Can Camouflage Keep up with Climate Change? Connecting Climate Projections to Adaptation for the Snowshoe Hare

Snowshoe hares are the primary food source of the federally threatened Canada lynx. In western Montana for example, snowshoe hare make up 96% of lynx diet. In fact, hares are critical players in forest ecosystems because most carnivores prey on them.
 
The main way that snowshoe hares escape predation is through camouflage. In response to changes in day length, snowshoe hares molt seasonally, changing color from brown to white in the winter to blend in with the snowfall and hide from predators. However, due to shorter snow seasons caused by recent changes in climate, snowshoe hares are turning white before it snows, making them more visible to predators. Because 21 other species around the world also undergo these seasonal coat color changes, snowshoe hares also represent a window to understand climate change effects on wild animals.
 
The goal of this project was to investigate the causes and consequences of climate change induced color mismatch in snowshoe hares, focusing on populations in the Seeley-Swan valley and Gallatin National Forest in Montana. With the cooperation of multiple partners, including the University of Montana, the National Science Foundation, NASA, the National Park Service, Glacier National Park, Yellowstone National Park, and the U.S. Forest Service, this research combined field data with climate projections to directly evaluate how well wild animals might be able to adapt and persist in the face of climate change. 
 
Results of this project show that snowshoe hares do not have much ability to adapt through behaviors such as hiding or fleeing more readily when they are white and mismatched against a brown snowless background. Also, they cannot readily adjust their color molt to track shorter snow seasons. Mismatched white animals on snowless ground were found to have a 7% higher chance of being killed each week by predators than color matched animals.
 
These results mean that without evolutionary changes, wild hares are highly likely to experience severe population declines by the end of the century. However, such declines are not inevitable, as the researchers note tangible ways that land managers could increase wildlife resilience to climate change by fostering ‘evolutionary rescue’ to climate change. In short, this project both provides specific information on snowshoe hares to wildlife managers, and also provides a novel way to foster resilience to climate change through evolutionary change.