Tuesday, October 18, 2011

Red-Tailed Hawk: predatory birds are ever-present and vital to nature's balance

Predators play an important role in maintaining balance within nature's ecosystems. When we think of a predator, we often think of large animals like sharks, lions, or wolves. But predators come in all sizes. In fact, any animal that feeds on another animal can be considered a predator and that predation helps to keep the populations of its prey healthy by weeding out the sick or aged, and keeping numbers in check by counteracting high reproductive rates.

In fact, for animals that are prey to several different kinds of predators, a high reproductive rate is nature's consolation prize of sorts for being the unwitting prize of a predator. In the seas, plankton, krill and many species of small baitfish have high reproductive rates as they are a food source for many different predator species ranging from small reef fish to massive whales. And on land, many rodent species - rats and mice in particular - reproduce in great numbers to offset predation from everything from coyotes to hawks.

Speaking of predatory birds, their roles are very similar to predators like sharks. Two roles actually, depending on the bird. Sharks play a critical role as scavengers and there are vultures and buzzards that play a similar role. Sharks are also hunters and hawks and eagles follow parallel duties. To hunt, the predator needs an advantage and for hawks it can often be incredibly sharp eyesight combined with lightning speed.

In the Sioux Falls Argus Leader, writer Jerry Stanford writes of his admiration for the red-tailed hawk, a common predatory bird in South Dakota,
"In mid-September, my wife and I traveled south of Sioux Falls to watch the ever-changing season turn from lush green to golden yellow. While enjoying the wonderful wide-open spaces, we managed to observe several majestic red-tails swirling in the deep blue-sky updrafts, sometimes to the point where the feathered acrobats disappeared among the billowing clouds. During our half-day jaunt, I was constantly reminded of the great bird's flexibility as it grabbed hold of invisible updrafts that somehow managed to help navigate the acrobat to where it wanted to go."

Stanford cites the writings over fifty years ago of Charles Flugum who identified the important role the hawk plays and the importance of not regarding them as a nuisance,
"The role of hawks in the balance of nature is to counteract the dangerously rapid reproductive rate of mice and other rodents. It is sound conservation practice to protect all our hawks, except those individuals actually caught in the act of taking poultry. There has been some improvement in the attitude toward our birds of prey in recent years, especially in securing legislation for their protection. We have a long way to go, however, before an enlightened and aroused public will give these laws the support they need to make them really effective."

In Southern California, where I live, one doesn't have to go far, even within a suburban setting, to find an occasional hawk circling overhead. Hawks have adapted somewhat to the presence of human urban development - one pair of hawks became rather famous locally in New York for nesting on the side of an office building and raising a family, subsisting on the many rodents that live in the city. And I wonder how quickly we would be overrun by mice and rats if we were to be without these aerial rodent exterminators.

Predatory birds face many threats, even with conservation and protective regulations in place. Poisons ranging from lead shotgun pellets - consumed by eating prey which survived a previous encounter with a hunter - or fertilizers and insecticides, and even rodent poisons which would weaken or sicken a rat or field mouse, making it an easy target for a hawk. And then there are the direct, man-made threats from hunters, or poultry farmers protecting their birds And for large eagles, buzzards, or condors, there is the threat from coming in contact with high power electrical lines.

The relationship between predators and prey can sometimes be a bit like the classic chicken or the egg conundrum - which came first? Did nature evolve a predator to combat the population growth of a highly reproductive species or did the prey develop the ability to grow in great numbers to counteract predation? Such is the complexity of nature's ecosystems and we must be always mindful of the natural balance that occurs. One wrong step on our part and an ecological card castle can come crashing down.

Read Jerry Stanford's recollections of the red-tailed hawk in the Argus Leader.

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