Blending in

Some animals that live in snowy places are masters of hide-and-seek. Unlike the popular children’s game, however, the stakes in this version of hide-and-seek are life or death. Blending in with the environment makes an animal harder for a predator to see.

Camouflage is an adaptation that allows an animal to hide in plain sight by changing its appearance to match its surroundings. In many northern places, the landscape is a combination of brown, green, and gray in the summertime, whereas the snow-covered winter landscape is white. Over time, animals that inhabit snowy places year-round, such as the snowshoe hare, ermine, and Ptarmigan (Willow, Rock, and White-tailed) have evolved to grow white fur or feathers in the winter and brown-ish fur or feathers in the summer.

Ptarmigan, snowshoe hares, and ermine are are important  sources of food for predators such as  lynx, foxes, and predatory birds. The ability to blend in with their winter and summer environments helps them to avoid being detected and eaten by predators, allowing more of them to survive and produce young.

Which of these animals can you find in the winter and summer photos below?

Double duty

The ermine is the only North American weasel that turns white in the winter. Wildlife biologists think that its black tail acts like a “decoy” that predators such as owls aim for. If an ermine loses a tail, it can survive, but if a predator attacks its head or body directly, it can’t.

Can you find the bird in each picture?

The Willow Ptarmigan is a master of camouflage. Here, it blends in with the tundra in Denali National Park and Preserve in Alaska in winter (left) and summer (right).

How many hares?

The snowshoe hare (related to rabbits, but not the same type of animal) is one of the most well-known examples of camouflage, not just in winter, but also in summer. How many hares do you see in the trail camera photo on the right?

Adaptation through evolution

Animals aren’t able to decide to change color based on when there is snow on the ground and when there isn’t. How do they know when to turn from brown to white and back again? Hormones in their bodies respond to changes in day length by causing their fur and feathers to change colors (growing new fur/feathers or in the case of the hare, changing color of hair tips to white) in the fall and spring. In years when snow doesn’t cover the ground until later than usual, or when it melts earlier than usual in the spring, these animals are easy to see when they are white while the environment is still brown. Likewise, when snow falls earlier than usual in the fall or persists late into the spring, they might have their brown summer coats, standing out against the snowy, white background. Blending in helps animals to hide from predators, and those that are successful in avoiding predation survive to produce young with similar traits. Because parents pass along traits to their young, adaptations like camouflage become more common in a population of animals (or plants) over time.