Do bulls really charge because of the color red?

Bulls do not charge because of the color red. The idea comes from the red cape, the muleta, used in the final stage of a bullfight. Fact-checkers and science writers say the bull responds mainly to the cape's movement and to the matador's presence, not to its color. [1] [2]

Cattle have two types of color-detecting cone cells, while humans have three. This is called dichromatic vision. Snopes, citing Temple Grandin, says bulls lack red receptors and see mainly in yellowish-green and bluish-purple light. The Indian Express says that what looks red to a person probably looks like a dull yellow or grey to a bull, and notes that many mammals, including dogs, share this limitation. [1] [3]

The Naked Scientists put it a little differently: bulls are not blind to red as such, but they see colors much as a color-blind person does, so red has nothing special about it for them. [4]

In 2007 the Discovery Channel series MythBusters tested a live bull. The bull charged stationary red, blue and white flags alike, whether shown one at a time or together. When a blue flag moved on a zip line next to a still red flag, the bull chased the blue one. With dummies holding flags, it charged the white one first and the red one last. Finally, a motionless person dressed in red was ignored while two professional bullfighters moving around the arena were charged. Snopes and Live Science both report these results, though they differ slightly in how many tests they describe. This was a single television experiment rather than a formal study, but it matches what the other sources say. [1] [2]

Live Science adds that bulls charge the larger capote with equal fury, even though it is magenta on one side and gold or blue on the other. [2]

Several sources point to motion and threat. The Centre of the Cell says the matador's aggressive whipping of the muleta sets off the bull's fight-or-flight response. Snopes cites the International Longhorn Association on the cattle flight zone: when a person enters an animal's personal space it moves, and it may flee or try to remove the threat. The Indian Express adds that pain from spears and prods contributes, making the charge an act of fear and desperation rather than rage at a color. [5] [1] [3]

Live Science states that the muleta is red because the color helps mask the bull's blood in the final stage of the fight. Snopes says this explanation is commonly repeated but that it found no definitive evidence for it. It notes that the red muleta is part of a centuries-old tradition and that the earlier capote is brightly colored too, even though blood is already drawn by then. The reason for the color is therefore not firmly established in these sources. [2] [1]