LOS ANGELES (AP) - Human encroachment threatens 59 percent of California's wildlife corridors, a new study has found.

The 79-page report details for the first time 232 migration corridors used by the state's wildlife. A majority of those are threatened by development and 14 percent have already been lost, according to the study.

The thin links are crucial for the long-term survival of species such as chinook salmon, bighorn sheep and bald eagles, scientists said. In California, many of those animals already live on isolated preserves hemmed in by development.

"Wildlife corridors are an essential component of any conservation strategy on the basis that the natural habitats have been fragmented," said Paul Spitler, executive director of the California Wilderness Coalition.

The Davis-based group cosponsored the study with The Nature Conservancy, U.S. Geological Survey, Center for the Reproduction of Endangered Species and the California Department of Parks and Recreation. The goal is to promote the issue in discussions of conservation policy, which has focused on core habitat areas but not on the links that join them.

In November, 160 scientists met at the San Diego Zoo to discuss the issue. "Missing Linkages: Restoring Connectivity to the California Landscape" was the result.

The survey - believed to be the first to canvass an entire state - stresses the importance of corridors in preserving genetic diversity and the long-term health of wildlife populations, scientists said.

"They foster or maintain genetic flow - that is when animals move from one small population to another, they take their genes with them and thereby increase the genetic diversity of the population at large," said Barbara Dugelby, a Texas wildlands ecologist and expert on the issue. "It's true for everything from cougars down to butterflies."

M.A. Sanjayan, director of conservation science for The Nature Conservancy, said Southern California fares the worst. Eighty percent of its corridors used by wild animals are threatened.

"Movement corridors are of critical importance if we are to maintain the pieces we already have in the long run. Otherwise, these islands of habitat will continue to erode in biodiversity," Sanjayan said.

Rolling back the threat can be as simple and cheap as placing a culvert under a highway project or as complicated and expensive as securing and preserving land slated for development, Spitler said.