Small, iconic, and endangered, California least terns return every year to one of the largest nesting colonies on the Northern California coast, in Alameda. This year marks 31 years since Susan Ramos, a naturalist at the Doug Siden Visitor Center at Crab Cove and Crown Memorial State Beach, initiated bus tours for the public to enter restricted land to view the least terns on their nesting grounds. The colony initially established itself on barren ground, right between active runways on the Naval Air Station, Alameda (NAS Alameda).
The nesting colony’s success started with a bird watcher. In the early 1970s, the NAS Alameda base commander’s wife—an avid bird watcher—recognized the small birds nesting between the runways as California least terns, listed as a federally endangered species in 1970. With only about 8.5 inches from the tip of their beak to the end of their forked tail, and a 20-inch wingspan, the white-and-gray birds with a black cap and white forehead are distinctive. About 10 pairs had established a nesting colony. The base commander’s wife made sure they were protected during their summer nesting season (approximately April through August). The least terns continued to return every summer and their colony grew.
The California least terns usually seek out sandy beaches scoured free of vegetation by tides to create their “scrapes,” small depressions in the sand, where they lay one to three speckled, well-camouflaged eggs. Both parents incubate the eggs for about three weeks. They both care for the young, foraging for small fish to bring back to their own chick(s) in the nesting area. The parents provide shade for the young chicks and fly up en masse with loud calls to drive avian predators away from the colony. Chicks fledge at three to four weeks old. After the chicks can fly independently, they prepare for their annual migration south to Mexico or Central America in late August or early September. It’s another mystery—scientists don’t know exactly where they go in winter.
California least tern numbers were diminished in the late 1800s when their bodies and feathers became fashionable for ladies hats and accessories. In 1940, the building of Highway 1 along the California coast further encroached on their nesting habitats. Development of coastal housing and businesses, and beach recreation severely curtailed their nesting success. The development and activity also brought predators to their colonial nest sites, especially cats, dogs, and wildlife. These developments forced the terns to attempt to occupy less suitable habitat from mudflats to airplane landing fields. To put California least tern population numbers in perspective, there were just 225 nesting California least tern pairs recorded throughout California in 1970 when they were placed on the endangered species list.
Fast forward to 1994 and the first public tour of the California least tern nesting site. The government had determined that NAS Alameda was destined for closure. Sherry Withrow, from the NAS environmental department in charge of protecting the California least terns and other wildlife on the base, got in touch with Susan Ramos and set up the first public bus tour of the nesting colony. Laura Collins, a wildlife biologist, also helped lead the trip. The Navy wanted to make sure the public understood the importance of the off-limits area as a vital habitat for the least terns and other wildlife.
The tour provided Bay Area residents with their first glimpse of the vibrant least tern nesting colony—parent birds sitting on their eggs, young chicks running around and sheltering among the shells provided for them, parents flying in with one fish at a time to feed their mate-on-the-nest or hungry young—along with a wide-ranging tour to other parts of the base to view a nesting great-blue heron and the nesting areas of other tern species and gulls.
At the time, the least tern colony was protected by an electric fence to keep predators from hunting the young and adults as well as the eggs. There were also dedicated staff to control avian predators such as burrowing owls, crows and ravens, peregrine falcons, and American kestrels. Under the Navy’s protection, the colony grew from those first 10 pairs with 10 fledglings in 1976 to 127 pairs of birds with 210 fledglings by 1993.
After the Navy left, the colony was managed by Point Blue (formerly Point Reyes Bird Observatory) staff for two years until finally being taken over by the U.S. Fish and Wildlife Service (USFWS). Friends of the Alameda Wildlife Reserve (FAWR) was formed in 1995, one of Golden Gate Bird Alliance’s three Conservation Committees, to advocate for the protection of the nesting colony as well as educate school children and the public about these amazing birds. The colony site is now under the Veterans Affairs, which contracts with USFWS to monitor, protect, and enhance the Alameda Point least tern Reserve.
The Alameda nesting colony, along with several others around San Francisco Bay (including Hayward Regional Shoreline’s “Tern Town” island), represent about 6% of the total breeding population of least terns. Alameda’s is the only colony around the Bay that offers the public a close-up opportunity, once a year, to view the nesting area by bus through the collaboration of staff at USFWS and East Bay Regional Park District (EBRPD) Doug Siden Visitor Center at Crab Cove.
“With protection of their nesting colonies from development, degradation and disturbance, and active predator control programs…” their numbers steadily increased in 2004 to 6,561 pairs in California, according to The Center for Biological Diversity’s website. Protection of the nesting colonies will be needed far into the future as these small birds remain vulnerable to multiple predators—both domestic pets and wildlife—in their remaining nesting colony areas.
Climate change and rising sea levels also are a potential problem for these small birds with their need for shoreline habitat. Last year the Alameda least tern colony did very well with over 500 nests and potentially around 800 young fledged. Their future remains in our hands.
This is a good time to start watching for California least terns in action around the Bay as they hunt in the shallow, nearshore waters for small fish. You can search for the adults as they hover over the water, then dive to catch fish. You may see some resting on the beaches or mudflats. Don’t disturb them if they’re resting in accessible areas.
You may also want to sign up for one of the bus trips to the colony offered by EBRPD; three bus tours are scheduled on Saturday, June 28. For more information, visit the East Bay Regional Park District website and search “Return of the Terns.”
To learn more about the wild birds around us, join the Golden Gate Bird Alliance (GGBA) for free walks around the Bay Area.
This article is part of a monthly series for the Alameda Post by members of the Friends of the Alameda Wildlife Reserve (FAWR), a Conservation Committee of the GGBA.
Sharol Nelson-Embry is the co-chair of FAWR and a GGBA board member. She retired from the East Bay Regional Park District where she supervised the Crab Cove Visitor Center for 26 years.
Rick Lewis is a long time Golden Gate Bird Alliance member and also belongs to other environmental organizations. He often contributes photographs to Bay Area and Central Valley birding groups that promote wildlife & habitat conservation.
