Snowshoe hares may provide clues about climate change
I knew we were in trouble when I saw the third snowshoe hare. Don’t get me wrong. I like bunnies and I was not in danger. After all, it was almost noon on the first day of elk season in early November. I had a knife, hunting rifle and adequate ammunition. Yet, what I realized made the hair stand up on the back of my neck. I felt immediately threatened. As we all are.
Here in Colorado we have not felt the initial impacts of climate change. No oceans are lapping at the shores of Denver, and no glaciers are calving off Mount Garfield near Grand Junction. Yes, we read about polar bears in the Arctic having a difficult time of it because ice breaks up earlier and seals are harder to pursue and eat. On some islands in the Pacific, natives worry about being relocated and abandoning their ancestral homes. Scientists clamor that we’ve passed the tipping point and that humans in a new geological era labeled the anthropocene have warmed the atmosphere, but in the Rockies we have yet to discern the beginning effects.
Although the weather has been odd. Too cold in some places and too warm in others. The beetle infestation keeps killing hundreds of square miles of pine trees, and aspens may migrate to higher elevations, but unlike other parts of the world, on the Western Slope it is difficult to perceive climate change as occurring.
“It was taken for granted that the process was not something that could be observed in real time, an assumption that has now been proven false,” writes Elizabeth Kolbert in “Field Notes from a Catastrophe: Man, Nature and Climate Change.” In Ithaca, N.Y., she notes that four out of six frog species have begun to mate 10 days earlier and at the Arnold Arboretum in Boston, spring-flowering shrubs have advanced by eight days. In California’s Sierra Nevada a butterfly named Edith’s Checkerspot now lives 300 feet higher than it did a century ago.
Kolbert explains that over a period of two million years, Earth’s temperature has swung wildly yet remained in certain limits. She adds, “The planet has often been colder than today, but rarely warmer, and then only slightly.”
Kolbert cautions, “It is only in the last five or 10 years that global warming has finally emerged from the background ‘noise’ of climate variability. And even so, the changes that can be seen lag behind the changes that have been set in motion.”
As I was elk hunting in Colorado’s magnificent high country, the last thing I had in mind was climate change. There had been a little early snow so I’d finally bought insulated high-top boots that I should have purchased years ago. With toasty toes and warm gloves I felt ready to hunt all day. My partner Ron and I had topped the ridge by 9 a.m., seen elk tracks, though not fresh ones, and had gone our separate ways, vowing to meet at camp by noon.
So, I was on my way downslope when I saw my first rabbit. Pure white, the snowshoe hare quivered in a snowdrift next to fallen timber. He was doing his bunny best to be camouflaged, but on that south-facing mountain the previous week’s snow melted fast. Forty yards farther I spied bunny No. 2 with his nose twitching and pink ears swiveling. He ran off and hid near more snow, but he had to cross bare ground to do it. That was when I found the third rabbit almost at my feet. He glared white against tan pine needles, and I sensed something was wrong.
Hunters must be wary of approaching storms, and no future precipitation was predicted for several weeks. In that time the snow crunching under my new boots would be gone, yet the bunnies would still be white and totally vulnerable to predators. Snowshoe hares should know better. Why were they white in early November with limited snow on the ground? What was happening?
“I’ve seen and had many reports the last three years about mismatched hares and habitat, mostly in the fall when hares are turning white before much snow cover,” explains Scott Wait, Southwest Region senior biologist for Colorado Parks and Wildlife. “But I’ve also seen white hares in the spring when some of our snow has melted from dust storm deposition leading to early snowmelt.”
Snowshoe hares survive by mimicry or camouflage, and the species evolved to be brown in summer and white in winter. Wait told me, “Color change is initiated due to daylight length, which might be related to snow accumulation on an evolutionary time-scale. If snow accumulation varies from normal, the hare continues to change color but might find itself wearing the wrong color, white on a brown background, or brown on a white background.”
So that was it. Snowshoe hares have adapted not to snow on the ground but to the length of daylight. That first day of third rifle season, or the first weekend in November, there should have been more snow, but there wasn’t. The rabbits had planned on winter snow cover that had already begun to melt. I had seen climate change in action, or so I thought. Scientist Scott Wait isn’t sure. He added, “Are the mismatches seen by many elk hunters in recent years due to climate changes, annual variation, or merely an increase in hare abundance?”
I hope he’s right. I hope what we hunters are describing is an increase in snowshoe hares that will provide food for raptors, coyotes and the introduced Canadian lynx, a federally endangered species. Dr. L. Scott Mills at the University of Montana goes even further to suggest that genetic variation may already be resulting in rapid rabbit adaptation.
Maybe. But not where I was hunting. I saw three bright white bunnies in small snow patches on an otherwise dull brown turf. I hope they make it through the winter. I hope they can adapt to climate change. I wonder if we Americans will.