Wild Tracks

On behalf of the world's wild species

(In)visible Hare

Now here’s a thought.

What if your very survival depended on the color of your fur? And what if the colour of your fur suddenly caused to you stick out like a neon sign?

In all the articles on climate change floating around out there, one unusual aspect of global warming is coming from the University of Montana.

Dr. Scott Mills and his students have noticed an exceptional number of white snowshoe hares on brown earth. He contends that climate change and the color mismatch are causing much more hare mortality.

Winter snowshoe hare

Winter snowshoe hare

Snowshoe hares evolved with plentiful winter snow in the boreal forests of North America. In winter, they grow long white guard hairs to match the snow. In summer, they shed white for mostly rusty brown coats to blend with trees and soil. They depend on their cryptic coloration to hide from predators that include lynx, coyotes, foxes, wolves, pine martens and birds of prey. Radio telemetry data revealed spring and fall to be the most deadly seasons for hares and a bonanza for predators.

It’s not only snowshoe hares that change color in the winter. Weasels, ptarmigans, arctic foxes and barren ground caribou all change with the seasons.

The signal to shift coat color comes from the pineal gland in the brain that senses changes in daylight length. Shortening days of autumn trigger the coat color change from brown to white. Lengthening daylight in the spring reverses the change. But as global warming becomes even more prevalent, the length of the daylight will not change.

Increased temperatures also mean less snow cover. While snow levels vary from year to year, the number of days with snow on the ground appears to be decreasing. Will coat colors continue to shift regardless of how much snow is on the ground? Or will these animals adjust in time to fit new conditions?

Across Canada, snowshoe hares follow a synchronized population cycle of 10-year highs and lows. Hare numbers in the Yukon can peak at 200 to 300 per square kilometer and then drop to about seven. Snowshoe hares are important prey species for every animal in the forest that eats meat. Without them, the ecosystem completely collapses.

Left on their own, wild animals can slowly adjust and adapt to any new conditions. But the pace of global warming is the problem – not the increased temperatures. Scientists have little or no data on how fast animals can adapt, but the suspicion is that the climate is just changing too fast.

This cute little white ‘bunny,’ once the most numerous animal in the boreal forest, may be the next poster animal for global warming.


One response to “(In)visible Hare

  1. deya December 26, 2009 at 7:12 am

    it”s a very very very cute image! i love animals. i love this picture. i would like to thank the photographer of this sweet photo.

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