Article By: Jei Florentino & Ross Griswold
Photos By: Ross Griswold
Among the hundreds of bird species that call Bolsa Chica home are the endangered California Least Tern (Sternula antillarum browni) and threatened Western Snowy Plover (Charadrius alexandrinus nivosus). In collaboration with the California Department of Fish and Wildlife the Bolsa Chica Conservancy launched the Eyes On Nest Site (EONS) program in 2010 to monitor the nesting success of these species as well as engage the public to learn more about nesting birds on the Bolsa Chica.
California Least Terns live along the Pacific coast and like to nest on open beaches. These terns can be found at Bolsa Chica during their mating season which usually begins in late April or May. The males perform aerial displays and then offer the females a fish. Shortly after, they begin to make a nest which is a simple scrape in the sand. Both parents help incubate and care for their young. For defense, this species will mob and defecate on potential predators.
Although they may be hard to find, Western Snowy Plovers can be found at Bolsa Chica year round and also like to nest on open sand and beaches. During their breeding season which starts around March, males make scrapes in the ground that the females lay eggs in. Both parents help incubate the eggs; females incubate during the day while males incubate at night. Western Snowy Plover chicks are precocial (hatch with eyes open, a covering of down fur, and have the ability to search for food) and leave the nest within 24 hours of hatching. For defense, this species prefers to run rather than fly and will sometimes fake a broken wing to lead predators away from its chicks.
The 2016 EONS monitoring season has been a recent success due to increased volunteer participation, nest site restoration, and a variety of new strategies. One of these strategies included the use of California Least Tern and Western Snowy Plover decoys to attract these species to our nesting site located at the end of the south parking lot’s walkbridge. The California Department of Fish and Wildlife even installed cameras to further monitor our species of concern. In recent years the monitoring season has ended in mid-June, however this year the monitoring season ended in early July! This season has also experienced a significant increase in nesting activity. In 2015, there were only 2 confirmed California Least Tern nests while currently we have 9 volunteer-confirmed California Least Tern nests.
EONS volunteers are trained to record the behavior of our two species of concern and are taught a variety of skills including how to use a scope and binoculars. Our volunteers have been trained to spot not only California Least Terns and Western Snowy Plovers but they are also able to identify a variety of other bird species whether they are friend or foe. Although the 2016 monitoring season has come to an end, volunteers interested in the EONS program can look forward to EONS 2017 which will occur sometime in February 2017 – August 2017.