Wildlife can be elusive — it’s a survival technique. Even if you can’t see the animals while visiting regional parklands, though, you can still identify them by the sounds they make.

Find out more during “Sonidas En La Naturaleza — Sounds in Nature,” a program from 9 to 10:30 a.m. Saturday at Coyote Hills Regional Park in Fremont with naturalist Martha Cerda.

As the title implies, this is one of a series of bilingual programs in English and Spanish. The group will explore and appreciate some of the different and beautiful sounds that are made by wildlife throughout Coyote Hills. Meet at the visitor center.

The program is free and open to all ages. Parental participation is required, but registration is not necessary. Coyote Hills Regional Park is at the end of Patterson Ranch Road, off Paseo Padre Parkway. There’s a parking fee of $5 per vehicle. For information, call 510-544-3220.

Also in Fremont: Monarch butterflies have returned to Ardenwood Historic Farm in Fremont this year in respectable though not large numbers. Monarch butterflies have a complicated life cycle. They undergo an annual migration for thousands of miles north and south; some populations migrate between Canada and Mexico. Individual butterflies complete only part of the full distance.

According to the Ardenwood naturalists, the monarchs that overwinter there are part of a western population that doesn’t migrate to Mexico. They come from all over the northwest United States west of the Rockies. The butterflies then settle in the park’s eucalyptus groves in winter, conserving warmth by overlapping like roof shingles, and occasionally launching into flight.

No formal butterfly programs are planned at Ardenwood this season. However, if you visit the park, stop by the farmyard, and the park staff will be glad to direct you to where you can view some of the monarchs. Ardenwood is at 34600 Ardenwood Blvd., just north of Highway 84. For information, call 510-544-2797.

San Leandro: Another recurring program in the park district is Saturday Strolls. The strollers will meet Saturday at Oyster Bay Regional Shoreline for an easy, 3-mile walk from 9:30 to 11:30 a.m. with naturalist Susan Ramos.

Participants will see how the former landfill site has been transformed into a park that is a stopover for migrating birds and overwintering butterflies. It has great views of San Francisco Bay too.

The hike is free, and registration is not necessary. To get to the trailhead from Interstate 880 in San Leandro, exit at Marina Boulevard and drive west. Turn right onto Neptune Drive, and park at the end of the street. For information, call 510-544-3187.

Berkeley: From before the arrival of the bow and arrow, the East Bay’s Native Americans used a device called an atlatl while hunting.

You can try your hand at this ancestral skill during a program from 2 to 3 p.m. Saturday at Tilden Nature Area near Berkeley with naturalist Anthony Fisher. On a personal note, I’ve tried using an atlatl myself during a similar program. I’ll say only that any potential food source would have been safe. Accuracy requires a lot of practice.

Anthony’s program is free, and registration is not necessary. Meet at the Environmental Education Center. It’s at the north end of Tilden’s Central Park Drive, accessible via Canon Drive from Grizzly Peak Boulevard in Berkeley. For information, call 510-544-2233.

Antioch: Millions of years ago, a shallow sea covered the area that is now Black Diamond Mines Regional Preserve in Antioch. To see evidence of this ancient seascape, in the form of sea creature fossils, join naturalist Jaclyn Caldwell on a short, leisurely stroll from 2 to 3 p.m. Saturday.

Meet Jaclyn in the parking lot at the park offices, on the left just past the park entrance kiosk. The park is on Somersville Road, about 3½ miles south of Highway 4. The program is free, and no registration is required. Black Diamond Mines has a parking fee of $5 per vehicle when the kiosk is staffed. For information, call 510-544-2750. No underground mine tour is included.

Oakley: You can help to track the health of the Sacramento-San Joaquin River Delta during ongoing water quality testing programs at Big Break Regional Shoreline in Oakley. Learn how water quality changes affect the ecosystem.

There’s a program from 9 to 10 a.m. Jan. 8 with the Big Break naturalist staff. It’s free, and registration is unnecessary. Big Break Regional Shoreline is at 69 Big Break Road off Oakley’s Main Street. For information, call 510-544-3050.

Online: These are just a few of the programs and activities available in the East Bay Regional Park District. For full information, visit ebparks.org/things-to-do.

Ned MacKay writes about East Bay Regional Park District sites and activities. Email him at nedmackay@comcast.net.