The long-standing cultural image of a raging bull charging a matador’s red cape is one of the most enduring myths in animal behavior. Bulls do not get angry when they see the color red. This dramatic visual has led to the widespread but incorrect assumption that the crimson hue is a specific trigger for bovine aggression. The premise is a misconception rooted in the spectacle of bullfighting, where the color of the final cape is more about human tradition and less about the animal’s perception. The bull’s reaction is entirely based on other stimuli.
The Truth About Bull Vision
The biological reality is that bulls, like other cattle, are not capable of perceiving the color red as humans do. Bulls possess dichromatic vision, meaning their retinas contain only two types of cone cells, which are the photoreceptors responsible for color detection. Humans, in contrast, have three types of cones, allowing for a much broader spectrum of color recognition, known as trichromatic vision. The bull’s two cones are sensitive to blue and green wavelengths of light. Consequently, the color red appears to a bull as a shade of gray or perhaps a dark, muted yellow, proving the idea that a bull is enraged by a color it cannot distinctly see is scientifically inaccurate.
What Actually Provokes the Bull
The bull’s aggressive behavior is an instinctual response to threat and movement, not color. Bulls are naturally reactive to sudden shifts in their environment and are bred specifically for their aggressive nature in the context of bullfighting. When a matador is in the ring, the animal perceives the person and the flapping cape as a potential threat, triggering a defensive fight-or-flight response. The rapid, erratic motion of the cape—regardless of its color—is the true provocation that encourages the bull to charge. Bulls will charge any color flag or object with equal fury, as long as it is being moved aggressively, because the animal’s visual system is highly adapted to detect movement.
The Role of the Muleta
The traditional red color of the muleta, the small cape used in the final act of a bullfight, is a choice made for the human audience, not the bull. The muleta is introduced late in the fight, and the larger cape used earlier, the capote, is typically bright magenta and yellow, yet it provokes the same charge response. If the bull were reacting to the color red, the non-red capote would be ineffective. The primary practical reason for the muleta’s crimson color is to mask the blood that the bull inevitably sheds during the final stages of the fight. The red dye conceals bloodstains, which helps maintain the aesthetic of the performance for the thousands of spectators, serving a long-standing cultural and theatrical purpose.