Flight and Migration

“If I had to choose, I would rather have birds than airplanes.”- Charles A. Lindbergh

Feathers

• Modified from epidermis – lots of keratin protein (as in scales, nails, skin, hair)

• Function:• Insulation• Flight• Regulate body heat (endotherms)• Sexual display

Types of Feathers

1. Down- irregular shape (dead air space)

2. Contour- give body a smooth, aerodynamic shape- some are specialized specifically for

flight

Feather Structure

Molting• Feathers are a dead structure

(analogous to hair in humans)• Molting essential to replace worn

feathers• Kinds of molts• Complete (patchy look)• Partial (gradual)

* Molt 1-2 times/year (lots of energy spent)

Migration• Migration = the regular, seasonal shift of

birds from one region to another (Instinctive)

• Origins of migration:• Glacial era• Ancestral home in tropics• Went north to avoid crowding when

breeding• Stimulus to start migration (“Biological

Clock”)• Inherent in hormones, related to length of

daylight

Why Migrate?• Adequate supply of food (or enough

daylight to find it)• Favorable climate in which to live• less stress on thermoregulation and

young• Most migrations are latitudinal (N-S)• Some permanent residents – tropical

birds• Some far north to far south (ex. Artic

Tern 11,000 miles one way!!)

Factors Used for Navigation

• Topographical features• Position of sun (starlings and pigeons)• Star patterns• Magnetic fields• Prevailing winds• Sounds and smells

Routes• Well established flyways• Blue Goose (James Bay Louisiana

5,000 km nonstop)• Ruby Throated Hummingbird (1000 km

across Gulf of Mexico

* Arrivals are often very precise and can range from slow (4 months) to fast (several weeks)

Routes

Hazards to Migration

• Hunters• Planes• New predators • Storms• Population densities

Studying Migration

• Tagging/banding• Radar