Case Study #1: The Bald Eagle
|The bald eagle, an American symbol,
has become a model for the successful recovery of an endangered
species. Once, only a little over 400 nesting pairs of these predatory
birds existed in the lower United States.
Today, under the protection of the Endangered
Species Act, that number is almost 6,000.
Although promising, one would wonder how over 200,000 of
these birds came to be on the brink of extinction in just a few
During the mid-1800ís, hunters began killing large
numbers of prey species, like waterfowl, that support the bald eagle in
its ecological niche. Along
with this, the bird itself also became a target.
events led to governmental intervention in the form of laws
protecting bald eagles from hunters and merchants.
But other unseen threats were even more serious.
Pesticides, specifically DDT, caused the shells of eggs to thin
and prevented reproduction (see
Story Time about
Rachel Carson). Once again, the actions of humankind upset the delicate
ecological balance of the bald eagle population.
After DDT was banned, the population of these magnificent
predators began to rise.
Case Study #2: A Look at Whooping Cranes
National Wildlife Refuge, located on the Texas
Gulf Coast, is home to some of the best bird watching our nation
has to offer. Perhaps this same place is also the birthplace one of our
most unique efforts to rescue an endangered species. About sixty years ago, ecologists estimated that only 15
whooping cranes remained alive. Their
numbers had been decimated by the human activities of hunting and
farming. So the Wildlife Refuge was
created where no hunting was allowed. Today the Aransas population is estimated to include
174 whooping cranes, which has inspired other notable efforts to save
The ecosystem at Aransas cannot support infinite
numbers of whoopers. So, ecologists came up with a clever idea of
training young whoopers to migrate to another safe winter haven, in
||In fall 2001, a group of 5 whooping
cranes literally took off from Necedah Wildlife Refuge in
Wisconsin in what was to become one of the most unique attempts to
rescue an endangered species to date.
These birds, guided
by an ultralight plane, were led to Chassahowitzka National
Wildlife Refuge in Florida. As everyone had hoped, they
returned back to Wisconsin on their own the following spring. We
hope they now know how to get to Florida and will set up the
nucleus of a new wintering place in Florida. Efforts are currently underway to introduce at least ten
more birds into this program.
Still interested about learning about whooping cranes?
Track their migration progress at http://www.operationmigration.org.