When the environment changes dramatically, animals from mollusks to crows can make big changes in their behavior that enable them to survive. For example, marmots and ground squirrels in California are spending more time in wet vegetation and on steep slopes to counteract warmer temperatures. Polar bears, losing their floating ice habitats, are spending more time on land and adding birds' eggs and reindeer to their diets. And lake trout in Ontario, which rely on external water temperatures to maintain a healthy internal temperature, shift to cooler, deeper waters and eat smaller prey when the water becomes hotter than usual.