Blane Klemek column: Raptors are fascinating and diverse
Raptors are a group of birds that include owls, eagles, ospreys, hawks, harriers, kites, falcons, and vultures. They are what we typically refer to as birds of prey. Most raptors make their living by capturing, killing, and eating other organisms, but not all of them.
The diet of raptors depends mostly on how large the particular species of raptor is. For example, the diminutive saw-whet owl and American kestrel will readily capture large insects for a meal, whereas the great horned owl and red-tailed hawk will feast on prey as big as skunks and hares, to as small as shrews and chipmunks.
Hunting and capturing live prey is difficult, even with the supreme weaponry possessed by birds of prey. However, some raptors do just fine by supplementing their diet with carrion (dead animals). Birds with these tendencies are also called scavengers. Vultures are considered to be the ultimate scavenging bird of prey, although not technically considered by some ornithologists as a raptor at all--indeed, a bird belonging to an entirely different group.
Even our noble and majestic national emblem, the bald eagle, is a scavenger. This impressively large and able eagle is no slouch, but it well knows that the easy pickings offered from dead animals, such as the many deer that die on roadways, present a welcome source of food, especially during the lean times of winter and for immature eagles earning their wings.
I sometimes wonder if the abundant white-tailed deer is part of the reason for the steady increase in the bald eagle population. Granted, the outlawing of the harmful pesticide, DDT, was the primary reason for the bird's recovery. Still, for any animal to survive and flourish, habitat and food are two vital elements that will assist and sustain a population's health and growth. And with the many deer that die as a result of collisions with vehicles, birds like eagles, turkey vultures, crows, ravens, magpies, and others, make certain that nothing in nature goes to waste.
All raptors have anatomical features similar to one another. Though owls and hawks are indeed physically different from one another, a closer look reveals remarkable likeness. Most notably are the feet of raptors. Powerfully muscled legs and feet as well as toes and sharp talons to clutch struggling prey are the primary tools of most birds of prey.
Beaks, too, are important tools of raptors. While owls' beaks are comparatively small and weak, the beaks of hawks, eagles, ospreys, and vultures are strong and specially designed. Large and hooked, these beaks are used to tear flesh from their prey.
While owls may lack in the beak department, they certainly compensate for this shortcoming in other ways. Owls have the unique ability to ambush their prey silently because of their feathers. Most birds have stiff wing-feathers that produce sound as air passes through the feathers while the bird is flying. Owls, on the other hand, have soft feathers throughout their body, including the wings. These soft feathers are virtually silent in flight and thus enable owls to capture their prey swiftly and quietly.
All raptors have exceptionally keen eyesight and hearing. Again, these are tools of the trade. And just because birds of prey are so equipped, doesn't necessarily mean that the critters they hunt are easy targets. Prey species are pretty good at detecting and escaping capture. Rodents, rabbits and hares, small birds, snakes, and insects have all devised ways to avoid being eaten. These and other potential prey of raptors can move fast, hide well, and hear and see and smell those creatures that are hunting them.
For obvious reasons, eyesight is extremely important to birds of prey. It is believed that hawks can see a mouse or vole from a mile away. And the eyes of those species of owls that hunt under the cover of darkness are specifically outfitted for nocturnal vision.
There is, however, one sense that is undeveloped in all but one species of raptor: smell. In fact, birds in general have little or no olfactory ability. But vultures, including our resident turkey vulture, have highly developed senses of smell. For vultures, being able to smell well is imperative to their survival. Without it they would have to rely exclusively on their vision to locate prey, which, especially in the forested regions of their range, would be almost impossible to do if not for their ability to smell animals that have died and to reach them before other scavengers do.
To understand this amazing ability, one need only to examine the nostril openings located on both sides of a vulture's beak. The openings are large, which enable vultures to scent thermal updrafts as they soar effortlessly above forests and fields searching for food. Able to scent the faintest of odors, including freshly dead animals, our own turkey vultures and other vultures have little difficulty in locating dead prey.
Raptors are fascinating and diverse birds. Some are only summertime residents, like American kestrels and northern harriers, while others remain here the year around, such as great horned owls and northern goshawks. They are at the top of the food chain in the avian world and they help to keep populations of some animals in balance.
These birds of prey -- raptors -- are yet another interesting and highly specialized group of birds to observe and appreciate as we get out and enjoy the great outdoors.
BLANE KLEMEK is a Minnesota DNR wildlife manager. He can be reached at firstname.lastname@example.org