They don't.
It's a myth. The cape is red because it suggests "danger" to us people.
In fact, bulls don't can't particularly see the colour red at all. They can see yellow quite well, though.
In her book Animals In Translation Temple Grandin goes into a lot of detail about what colours cattle can see (mostly green and blue and black and white) and what they can't see. Using additive colour theory, green+blue = yellow so that's the colour that stands out most to cows. A flapping yellow object is the scariest thing at all to many cows.
So why do bulls in a plaza de toros (bullring) react so dramatically to a red cape being waved at them?
Because it's moving. Temple Grandin also explains how flapping objects alarm cattle. And because the bulls have been conditioned by many preliminary bullfights to respond to the flapping cape. AND because they are usually already in pain, as they are normally speared in the shoulders before the Matador makes an appearance (this prevents the bull from raising his head fully).
AND they are aggressive and brave animals, anyway.
It's a myth. The cape is red because it suggests "danger" to us people.
In fact, bulls don't can't particularly see the colour red at all. They can see yellow quite well, though.
In her book Animals In Translation Temple Grandin goes into a lot of detail about what colours cattle can see (mostly green and blue and black and white) and what they can't see. Using additive colour theory, green+blue = yellow so that's the colour that stands out most to cows. A flapping yellow object is the scariest thing at all to many cows.
So why do bulls in a plaza de toros (bullring) react so dramatically to a red cape being waved at them?
Because it's moving. Temple Grandin also explains how flapping objects alarm cattle. And because the bulls have been conditioned by many preliminary bullfights to respond to the flapping cape. AND because they are usually already in pain, as they are normally speared in the shoulders before the Matador makes an appearance (this prevents the bull from raising his head fully).
AND they are aggressive and brave animals, anyway.
