Do Bulls Hate Red? Cattle Color Vision Explained

Where the red myth comes from

The idea comes mainly from Spanish-style bullfighting. In the final stage of a fight, the matador waves a small red cloth called the muleta, and the bull charges it again and again. To an audience, it looks as if the red is driving the bull wild, and the phrase “like a red rag to a bull” has become an English idiom for something that provokes instant anger.

In fact, the muleta is red by tradition. A common explanation is that red hides bloodstains from the wounded bull. Earlier in the same fight, the bullfighters use a much larger cape, the capote, which is magenta on one side and yellow or gold on the other. Bulls charge the capote just as fiercely, which already suggests that the color red is not the trigger.

How do cattle see color?

Color vision depends on cone cells in the retina. Humans usually have three types of cones, sensitive to short (blue), medium (green) and long (red-yellow) wavelengths of light, which lets us tell red from green. Cattle, like most mammals, have only two types. This is called dichromatic vision.

A 1998 study by Gerald Jacobs and colleagues measured the light-sensitive pigments in the eyes of cows, goats and sheep. It found one cone type most sensitive to short, blue-violet wavelengths and another most sensitive to middle wavelengths in the yellow-green range. With only these two, cattle can distinguish blue from yellow, but red and green fall on the same side of their color scale.

To a bull, then, a red cloth probably looks like a dull, darkish shade, not a vivid warning color. A person with the most common form of red-green color blindness sees the world in a broadly similar way.

What cattle see well

Cattle make up for limited color vision in other ways. Their eyes sit on the sides of the head, giving a panoramic field of view of about 330 degrees, so they can watch for predators almost all around without turning. The trade-off is a narrow zone of about 30–50 degrees in front where both eyes overlap and judge depth well, compared with about 140 degrees in humans. There is also a small blind spot directly behind them.

As prey animals, cattle are very sensitive to movement, especially sudden movement at the edge of their vision. They are also wary of sharp contrasts, shadows and bright patches on the ground, which is one reason they may balk at entering a dark shed or crossing a line of light.

What the MythBusters bull tests showed

In a 2007 episode of the US television series MythBusters titled “Red Rag to a Bull,” the team tested the red myth with real bulls:

• When red, blue and white flags were set up standing still, the bull charged all three colors alike.
• When dummies dressed in different colors were placed in the ring, the bull charged the white one first, then the blue one and the red one last.
• Finally, a team member dressed all in red stood completely still in the ring while two rodeo cowboys moved around. The bull chased the moving cowboys and ignored the person in red.

This was a television test with a few animals, not a scientific study, but its results match what is known about cattle vision: movement, not color, gets a bull’s attention.

So why do bulls charge?

A bull charges because it feels threatened, is defending its space or its herd, or is provoked. In Spanish bullfighting, the animals are fighting bulls (toros de lidia) bred for centuries for aggression and raised with little human contact; by the final stage they have also been weakened and goaded. A waving cloth is the most obvious moving target, so they charge it.

Ordinary farm bulls can be dangerous too, whatever color people wear. Dairy-breed bulls are known for being unpredictable, and bull attacks are a significant cause of serious injury and death among farm workers. Cows with young calves can also be very protective. Walkers crossing fields with cattle should keep their distance, stay calm, avoid getting between cows and calves and leave the field if animals approach. In an emergency, call 911 (US), 112 (EU) or 999 (UK).

Color vision in other animals

Most mammals share the two-cone vision of cattle, including dogs, cats, horses and deer; humans, apes and Old World monkeys are among the few mammals with three-color vision. Many birds, reptiles and fish, by contrast, have four types of cones and see more colors than we do, including ultraviolet. For more about cattle, read How long do cows live? and What is the difference between a cow and a bull?.