On the Tree Of Life, the birds represent the various stages of human life.
Starting in the lower right-hand corner and proceeding counter-clockwise:
- The light gray bird symbolizes infancy.
- The red bird symbolizes childhood.
- The green bird symbolizes youth.
- The blue bird symbolizes adulthood.
- The orange bird symbolizes old age.
In ancient Egypt, the direction east was considered the direction of life, because the sun rose in the east. West was considered the direction of death, of entering the underworld, because the sun set in the west. They believed that during the night, the sun traveled through the underworld to make its way back to the east so it could rise in the east again on the next day.
On the tree of life, note that the birds representing the first four phases of life all face to the east, but the bird representing old age faces to the west, anticipating the approach of death.