Whether a creature has one feature that’s red (like the eyes of a loon) or its entire body is red (like a red ant), the color red serves a real purpose in the animal kingdom.

Seeing Red. Many common birds, fish, and reptiles with red eyes are nocturnal. Red eyes have been linked with enhanced night vision because they cancel out the blueish glare of moonlight. For example, a Northern Goshawk’s red eyes help it see rabbits, squirrels, and other prey at dawn and dusk when this bird prefers to hunt.

Wildlife with red eyes can also see the color red in the landscape, which helps them find others of their ilk. For example, the red eyes of bass stand out among green aquatic weeds, and the fish key in on each other’s eyes to school together.

DID YOU KNOW?
An oriole’s bright orange plumage is a warning to stay away – and this bird means it! The oil on an oriole’s feathers causes numbness in humans and can be fatal to small predators.

Female birds use color cues, including eye color, to select mates that are healthy. Cataracts are particularly easy to see in red-eyed species. Among night herons, which have red eyes, a clear-eyed male is more likely to attract a mate.

Don’t Eat Me! The color red is a signal to predators that potential prey is poisonous. Many common ladybugs are toxic to eat, and their red backs signal bug-loving birds to stay away. Other creatures might look poisonous but aren’t. Milk snakes, with their orange, black, and white stripes, look very similar to a venomous coral snake but are really harmless.

Stand Out or Hide. Some creatures are red to attract a mate or, surprisingly, for concealment.

Female cardinals are attracted to male cardinals for their brilliant red plumage. The males in other species of birds may be only partially red, like Purple Finches (which are red despite their name) and Pine Grosbeaks, but they are stunning nonetheless – to potential mates as well as birdwatchers.

WORD WISE
An albino appears white because it has no pigmentation in its skin, fur, or feathers. Its eyes appear red because you can see the blood vessels in them.

On the other hand, among deep-dwelling fish and jellyfish, red is not an attractor – it’s camouflage. Red light waves cannot penetrate below 100 feet of water, so red-colored fish deeper than that appear black to other fish, which makes them invisible in dark water. Interestingly, the bellies of clear jellyfish turn red after they eat to help them hide from predators.

Red serves different purposes for different types of wildlife. It helps many creatures – especially small, vulnerable ones – avoid getting eaten, attract a mate, find food, and sometimes to hide. It’s a color of substantial consequence in the natural world.