Indeed, under the Endangered Species Act he and the agency that employs him are under a congressional mandate to do exactly that.

But instead of offering Mr. Eller a promotion for his dedication and zeal, his bosses at the Fish and Wildlife Service want to fire him. They say he is inefficient and his work is substandard.

Eller and his supporters say the real reason he's on the chopping block is that he was too tough on developers seeking permits that would cut away at the last remaining expanse of Florida panther habitat.

The case is raising questions about whether the Fish and Wildlife Service's mission of environmental protection has been co-opted in favor of politically connected developers and business interests.

Defenders of the wildlife service's approach say there is nothing wrong with cooperating with developers. Critics say the cooperation is changing the face of southwest Florida and jeopardizing the survival of the panther.

"My primary concern was that the panther was not getting its due - that we were losing habitat one and a half times as fast as it was being preserved," Eller says. "Once the habitat is gone, the panther is gone."

John Kostyack, a lawyer with the National Wildlife Federation, agrees with Eller's assessment and has filed lawsuits to force a closer look at the role of the Fish and Wildlife Service in Florida development.

"The agency repeatedly looks at a project in isolation and says this project is not going to be harmful to the panther in the long haul," Mr. Kostyack says. "The problem is that the panther is suffering a death of a thousand cuts."

The Florida panther is actually a puma, resembling cougars found in the American West. The Fish and Wildlife Service estimates there are roughly 80 panthers remaining in Florida. Although they once prowled throughout the peninsula, widespread urbanization has pushed the big cats from all but the state's southwestern region.

Since the early 1990s, southwest Florida has been one of the nation's fastest developing areas. Much of the new construction activity is taking place east of I-75, where large areas have been transformed - piece by piece - into roads, shopping malls, and golf-course communities.

Eller says his "employment" problem began several years ago when he started to examine the cumulative effects of piece by piece development in a five-county area of southwest Florida that comprises the best remaining panther habitat in the state. State land-use statistics show that panther habitat is being lost at a rate of 30,000 acres a year, Eller says.

Rather than sharing his alarm, Eller says managers at the wildlife service told him not to raise the cumulative effects issue when reviewing proposed development projects. "My supervisor told me that if I did [raise the issue], he would give me a poor performance evaluation," he says.

Eller adds that he was also instructed to use inflated panther population estimates and was warned against writing anything in his reports suggesting a project might jeopardize the panthers.

The Fish and Wildlife Service disputes this. "The issue of removing Mr. Eller from his office is not really related to this issue with the panthers," says Bert Byers, a spokesman for the Florida office of the wildlife service.

The Eller case arises as the Fish and Wildlife Service finds itself in the midst of a major debate over the quality of science that has helped justify the massive development taking place in southwest Florida.

The wildlife service placed great weight on a study that suggested that Florida panthers live primarily in forested areas. That conclusion was worth billions of dollars to developers eyeing large expanses of non-forested, or semiforested land.

But subsequent studies suggest panthers use and need much larger areas - including nonforested areas. The wildlife service is now rewriting its panther survival strategy.

Not all of this reassessment has come voluntarily. Last month, a federal judge in Washington, D.C., invalidated government permits allowing development of a limestone mine on a 6,000-acre site near the Southwest Florida International Airport.

US District Judge James Robertson invalidated the permits after ruling that the Fish and Wildlife Service had not adequately explained its conclusion that the mine project would not jeopardize the big cats. He also criticized the wildlife service for failing to analyze the potential cumulative effects of development.

Eller was the Fish and Wildlife Service biologist who worked on the proposed mine project. His conclusions raising similar concerns were edited and censored, he says.

John Milton is chief financial officer of Florida Rock Industries, which wants to operate the mine near Fort Myers. "Florida Rock is not an enemy of the panther," he says. "But by the same token we don't think it is our private mission to foot the bill for the panther's survival."

During the permit process, Florida Rock agreed to establish an 800-acre "wildlife corridor" and was willing to preserve an additional 1,000 acres undisturbed. "It is a little bit disconcerting that [the judge] didn't think those contributions counted," Mr. Milton says.

Eller hasn't been alone in fighting to keep his job. Public Employees for Environmental Responsibility (PEER), a group in Washington, D.C., has filed suit on behalf of Eller under the Data Quality Act for allegedly censoring his scientific conclusions.

"The same scientific defects pervade all of the other decisions the Fish and Wildlife Service has been making in the western Everglades for the past four years," says PEER director Jeff Ruch. He says PEER has located other wildlife service biologists whose reports have also been censored.

"We talked to a number of [Eller's] colleagues, they are literally scared to death and feel if they spoke out about their professional concerns they would be committing career suicide," says Mr. Ruch.

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