MOST U.S. ENDANGERED SPECIES LIVE IN `HOT SPOTS,' REPORT SAYS.

Byline: William K. Stevens The New York Times

Populations of most endangered species live in a relatively few critical ``hot spots'' covering a surprisingly minuscule portion of the United States, scientists have found in the first county-by-county analysis of the species' distribution.

The hot spots, according to a report appearing today in the journal Science, are concentrated most heavily in Hawaii, California and the Southeast, especially Florida.

Conservation biologists see a number of practical implications in the findings. By focusing conservation funds and effort on the hot spots, for example, ``you could get a big bang for your buck,'' said Dr. Andrew Dobson, an ecologist at Princeton who is the study's chief author.

And since most of the critical tracts are on private land, Dobson said, the findings make a strong argument that the government should offer private property owners tax incentives to protect endangered species.

The Endangered Species Act is up for reauthorization, and Congress and the Clinton administration are expected to grapple with the contentious issue of revising it this year. Among other proposed revisions, various types of property-owner incentives have been suggested.

In general, the hot spots have two salient characteristics: They contain species confined to a small range; ecologists call these endemic species. And they are being disturbed by such human activities as urban development and agriculture.

``That's the formula for extinction these days: small range plus development pressure,'' said Dr. David Wilcove, an ecologist with the Environmental Defense Fund who is a co-author of the new study, along with Jon Rodriguez and W. Mark Roberts of Princeton.

Earlier studies found that endemic species accounted for most recent extinctions worldwide. But until now, no analysis had uncovered the United States' pattern of overlap between endemic species and areas disturbed by humans. Hawaii, California and Florida have the most endemic species and the most endangered species.

Working from government data, the researchers found that representatives of officially endangered and threatened species live on ``a surprisingly small amount of the total land mass,'' Dobson said.

For example, only 13 counties, accounting for 1.33 percent of the nation's total area, contained populations of more than half of its endangered plant species.

The investigators also found that for the most part, the territory of the endangered species did not overlap. Conservationists have long believed that by protecting birds, for example, they would be protecting other kinds of organisms, too. The new study found that while endangered birds and arthropods do indicate the presence of other endangered species, groups in general overlap ``only weakly.''

The major exceptions - places especially rich in endangered species - were two counties in California where hot spots for three groups of organisms converged: San Diego (fish, mammals and plants) and Santa Cruz (arthropods, reptiles, amphibians and plants).

Nine other counties were hot spots for two groups each: all four counties in Hawaii; Los Angeles and San Francisco counties; Bay and Monroe counties in Florida, and Whitfield County in Georgia. The last-named county has relatively large numbers of endangered fish and mollusks.