COMMUNITY COMMENTARY:

Fall is an exciting time at Upper Newport Bay — the “Back Bay.”

The mudflats come alive with thousands of birds picking at horn snails on the surface or probing for worms or clams a few inches down in the sediment.

Flocks of tiny least sandpipers flit to and fro in unison above the tranquil open waters of the bay, as if following some carefully choreographed ballet routine.

They truly are a joy to watch. The least sandpiper is just one of the many species of migrating birds that fly south from Canada and Alaska for the winter and either stop over before continuing on to Central or South America, or stay here until springtime beckons them north again.

The bay is the largest of only a few remaining protected estuaries in Southern California. An estuary is a coastal wetland where salt water from the ocean mixes with nutrient-rich fresh water from inland sources to provide a fertile feeding area for birds, fish and other animals.

The abundance of food is important to the migrating birds that must replenish the body fat lost during their arduous journey south.

When the Spanish missionaries arrived in California in the 18th century, coastal wetlands were numerous.

Gradually these tidal areas have been lost to development. Now only about 10% of the original coastal wetlands remain between Santa Barbara and the Mexican border.

Cordgrass, the signature saltmarsh plant, thrives here, adapted to growing with its roots submerged in salty water. As the leaves and stalks die off they break down into small fragments that are partially decomposed by microbes in the water, which in turn are food for fish larvae.

Luxuriant algae mats extend out from the cordgrass into the mudflat providing food for the horn snails and crabs.

The water is rich in plankton that is easily consumed by the clams and other filter-feeders hiding in the mud. With so much variety of food, it is no surprise that nearly 200 species of bird and nearly 100 species of fish can be found here at Upper Newport Bay.

If you are interested in learning more about the bird, plant and marine life of the Back Bay, and the Native Americans who lived here for several thousand years, join us Saturday at the Friends Lookout, on the corner of Back Bay Drive and Eastbluff Drive, just off Jamboree Road in Newport Beach.

Docent-led groups depart from the lookout roughly every 15 minutes from 9 to 10:15 a.m. for a short walk along the bay stopping at education stations along the way where subject specialists use exhibits to illustrate their talks.

These “Friends Tours” take place the second Saturday of the month from October through March.

They were started in 1968 to call attention to the ecological importance of the bay and to enlist broad support for the retention and protection of the bay in its relatively natural state. For more information, visit newportbay.org.

ROGER MALLETT is a member of Newport Bay Naturalists and Friends.