Ornithology Exam 2

What do feathers do once they reach full size?

They die (lose blood supply)

Feather functions

- Insulation/protection

- Flight

- Display, camouflage, and other color functions

Follicles

sites of feather attachment

Pterylae

feather tracts

apteria

areas without feathers (between pterylae)

pterylosis

pattern of pterylae and apteria

types of feathers

- Contour

- Down

- Semiplume

- Filoplume

- Bristle

- Powder down

contour feathers

large feathers that give shape to a bird's body and help with flying

- like shingles on a roof

- protects against water/temperatureCon

Types of contour feathers

- Body feathers

- Flight feathers

Contour feather construction

Study This:

barbs

Rachis

remiges and retrices

flight feathers

remiges

Primaries: help with flight most

- attach to hand bones

- 10 most common

Secondaries:

- Attach to ulna

- 6-40 (hummingbirds-albatrosses)

- 10 most common

- more variation in length of secondaries

Owl Remiges

Built for silence (small hair like structures on remiges)

Retrices

Attached to the pygostyle (fused caudal vertebrae and associated musculature)

- 12 common

Down feathers

Feathers with smooth barbules but no hooked barbules

- soft used for insulation

- beneath contour feathers

- lacks rachis or rachis shorter than longest barb

body down

- down of adult birds

- Trap air, excellent thermal insulation

- Most dense in water birds, especially northern ducks

- very cold oriented

Natal Down

first plumage upon hatching

- young remaining in nest are warmed by parents (altricial)

- Young that leave the nest soon after hatching (precocial)

altricial

Offspring that are completely dependent on parental care

precocial

Offspring that can walk, run, swim, and feed themselves at hatching

What's unique about natal down?

- Lacks barbules on outermost barbs (fuzzy appearance)

- Produced by follicles that will later produce contour feathers (unlike body down)

Semiplumes

- Under contour feathers with light insulation

- barbules lack hooks and barbs don't form vein but the rachis is longer than the longest barb

- provide streamlined form in overlying contour feathers

Filoplumes

- Hair-like feathers that are stiff

- Bare rachis with barbs only at tip

- sensory structures associated with follicles that monitor feather movement within feather coat (determine if feathers are properly aligned)

Bristles

- specialized contour feathers which have a stiff rachis and lack barbs along outer tip

- Usually found around eyes and mouth (rictal bristles)

- May help protect eyes and detect movements of prey in bill

rictal bristles

bristle-like feathers around the corner of the mouth

Powder Down

- Specialized feathers found only in a few groups of birds (parrots & herons)

- Similar to fluffy contour feathers or body down

- Disintegrate at tips to produce fine powder

- May function in waterproofing or stain prevention

- never molted grow continuously

Feather care

- Most feathers are non-living and must be maintained

- Preening

Preening

in birds, the act of grooming and maintaining their feathers

- waterproofing feathers (uropygial gland)

- conditioning feathers

- Helps prevent infections

uropygial gland

gland located at the base of the tail that secretes oil for preening feathers (in front of retrices)

- oil or preen gland

Bathing in birds

- Water used

- dust used

(controls ectoparasites and helps clean plumage)

sunning

spread postures to enable sun rays to dry/condition feathers

anting

- Birds use ants to remove ectoparasites from their feathers

- may be passive (allow ants to swarm over body) or active (rub ants or other chemically-potent objects over body)

Feather growth

- Papillae on the skin develop into follicles

- Pin feathers (growing feathers enclosed within feather sheath) develop from follicles

blood quills

Blood vessels in dermal tissue extend into feather shaft, nourishing the growing feather

Feather colors

Pigment colors- caused by chemical compounds in feathers

Structural colors- reflected colors created when sunlight is reflected off of feather structures

Melanin feather pigment

gray, black, brown, and buff colors

(synthesized from tyrosine and other amino acids)

Porphyrins feather pigment

red, brown, green, and pink colors

(Nitrogen and metal-containing molecules that are modified amino acids)

Carotenoids feather pigment

bright red, yellow, and orange colors

(Cannot be synthesized, must come from diet)

structural colors

Caused by scattering of certain wavelengths of light (usually BLUES) by air vacuoles in keratinized feather cells or other structural layers in feathers

- Produces bright blues, greens, and iridescence

plumage

a bird's feathers collectively

natal plumage

the plumage a bird is hatched with

Juvenal plumage

the plumage a bird leaves the nest with (replaces natal down)

Subadult (immature) plumage

replaces juvenal plumage

Definitive (adult) plumage

worn by adult birds

Age to Maturity

The age at which birds reach definitive plumage varies among bird groups

- Many songbirds <1 year

- Gulls 3-4 years

- Eagles 4-5 years

- Albatrosses 7-8 years

Seasonal Plumage Change

- Some adult birds only have 1 plumage per year (e.g. geese)

- Many birds have 2 or more different plumages that are replaced seasonally

Molt

The replacement of feathers of one plumage with feathers of another plumage

asynchronous molts (most birds)

gradual molts (feathers replaced sequentially)

synchronous molt (some birds)

whole feather tracts replaced (e.g. waterfowl flight feathers)

- can not fly when feathers fall out

Basic plumage

an adult bird's main plumage each year that is produced by a complete molt (NON-BREEDING PLUMAGE))

Alternate plumage

the plumage that results from a PARTIAL molt of the basic plumage before breeding (BREEDING PLUMAGE)

Supplemental or supplementary plumages

some birds have 3 or more plumages per year (happen as needed (e.g. harsh winters causing feather damage)

Molt Terminology

- most widely accepted system is based on the acquired plumage

Molt Ecology

- Replacing feathers is energetically & nutritionally expensive

- During molt, bird feathers are less efficient

(birds with a synchronous wing molt are vulnerable when flightless; those with asynchronous wing molts have impaired flight ability for LONGER PERIODS)

When does molting usually occur?

- during times of low energy demand (not during migration or when breeding)

- occurs in habitats with sufficient food to support feather growth (and sometimes with places to hide if flightless)

- sometimes switch to high protein foods

- Birds often stop the molt and resume it later as needed (e.g. migration)

shock molt or fright molt

is the shedding of many feathers at once when frightened or threatened

Eye color of birds

most standard color is dark brown

- white

- yellow

- orange

- blue

- red

uncommon eye colors

- eye color of some species change with age

- sexual dimorphism in eye color in some species

Bill

- Consists of hard, horn-like keratinized skin overlying bone

- inner layers are alive and replace worn away outer layers

What influences bill shape

Diet

seabird bills

Have bill modifications to dispose of excess salt (tube-nosed birds)

Birds of prey bills

have hooked bills and ceres (fleshy bases)

Bird feet

Birds walk on their toes (tarsometatarsus serves as the lower leg bone in birds)

- most birds have 4 toes

- Toes are numbered by the number of toe bones (phalanges)

- toe 4 has the most bend & toe one has the least bend

name of bird toes

phalanges

zygodactyl

having the toes arranged two in front and two behind

anisodactyl (most common)

one toe faces the rear, other three face forward

Heterodactyl (least common)

3, 4 in front

1, 2 in back

Palmate webbing

between 3 forward toes

Totipalmate webbing

webbing of all 4 toes

semipalmate webbing

Webbing doesn't extend to toe tip; or just 1 side

Lobate webbing

Each toe has its own web

raptorial

bird of prey foot

scutellate

large scales

reticulate

small scales

Scutellate-reticulate

scutes and reticulate scales (large and small)

booted (least common)

large scales on toes

special adaptation of birds

- hooked toes for climbing

- long toes for walking

- feathers for warmth "snow shoes"

Bird skeletal system

- bone, cartilage, tendons, and ligaments

- bones are modified to minimize weight (struts inside for structure)

pectoral girdle

scapula, furcula, and coracoid (prevent collapse of chest cavity during wingbeats)

Carina

(keel) attachment point for flight muscles

Muscular system

- skeletal muscle, smooth muscle, cardiac muscle

- cells bound together in muscle fibers (shorten when stimulated by nerves)

- skeletal muscles generally arranged in opposing pairs

Supracoracoideus

raises wing

pectoralis

lowers wing

muscle action

Pectoralis muscle contracts on the downstroke, and the supracoracoideus contracts on the upstroke.

Flight muscles

- make up 20-30% body mass

- most muscle mass carried below the wings (low center of gravity stable

muscles consist of two types of fibers

• Red fibers needed for sustained flight(efficient aerobic metabolism)

• White fibers needed for short-term power(anaerobic metabolism)

• Most skeletal muscles have both types, but ratio differs

Two primary thigh muscles

- iliotibialis extensor

- semitendinosus flexor

Two primary lower leg muscles

- peroneus longus

- gastrocnemius

esophagus

storage organ in birds (like a stomach WITHOUT digestion)

crop

esophageal pocket

crop milk

pigeons and doves specialized crops that make this and they feed the milk to their young (highly nutritious liquid)

Proventriculus

secretes digestive enzymes

gizzard

grinds food (grinding organ)

What do birds eat to help grind food?

small pebbles

small intestine

Digestive organ where most chemical digestion and absorption of food takes place

Large intestine

absorbs water (begins at the junction of the paired ceca)

ceca

aid in fiber digestion

kidneys and intestines

excretion of water and nitrogenous waste

What nitrogenous wastes do birds excrete?

uric acid (concentrated in cloaca)

Cool fact about uric acid

2X as much Nitrogen as urea

where are the kidneys located in birds

inside the fused vertebrae of the back