On Mexico's flag, what animal is the eagle shown devouring?

On Mexico’s flag, the eagle is shown devouring a rattlesnake.

The scene appears in Mexico’s coat of arms, placed in the white stripe of the national tricolor. A Mexican golden eagle perches on a prickly pear cactus growing from a rock in water while gripping and biting the snake. The image is linked to the Mexica story of the sign that revealed where to establish their capital, Tenochtitlan.

The emblem is commonly connected with the founding of Mexico City, but the historical tradition is more complex than the familiar picture suggests. Some pre-Hispanic depictions show an eagle without a snake, while other sources depict an attacking serpent or a different symbolic object. The rattlesnake became the standard modern interpretation.

The bird is officially treated as a golden eagle, although ornithologist Rafael Martín del Campo argued in 1960 that some earlier representations may have depicted a crested caracara, a falcon relative. That uncertainty does not change the flag’s canonical answer: the animal being devoured is a rattlesnake.