ornithology exam 2

Plumage

All of a birds feathers

Pterylae

Feather tracts (patterns on skin)

Arterial

Featherless areas on skin

Pigments

Chemical compounds within the cells

Structural colors

Produced through the scattering of various wavelengths

Melanins

Blacks, browns, grays,

Carotenoids

Yellows, oranges, reds (some greens when blue structural color overlays)

Porphyrins

Rufous brown or greens, reds and blues, only in Turacos, bustards, and owls

Psattacofulvins

only in parrots, yellow, orange, and red

Sphenuscins

Yellow pigments only in penguins

Benefits of Melanin

Crypsis

Signaling and pattern

Thermoregulation

UV light protection

Resistance to abrasion

Resistance to bacterial breakdown

Lift at wingtips?

Eumelanin

Brown and black melanin

Pheomelanin

Reddish and yellowish melanin

Melanin production

Melanocytes in basal skin layer produce melanin which is transported to outer layers of dermis and incorporated into feathers

Iridescent feathers

Allow the passage of light through the feather. Can appear multicolored depending on angle of light. Formed from melanin packed in stacks that scatter reflected light

Blue feather coloration

Always structural, air pockets layers between melanin and keratin

Structural coloration

Scattered wavelengths reflected from a particular arrangement of melanin granules and the open space between them in the cells

White coloration

Can be due to the absence of melanin or a structural artifact of melanin (all wavelengths of light scattered back)

Carotenoids source

Obtained from diet

Psittacofulvins benefits

Also resistant to bacteria

Turacin and turacoverdun

Porphyrin pigments that have a copper base instead of iron. Only in turacos

Bird eye cones

They have 4, red, green, blue and ultraviolet

Lammergeier

A bone eating bird that rubs mud on its feathers to stain them with iron oxides

Poisonous feathers

Presumably due to eating beetles

Manakin

Bird that sings with its wings

Basic plumage

Feathers the bird has through most of the year

Alternative plumage

Plumage worn for a shorter time (breeding season)

Pre-basic molt

Results in the basic plumage

Pre-alternate molt

Results in alternate plumage

Birds without pre-alternate molt

Chickadees, thrushes, most wrens, jays, crows, mockingbirds, thrashers, doves, most sparrows

Birds with pre-alternate molt

Warblers, buntings, tanagers

Plumage sequences in passerines

Nestling - hatched naked, grows Juvenal plumage (10-14 days)

Juvenal plumage worn for several weeks of summer

Pre basic molt - late summer

Produces basic plumage, does not include flight feathers in juveniles

Molt limit

Contrast in old feathers and new used to age birds

If there is a molt limit

It is a a bird that is less than one year old

If there is no molt limit

The bird is older than 1 year old

Altricial

Young hatched naked and 100% dependent on parents

Precocial

Young hatched downy and in short order can walk, swim, find their own food etc.

Aging birds - Egg

Egg

Aging birds - nestling

Baby bird confined to nest

Aging birds - fledgling

Just left the nest, still begs parents for food

Aging birds - local/juvenile

Still on parents territory but independent

Aging birds - immature

General term for birds not old enough to breed

Hatch year bird (HY)

Bird that was hatched that year

Second year bird (SY)

Hatch year birds after January 1st

After-hatch year Hurd (AHY)

More inclusive term, used on all unknown birds after January 1st

After-second year bird

A bird not SY between January-July

Definitive plumage

Once a bird attains adult plumage

Skulling

Most definitive way to determine age

Advantages of flight

Speed for catching prey

Speed for evading predators

Agility for access to food/nesting sites

Ease of travel through large home range

Ease of dispersal

Ease of migration to take advantage of favorable environments

Disadvantages of flight

Modification of forelimbs to be not much use for things other than flying

Extreme skeletal modification to reduce weight

Energetically costly to maintain ability to fly

Selection towards high-energy foods

Four forces acting on flying bird

1. Gravity

2. Lift

3. Drag

4. Thrust

Gravity

Pulls towards the ground

Lift

Upward air pressure that counteracts gravity

Drag

Slowing force from turbulence and friction

Thrust

Forward force that counteracts drag

Airfoil

Any shape that produces the effect of lower pressure above and higher pressure below (creates lift)

Angle of attack

Deviation of the leading edge of an airfoil from the direction of airflow

Chord

Straight line width of an airfoil from leading to trailing edge

Camber

Convex shape to an airfoil in cross section, greater close to the body than at the wingtip

Slotting

The narrow emarginations on the outer primaries of many soaring birds. At the primary tips each feather acts as its own airfoil to reduce drag

Wing loading

The total mass supported by the wing surface area (heavy birds and lighter birds with proportionally small wings have high wing loading)

Highest wing loading

Heaviest flying birds (bustards) as well as smaller birds with proportionally smaller wings (alcids)

Aspect ratio

Shape of a birds wing as a ratio of wing length to wing width.

High aspect ratio

Long thin wings of albatross, better for soaring and gliding

Low aspect ratio

Broad stubby wings of grouse, better for maneuverability

Additional energy savings in flight

Riding thermals

Riding updrafts

Riding updrafts along waves

Dynamic soaring

Albatross, takes very high aspect ratio, utilizes turbulent air closer to surface and fast smooth air higher up

Hummingbird flight

Flap their wings in a figure 8 pattern so both sides of the wing push air downwards

Metabolism

Sum total of biochemical processes in an organism, increases with temperature

Benefits of high metabolic rate

Nocturnal activity

High latitudes

High elevations

Speed

Endurance

Migration

Improved mobility

Basal metabolism

Energy expenditure needed to simply stay alive (maintain homeostasis), birds have a higher basal metabolic rate (BMR)

Blood oxygen carrying abilities

Mammalian blood actually carries more oxygen

How do birds deliver more blood to their tissues

Avian heart is larger

Higher stroke volume

High blood pressure

Myoglobin

A globular protein in MUSCLE tissue that contains and iron-rich gene group with a high affinity for binding oxygen

Hemoglobin

Iron rich pigment in blood with high affinity for binding Oxygen

Bar-headed Goose

Highest flying bird

Migrates over the Himalaya

29,500 feet

Bar-headed goose adaptations

Larger lungs

Form of hemoglobin with extra oxygen binding affinity

More myoglobin

Emperor Penguin

Deepest dive

1,752 feet deep

Holding breath for over 30 minutes

Emperor Penguin adaptations

1. Storage of oxygen in myoglobin in muscles

2. Bradycardia

3. Peripheral vasoconstriction

4. Tachycardia on surfacing

Rufous Hummingbird

Too small to survive as an endothermic home therm at high altitude and latitude

Rufous hummingbird adaptation

Torpor - facultative hypothermia

Daily torpor

Greater efficiency in gas exchange overall

Downside of greater gas exchange efficiency

More vulnerable to toxic fumes

Mammalian respiratory system

Gas exchange takes place in capillaries associated with alveoli

Oxygen only taken in during inhalation

Residual dead air in alveoli

Unique avian respiratory system characteristics

Avian air sacs (9)

Unidirectional flow through lungs (no dead air)

Lungs spongy but rigid, don’t expand and contract

Oxygen taken in during both inhalation and exhalation

No diaphragm

Avian respiration picture

Parabronchi

Tubes within the avian lung that are the site of gas exchange

Concurrent flow

Moving same direction

Once the concentration approaches 50% there is no gradient

Counter-current flow

Positive diffusion gradient is maintained near 100% exchange can occur

Mammalian gas exchange

Concurrent

Avian gas exchange

Cross-current

Not as efficient as counter current but significantly better than concurrent