migration of birds

 

Migration of birds

Birds navigate by several methods 

1 Visual clues like shape of mountain ridges, coastal lines, topographic features on their route,rivers and streams and so on. 

2 Solar navigation _ Honey bee uses the sun to navigate .For humans, one should have sound knowledge of trigonometry for locating the sun.

 3 Magnetic fields _  Homing pigeons use magnetic field lines of the earth to find their way home. These birds have magnetic compass on their head which is demonstrated by attaching small magnets to their heads .

 4 Star navigation_  Indigo bunting  a Bird uses stars to navigate at night. They learn the star patterns sitting in the nest while they were still small.  Some birds get disoriented in the cloudy nights . The Indigo Bunting is the only bird which has been demonstrated to have used celestial navigation.

5 Polarised Light it seems birds can distinguish polarization patterns in sunlight, as the sunlight passess through earth's atmosphere tiny molecules of air particles allow light waves passing in certain direction topass through it,others they absorb This creates paterns like bow tie effect usually seen in the evening above head with north =south direction.The birds may not be seeing this like us.They may be seeing actual gradations 

further reading " Those amazing flying mathematicians"

https://www.maa.org/external_archive/devlin/devlin_10_99.html

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