Dropped Prey of the Endangered California Least Tern

Explore the foraging habits of the California least tern in San Francisco Bay! This endangered seabird nests in Alameda during the summer, plucking fish from the upper waters of the Bay and bringing them back for their chicks to eat. Sometimes the terns drop the fish on the ground. Why would they do that? It could be the fish is too large for a chick to eat, the chicks aren’t hungry, or the parent drops it by accident. In any case, it will not be eaten, and this presents an opportunity for scientists in the marine lab at Point Blue Conservation Science to learn about the prey available to the least tern. 

In studying what the least terns actually eat (through analyzing feces and regurgitated pellets) and what they drop on the ground, we have learned that the species dropped are similar to those that are consumed. Jacksmelt, topsmelt, and northern anchovy are some of the least tern’s favorite fish, but other species, such as Pacific herring and shiner surfperch, also appear in dropped prey collections. Learn how we identify these fish, and what implications different prey have on the recovery of this endangered seabird.