Animals whose fur changes color with the seasons, the better to camouflage them in warmer months vs. snowy ones, are in serious danger as the world warms up. Climate change is affecting not only how much snow falls, but also how long it sticks around — and animals such as snowshoe hares who change from brown to white in winter do so based on the calendar, not the climate and temperature.
Researchers at the University of Montana studied 148 hares over the course of three years and looked at how white they were in comparison to their environment. What they found was that, while the amount of snowfall affects when hares change their color in the spring, it does not in the fall.
In the fall, the researchers found that the brown to white color change took 40 days. The hares changing the color of their coats at such fixed times is a “not surprising” phenomenon, as their fall molting is linked to their daily exposure to light. That is, it’s not the appearance of snow that causes snowshoe hares to molt; their coat change is a response to shortening days.
In contrast, the rate at which the hares’s fur changes was found to vary in the spring. At the researchers’ western Montana study site, the winters of 2010 and 2011 were the least snowiest. 2011 had the longest snow season and, in that year, the hares took 16 days longer to go back from being white to brown than they had in 2010.
The researchers also found that female hares also changed their fur color at a faster rate than makes, doing so 11 days earlier — a sign of the females having some capacity for adapting to change a bit more quickly?
If snowshoe hares can change the rate at which they molt, it would be to their advantage. As the University of Montana researchers point out, because snowpack in the region is predicted to last for a month less by midcentury, and by two months by the end of the century, the snowshoe hare’s survival is in question. There will simply be more days (four to eight times as many) that white hares “will be mismatched on a snowless background” as a result of a “novel and visually compelling climate change-induced stressor,” the scientists write.
Currently, 85 to 100 percent of snowshoe hares’ deaths occur due to predators. Their camouflaging coats play a big role in hiding them from, to name one predator, the endangered Canadian lynx. While climate change could mean the lynxes (who also live in the U.S.) have plenty to eat for the short run, their long-term feeding habits could well be compromised, notes Mother Jones.
At least nine other animals undergo seasonal color changes: arctic foxes, collared lemmings, long-tailed weasels, stoats, mountain hares, arctic hares and white-tailed jackrabbits. They, too, could find their survival compromised as their centuries-old strategy of changing their fur from dark to white and back again fails in a climate changed world.
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