Naval Air Station-Alameda gained notoriety as a refuge for the endangered California Least Tern when the base closed in 1997. Over 500 acres were dedicated to protecting the terns’ adopted nesting site next to a runway formerly used by jet aircraft.
This unlikely bird habitat for the Least Terns some 400 miles north of their historic breeding grounds along the southern California coast offered the birds something they had lost, which drove them to the brink of extinction – nesting sites free of human disturbance near a source of small fish to feed their chicks.
Surprisingly, two other tern species have recently begun nesting in the vicinity. Elegant and Caspian Terns seem to be thriving there, while the endangered Least Terns are struggling.
The annual tours to the least tern colony at Alameda Point were sold out again this year. Three groups totaling about 100 people listened to a presentation about the endangered birds before boarding a bus at the Crab Cove Visitors’ Center.
It is the only time that the general public is permitted to enter the federally owned former aircraft runway area to view the terns nesting. Guests are not allowed to leave the bus.
This once-a-year glimpse of Alameda’s colony, managed by the U.S. Fish and Wildlife Service (USFWS), is very different from the daily opportunities to view the Huntington State Beach least tern colony near Los Angeles, managed by the California Department of Parks and Recreation.
The 9.6-acre Alameda Point least tern nesting site has a 500-acre buffer zone. During the nesting season, volunteers monitor and record tern behavior and threats from predators, such as hawks and falcons, while sitting in their vehicles.
The 13-acre Huntington State Beach Least Tern Natural Preserve is protected by a 15-foot buffer zone on three sides. The Huntington Beach Bike Trail hugs the fourth side of the colony, with the busy Pacific Coast Highway only 40 feet away.
At Huntington State Beach, docents amble around to educate visitors about natural history and conservation while recording observations about predators. Over the recent Memorial Day weekend at Huntington Beach, people casting fishing lines into the ocean, throwing Frisbees, and laying on blankets were often not more than 30 feet from adult least terns loafing and sometimes mating on the beach.
During the non-nesting season in Alameda, volunteers remove weeds by hand, and pick up terracotta tiles, wooden A-frames, and oyster shells used for sheltering the chicks, and then re-distribute them in April before the terns arrive. USFWS sprays an herbicide before the terns arrive to minimize vegetation that sprouts up on the bed of imported sand. This is to help to maintain the look of a beach with good sight lines preferred by terns.
At the Huntington Beach Preserve, the state park department stopped using shelters. They, too, use an herbicide, but only for grasses. The low-growing flowering vegetation on this natural beach is allowed to remain and serves as camouflage for nesting adults and for the chicks when they hatch.
At Huntington Beach, certified volunteers count the nests, eggs and chicks twice a week. They walk through the site inside of sand-colored canvas blinds held together with PVC pipe that they carry. At Alameda Point, the wildlife biologist does not employ the use of a blind.
The Huntington State Beach Least Tern Natural Preserve was established in 1973 as the first fully protected tern colony in California. This preserve implemented the central tenet of the USFWS-approved recovery plan for the least tern by providing a well-defined nesting site that is secure from casual disturbance, primarily by human recreational activity often accompanied by canine companions. The wisdom of this practice is illustrated at Alameda Point: No least terns have ever nested outside of their fence.
The two other determining factors in the breeding success of the terns are the presence of small fish in nearby waters, which can vary due to climate and current, and the presence of predators, which can vary by location. No scientific formula exists to prescribe how far away human activity must be for successful nesting of the terns.
This year, as of June 20, there were 500 nests at the Huntington Beach Preserve. Alameda Point had a count of 315. There are 27 sites in California that had 10 or more nesting pairs in 2014. Both Alameda Point and Huntington Beach typically rank in the top five. Huntington Beach least tern nesting news updates are posted on the Sea and Sage Audubon Society website. There are no published news updates or progress reports about Alameda Point least tern nesting activity.
The annual Alameda Point “Return of the Terns” tours happen every June.
Originally published in the Alameda Sun.
Huntington Beach photo gallery
Least Tern Preserve with lifeguard tower in the background on the beach.
Cyclists on Huntington Beach Bike Trail on Memorial Day weekend 2015.
Huntington Beach Bike Trail at the bridge over the Talbert Channel.
Least tern on nest. Vegetation is not part of the nest.
Recording observations about the number of nests, eggs, and chicks.
Recording data in the nesting area.
Least terns on the beach.
Least tern male with fish in mating posture. On the beach outside of nesting area.
Talbert Channel, with Least Tern Preserve in background.
Huntington Beach, with Least Tern Preserve in background.
Santa Ana River. Newport Beach on the left, Huntington Beach on the right.
Side channel in Santa Ana River where the terns bath and hang ot.
Parking lot next to Least Tern Preserve. Bike trail runs between parking lot and tern preserve. Main beach area is to the right.
Sign on fence at Huntington Beach Least Tern Natural Preserve urging people to stay 15 feet away.
The 9.7-acre nesting area for the endangered California least terns at Alameda Point received a new layer of sand this year. Sixty dump truck loads of sand were delivered to the site on the old Navy airfield in March, paid for by the U.S. Fish & Wildlife Service (USFWS).
After the sand was moved into place, USFWS and volunteers set up a numbered cinderblock grid system used for recording behavior and also distributed chick shelters and oyster shells for the chicks to use as protection from the elements and predators.
On Sunday, April 13 a dozen volunteers showed up for the last work party prior to nesting. The task of the day was distributing oyster shells around the site, which provide a nominal amount of sun protection for chicks and, in theory, helps make it more difficult for avian predators like red-tailed hawks and peregrine falcons to spot the chicks amongst all the white shells.
From now until the end of the nesting season in mid-August, volunteers will be participating in another program called the Tern Watch Program. Participants monitor behavior and watch for predators from their vehicles outside the nesting area.
Throughout the nesting season a USFWS biologist makes periodic walks through the site and places numbered plaster markers next to nests so that the number of eggs and success rates can be accurately recorded. If there are three eggs in a nest one week, for example, and one egg the next week with no chicks, it’s an indication that predators have grabbed the eggs.
Each year following the end of the nesting season in August, volunteers at monthly work parties gather up the oyster shells, the wooden A-frames, drain tiles, grid markers, and the hundreds of numbered markers used to identify nests. Clearing the site makes it easier to remove weeds and grade the sand, which can erode during rains. The volunteers pull weeds from inside and around the perimeter of the fenced-in site. The volunteer program during the non-nesting season is organized by the Golden Gate Audubon Society’s Friends of the Alameda Wildlife Reserve committee, in conjunction with the USFWS biologist in charge of the Alameda Point tern colony.
The effort to protect the least terns was begun by the Navy when nesting activities were first noticed in the 1980s. The likely reason for the terns choosing such an unlikely place to nest was the absence of people who might trample on the nests. The nesting site was chosen by the terns, not by the Navy or USFWS, and has been expanded to its current size as the colony expanded. The sandy substrate that approximates the traditional beach nesting habitat for terns is on top of old airfield pavement. Due to erosion caused by wind and rain, the sand has to be periodically replaced, as it was in 2009 and 2011.
Training sessions for this year’s Tern Watch Program will be held at the USFWS office at Alameda Point on April 26, April 30, May 28, and May 31. Volunteers do not have to be a bird expert, just be very interested in observing and reporting about them. Participants are required to attend one training session and commit to signing up for a minimum of three of the 3-hour shifts. Also required are binoculars, cell phone, and personal vehicle. Reservations for the training sessions can be made by calling Susan Euing at 510 521-9717 or by emailing firstname.lastname@example.org. Directions and registration materials will be sent by email.
The annual Return of the Terns bus tour to the nesting area will be held on June 14 this year. The tour departs from the Crab Cove Visitor Center in Alameda. Registration required through the East Bay Regional Park District’s website or at the visitor center.