13

Navigation—A General Overview

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location. Birds remember previously visited places and navigate those places easily

by familiar area map mechanism [10].

b.

Star Patterns at Night

Nocturnal fliers make use of navigation based on bright star (Stellar) pattern. The

large numbers of stars are visible in the sky with different patterns at different times

in the night. Probably nocturnal migrants own some form of star patterns for their

migration [15]. Indigo buntings are using specific star patterns.

c.

Sun Compass

The sun compass is related to the flier’s internal circadian rhythm. This is more useful

for high altitude migration and in arctic region, where the sunlight is continuous and

the magnetic directions are not clear. Sun compass is a regular explicitly movement of

the sun across the sky. Hence it is time dependent. Solar arch is mainly dependent on

the geographic latitude and season. Diurnal migrants are primarily using this method

for orientation [11]. Pigeons consider only the azimuth of the Sun and ignore its

elevation above the horizon.

d.

Moon Orientation

This is also common in some nocturnal fliers. Moon compass is the polarization

pattern in the sky created by the moon. Insects can use the moon as a compass. Some

studies are needed to find out if the variable intensity of light of the moon changing

day-to-day is used by the nocturnal fliers.

e.

Meteorological Features

These involve the detection of wind velocity, pressure, temperature and moisture,

which is done in insects by the use of antennae and sensory hairs (Tricho-bothria).

Birds and migratory mammals also respond to such meteorological features.

f.

Geomagnetic Field

Certain microorganisms to mammals have the capacity to detect and react to the

earth’s magnetic field over a wide range. Migratory species have considerable number

of magnetic particles in their body cells. Migrating birds can perceive information

based on intensity and direction of the geomagnetic field, and these are transmitted

to the brain. Migrating bird’s capacity of finding position is at the scale of hundreds

and thousands of kilometers. The magneto reception mechanism has been recently

proposed to help in navigation and the reactions occur in the eye in the eye of the

migrants [See Chap. 15].

g.

Polarized Light

It consists of electromagnetic waves. The rotation of polarized light along with the

sun reveals the North direction. Many insects and birds use the polarized light during

the cloudy days.