SESPE CONDOR SANCTUARY, Calif. -- Thursday morning, the quiet in the isolated peaks in the southern tip of the Los Padres National Forest will be shattered by the concussive noise of helicopter rotors.
California condor chicks, one in each of two separate flights by a Ventura County sheriff's chopper, will be huddled in hooded traveling cages of the noisy cargo bay.
They are among the last of their kind -- and the best hope for renewal of the species.
Primed to reassert a beachhead they were forced to yield more than four years ago when the species was nearly lost, biologists will be anxiously waiting for delivery of the precious cargo on a ledge of the steep cliff.
The chicks -- Chocuyen (pronounced Cho-coo-yen) and Xewe (Gay-wee) named from the dialect of ancient tribal residents who roamed these folded ridge lands -- will be returned to a home their species has known since before the retreat of the last continental ice sheets.
The reintroduction is part of the Endangered Species Act that was designed to bring wildlife back from the brink of extinction.
In California, years of intensive recovery efforts have brought back from that brink the bald eagle and peregrine falcon. Other programs have put the southern sea otter in a position to recover, as well as the tule elk, the pronghorn antelope and the big horn mountain sheep.
Much is riding on Chocuyen and Xewe, who were hatched and reared in total isolation in two of the nation's most popular zoological parks -- the San Diego Zoo's Wild Animal Park and the Los Angeles Zoo.
The helicopter will make two flights starting at 9 a.m. Thursday, dividing the cargo to guarantee against the loss of both birds should an accident occur.
The flights mark the latest stage of a long-planned exercise in ecological manipulation.
Once the cages are dropped, the chicks will be let loose in a net-covered run on the rim of Arundel Cliff in the rugged heartland of the national forest, just a few miles from where the last condor was trapped by biologists on Easter Day 1987.
A portable plywood box, shaped and textured with gunite to mimic nearby ancestral nesting caves, will be their refuge. It will be snugged up to the base on a ledge of the steep cliff, midway between the slanting canyon floor hundreds of feet below and the windy ridge top.
A cyclone wire fence, ribbed with electrified wires, protects the pen's perimeter. It is charged to repel bears and mountain lions that either would out-muscle the condors for free lunches or turn them into one.
Condors -- part of the vulture family -- do not attack live prey but eat only carrion. For the first two months, workers will quietly deposit stillborn calves in the cage, usually on windy, moonless nights when their presence and movements would be best obscured from the sleeping chicks.
Once the birds are acclimated, the nets will be dropped and the condors will be enticed to a series of natural feeding sites on nearby rock outcroppings and ridge tops. Recovery team biologists said the artificial feeding is intended to prevent the birds from eating lead-tainted carrion, a chief cause of the decline of the species.
From more than half a mile away, hidden observers will watch the condors almost continuously during daylight, through powerful spotting scopes. Once the nets are lowered and the birds take flight, they will be tracked by wing-mounted radio transmitters.
The chicks won't be in total isolation. On Thursday, they will be accompanied by a pair of young Andean condors to ease their social adjustment.