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Helping the California Least Tern

Updated on February 20, 2016

Endangered subspecies gets help from humans

I live in San Diego which is in the breeding range of the California least terns, the smallest of all the terns. Least terns, overall, are not endangered, but the California and interior subspecies are endangered. The reason why they're endangered is because of habitat loss due to development and destruction. In San Diego, they like to breed on Mission Bay, once a natural, marshy bay that was dredged and reshaped for human recreation. While there were still places for the terns to nest on the bay, the dredging process caused the soil composition to change allowing for invasive plants to grow and obliterate the areas where the terns liked to nest. Other places where they nest are Ocean Beach, Tijuana Slough, and the San Diego Airport.

Volunteers with the San Diego Audubon Society as well as other environmental groups help clear and prepare nesting sites just prior to the terns arrival from Mexico and places south to nest. They pull weeds and repair chick fencing that helps keep the chicks from wandering off the site into rocks and prevents snakes and other small animals from entering the nesting area. Later, biologists band and measure the chicks to keep track of their health and provide more information on how to further protect this species from going extinct.

**If you come across a special nesting area that is fenced off from the rest of the beach or bay, please respect the signs and stay out. Also, please don't let your dog roam around these areas or bark at the birds. Not only is it just not cool, you can get fined pretty good. Just as you enjoy being at the beach with your dog, there are people who enjoy being at the beach with the birds.

Photo Credit: USFWS Pacific Southwest Region, Rinus Baak.

California Least Tern
California Least Tern

About the California least tern

California least terns are about the same size as a killdeer or small dove. They make a short "pip pip" sound as they fly around, unlike the other terns in the area who normally make a screeching sound (though they will screech when they are protecting their chicks). They begin arriving in late April and usually stay until September or sometimes early October. Soon after they arrive, they begin courtship and nesting. They are mostly loose colonial nesters though they can also breed alone.

Least terns like to eat small fish such as anchovies and smelts. But, they will sometimes pick up a small crustacean or two. They like to roost out in the open. Their nests are also out in the open, though small "hiding places" are provided by humans on some nest sites for chicks to hide under. The nests usually have two to three eggs, though some nests might have only one egg and others will have four. The chicks are mostly precocial, or covered with down and can walk a little. However, unlike other precocial chicks, they do not wander around much or leave the nesting area. The chicks are usually heavily brooded for a few days and then brooded less until they're four weeks old when they begin flying.

The primary predator of least tern chicks are gulls, other terns, burrowing owls, hawks and falcons. Gull-billed terns are a big problem for San Diego's least tern chicks, though they're not as common here as they are back east. Wandering cats, coyotes, foxes, skunks and opossums are also a threat to eggs and chicks. Falcons and hawks are a big danger for adults and will often catch them in the air.

Photo provided by Robert McMorran/USFWS Pacific Southwest Region

Biologists record measurements and band chicks

Here, a biologist is measuring the little wing of this California least tern chick. The main biologist for the least terns in San Diego is currently Robert Patton, but I don't know if this is him in the photo.

Photo is provided by: R. Baak/USFWS Southwest Pacific Region

Loveable least tern

A biologist measures and (tries to) weigh a least tern chick at Lindbergh Field in San Diego. Here, he is showing others how he does his job. Later, the banded chick is released back to his nest.

Laverne, the Runway Stowaway

This following video a short news clip about a fictional children's book written by an airport employee about a least tern living there and her misadventures. The book is available from, local libraries and sometimes the San Diego International Airport's webpage.

Laverne, the Runaway Stowaway
Laverne, the Runaway Stowaway

Sorry, there's no preview available. But, here's the Amazon link to the copy of Laverne, the Runway Stowaway. You can find a copy of the book for less than a dollar, but recommend checking out all sellers before doing so.


Books on volunteering and terns

Here are some books on nature volunteering (stewardship) and some on terns. Some of these items are geared towards young people. I also have a link to Amazon's copy (mostly used) of Laverne, the Runway Stowaway listed here.

Stokes Beginner's Guide to Shorebirds
Stokes Beginner's Guide to Shorebirds

Pocket sized guide to the most common shorebird species. It's easy to carry and has clear photos of the most common shorebirds in North America.

Volunteer helping the least tern on Fiesta Island
Volunteer helping the least tern on Fiesta Island

Volunteering to help the terns

Each spring, volunteers from the San Diego Audubon Society and other environmental activist organizations go out and help pull invasive plants and repair chick fencing in the areas where the least tern normally nest around Mission Bay. Least terns like to nest on bare ground and many of these invasive plants completely obliterate the nesting sites. Also, chick fencing is checked and repaired to prevent chicks from wandering into areas of heavy brush or falling down between rocks where they are likely not to be rescued and may get injured or starve to death. The fencing also helps prevent snakes and rodents from getting into the nesting site. Pieces of terracotta roof tiles are placed around the area to provide chicks with shelter from the winds and sun and for protection from predators.

Later, biologists mark each nest and monitor the areas which are fenced off from the public.

Photo credit: Photo taken by me.

Do you volunteer to help your local wildlife? What do you do and what species do you help?

Do you volunteer to help wildlife?

See results

Over 100 nests were built at one of the places San Diego volunteers helped at in 2013. In 2014, at least 60 chicks fledged.

I help the least tern

Here I am in January at Fiesta Island pulling cockle-burrs out from a potential least tern nesting site. I'm usually a lot more fixed up than I am in this photo, except when I'm doing stuff like this or exercising.

Decoys waiting to be placed

Least Tern Decoys
Least Tern Decoys

Least terns are colonial nesters and seem to respond to decoys placed in suitable nesting areas. Here, we had to divide them up into groups of 20 so that they could easily be divided up between the different nest sites. My piles are the messy ones all jumbled together.

Photo taken by me.

Decoys placed on nest site

Least tern decoy pair
Least tern decoy pair

And, here's what it looks like when they're placed on the ground. Sometimes they're placed together like they're a pair, sometimes they're singly placed. We had to make sure they faced into the wind because that's the way they usually face when they're on the nest.

Photo taken by me.

Upcoming least tern volunteer days for 2015-2016 San Diego Area

Help the least tern in the San Diego and southern California areas during one of the following events. All events take place from 9:30 a.m. to 12:30 p.m. Volunteers are asked to RSVP to or call 858-273-7800 X101

Most of the events take place around Mission Bay. Activities include pulling invasive plants, fixing chick fencing, or surveys. Tools and gloves provided. Volunteers must wear closed-toe shoes, long pants, and should wear sun protection.

The 2015-2016 volunteer season is nearly over!

There are still a few projects available not just for the terns, but for other shorebird projects including a large Mission Bay restoration program. Call the San Diego Audubon for more details on dates and time.

Other birds take advantage of the least tern nesting area

Killdeer on nest
Killdeer on nest

Other birds, like this killdeer, take advantage of the cleared and fenced area to raise their chicks. They often start nesting a month or two before the terns arrive. The only issue is that their chicks move around and may find it harder to leave the area because of the chick fencing. However, it seems that they have found their way around the fencing as there has never been a sign of any killdeer chicks starving or dying in the least tern nesting area.

Photo credit: Photo taken by me.

The end result!

Of course, all of this is for the benefit of the California least tern chicks and promoting their survival.

Photo by R. Baak, USFWS headquarters

Least tern chick

Least tern chick
Least tern chick | Source

California least tern links

Here are some helpful links to information about the California least tern

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    • TonyR2012 profile image

      TonyR2012 4 years ago

      Glad to hear that efforts are being taken in order to preserve a such a beautiful animal.

    • Shorebirdie profile image

      Shorebirdie 5 years ago from San Diego, CA

      @flycatcherrr: They have a unique wing shape and beat. Once, I spotted a least term where it wasn't supposed to be. I proved my sighting by taking a photo of it, but it was blurry. However, they were able to confirm it because of the way the wings were in flight.

    • flycatcherrr profile image

      flycatcherrr 5 years ago

      The shape of the wings in flight is so elegant! Good to hear about the habitat protection work going on.