25 messages from wildlife

In the last quarter century, nature has often reminded us that the fates of wildlife and our own species are intertwined

As celebration of the first Earth Day took place cross the country in April 1970, brown pelican eggs on Anacapa Island off the coast of Ventura, California, were breaking under the weight of incubating adults. For four months, the birds laid eggs in a total of 552 nests without producing any young. Finally, in July, a single chick hatched on the island, the species' only regular nesting ground in the state. The cause of the eggshell thinning: DDT poisoning.

Of course, Anacapa's brown pelicans were not the only animals harmed by DDT; nor were they the only pelican population in serious trouble. But for a nation waking up to the idea that the fates of wildlife and our own species are intertwined, the island's one chick 25 years ago delivered a notably poignant message. And in that respect, the young bird was not alone. For every so often, the natural world delivers to our own species lessons that we are able to comprehend particularly well - lessons that are in many cases taught more quietly by many other animals and plants.

In honor of the 25th anniversary of Earth Day, the following list chronicles 25 of the most resonant messages this country has received from wildlife during the last quarter century. It is no accident that many are from birds; ever since the proverbial coal miners' canaries, birds have been our most telling harbingers of news from and about nature.

1 BROWN PELICANS

DDT poisons birds: Only a decade before a single brown pelican chick hatched on Anacapa in 1970, the species' young may have numbered in the thousands on the California island. But 25 years ago, DDT came close to wiping out the colony. The widespread pesticide and related chemicals had also long been poisoning brown pelicans in southeastern states - as well as ospreys, bald eagles, cormorants and many other species all over the country.

By 1972, the Environmental Protection Agency (EPA) had banned the use and manufacture of DDT, not only for the sake of wildlife, but also because it was a suspected human carcinogen. That possibility was made all the more alarming by the knowledge - detailed by biologist Rachel Carson a decade earlier in her landmark book Silent Spring - that DDT had become ubiquitous, even showing up in human milk. The EPA now lists DDT, which has diminished in the environment but is still widely present, as a probable human carcinogen.

2 WHALES

Taking action can work: The supply of whales and the uses for their meat, oil and other parts once seemed endless. But by 1972, despite some protections, many species were nearly extinct - including the massive blue whale, the "singing" humpback and the right whale. That year, the United States declared eight whale species endangered and passed the Marine Mammal Protection Act to protect whales and dolphins in U.S. waters. But many countries kept whaling. Of course, whales were hardly the first hunted animals to convey by their very absence the need for a chance to recuperate. Bison, pronghorn and cougars, just to name a few, were in serious trouble until they were protected. But in the case of whales, the message was arguably heard the loudest of all, and "Save the Whales" became a rallying cry. In 1982, the International Whaling Commission finally agreed to a moratorium that started in 1986. Though not absolute, the uneasy truce has helped many whale species survive and even show some signs of recovery.

3 LAKE TROUT

Humans can ingest potent doses of poisons passed up the food chain: Though the United States and Canada joined forces in 1972 on a long-range cleanup of the Great Lakes, hundreds of pollutants (some wind-borne from around the world) still contaminate the region. Many wildlife species are now doing much better than they were 23 years ago. But because of the way toxics accumulate in the food chain, they become concentrated in fish. Many of the lakes' fish-eating birds and mammals still have abnormal reproductive problems. In 1970, Michigan issued the first fish-eating advisory for people. Today, every Great Lakes state warns of human health risks from eating the region's fish - particularly lake trout and carp. Similar warnings have been posted for fish from many other U.S. waters.

4 FIDDLER CRABS

Oil spills can have long-term, sublethal effects: In the 1970s, scientists at a number of research institutions started reporting results from studies of a 1969 oil spill in West Falmouth, Massachusetts. Researchers still refer to that work, important because it was impartial (not funded by industry) and extensive. In 1977 one study revealed that fiddler crabs were still suffering physiological and behavioral damage. Most striking, the oil was impairing their ability to dig burrows critical to their survival.

The oil's persistence and its sublethal effects in the marsh prefigured the ongoing damage in Alaska from the 1989 Exxon Valdez oil spill - even though the two ecosystems radically differ. Oiled mussel beds in Alaska were still fouled more than five years later. And some mussel predators in the area - including young sea otters and many species of sea ducks - are suffering population problems that may be related to ingested oil.