Auburn University, or more specifically its football team, does not have two mascots, but rather one: Aubie the Tiger. It is a common misconception that Auburn has both a tiger and a "War Eagle" as mascots. In fact, "War Eagle" is the Auburn Tigers' battle cry.
The most popular history of this battle cry dates back to 1892, to the year of the first football match between Auburn and the University of Georgia. During this game, an eagle belonging to a Civil War veteran is said to have soared above the field at the precise moment that Auburn charged the end zone to victory. Shortly thereafter, the bird is alleged to have killed itself by flying straight down into the ground.
An alternative origin story has it that the eagle belonged to a professor of the university and that, during a losing game for Auburn, the bird took to the sky and circled the field, in turn prompting the students to chant "War Eagle." This chant boosted the team's morale and ultimately led to their turning the game around to win.
These tales are naturally dubious, and other accounts attribute the battle cry to a Native American superstition of wearing "War Eagle" feathers for good luck.