What is the story of the bird and serpent on the Mexican flag?

Answer: The seal in the midddle of the flag of Mexico is the nation's coat of arms. The bird is the golden eagle (Spanish: águila real literally, "royal eagle"). In 1960, the Mexican Rafael Martín del Campo (an ornithologist) identified the eagle in the pre-Hispanic codex as the northern caracara a species common in Mexico. Even so, the golden eagle is still considered the Mexican eagle for official purposes, and for the same reason is regarded as the official bird of Mexico. When the snake was introduced it was originally an aquatic serpent, but since 1917, the serpent has been portrayed as a rattlesnake. The design and colour of the snake on the modern coat of arms do not correspond with those of any species of snake. The symbolism of the eagle devouring the snake is the triumph of good over evil. The nopal which the eagle stands bears some of its fruits and the pedestal on which the nopal grows is immersed in an Aztec symbol meaning water, a precious commodity in the arid regions of Mexico.