Science - Seasonal Color Changes In Snowshoe Hares In Rockies Increasingly Out Of Sync With Seasons
After more than a decade of studying snowshoe hares in the Rocky Mountains, L. Scott Mills, a wildlife biologist at the University of Montana, Missoula, noticed that the animals were beginning to stick out more than usual. In winter their coats turn white; in summer they are a mottled brown. But Mills was beginning to see white hares on brown backgrounds.
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Each week, the researchers tracked down all the animals they could find and noted how well their coat color matched the local background by determining the percentage of white fur and of snow cover. They considered the hares mismatched if the coat color was 60% or more different from the surrounding 10 meters.
The hares couldn't adjust the date that they started to change color very much, Mills and his colleagues report online today in the Proceedings of the National Academy of Sciences. Each year, the animals started to molt around the same time—10 October in fall and 10 April in spring. "That happened regardless of whether there was a ton of snow on the ground or not," Mills says. In the fall, switching to white took 40 days. In the spring, the changeover to brown took between 30 and 50 days and lasted longer in the colder years, Mills says. "They do have some ability to speed up or put on the brakes [on color change]."
But that ability won't be enough to keep them in sync with future winters, Mills found. He and his colleagues used more than a dozen climate models to determine the temperature and likely snow duration in the study area for 2050 and 2099. By midcentury, the snow season will be a month shorter, and by the end of the century it could be up to 2 months shorter, they report. With the initiation dates for molting fixed, that shift would result in hares being mismatched for as much as 36 days by 2050 and for double that amount of time by the end of the century.
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http://news.sciencemag.org/sciencenow/2013/04/color-changing-hare-cant-keep-up.html
