Environment : Notes about your surroundings.

RETURN OF THE BIRDS: The northward spring migration of birds is beginning, with hummingbirds and swallows among the first to pass through the county. Shorebirds, many of which stay in the county through the winter, will slowly diminish through March as they begin their treks to breeding grounds north. Later in March, many will begin to change into their breeding plumage.

The migration will peak later in spring, according to Sylvia Ranney Gallagher, bird information chairman of the local Sea and Sage Audubon Society. “April is the main month when things are passing through,” she says.

EVENTS: Local collector Norman Campbell, who has chased butterflies on numerous trips in South and Central America and Australia, will lead a four-week course entitled “Butterfly Mounting and Collection” at the Museum of Natural History and Science (formerly the Orange County Natural History Museum.) The classes, which will cover collecting, pinning, labeling, storing and entomology, will meet every Saturday in March from 10 a.m. to noon at the museum, 2627 Vista del Oro in Newport Beach. The cost is $7 per class for museum members and $10 for non-members (materials are included). Information: (714) 640-7120.

The Santa Rosa Plateau, a Nature Conservancy reserve in the Cleveland National Forest near Temecula in Riverside County, is the subject of a March 12 Family Workshop in Natural History organized by the Santa Ana Zoo. During an easy-paced four-mile hike, zoo staff will guide visitors to the area’s spring display of wildflowers and bird life. The plateau is home to five endangered species and several rare plant communities, including the vernal pools and southern oak savannah. Tuition per parent-child pair is $25 and includes a field workshop, instruction packet and transportation. Information: (714) 836-4000.

The annual Seal Beach National Wildlife Refuge work party and tour is scheduled for March 26 this year. Because the site is part of the Seal Beach Naval Weapons Station, this will be the only chance for many people to see the salt marsh refuge, home to breeding populations of the endangered light-footed clapper rail and California least tern.

The work party will last from 8 a.m. until 1 p.m., when all who must leave then will be escorted out. Those who can stay will be given a tour of the wetlands from 1 to 3 p.m.

Volunteers will meet at 7:45 a.m. at the main gate to the Weapons Station on Seal Beach Boulevard.

To meet Navy security requirements, organizers must have the names and addresses of participants by March 18. Those who plan to take part can send a card to Larry T. Lee, 5471 El Jardin St., Long Beach 90815. Cameras are not allowed.

Compiled by Rick VanderKnyff