To the nation’s founders, the big, white-headed bird represented freedom and majestic beauty, and it quickly became a national symbol. Today, the bald eagle is also an example of an environmental success story.

A bald eagle.

Mike Lockhart, U.S. Fish & Wildlife Service

In the 1960s, only about 400 breeding pairs of bald eagles remained in the lower 48 states. Now, thousands of bald eagles soar U.S. skies, and their numbers continue to grow.

“You hear a lot of bad news about what happens to wildlife, and species are added to the endangered species list all the time,” says John Kostyack of the National Wildlife Federation in Washington, D.C. But “we do have success stories,” he adds.

Bald eagles have recovered so well that the U.S. Congress may soon remove them from the list of endangered and threatened species. However, scientists are still debating whether this change ought to occur. The final decision should come this summer.

Endangered species

Trouble for bald eagles and other birds began when farmers began to use a chemical called DDT, which protected crops from insects but also killed birds and made the shells of their eggs dangerously thin. The U.S. government banned DDT in 1970, and bird populations started to rebound.

A bald eagle in flight.

Steve Hillebrand, U.S. Fish & Wildlife Service

A law called the Endangered Species Act (ESA) also helped. Passed in 1973, the ESA makes it illegal to harm plants and animals listed as endangered or threatened. It also protects their habitats. If anyone wants to build on land where listed species live, scientists must review the proposal first.

“The act is a safety net intended to stop us before we drive a species to extinction,” says Cat Lazaroff of the law firm Earthjustice. “It helps us look before we leap and make decisions that allow us to live side by side with the wildlife in this country.”

The bald eagle’s recovery, Lazaroff says, is a perfect example of how well the ESA can work. It also illustrates how science and the law can team up to battle environmental problems. Organizations such as Earthjustice sometimes go to court to stop construction projects if scientists believe that development will put an endangered species at risk.

Coastline nests

Even though bald eagles are making a strong return, some scientists aren’t sure that these birds should be removed from the endangered species list anytime soon. To qualify for removal, a bird’s population must reach a certain size, and there must be strong evidence that the numbers will stay high.

For the bald eagle, there’s no guarantee of continued population growth, says Bryan Watts. He’s a bird ecologist at the College of William & Mary in Williamsburg, Va. One problem is land development.

A bald eagle and its nest.

Mike Jacobson, U.S. Fish & Wildlife Service

Eagles prefer to build nests along coastlines, Watts says, often in the same places where people want to live too.

“From a biological standpoint, bald eagles have recovered,” Watts says. “But every year we see larger and larger tracts of land being developed. If we look 50 years down the road, we’re concerned that . . . recovery will be reversed due to habitat loss.”

Watts also worries that taking bald eagles off the list might reduce scientific interest in the species. For 50 years, scientists have been monitoring eagle populations and gathering information about how to keep them healthy.

Bald eagles prefer to live along coastlines.

Dave Menke, U.S. Fish & Wildlife Service

In one recent study, William & Mary graduate student Catherine Markham, who studies eagle populations in the Chesapeake Bay, found that eagles reproduce best in certain areas of the bay where the salt concentration, or salinity, of the water is low. The Chesapeake Bay is on the eastern coast of the United States.

This tells us that “low-salinity areas have to be the focus of conservation efforts,” Watts says. “That’s where the heart of the [bald eagle] population is.”

Monitoring populations

Yearly monitoring has shown that a bald eagle needs to have an average of 0.7 chick per year to sustain the population, Watts says. When DDT contamination was high, that average dropped to 0.2 in the Chesapeake region. Now, the average is a healthy 1.8 chicks per year.

Keeping an eye on these numbers is essential for identifying population crashes in the future.

Bald eagle chicks.

Dave Menke, U.S. Fish & Wildlife Service

Every March in the Chesapeake Bay, for example, Watts and his colleagues fly above the treetops to count eagle nests. In May, these researchers swoop into the canopy to count eggs. They also climb trees to mark birds. This lets them track the birds’ eating habits and other details of their behavior.

Such monitoring is important, Watts says, because the needs of society conflict increasingly with those of endangered species.

Opinions welcome

The U.S. Fish and Wildlife Service is accepting comments about the proposal to remove bald eagles from the endangered species list until May. If you have an opinion, there are several ways to make yourself heard.

A bald eagle.

Gloria Meschmeyer, U.S. Fish & Wildlife Service

Through the Eagles Forever! Web site at http://eaglesforever.org/ , you can write to your senators in the U.S. Congress about bald eagles or about a recent proposal to weaken the Endangered Species Act.

You can also enter a contest by writing a story or drawing a picture about why you think eagles are important to the United States. The winner in each category will win a trip for four to Washington, D.C. The visit includes a behind-the-scenes visit to the National Zoo and meetings with celebrity judges. The deadline is April 30.

Good luck!

Going Deeper:

Additional Information

Questions about the Article

Word Find: Bald Eagles

Canadian scientists have found a worrisome, new example of the power that birds have to spread stuff around. Way up north in the Canadian Arctic, seabirds are picking up dangerous chemicals in the ocean and delivering them to ponds near where the birds live.

The high cliffs of Devon Island in the Canadian Arctic house seabirds known as northern fulmars. Droppings from these birds fertilize the green ponds below the cliffs and dose the ponds with mercury, pesticides, and other pollutants.

Image courtesy of Mark Mallory.

Some 10,000 pairs of the birds, called northern fulmars, make their nests on Devon Island, which is 640 kilometers (400 miles) north of the Arctic Circle. The fulmars travel as far as 400 kilometers (250 miles) over the sea to find food. When they return home, their droppings end up all around their nesting sites, including in nearby ponds.

Previously, scientists have noticed pollutants arriving in the Arctic with the wind. Salmon also carry dangerous chemicals, such as polychlorinated biphenyls (PCBs), as the fish migrate between rivers and the sea. The bodies of fish, people, and other meat-eaters can build up high levels of the chemicals.

A northern fulmar.

Image courtesy of Mark Mallory.

To test the polluting power of northern fulmars, researchers from the University of Ottawa in Ontario collected sediment from 11 ponds on Devon Island. In ponds closest to the colony, the results showed that there was 10 times more of the pesticide hexachlorobenzene, 25 times more mercury, and 60 times more DDT than in ponds less affected by the birds.

The pollutants in the ponds, the study suggested, appear to come from fish that the birds eat when they’re out on the ocean.

People who live, hunt, or fish near bird colonies like those on Devon Island need to be careful, the researchers say. The birds don’t mean to cause harm, but the chemicals they carry can cause major problems.—E. Sohn

Going Deeper:

Milius, Susan. 2005. Arctic foulers: Foraging seabirds carry contaminants home. Science News 168(July 16):36-37. Available at http://www.sciencenews.org/articles/20050716/fob5.asp .

You can learn more about the northern fulmar at www.mbr-pwrc.usgs.gov/Infocenter/i0860id.html (U.S. Geological Survey) and collections.ic.gc.ca/arctic/species/northful.htm (Government of Canada).

Scientists have just discovered that these deaths occur because the vultures are getting an accidental dose of medicine from the cattle meat. Farmers had given a drug to their livestock to heal the animals. To vultures, however, the drug turned out to be poisonous.

Oriental white-backed vultures make short work out of an animal carcass.

M. Virani

Finding the cause of the vultures’ deaths was like solving a mystery. At first, researchers thought the birds might have been dying of some mysterious plague.

Veterinarian J. Lindsay Oaks at Washington State University examined the internal organs of some dead birds to check for signs of disease. No disease. Instead, Oaks discovered that the birds’ kidneys had failed—not due to disease but due to poisoning.

Scientists already know that certain chemicals, such as the metal cadmium, are harmful to birds’ kidneys. But in their tests on the vultures, Oaks and his colleagues found no traces of cadmium or other familiar, harmful substances.

Next on the scientists’ list of suspects were any drugs used to treat livestock. The researchers checked to see what drugs farmers in the area used. They noticed one drug on the list known to hurt birds’ kidneys if the birds eat something with the drug in it. The culprit is called “diclofenac,” a veterinary medicine used by farmers in Pakistan and India to shrink swellings.

Losing the vultures could have all sorts of unwanted side-effects. With fewer vultures around to devour animal carcasses, there’s less competition for food—allowing the number of foxes to increase. The increase in the fox population has led to the spread of rabies. It’s an example of the complex chain of unexpected effects that can occur in nature.

The vultures are useful to farmers, too. When an animal dies, a farmer can leave the carcass out in the open for vultures to dispose of. Without vultures, farmers would have to find new ways of dealing with waste carcasses.

The researchers say the vultures might recover if the farmers stopped using the drug. But that might not be so easy for the farmers.

The vultures don’t have much time, though. Rick Watson of the Peregrine Fund in Idaho claims that if farmers don’t do something, three species of vulture will die out within 5 years.—S. McDonagh

Going Deeper:

Milius, Susan. 2004. Vanishing vultures: Bird deaths linked to vet-drug residues. Science News 165(Jan. 31):69-70. Available at http://www.sciencenews.org/20040131/fob6.asp .

You can learn more about vultures in Pakistan at edu.iucnp.org/newbirds/pstory2.htm (World Conservation Union/IUCN).