Why are the cardinals named the cardinals?

The squirrel, known by St. Louisans as the "Rally Squirrel", was one of two unofficial mascots adopted by the team and fanbase during the 2011 season (the other was Allen Craig's pet tortoise, "Torty". Craig was quoted multiple times that season saying "Do it for Torty!"). The legend was born on October 5, 2011 in the St. Louis Cardinals' home field, Busch Stadium. This was technically the squirrel's second appearance (he had ran onto the field the night before but didn't really impact play). The squirrel ran across home plate during a Cardinals at-bat during game 4 of the NL Division Series, causing a distraction that resulted in pitcher Roy Oswalt throwing a poor pitch to Cards batter Skip Schumaker, and made his escape into the stands. A squirrel would make another appearance before game 5, however since the final game was played in Philadelphia, one can assume this was a different squirrel. Since the Cardinals won games 4 and 5, the Rally Squirrel became a good-luck charm and Squirrel fever followed the Cardinals and their fans all the way through October, en route to the team's 11th World Series championship. The hat you're referring to is probably some themed merchandise licensed by the team during this time to capitalize on the phenomenon