It’s tern up time in California

Apr 7, 2021

Written By

white bird with black head markings sits on egg in sand — An adult California least tern sits on its nest.

California has once again welcomed tiny and graceful visitors to beaches, estuaries, river mouths and lagoons. The federally endangered California least tern (Sterna antillarum browni), the smallest of the tern species, returns to California — from the bay to the border — each year during the first or second week of April to feast, rest, and nest.

Least terns hover over the surf zone or shallow estuarine waters and can be seen plunging into the water from 10–30 feet to capture small, slender-bodied fish like anchovies and topsmelt. They target and capture the fish in the top few feet of the water column.

underside of white bird flying in sky with white fish in its mouth — A California least tern carries its catch.

For the first few weeks after their arrival, least terns prepare for nesting by spending time fishing, resting, and courting. A tasty topsmelt is the perfect gift!

one bird with fish in its mouth stands next to another bird lying in sand — A California least tern presents a fish to its mate.

Least terns nest directly on un-vegetated sandy areas of beaches, coastal strand and salt flats. Each pair creates a small depression in the sand and may even do some decorating using small shell fragments. One or two eggs are laid, and the pair spends about three weeks incubating the vulnerable egg(s) before hatch.

flying adult bird is landing on sand next to its chick — A least tern parent checks in on a chick.

Many California beaches have become too busy with human activity for least terns to nest, so the U.S. Fish and Wildlife Service and its partners collaborate to protect human-made nest sites, as well as discrete segments of natural beach habitat. These nest sites, which are in surprising locations, are part of the tern’s recovery plan to compensate for impacted habitat. For example, least terns now nest on several sites adjacent to airports, military training ranges, port terminals, and salt production facilities.

closeup of two white eggs on rocky sand with airplane and control tower in background — An airplane taxis by a least tern nest on a protected airport nest site.

Created sites and natural beach habitat have a few things in common: they are close to least tern food resources, they have little vegetation and human traffic, and they are flat and usually sandy. Protected areas are often marked with signage and fencing, and may require routine removal of weedy vegetation to maintain open, sandy conditions, and predator management to sustain successful nesting.

white sign in sand with green and red lettering and ropes on either side — A roped off area and sign mark protected natural beach habitat.

Ways to help conserve the California least tern include abiding by natural resource signage on beaches, keeping dogs on leash in coastal areas, keeping beaches clean of food and trash that can attract nest predators, and assisting with beach cleanups, pre-season habitat restoration events, and locally coordinated volunteer efforts to document nesting and predators.