attached to humerus)

Flight adaptation evolution from oldest to newest

Asymmetrical wings

Pygostyle

Keeled sternum

Uncinate processes

What metrics are used to categorize wings?

Wing loading: Mass of bird / wing area

Wing aspect ratio: Length of wing / width of wing

What are broad wings better for?

Slower air speeds and reducing INDUCED drag

Which bird is an example of one with broad wings?

Eagles

What are sleek wings better for?

High air speeds and reducing PROFILE drag

Which bird is an example of one with sleek wings?

Hawks