From swans to seals, species rebound in US

As wildlife management techniques improve and concern for endangered species grows in the United States, experts say man is making his peace with many once-threatened animals. For example:

* When a visitor to the Travelers Tower in Hartford, Conn., established a permanent home on a 21st-floor ledge, a few corporate feathers were ruffled. Meetings were held, a flurry of memos passed, and a proper bureaucratic solution reached: Build it a nest. It seems a peregrine falcon, confusing the skyscraper for the cliffs on which it makes its home, was using the ledge as a launch pad for raids on unsuspecting pigeons. The bird has yet to declare the gravel-filled wooden box it was provided home, but corporate bird lovers remain hopeful.

* The baleful bellowing of elephant seals echoes from beaches along the California coast. The massive mammals number more than 65,000 today, but in 1892 , barely 20 existed anywhere. Now the seals, which prefer to breed on offshore islands, are so numerous that they are establishing themselves on mainland beaches.

* In Vermont, a gradual reforestation of abandoned farms and grazing lands has led to the reappearance of species once extinct in the state. Coyotes, cardinals, opossums, beavers, and white-tailed deer have all taken up residence in the state once again. Moose now number 100 to 200, and the wild turkey population that totaled 31 only 14 years ago has passed the 10,000 mark.

''Wildlife is in better shape now than it has been in a century,'' says Lonnie L. Williamson, secretary of the Wildlife Management Institute, a private, nonprofit environmental group based in Washington, D.C. ''There is a misconception on the public's part that because some species are declining, they all are. That is certainly not the case.''

The tally of success stories reads like a checklist for Noah's Ark: Pronghorn antelope, which numbered 13,000 in 1925, now total more than half a million; bison, which dwindled to 800 survivors in 1895, now total more than 10,000; white-tailed deer, which were hunted until no more than 300,000 remained in 1885 , now have a population of 15 million to 20 million; fur seals, which were down to 215,000 in 1911, now number in excess of 2 million.

Similar rescues from the brink of extinction have been recorded for trumpeter swans, peregrine falcons, and sea otters. Beavers were eliminated from the Mississippi Valley and the East Coast, except for Maine, by the late 19th century, but they can now be found in all of the contiguous 48 states.

Still, environmentalists warn against concluding that because some species are regaining their lost vigor, that all species are. ''Many of the animals being saved are the attractive, larger mammals. We are concerned with the thousands (of smaller animals and birds) that are still facing the threat of extinction,'' says Ginger Merchant, endangered species specialist for Defenders of Wildlife.

A good deal of the success in rebuilding wildlife populations is attributable to more sophisticated wildlife-management techniques on both the public and private levels. Until recently, state wildlife offices concentrated most of their efforts on rejuvenating game animals, because hunters were picking up the tab for their services through license fees. Greater public environmental concern has led to a loosening of the purse strings on the state level, which in turn has freed wildlife managers to turn their attention to a wider variety of species.

On the federal level, Congress recently reauthorized the Endangered Species Act, which funds projects such as land acquisition to protect the habitats of endangered species. But environmentalists complain the Reagan administration has turned it into an empty shell.

''There are guarantees for wildlife protection on paper but they aren't being implemented,'' says Robert Davison, legislative representative for the National Wildlife Federation.

Listings of endangered species dropped from an average of 45 the last two years of the Carter administration to 4 in 1981 and 13 in 1982. But Megan Durham , spokeswoman for the US Interior Department, says new listings during 1981 and 1982 were held down because of a cumbersome accounting procedure that has since been streamlined. She adds: ''This administration has put a lot of emphasis on the recovery of endangered species, not just on the administrative listing of them.''

One of the factors playing a key role in wildlife resurgence is stricter pollution controls and curbs on pesticide use. The pesticide DDT had the effect of thinning the shells of peregrine falcon eggs, causing the shells to crack before the chicks were hatched. The disappearance of DDT, which has been banned since 1970, has led to the reappearance of the bird not only in Hartford, but in New York City as well. Several pairs of the birds are nesting on bridges there for the first time in two decades.

Not all attempts at wildlife population control have worked. A three-year effort begun in 1979 by federal and state officials aimed at reintroducing bighorn sheep into California's Sierra Nevada mountains has met with limited success, according to an official in the California Fish and Game Department. The same problems that nearly led to their extinction in the 1940s have yet to be fully solved: loss of habitat to development and grazing land, poaching, disease transmitted through domestic livestock, and a new one - mountain climbers who scare the animals away from their preferred habitat.

The reappearance of wildlife in various parts of the US, while pleasing to environmentalists and nature lovers, is not without its problems. The spillover of wildlife into urban areas has raised a number of safety concerns. A proliferation of coyotes in southern California has resulted in several attacks on children. In Pennsylvania, deer present a safety hazard on roads. More than 30,000 deer are killed each year in the state in traffic-related accidents.

There can also be an adverse economic impact. Farmers in any number of states are grumbling over the damage deer and other wildlife do to their crops, and Pacific Coast fishermen are angered about the depletion of fish stocks by seals.

Despite the difficulties, most wildlife specialists are confident that animal populations will remain stable. Says Mr. Williamson: ''If the human population can be brought under control - and that's the key - I'm very optimistic about the future of wildlife.''