Endangered Birds Flourish - Hayward Regional Shoreline


The East Bay Regional Park District is experiencing a baby boom in the California least tern colony at the Hayward Regional Shoreline, with about 180 of the endangered birds flying around the island known to volunteers and staff as Tern Town.

“Something amazing is happening – we added 40 new nests in just one week!” said David Riensche, a certified wildlife biologist with the East Bay Regional Park District. “We are seeing lots of courtship, mating, scraping of new nest cups in the sand, and the remodeling of previously used nests.”

Park District staff and volunteers to date have counted a record 150 California least tern nests and a total of 245 eggs. The highest previous season record was 80 nests. Of these nests a total of 50 have hatched, producing 75 chicks and about 20 fledglings so far.  The colony is more than 35 percent ahead of last year’s productivity rate.

The migratory California least terns come here during May to nest at the shoreline park. The eggs incubate for about 21 days, and the chicks start to fly 19-20 days later. Then they will live  about 22 years.

Located along the eastern shore of San Francisco Bay, the island was built in 2001 specifically to provide habitat for  California least terns, listed by the US Fish and Wildlife Service in 1973 as an endangered species. Hundreds of volunteers and dozens of stakeholder organizations and sponsors created an island for this delicate, disappearing native bird.

More than 3,500 people have volunteered over 15,000 hours to the project over the years, monitoring the population and managing the environment. Today Tern Town is the second-largest least tern colony north of San Luis Obispo.

In the last five years, invasive mayweed chamomile (Anthemis cotula) took over much of the island, making it less desirable habitat for the birds, which prefer only 10 to 20 percent vegetation for their nesting sites.  Again, with the assistance of partners and sponsors, the weeds have been reduced, and this is a significant factor in the current boom of nesting activity.

Another listed species, the western snowy plovers, have fledged their young in this improved habitat, said Riensche.

 “This is the fourth time that both these special status species have reproduced on the island. Currently we also have three other bird species nesting on the island.”  

Wildlife specialists from the Park District and other agencies are continuing their predator management activities, and the wildlife volunteer tern colony monitoring program is in full swing. The nests are in a protected area, restricted from visitors; an interpretive panel and views of the birds and fledglings is at the south end of Cogswell Marsh.

For information on how you can get involved, visit, or contact David “Doc Quack” Riensche at (510) 544-2319 or

Carolyn Jones
(510) 544-2217