When asked to name the one distinguishing feature that sets birds apart from other creatures, many people answer that the ability to fly is unique among birds and birds only. While this is a good answer, it is not the best answer. In fact, not all birds can fly (think penguins, ostriches, and emus).
Perhaps you thought eggs were unique to birds? That, too, isn't quite accurate because many critters lay eggs other than birds. Among them are insects, fishes, reptiles, amphibians and yes, even a few species of mammals.
Indeed, what really places birds into quite literally a class of their own is their body covering; that is, feathers. No other organism, great or small, has feathers except for birds.
But getting back to flight again, other creatures have evolved fight capabilities, too. In the insect world, for example, near countless species can fly and fly well. Even the gazillion beetles of forests and fields - often bulky and cumbersome looking - can spread their outer shells to expose a pair of wings that carries them aloft where ever they please. And, of course, there are butterflies, moths, dragonflies, damselflies, flies, midges, gnats, mosquitoes - you name it.
Dragonflies, believed to be the most aerially accomplished of all insects, if not all flying organisms, can be compared to hummingbirds for their amazing maneuverability. But while hummingbirds have only one pair of wings, dragonflies have two pair that work independently.
Dragonflies can fly backward, change directions instantly, stop in mid-air and can accelerate to maximum speed in a split second. They are masters of the sky.
Fish? Well, not in the purest of forms, but there are species of fish that can "fly." "Flying fish," for example, have evolved incredibly long pectoral fins, while some species have, in addition, oversized pelvic fins. While swimming fast near the ocean's surface, flying fish can escape predators by launching themselves into the air and gliding several yards before entering the water again.
Reptiles and amphibians? Even some of these species have evolved ways to "take to the air." None of them, however, actually have wings, but some non-Minnesota frogs have evolved extra large feet. When their toes are spread, some species of tree frogs inhabiting tropical rain forests can sail through the air in order to land on nearby trees or ponds - their webbed toes acting like miniature parachutes.
There is also a species of snake from Asia that can flatten its body to such a degree that it, too, can sail from the height of a tree and, like a ribbon, squirm through the air to reach nearby limbs! Additionally, some species of geckos and other Asian lizards, including a species of lizard from Africa, have evolved the ability to glide.
For instance, there are species of gliding geckos that possesses flaps of skin along their limbs, torso, head and tail. When aloft, these skin folds catch the air, thus enabling them to glide with ease.
Another species of lizard glides on folds of skin similar to that of flying squirrels, but, unlike flying squirrels, the "gliding membrane" is attached to extended ribs rather than their legs such as what is common for flying squirrels. These species of gliding lizards can glide as far as 200 feet while losing only 30 or so feet in height.
Mammals? Not counting human ingenuity of airplanes, gliders, balloons, rockets and so on, there are several furry mammals that have conquered gravity as well. Two of them live right here in Minnesota, both of which are active only at night.
Two species of squirrels, the northern and southern flying squirrel, are pretty adept at "flight," although true flight is never accomplished. Yet, from high in a tree and by spreading their legs to reveal the connecting folds of skin, these little bug-eyed squirrels can glide through the air and can cover astonishing distances in the process.
Other species of mammals that have obtained the ability to glide include species of marsupials found in Australia. Flying phalangers and greater gliders are among those mammals that can glide with the aid of folds of skin attached to their limbs. There are species of opossums and lemurs that can glide, too. Nevertheless, bona fide mammalian flight occurs in only one group of mammals - bats.
A few evenings ago while standing in my front yard, I watched two tiny bats, "little brown bats" as this particular species is called, in the twilight sky hunting for flying insects. The acrobatic creatures darted through tiny gaps between branches of trees and around my house and garage, dove abruptly while they chased moths and flew so close to me that I could clearly hear their wings as they maneuvered and chased their meals.
Without a doubt, the ability to fly and glide has evolved in many creatures. From flying fish to flying lemurs, taking to the air is a mode of locomotion utilized by critters the world over. But only insects, birds and bats have truly mastered flight.
Such as it is, there are probably more creatures flying and gliding around than you might have known as you get out and enjoy the great outdoors.
Blane Klemek is the Bemidji area assistant wildlife manager, DNR Division of Fish & Wildlife. He can be reached at firstname.lastname@example.org.