Environment : notes about your surroundings

COUNTING SHEEP: The state Department of Fish and Game is looking for volunteers to head into the rugged Santa Rosa Mountains in Riverside County next weekend in a project to help save a band of native wild sheep.

Department wildlife biologist Gerry Mulcahy will lead a group laden with equipment and supplies into a remote northern section of spectacular Anza Borrego Desert State Park, home to a population of peninsula bighorn sheep. The volunteers will construct a mile of 5-foot barbed-wire fencing to keep out cattle.

Feral cattle have been identified as the source of a respiratory virus highly infectious to native wild sheep. The virus has caused poor lamb survival and a subsequent decline in the total population.

The two-day fence construction project will begin at 6:30 a.m. Saturday and will be completed Sunday afternoon. Camping gear, food and water for two days and one night must be packed in by each volunteer. About 80 volunteers are needed.

For information, call the Fish and Game wildlife management office in Long Beach at (213) 590-5158.

ARBORETUM WALKS: The season opening of Wednesday Walks--short lunchtime tours of the Fullerton Arboretum grounds--is Wednesday. Ted Hanes, biology professor at Cal State Fullerton and past director of the arboretum, will focus the tour on the plant collections that make up the center of the arboretum grounds.

The one-hour walk will begin at the waterfall at noon. Brown bag lunches may be taken on the tour. For information, call (714) 773-3579.

PROGRAMS: Reptiles are the focus of “Snakes Alive and Leapin’ Lizards,” the Saturday program at the Oak Canyon Nature Center in Anaheim Hills. The program begins at 10 a.m. For information, call (714) 998-8380.

Also Saturday, the Museum of Natural History and Science in Newport Beach will conduct a natural history festival, featuring walking tours of Upper Newport Bay and programs on a variety of natural history topics. The event is from 10 a.m. to 4 p.m. Call (714) 640-7120 for information.