That's a Lot of Bull
Matadors, matadoras and their assistants fight four-year-old specially bred bulls weighing approximately 1,300 pounds (590 kilograms). The bulls in Spanish bullfighting are bred on ranches, where they are tested for bravery and ferocity. The ones that pass the tests -- performed by men on horseback, not by matadors with capes -- fight in the arena.
Bulls are never exposed to more than one fight because they have good memories, which is why the tests are not performed by men with capes. They'd be dangerous to matadors during cape work, which is the highlight of the bullfight, if deployed a second time.
The capes used in bullfighting are red, not because this is a color to which bulls react, but to hide blood and other stains and to be more visible to spectators. Some people believe that bulls become angry when they see red, but that's simply not the case. Bulls are colorblind; they respond to the movement of the capes, not to the color.
Throughout history, people have altered bulls to make them easier for bullfighters to fight. For example, they've clipped bulls' horns in order to make them safer or overfed bulls, which makes them fat and slow. Dedicated followers of bullfights can spot altered bulls, and there is a process for calling them out in the ring. Bulls deemed unfit are replaced by a substitute.
Toreros, or bullfighters, often come from areas surrounding the breeding ranches. They grow up watching bulls and learning bull behavior, in order to compete successfully against them [source: McCormick].
Training may begin by watching, but for novices, it soon progresses to fighting two- and three-year-old bulls that weigh up to 1,000 pounds (454 kilograms). When a bullfighter is ready, he or she receives the alternativa, a ceremony during which a senior matador recognizes the bullfighter as a professional and equal. At this point, the new bullfighter is ready to fight the four-year-old bulls.