FROM a rocky crown in the Santa Ana mountains, David Kossack looks out across a series of chaparral-dimpled canyons where mountain lions, eagles, falcons, and rattlesnakes live amid the sage and scrub.
``This is one of the last little niches of Orange County that has not been conquered and controlled,'' says Mr. Kossack. He and other environmentalists hope to keep it that way.
They are among the backers of an unprecedented land swap being considered in which thousands of acres of privately owned land in northeastern Orange County would be traded for a nearby military base. Under the still-nascent idea, the Irvine Company, owner of the pristine property, would exchange some of its land for a portion of the El Toro Marine Corps Air Station, near Irvine, which is scheduled to close in 1999.
The canyon lands would be turned into a conservation preserve. The company would gain control of a coveted piece of real estate.
Though it is just an idea now, and may never be carried out because of a number of conflicting interests, the land swap is part of a quiet push by United States Secretary of the Interior Bruce Babbitt to take advantage of military base closures to protect endangered ecosystems.
Across the US, Interior Department officials have identified at least two dozen sites where military lands could potentially be used to benefit nearby conservation projects.
Efforts are under way in Virginia, for instance, to incorporate land from an Army research facility into a national wildlife refuge. And the National Park Service is looking at adding part of Fort Vancouver in Washington State to its system.
In some cases, the deals would involve trades. At March Air Force Base in Riverside County, Calif., Interior officials have proposed the exchange of 2,000 acres of ``low-grade'' habitat that harbors the endangered Stephens's Kangaroo Rat for better habitat somewhere else. The theory: Since the land on the base is mediocre for the rodent but desirable for development, it could lead to an exchange that would prove a boon, both economically and environmentally.
The proposed Orange County swap is perhaps the most ambitious and complex of all the base deals Interior is considering. ``It is a unique idea both in terms of the scale and the opportunities,'' says Babbitt aide Jay Ziegler. On the surface, the swap would seem a good idea for many of the parties interested.
Local conservationists have long wanted to preserve the Irvine-owned canyon land. They were the first to propose the idea of a trade to federal officials.
Encompassing more than 10,000 acres, the land is home to the gnatcatcher, a threatened bird, the rare orange-throated whiptail lizard, and other unusual plants and animals. Establishing a preserve would fulfill the goals of both environmentalists and the Interior Department of trying to protect vanishing ecosystems before the species in them vanish.
In gaining control of all or part of the base, the Irvine Company would be getting strategically located real estate in exchange for difficult-to-develop canyon land (though the company does have plans now to build on part of it).
The firm already owns much of the acreage surrounding the base. A swap would extend its control.
There the difficulties begin: Local environmentalists such as the Friends of Tecate Cypress, of which Kossack is a member, want all 10,000 acres of the pristine property included in any deal. What they don't want is a planned toll road that would run through the would-be preserve.
The eight-lane highway, however, has its own powerful backers. It is unknown whether the company would want land set aside for the road as part of a trade, or whether Interior would agree.
Then comes the problem of a commercial airport that is being considered for the Marine base once it closes. The airfield is backed by some of the county's biggest business interests. It is opposed by residents concerned about noise and other problems.
An initiative is set for the November ballot to decide the issue.
Airport proponents presume that, if Irvine officials were to gain control of the base, they would go along with converting it to a commercial airfield, since the company would likely stand to gain economically from it.
But opponents hold out hope that the firm would not want to subject Irvine, its marquee master-planned community, to the environmental impact of an airport. Publicly, all company officials are saying about any of this is that the swap is an ``intriguing'' idea they are willing to explore.
There are other considerations as well. Any trade would have to dovetail with the interests of other federal agencies. The US Bureau of Prisons wants to build a facility at El Toro. Would it go up? The base faces a huge environmental cleanup. Who would do it?
Local authorities have to be consulted in any base closing. Though some members of a local board overseeing redevelopment of El Toro welcome the idea of working with the Irvine Company as landlord, others have qualms.
``My concern is not so much whether the swap is reasonable, but whether we are going to have a say in how the land is used,'' says Christina Shea, an Irvine Councilwoman and member of the El Toro Re-use Planning Authority.
Interior officials promise to produce a swap proposal by December. The details will probably determine whether the trade will remain just a provocative idea, or pioneer a way of turning swords into bird habitat.