Waiting for your Tern

November 14, 2019

Collaboratively written by Meredith Elliott, Dan Robinette, Emily Rice, and Lishka Arata

Point Blue Biologist Emily Rice waited as she watched hours of video footage and she finally found: a hatching California least tern! See if you can identify the minute when 2 eggs become 1 egg and one chick in the video below.

It is a challenging and multi-faceted job to figure out how to help an endangered species, but one that Point Blue scientists are well versed in. It requires partnership, rigorous science paired with creative outreach, and innovation to try new approaches.

The California least tern, Sternula antillarum browni, a subspecies of the least tern, is a federally and state listed endangered bird species. It is a small diving seabird that makes a very simple open nest and raises young right on the ground along a very limited range of beaches and bay shores along Southern and Central California, in San Francisco Bay, and in northern regions of Mexico. It’s endangered because it has lost much of its open breeding habitat to coastal development throughout the 20th century. Climate change will likely affect this species through sea level rise by further reducing their available habitat and rising ocean temperatures which may affect the abundance and distribution of the fish they eat.

Since 2000, Point Blue, in partnership with the US Fish and Wildlife Service, US Navy, and Veteran’s Administration, has assisted in monitoring the nesting colony of this sensitive subspecies at VA Alameda Point, a former Naval Air Station in the city of Alameda, California. California least terns have been nesting there since the mid-1970s when it was still an active naval air station. We document how many breeding adults are present, how many eggs are laid, and how many young are produced each year. This gives us a gauge of how well the population is doing and if it’s on the road to recovery.  Our monitoring and analysis has shown that the Alameda site is the most successful colony in San Francisco Bay, and it’s one of the more productive colonies in the state, making it a key location to protect to help the species get back to viable numbers. Point Blue has also been monitoring the colony at Vandenberg Air Force Base, just west of Lompoc, California, since 2001. Though reproductive success at Vandenberg has been more variable when compared to Alameda, the colony is doing well with reproductive success being above the statewide average in most years. Additionally, Point Blue has examined the diets of least terns at Alameda and Vandenberg by analyzing feces and regurgitated pellets (which contain the indigestible fish parts that terns puke up) collected at these colonies to determine what the least terns are eating and how it has changed through time. In order to get a better idea of what factors are driving the ups and downs of the California least tern throughout its range, we have expanded our study to 11 more colonies throughout the state in partnership with the California Department of Fish and Wildlife and the U.S. Fish and Wildlife Service. 

In 2015, we added a camera monitoring component to our diet studies, and we captured some exciting footage of chicks hatching and parents feeding young chicks. This camera footage will help us understand how the local availability of prey affects nest attendance, chick feeding rates, and overall breeding success. See these hatched chicks being fed by their parents in the video below.

So far, this research has shown that low abundances of local prey are likely causing chronic low breeding success at Southern California colonies compared to colonies in Central California and San Francisco Bay. Our continued diet and camera monitoring helps our partners at the US Fish and Wildlife Service and the California Department of Fish and Wildlife better understand the impacts of local prey availability throughout the California least tern’s breeding range so that they can prioritize their management actions and work with other agencies to protect local fish stocks.

There is a lot that we’re doing and will continue to do on the science side of things with our partners, but we also need your help. Some things you can do to help threatened and endangered beach birds like the California least tern are: 

• Respect and do not enter areas closed for breeding least terns
• Give least terns space and observe them from a distance with binoculars
• Never handle eggs or chicks if encountered on the beach
• Obey regulations regarding dogs and always keep your dog on a leash at the beach
• Support Point Blue and partner organizations in studies to improve the conservation of sandy beach and nearshore marine ecosystems

For questions or to learn more about this work, feel free to reach out to us at sciencenews@pointblue.org.