White creatures changing with
By NED ROZELL
April 20, 2009
This morning, through the west window, I noticed a flash of white
on white. I looked up from breakfast to see a short-tailed weasel
popping from a hole in the snowpack. He was sleek, streamlined
and snow-white, except for where his tail looked like he dipped
it in black paint.
Then, when I skied to work, I saw a leggy snowshoe hare bound
away, and then pause nervously. The sightings inspired me to
call a neighbor that could tell me more about the animals' white
coats-the ones that won't be white for much longer.
The white fur of a
snowshoe hare is the perfect camouflage during winter.
Photo by Donna DiFolco.
My neighbor, who may be hosting the weasel at this moment (their
home range can be as expansive as 40 acres), is Dave Klein. Klein
is curious about Alaska animals great and small, and has been
since before he first drove up the Alaska Highway in the 1940s.
Klein, a professor emeritus of wildlife management at the University
of Alaska Fairbanks, said that both weasels and hares undergo
a molt that changes them from winter white to summer brown. That
means they will soon replace all their white fur with brown fur,
presumably to remain camouflaged for the change of seasons.
Triggering this color change is daylight, "but over long
periods of time, (the fur-color change) is related to changes
in timing of the melting of snow," Klein said.
For example, if warmer spring temperatures start to melt snow
earlier, hares and weasels would be able to adapt and remain
inconspicuous. According to Klein, that adaptation could take
several generations, though.
Early adapters to a changing climate would pass on their genes.
Late adapters might become lunch for great horned owls. Or, in
the case of weasels, they might get no lunch at all.
Klein also offered up a few observations of animals that change
fur color with the season. Arctic hares (larger than snowshoe
hares and not confined to forests, often living on open tundra)
in the high arctic of Canada and in Greenland stay white all
year round. Replacing white fur with brown during the brief summer
might be too costly energy-wise for those far-north hares.
"You can spot them from miles away in summer," Klein
Arctic foxes also show some fur-color variation, depending on
where they live. On the Aleutians and the Pribilof Islands, most
arctic foxes don't turn white, instead they morph to a "blue"
As you move farther north, arctic foxes have differing degrees
of whiteness in winter. For example, while only a few foxes turn
white on the Pribilof Islands, most of them living on St. Lawrence
Island turn the color of snow.
Arctic foxes on the North Slope
always change to white, which Klein thinks might be important
so "they can sneak up on polar bears on the adjacent sea
ice and grab a snack," from a seal kill.
Brown lemmings, abundant in places like Barrow, don't change
the shade of their fur. Collared lemmings' fur does change, perhaps
because they leave the subnivean world under the snow more often
than brown lemmings. The whiteness of collared lemmings gives
them a chance to remain undetected by other hungry creatures
wearing similar winter camo., like snowy owls and arctic foxes.
Those of you who read last
week's column may have expected more on Alva Wisdom of Seward
and the 1964 earthquake. I was planning on writing up Luke Reid's
account of that evening in Seward, but Reid requested we keep
that story between himself and Wisdom's family. Al Wisdom died
in Seward when a tsunami wave engulfed him on the evening of
March 27, 1964, as he helped clear the only road out of town.
This column is provided
as a public service by the Geophysical
University of Alaska Fairbanks, in cooperation with the UAF
Ned Rozell [email@example.com]
is a science writer at the institute.
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