Sticking Out?

On a cold winter day, a rabbit-like animal with extra-large feet called a snowshoe hare hops through a Montana forest. Snap! Did a predator make that noise? The hare freezes. If it blends into its surroundings, it might avoid becoming a meal.

Weeks ago, the hare shed its brown summer coat and grew thick, white fur. In a typical winter, the color acts as camouflage (see “Vocab Lab” ), hiding the hare in the snow. But winters are warming up. When there isn’t any snow on the ground, a white hare is easy to spot.

It’s a cold winter day in a forest in Montana. A rabbit-like animal with extra-large feet hops by. It’s a snowshoe hare. Snap! Did a hungry predator make that noise? The hare freezes, helping it blend into its snowy surroundings. That could help it avoid getting eaten.

The hare shed its brown summer coat weeks ago. Then it grew thick, white fur. The color usually acts as camouflage in the winter, (see “Vocab Lab" ). It helps the hare hide in the snow. But winters are warming up. Sometimes there isn’t any snow on the ground. Then a white hare is easy to spot.

A changing climate creates challenges for these hares. Over the past century, the average global temperature has been increasing. Many areas receive less snowfall. As a result, more hares no longer match their surroundings during the winter, says Scott Mills. He’s a biologist at the University of Montana.

For more than 25 years, Mills has studied snowshoe hares and other northern animals that turn white in the winter. He wonders: As the climate warms and snowfall decreases, can these animals survive?

A changing climate is making it hard for hares. The average global temperature has risen over the past 100 years. Many areas get less snowfall. Hares no longer match their surroundings during the winter, says Scott Mills. He’s a biologist. He works at the University of Montana.

Mills has studied snowshoe hares for more than 25 years. He’s also studied other northern animals that turn white in winter. He wonders whether these animals can survive with less snow?

Snowshoe hares live in forests across the northern U.S. and Canada (see “Where Do Snowshoe Hares Live?” ). They’re a key food source for animals such as owls, coyotes, and bobcats.

In the summer, brown coats help the hares blend in with the forest floor. In the fall, the days get shorter. This decrease in sunlight triggers a process inside the hares’ bodies. They begin to molt, or shed their fur. First the tips of a hare’s ears and nose lose their color. After six weeks, right on time for the arrival of wintry weather, the animal is all white.

Snowshoe hares live in forests across the northern U.S. and Canada (see “Where Do Snowshoe Hares Live?” ). They’re a key food source for many animals. They include owls, coyotes, and bobcats.

Hares have brown coats in the summer. It helps them blend in with the forest floor. The days get shorter in the fall. Less sunlight triggers a process inside hares’ bodies. They begin to molt, or shed their fur. First the tips of a hare’s ears and nose lose their color. The animal is all white after six weeks. It’s right on time for wintry weather.

In our rapidly warming climate, snow is falling later and less often. It’s melting more quickly in areas where the hares live. The mismatched hares are easier to spot. “It’s like a white light bulb sitting on a brown carpet,” says Mills.

Predators have an easier time catching prey that stands out. Mills and other scientists have tracked snowshoe hares in Montana. They found that hares that didn’t match their surroundings were less likely to survive the winter. In some areas, such as parts of Wisconsin, snowshoe hare populations are dropping.

A decline in hares can have a big effect on other animals in the area. For example, if the hares die out completely, the predators that eat them will have to switch to other prey like squirrels and mice to survive. But some animals might not be able to make such a big change.

Canada lynx, a type of wildcat, are excellent snowshoe hare hunters. They have adapted to catching hares and rarely eat other prey. This predator would likely be the first to decline if snowshoe hares died out, explains Mills. When predators die out, the ecosystem can get knocked off balance.

Snow is falling later and less as the climate rapidly warms. It’s melting more quickly in areas where the hares live. Hares are easier to spot when they’re the wrong color. “It’s like a white light bulb sitting on a brown carpet,” says Mills.

The hares stand out. And predators have an easier time catching them. Mills and other scientists have tracked snowshoe hares in Montana. They found hares that didn’t match their surroundings. They were less likely to survive the winter. And snowshoe hare populations are dropping In some areas. That is happening in parts of Wisconsin.

Fewer hares can have a big effect on other animals in the area. If hares die out, the predators that eat them will have to hunt for other food. They might start eating squirrels and mice, instead. But some animals might not be able to make such a big change.

Canada lynx are a type of wildcat. They’re great snowshoe hare hunters. They have adapted to catch hares. They rarely eat other prey. This predator would likely decline if snowshoe hares died out, explains Mills. That could knock the whole ecosystem off balance.