Blane Klemek column: Patterns and colors help creatures blend in
To be seen or not to be seen – that is the solution, not the question. With creatures great and small the world over, the colors and patterns of their coverings are much more than just protection from the elements.
To be certain, few animals could survive for long without protective covering. But all those different color patterns that mix together in pelages, plumages, skins, shells, and wings and other things, helps critters blend into their respective environments.
In the world of birds, plumage color patterns are essential to individual species survival. In fact, the primary role of plumage color is concealment. Abundant and familiar examples exist right here in our own region.
A couple of common gamebirds that readily come to mind are ruffed grouse and American woodcocks. At a glance it may appear that these birds are basically one color. But at close examination, many shades and patterns of those fundamental colors emerge. Clearly, however, the reason for such arrangement of plumage color pattern is within the environment the birds inhabit. Both species of birds sitting in a motionless posture on the forest floor mixed with fallen leaves, brush, and trees are nearly impossible to see.
The American bittern is another bird with an interesting plumage color pattern. Here’s a bird that spends its life within the tall vegetation and shallow waters of specific wetlands. Not just any old wetland will do for the bittern. Its lifestyle is one in hiding and, so, wetlands with cattails, tall grasses, and sedges, as well as reeds and other vegetation, attract bitterns.
Observing a bittern out in the open or in flight does little to illustrate just how cryptic their plumage color pattern is, until, the bird steps into the tall vegetation and performs its little disappearing act.
As a bittern slinks, almost sloth-like, into the herbaceous neighborhood it inhabits, stretches its neck upward, and points its bill straight up, it is suddenly just another clump of grasses or cattails. The body contour, the striped breast plumage, and all the surrounding vertical stems make for a bona fide Houdini act that’s tough to follow, let alone see at all.
We are all aware of the pelage color-changes of some mammals such as weasels, jackrabbits, snowshoe hares, and Arctic foxes. These mammals annually shed their brownish summer jackets for white winter coats through a molting process each autumn. Believe it or not, a certain bird way up north in Alaska does the same thing.
The three species of ptarmigan, which is a gallinaceous bird of mountainous snow-country and tundra, is a bird well suited for the changing landscapes of northern latitudes and high altitudes. During the wintertime ptarmigans are colored almost pure white in order to match its harsh surroundings.
However, in the spring as the snow melts away to reveal dark patches of earth, rocks, and ground vegetation underneath, ptarmigans’ plumage begins resembling this change as well. Ptarmigans take on a mottled look, displaying blotches of both brown and white. And by summertime, ptarmigans become finely barred in browns and blacks to match their snowless environment.
Disruptive patterns also help to conceal birds. Bold markings, often associated with the head and neck region, effectively lessen the difference between the shape of a bird’s body or outline and its normal habitat type. The black bands on a killdeer’s head, neck, and breast are examples of bold patterns that help to “disrupt” the contrast that would exist without the bands, which makes the bird difficult to detect on the ground.
Countershading is another pattern common in birds. First described by artists’ Abbott and Gerald Thayer in 1909, countershading helps to disguise a bird’s outline. We see this typically in shorebirds – that is, darker plumage above and lighter plumage below.
Shorebirds normally forage in open spaces along beaches and other riparian areas. In so doing the birds are exposed and somewhat vulnerable to predation. However, strongly contrasting colors of the top and bottom surfaces of most shorebirds act in partnership with sunlight.
Dark plumage on a bird’s back does not reflect light very well, and this contrasts sharply with the bird’s lighter colored bellies. The visual interaction helps to blend a bird’s outline with the background and thus, reduces its visibility.
That withstanding, countershading, as intuitive as it is, also occurs in its opposite form. Some birds such as male bobolinks, golden plovers, and black-bellied plovers display dark plumage on their underparts and lighter colored plumage on their upperparts. This seemingly maladaptive color pattern’s primary purpose is to enhance visibility rather than reduce it. The reason? Such color patterns are more important during the breeding season for attracting mates than it is for concealment. It’s a tradeoff where, evidently, reproductive success outweighs surviving potential predation.
Why birds and other animals possess the color patterns they do is a fascinating subject to observe and study. Regarding birds, plumage color patterns did not come about randomly. Such diversity in coloration and pattern evolved over time. In essence, it is what it is because it helps individual birds survive and reproduce.
Indeed, the next time you go birding or sitting and watching the birds on your backyard feeders, take note of the dazzling number of different plumage color patterns.
This awareness will surely enhance your days afield as you get out and enjoy the great outdoors.
BLANE KLEMEK is a Minnesota DNR wildlife manager. He can be reached at firstname.lastname@example.org.