BIRD BIO PRACTICAL

Bristle feather

Stiff, hair-like feather around face; used for protection (eyes/nostrils)

Filoplume

Hair-like sensory feather; detects movement of other feathers

Semiplume

Intermediate feather; insulation + adds body shape

Down feather

Soft, fluffy feather with no hooklets; traps air for insulation

Contour feather

Outer body feather; smooth, aerodynamic, gives shape

Remiges

Flight feathers on wings; used for lift and thrust

Rectrices

Tail feathers; used for steering and braking

Rachis

Central shaft of feather

Barbs

Branches off rachis

Barbules

Smaller branches off barbs

Hooklets

Tiny hooks that interlock barbules to form smooth vane

Why contour feathers are aerodynamic

Hooklets interlock to create smooth surface for airflow

Why down feathers insulate

Lack hooklets → trap air → retain heat

Quill (calamus)

Hollow base of feather shaft; reduces weight

Function of flight feathers

Generate lift and thrust during flight

Function of tail feathers

Steering, braking, maneuvering

Function of down feathers

Insulation

Function of contour feathers

Protection + aerodynamics

Pigment-based color

Color from chemicals (melanin, carotenoids, porphyrins)

Structural color

Color from light interaction with feather structure (iridescence, UV)

Melanin

Produces black, brown, gray

Carotenoids

Produce yellow, orange, red (from diet)

Porphyrins

Produce reds, greens, pinks (less common)

Why structural color can "change"

Depends on light angle (iridescence)

X-axis on sonogram

Time

Y-axis on sonogram

Frequency (pitch)

Trill

Rapid repeated notes (dense horizontal pattern)

Buzz

Thick vertical block; many frequencies at once

Whistle

Clear, simple horizontal line

Harmonics

Stacked frequency lines above fundamental frequency

Complex harmonic sound

Multiple frequencies layered (stacked lines)

Why songs differ by habitat

Sound transmission differences (vegetation vs open space)

Forest song adaptation

Lower frequency, simpler (less distortion)

Grassland song adaptation

Higher frequency, more complex (less obstruction)

Alarm call

High-pitched, narrow frequency, hard to locate

Purpose of alarm call

Warn others without revealing location

Mobbing call

Loud, harsh, broad frequency, easy to locate

Purpose of mobbing call

Attract others to harass predator

Difference between alarm and mobbing calls

Alarm = hidden, Mobbing = attention-grabbing

Pishing

Sound used by humans to attract birds (triggers curiosity/mobbing)

Purpose of pishing

Get birds to approach for better viewing

Hotspot

Area with high species richness

Species richness

Number of species present

Species overlap

Number of shared species between locations

Point count

Method of surveying birds at a fixed location

Limitation of point counts

Detection bias (not all birds detected)

Occupancy

Whether a species is present in an area

Can point counts determine true occupancy?

No, because detection is imperfect

Crown

Top of head

Supercilium

Eyebrow stripe above eye

Eyeline

Dark line through eye

Malar stripe

Stripe from bill down side of throat

Rump

Upper base of tail

Undertail coverts

Feathers under tail base

Primaries

Outer wing feathers (thrust)

Secondaries

Inner wing feathers (lift)

Alula

Small "thumb" feathers that prevent stalling

Why do birds molt?

Replace worn feathers, maintain flight efficiency and insulation

Why are down feathers effective?

Trap air due to lack of hooklets

Why are structural colors misleading in field?

Change with lighting angle

Why are alarm calls high frequency?

Harder for predators to locate

Why do open-habitat birds have complex songs?

Less vegetation interference