Some Animals Are Helped, Some Hindered, by White
Nature Notes
By Patricia Martin

It’s finally winter and a blanket of snow has covered the Island. The trees look like they’ve been frosted and the rocks have beautiful white caps on them. This is the “white” time of year for those of us in the north.

White is an interesting color. In fact, according to the physicists, it is technically the absence of all color, just as black is the presence of all colors. When something, like a leaf, appears green, what is really happening is that all the other wavelengths of light are absorbed into the leaf, but the green wavelengths are reflected back out, giving the leaf the appearance of being green. In the case where something appears black, the object is really absorbing all of the light and in the case of white, all of the wavelengths of light are reflected back away from the object. This is why most people like to wear light-colored clothing in the summer, because it doesn’t absorb as many wavelengths of light as darker colors, and therefore is not as hot (not as much energy is absorbed).

There are other reasons for an animal to be white. Take the case of several species of bird visitors that we see at Mackinac. Late last summer a pair of Tundra Swans (previously known as Whistling Swans) was seen along the east shores of Mackinac. These large white birds are fairly common in North America. They spend their winters along the Pacific and Atlantic coasts and, as their name implies, they head north in the spring to breed and nest, during the summer, in the Arctic tundra. They often pass through our area in the spring and fall during their migration. Sometimes they migrate so early in the spring that they build up ice on their wings like airplanes. Unlike the introduced Mute Swan, which is similar in color though larger, the Arctic Swan has a black bill with a yellow spot in front of the eye (the Mute Swan has a bright orange bill). These monogamous bird pairs build solitary nests in the open tundra and their white coloring gives them camouflage while they’re incubating their eggs.

Snowy Owl

Another white visitor to the Island is the Snowy Owl who, like the Arctic Swan, spends its summers in the Arctic and instead of just passing through in the fall, spends a large portion of the winter in Michigan. Just a couple of days ago one was seen again on the Island. The Snowy Owl is a predominantly white-feathered owl with occasional dark flecks (juveniles and females have more dark barring). These large owls have yellow eyes, a fairly large head, and no ear tuffs. Their coloring helps them all year around blend in to their snowy environment, but not just for protection. These birds are predators and their coloring helps them fade into the background while sitting motionless, watching and listening for their food. These owls may be active both day and night. Their favorite supper is rodent, especially lemmings and voles, though they will also eat birds and fish. The winter sightings of these birds vary greatly from year to year. If the rodent population in the north drops, as it does cyclically, the Snowy Owl heads south for better hunting, and we have a better chance of spotting one of these beautiful birds.

Birds are not the only organisms that use the color white to blend in to their environment. There are several mammals in our area that actually change their summer color and grow a white winter coat to match the changing environment. One of the most common of these is the Snowshoe Hare. Last summer, I was delighted to see several of these animals out and about on the Island. In the summer, the hare has a yellowish brown to rusty brown coat with a distinct dark band running down the midline of the back. The belly fur is white and there is a distinctive cinnamon-brown patch at the throat. The edges of their long ears are tipped in black. These hares are decidedly larger than the Eastern Cottontail, weighing in at three to five pounds and with large hind feet. They also lack the Cottontail’s white tail. The Snowshoe Hare is particularly adapted to northern winters. Its large, hind feet covered with stiff hair allow the animal to walk across deep snow without sinking in, thus giving the Snowshoe its name. Its color change also helps its winter survival. Beginning in September the Snowshoe Hare begins to shed its summer brown hair and replace it with its thick, winter white coat. This transformation is stimulated by the shortening day length (photoperiod) and the lower temperatures. It takes about 70 to 75 days for this change to be completed. The only dark fur left on this animal is the black edge around the ears. I remember as a child hearing the rabbit hunters saying that they liked it when the hares changed their coats early and the snow had not yet fallen. The white pelts of the hares stood out, and they were easier to spot. So this color change may have some down sides, too.

A couple of members of the weasel family also have the ability to change to white in the winter. The Short-tailed Weasel or Ermine and the Long-tailed Weasel both turn white in the winter, with the exception of the black tip of their tails, which is dark all year long. Like the Snowshoe, the color change is triggered by the cold and the shortened day length, so in the case of the Long-tailed Weasel, some members of the species who live in the more southern parts of their range remain brown all year. The Long-tailed Weasel can be found throughout most of the United States and down into Mexico. The Ermine’s range includes most of Canada and the northern tier of the United States. The white winter coloring helps both of these weasels hide from predators and camouflages them so they won’t be seen by their prey and as they’re active all year, this is a great advantage.

In some cases, being white is not healthy for the longevity of an animal or bird. This summer a pair of white doves were seen around the Island. Rock Doves, also referred to as “pigeons,” were introduced to North America in the early 17th century and have adapted to living around people. This species has been domesticated from a Eurasian species sometime before 4500 BC for meat and has been used as messengers, as well. Rock Doves come in a variety of colors, iridescent blue gray, red, tan, or white. White doves have often been associated with religious ideas, often symbolizing the Holy Spirit, purity, or love. Because of this, these birds are sometimes released at weddings. Unfortunately, their color makes them stand out against the green of trees or grass and makes them easy pickings for hawks and other predatory birds. The pair that has been seen on the Island may have come from such an event. This fall I found one of the white doves dead. More and more lately, the white doves released at weddings are homing pigeons that will return to home base after their flight at the wedding; this is helpful to prevent their predation.

Keep your eyes open for our white-winged and furred friends this winter. It sometimes takes good vision and good luck to pick them out from their snow surroundings.

I wish you all a Merry Christmas, a Happy New Year, and a wonderful snowy winter.

Trish Martin is a year-around resident of Mackinac Island, has earned a master’s degree in botany from Central Michigan University, and owns Bogan Lane Inn .