Navigational Theory 7: Ultraviolet Wavelengths

Research done in Dr. Kreithen’s laboratory indicates that homing pigeons are able to detect light with wavelengths from 305-750nM (305-400nM being the ultraviolet wavelengths invisible to normal human vision). Their vision helps them form images in the ultraviolet spectrum. Polarized skylight has directional patterns that we cannot see. This theory suggests that, much like bees do, pigeons might be able to navigate by reading the “map” of ultra-violet rays from the Sun.

• Ultraviolet light is electromagnetic radiation in a part of the spectrum between X-rays and visible light, approximately 180 nanometers to 400 nanometers. It differs from light only that it's wavelengths are too short to be seen by the human eye. U V-A , or long-wave radiation is 315 nanometers and above. U V-B, or medium-range radiation, is 280 nanometers to 315 nanometers. U V-C, or short wave radiation, is 280 nanometers and below.
  Source: http://www.uvlp.ca/ultravioletinformation.htm