As seasons turn, some wild animals adapt their looks to blend in

Hide and seek may be a favorite children's game, but for wildlife it is a survival tactic. Staying out of sight is important to daily life -- either to catch the next meal or avoid being the meal.

Many predators have to sneak up silently on their prey, and blending in with the surroundings helps. Likewise, one of the best defenses for prey animals, like rabbits and hares, is not to be seen. Using camouflage helps them as they remain very still to go unnoticed by a nearby predator. All is fair on nature's hunting grounds.

Snowshoe hares have a bigger challenge. Living at 8,000 to 11,000 feet elevation in Colorado, they spend the winters in snow-covered terrain. Their brown fur would stand out, so each autumn as days shorten, brown fur is shed and replaced by white fur that provides camouflage against the snowy background.

The fur itself does not change color; it is entirely replaced. Fur and feathers are dead tissue, like human fingernails. In order to change color, old fur must be shed so that new fur can grown in.

Winter fur color coincides with an increase in the production of the chemical melatonin, secreted into the blood by the brain's pineal gland. Darkness, or shorter daylight hours, triggers more of the chemical's release. The reverse color change takes place in spring as daylight hours increase and less melatonin is produced.

Snowshoe hares have other winter adaptations as well. Their large feet help them maneuver on top of the snow as they look for buds, twigs and bark to subsist on until spring returns.

The white-tailed jackrabbit (actually a hare), found from the plains to the tundra, also grows white fur in winter.

On the predator side, weasels turn winter white. There are two species of weasels in this area: short-tailed (also called ermine) and long-tailed. These fierce little critters make up for their size in attitude and strength. According to David Armstrong's Rocky Mountain Mammals handbook, short-tailed weasels are about 7-8 inches long, weighing only 1-2 ounces, and their long-tailed cousins are 12-18 inches long, weighing in at just 3.5 to 7 ounces. Armstrong notes that weasels use their long, slender bodies to wrap around prey to subdue it if needed, and land a powerful bite to the neck with their sharp teeth.

Weasels eat a variety of animals, including chipmunks, voles, baby hares or rabbits, small birds and amphibians, and other rodents, and often use the fur of their prey to line their nests.

Leanne Benton, interpretive ranger at Rocky Mountain National Park, is fascinated with weasels and does an evening program on the topic. She says in this region, weasels begin to grow white fur in October and regain their brown fur in March.

While fur color change is triggered by shorter or longer daylight hours, Benton says there seems to be a genetic component as well.

"Weasels in southern areas without snow don't turn white, and when brought north, they still don't turn white," she explains. "Northern weasels taken to southern areas will continue to turn white."

White fur may also provide an insulation benefit. "Without color pigments, the individual hairs have airspaces within them instead," says Benton, "and since air is a great insulator, white hairs keep you a tad warmer."

Mammals are not the only creatures that change color in winter. The white-tailed ptarmigan, a bird in the grouse family, subsists in the alpine tundra all winter long, losing its brown mottled feathers in late fall to be replaced by white feathers.

Even in summer, ptarmigans are difficult to see. They blend in so well with the brown colors of the tundra and are often not noticed by people until almost accidentally stepped on along a trail. In winter, their white feathers hide them in the snow, with only black eyes and beaks giving away their location.

Huddling under willow shrubs, ptarmigans stay warm in beds of insulating snow and subsist on willow buds. Their snowshoe feet are thickly feathered in winter.

Nature's colors are esthetically pleasing, but those color changes provide for lifesaving games of hide and seek. Look carefully and see what blends in.