Big Island ranch land that is habitat for endangered native bird species and plants will be protected from development under an agreement between the owners and the Nature Conservancy.

David and Josephine DeLuz donated a conservation easement for 4,500 acres on the northeastern slope of Mauna Kea to the conservation organization, according to an announcement yesterday.

The land is part of 10,200-acre Kukaiau Ranch, which has been in cattle and agriculture operations on the Hamakua Coast for 125 years. Continuous grazing, tree harvesting and brush fires have caused erosion problems, loss of stream flow and destruction of native plants, according to the Nature Conservancy statement.

The io, or Hawaiian hawk, and palila, a native forest bird, both endangered species, are seen on the upper slope, which extends to an altitude of 8,400 feet, said John Henshaw, director of the organization's conservation programs.

“;We hope this will become a model for other ranchers, a way to combine conservation with land management,”; Henshaw said. The owners may continue to have sustainable forestry and agricultural operations on the land, he added. It will be the ranch's responsibility to put up fencing to deter grazing, to protect native plants and to remove feral pigs and goats.

The ranchers do not relinquish ownership, but agree to the conservancy's limitations on its use.

“;A conservation easement is recognized as a tool to keep property together,”; Henshaw said.

DeLuz, owner of Big Island Toyota and Mazda dealerships, and his wife bought the ranch 15 years ago and now run about 1,100 head of cattle.

A previous owner “;subdivided land into 40-acre agricultural lots, so the whole ranch is zoned for that,”; said Josephine DeLuz. “;It's not our desire to sell it off in pieces. We bought it to revive it and put it back into ranching. It's our dream to restore it to what it was in the good old days.”;

She said her husband grew up on his father's small cattle ranch on the Hamakua Coast.

“;My husband can remember riding up towards the mountains where there were huge growths of koa trees,”; she said. “;Now they are nonexistent.”;

Henshaw estimated the value of the easement is between $1 million and $2 million, which can be applied for tax relief. The value of the land is much more than that, he said, but the conservation restrictions will lower its monetary value.

This is the first step of the DeLuzes' intention to protect the entire ranch property under conservation easement.