Lessons to Live by

by Margot F. McMillen

These animals' stories show us mistakes we've made-and ones to avoid in the future.


Conservationists magazinesContents

A plant or animal species survives by fitting into a certain environment. If the environment changes and the species can't adapt, the species may suffer or die out. Changes to the environment can happen for many reasons, but humans are the biggest cause of environmental change. Sometimes, we harm the environment when we act recklessly, in ignorance, or because we just make mistakes. We have caused many species of plants and animal to become extinct, but we can also act in time to prevent future disaster. Here are three case histories.

Passenger pigeons Extinct

"The air was literally filled with pigeons: the light of noonday was obscured as by an eclipse," wrote John James Audubon in 1813, "Before sunset I reached Louisville, the pigeons were still passing in undiminished number, and continued to do so for three days in succession. . . For a week or more, the population fed on no other flesh than that of pigeons."

What happened Once there were more passenger pigeons than any other bird in America. They nested in forests that covered hundreds of square miles.

Then settlers cleared forests to build towns and farms. Passenger pigeon habitat was destroyed. At the same time, the pigeons were hunted for meat. The birds could fly fast-as fast as 60 miles per hour-so it was a challenge to see who could shoot the most. There was no limit on how many a hunter could kill. By 1896, there was only one flock left.

One day in April 1896, hunters nearly destroyed the last flock in one hunt that killed an estimated 200,000 birds. And still, people hunted the remaining 5,000 or so. In 1900 the last wild passenger pigeon was shot.

After that, only three remained living in a zoo. The last passenger pigeon lived to be 29 years old and died on September 1, 1914 at 1 p.m. She was named Martha, after the wife of George Washington.

Conclusion Habitat change endangered the passenger pigeon, but the biggest threat was human greed. Even their huge numbers and a long life span didn't save this species. Today, we have laws to limit hunters' harvests and laws to help protect endangered species.

The American bald eagle

The American bald eagle is our national symbol. After signing the Declaration of Independence on July 4, 1776, the Continental Congress named a committee to design a seal. Ben Franklin, John Adams and Thomas Jefferson worked on the project, but the final design was made by Charles Thomson and William Barton and adopted in 1782. You can see their seal, with an American bald eagle in the center, on the $1 bill. The eagle's right talon holds an olive branch with 13 leaves representing peace in the thirteen colonies. In the eagle's left talon, 13 arrows show the colonies are willing to defend their high ideals. The banner bears a Latin phrase: E Pluribus Unum, meaning "one nation of many states."

What happened When bald eagles began to disappear, people noticed. Even immature eagles can spread their wings seven feet across! Scientists quickly investigated, but it was hard to figure out why this large raptor was disappearing. Many people shot raptors and collected their eggs, but what else was affecting them?

Eagles in the U.S. reached a low of 400 nesting pairs in the 1960s. Soon after, it was discovered that a pesticide called DDT was interfering with the raptor life cycle. DDT was sprayed to kill insects. Fish, snakes, frogs and other small mammals ate the bugs. Raptors then ate these creatures and got a big dose of DDT through the food chain. DDT does not break down when it enters the environment. Over the years, it increasingly builds up in plant and animal tissue. As a result, raptors laid eggs with shells so thin that the eggs broke before the baby birds could develop. On Flag Day, June 14, 1972, DDT was banned.

Eagles were put on Missouri's endangered species list in 1978. From 1960 through 1984, we had no productive nests in the state.

Restoration began with education: teaching people not to kill eagles. Much harder is the process of protecting and restoring eagle habitat. Eagles nest in tall trees and eat fish, so conservationists try to save wetlands and wooded areas near rivers and lakes.

Conclusion Eagles are making a comeback. From 1981 to 1990, the Conservation Department brought young eagles from other states and released them here. Baby eagles learn to recognize their home territory. Even though they might leave for a while, some of them come back to build nests and raise their young. In 1985, bald eagles resumed nesting in the state. In 1995, the eagle's status was changed from "endangered" to "threatened" for the entire U.S.

Jim D. Wilson, ornithologist with the Conservation Department says, "It's happened sooner than we thought." There were 45 active nests in 1998, and 36 produced offspring-65 to 70 new eagles born in Missouri!

Salem cave crayfish

" . . . thousands of rare cave animals, some never before seen by man at Maramec Spring, began washing out of the spring. We could only guess what lay ahead . . . The Salem cave crayfish was the rarest of the creatures that died. It has been seen only at a handful of locations in the Ozarks and is found nowhere else in the world . . . It may be years before we learn if any of these animals survived . . . " Ron Crunkilton, water quality research biologist, in Missouri Conservationist, November 1982.

What happened

In November 1981, a fertilizer pipeline broke and fertilizer flowed into a stream. The stream disappeared through a hole into Maramec Cave. This kind of waterway, called a "losing stream," is common in the Ozarks where the karst geology is made up of surfaces with thousands of passageways going to and from caves, springs, streams, sinkholes and deep hollows.

The fertilizer was mostly ammonia in deadly concentration. No one knows how much ammonia spilled into the creek, but 11 days later, dead sculpins, trout and other fish species floated to the surface in Maramec Spring. The spill killed rare Salem cave crayfish and southern cavefish. It killed other species too small to see. Some live animals were rescued and moved to temperature-controlled holding tanks at the St. Louis Zoo and Conservation Department.

It took about 30 days for the ammonia to wash through. By that time, all life in the cave was dead. Scientists worried that the cave would always be lifeless, but the damaged stream was just one part of a huge system. Losing streams disappear into the system and may bubble out again miles away. Luckily, there were animals that escaped the pollution, and the cave survived.

Conclusion

Little by little, the creatures came back and reestablished themselves. This process is called recolonization. In 1998, scuba divers found blind cavefish and blind crayfish back in Maramec Cave.

Damaged ecosystems never recover to their original condition, but the Maramec critters were lucky. Ammonia evaporates quickly. If the spill had been pesticide, oil, or other complex chemicals, the ecosystem might have been much more damaged. Today, the pipeline no longer carries liquids.

What we can do

We now have laws to prevent overhunting, the use of certain dangerous chemicals like DDT and careless handling of chemicals that could spill into streams. Besides following laws, people can do many things to help plants and animals. We can educate ourselves about rare and endangered species. We can also reduce our consumption of natural resources by changing the way we do things at home.

The Dewey-Care family is on their way to volunteer at a nature center, but they've forgotten to do their part at home. Can you identify mistakes they're making?