Snowy Plover and Least Tern Ask a Scientist
In March 2020, we started a social media campaign called Ask A Scientist, where we covered a different topic each week and invited people to ask questions which we answered ever Friday. One of our topics was our Snowy Plover and Least Tern research and recovery work.
Since 2003, SFBBO has been monitoring these small ground-nesting shorebirds in the South Bay, where most Snowy Plovers in the San Francisco Bay are found. The Pacific Coast Population has been listed as a Federally Threatened “Distinct Population Segment” since 1993 due to habitat loss, human disturbance, and predation. The SF Bay population has averaged ~200 adults in recent years (almost 10% of the entire Pacific Coast Population). Fun fact: Snowy Plovers are polyandrous; males and females share incubation duties, yet males raise the chicks while the female starts a second nest with another male!
Snowy Plovers lay eggs directly on the ground in lined scrapes, so camouflage is important for nest success. Snowy Plovers select nest sites with oyster shells, which provide camouflage for adults, eggs, and chicks. Past SFBBO research has indicated that nest success may also improve when Snowy Plovers nest within Least Tern colonies, likely because Least Terns aggressively defend their colony from predators. SFBBO works closely with partners such as the US Fish & Wildlife Service to provide high quality habitat for both of these imperiled species!
If you want to help threatened Western Snowy Plovers, keep an eye out for our next Mud Stomp habitat enhancement event!
Thank you to our Snowy Plover program team for answering these questions.
The endangered California Least Tern ranges from the Bay Area to the tip of Baja California. Historically, there were no breeding Least Terns in the San Francisco Bay except Monterey, but the creation of salt ponds provided suitable breeding habitat for them. We monitor a colony in Eden Landing - one of only 5 colonies in Northern California!
In March 2020, volunteers helped us place tern decoys at Eden Landing. The goal is to attract more endangered California Least Terns and encourage them to nest and form colonies at the site. This technique is called social attraction.