Do bulls really hate red? No, they don’t. It is the movement that they don’t like.
The fact that bulls hate red has become common knowledge. It is even in sayings, such as, “like a red rag to a bull” meaning a trigger to anger someone, and “seeing red”, meaning in such a blind rage that a person can’t think clearly. However, bulls not liking red it is not actually true. It turns out that bulls are colorblind.
We can see all of the colors from red up to purple. That is the visible light spectrum from 380 to 700 nanometers. Reds have a shorter wavelength at 380 nanometers and purples have a longer wavelength at 700 nanometers. We have evolved to see that color range because we need to be able to find different colored fruits and because we need to be able to see different color animals, both prey and predator. To be able to see these colors, we have three types of cones in our eyes, those for red, green, and blue. Different wavelengths activate different cones and our brain puts together the percentages of the signal from various cones and works out a color. For example, a lot of red, a lot of green, and not much blue would be a yellow color. Our eyes seem pretty special, but there are animals that can see the ultra violet spectrum, which we cannot.
By looking at an animal’s eye and see which cones are present, it is possible to work out what colors they can see. Cows, and bulls, don’t have the cones that would enable them to see red. They can see blues, yellows, browns, greys, blacks, and whites. Animals only see the colors that they need to see. Cows eat grasses, which are green, so they have no need to be able to see reds. If a cow evolved the ability to see red, it doesn’t confer any advantages or make that cow any more likely to survive than any other cow, so it is unlikely that the mutation would be passed on any more than regular cow sight. Incidentally, because their eyes are on the sides of their heads, like most animals that are often eaten by predators, they don’t have very good depth vision. They can, however, see 360°around their heads when they are grazing, which is far more than we can.
So, bulls cannot see red, which means red cannot be the thing that is enraging them. So, what is it and why do they go for a matador’s red cloak? It is the movement of the cloak that enrages them. The matador shakes and twirls the cloak and that is what the bulls are charging towards. The movement is irritating and provokes the bull into attacking. This can be seen in a bull fight because the other side of the matador’s cape is usually black or gold and the bull charges that side just as readily as the red side. In fact, Mythbusters proved it in a series of experiments. They used moving capes of different colors and the bulls attacked them all. They had stationary red capes and moving capes of other colors and the bulls only attacked the moving capes. So, if you happen to be in a field and you see a sign that says “beware of the bull”, your best bet is to walk really really slowly to the edge of the field.
Why are matador’s capes red, then? Red has long been the color of war and fighting. That is probably to do with the color of blood. And matadors go into a fight with a bull so red seems appropriate. However, the real reason seems to be that the red on the cape hides the blood of the bull. A matador’s job is to enrage and then dodge the bull, but they also have to stab the bull with swords, killing it in the end. A red cloak hides the distasteful color of blood.
Why do bulls get so angry? Well, it turns out that they are usually not that angry. They are very territorial and very protective of their herds, but if they are not threatened they don’t do anything. Bulls in a rodeo are angry because there is somebody sitting on their back and they want to get them off. Once the person is off, they tend to calm down. That being said, rodeo bulls are generally bred for their aggressiveness and they are far more likely to attack than a regular bull. In a bull fight, the bull is more scared than angry. The stadium is full of screaming people and that frightens the bull. Then the matador whips the cloak which scares the bull even more. The bull cannot find a way out, so it has to attack. Then the matador starts stabbing it with swords, which scares it even more. The bull is not aggressive, it is just a cornered animal. Albeit and very strong cornered animal. And this is what I learned today.
Photo by @coldbeer: https://www.pexels.com/photo/bull-at-a-rodeo-17134705/
Sources
https://www.livescience.com/33700-bulls-charge-red.html
https://www.wonderopolis.org/wonder/do-bulls-hate-the-color-red
https://askabiologist.asu.edu/colors-animals-see
https://www.worldanimalprotection.org.au/news/fascinating-facts-about-cows