Sacramento Fish & Wildlife OfficeServing the people, conserving the fish, wildlife, and plants of California
Kids' Species Information
California Least Tern
Listed as endangered. "Endangered" means that a species is in danger of dying out.
We now think the tern should be listed as "threatened." That would mean we are concerned about it but we don't think it is about to go extinct. We have to go through a legal process (44 KB PDF) to make the change. This is to let people give us reasons why they agree or disagree.
The species' population has increased from 600 in 1973 to roughly 7100 pairs in 2005. The number of California least tern sites has nearly doubled since the time of listing.
The CA Least Tern has a distinctive black cap. It has black stripes running from the cap across the eyes to the beak. These contrast with a white forehead. Other upper parts are gray. Underparts are white.
CA Least Terns have short, forked tails. Their bills and legs are orange. When a CA Least Tern is flying, you can see a black wedge on the end of its wings.
As its name implies, the least tern is the smallest of North American terns. It is 21-23 cm (around 8¼ to 9 inches) long. Its wingspan is 48-53 cm (around 19 to 21 inches).
Mostly small fishes. Learn more.
CA Least Terns live along the coast. They nest on open beaches kept free of vegetation by the tide. The typical colony size is 25 pair.
Other least terns live inland. The interior least terns (131 KB PDF) are also endangered.
Most least terns begin breeding in their third year. Mating begins in April or May.
Males perform elaborate aerial displays. After that, they offer fishes to the female. This is called the fish flight display. Nesting starts shortly after it.
The nest is a simple scrape in the sand or shell fragments. Typically there are 2 eggs. Both parents incubate and care for the young. They can renest up to two times if eggs or chicks are lost early in the breeding season.
Larger birds. Mammals such as raccoons and foxes. Domestic dogs and cats.
The Pacific Coast from San Francisco to Baja California. CA Least Terns winter in Mexico. When feeding, they follow schools of fish and are sometimes seen as far north as southern Oregon.
Dredging, habitat loss, nesting disturbance, pollution, predation by domestic and wild animals.
At this point, we don't know whether the West Nile virus will hurt the CA Least Tern. See the University of California Davis web page Potential Effects of West Nile Virus on California Wildlife. (5.6 MB PDF)
WHAT YOU CAN DO TO HELP BIRDS
There are many things you can do to protect birds. Here is some information on migratory bird conservation. It is about migratory song birds. But much of it applies to all birds.
Keep your cat inside. Cats kill millions of birds per year. Even well-fed cats kill birds. It is just their nature to hunt. Living indoors is also much safer for the cats themselves.
When you go to the beach, pay attention to signs warning you that birds are nesting. Many shore birds nest right on the beach. They are easily disturbed. Don't let your dog chase or bark at them.
Whenever you go to natural areas, observe any signs telling you how to protect wildlife and plants.
See What You Can Do to Help Wildlife and Plants (201 KB PDF) for more ideas.
You may be able to see a CA Least Tern if you go to the coast. Wherever you live, you can watch birds. See the American Birding Association's Young Birders' Home Page
The California least tern can be seen at several National Wildlife Refuges
- Don Edwards San Francisco Bay NWR
- Guadalupe-Nipomo Dunes NWR in San Luis Obispo County
- The Seal Beach, Sweetwater Marsh and Tijuana Slough units of the San Diego Bay NWR Complex
National Zoo Birds for Kids. Fact sheets and more.
Photo Credit: U.S. Fish & Wildlife Service
Words to Learn
Scientists who study birds are called ornithologists.
Ornithologists call least terns Sternula antillarum. Scientific names are in Latin or Greek.
The CA Least Tern is a subspecies. So ornithologists add browni. This makes the full name Sternula antillarum browni.
Terns are in the Laridae family.
The colors and patterns of a bird's feathers are called plumage.
The common names of bird species are capitalized. So we write California Least Tern. But if you are writing about terns in general, you should use lower case. Learn more from this Wikipedia article.
See a basic bird diagram. (483 KB PDF)
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Amphibians & Reptiles
- Alameda Whipsnake
- California Tiger Salamander
- Giant Garter Snake
- California red-legged frog
- San Francisco
- California Brown Pelican
- California Clapper Rail
- California Condor
- California Least Tern
- Least Bell's Vireo
- Bay Checkerspot Butterfly
- California Freshwater Shrimp
- Mission Blue Butterfly
- Valley Elderberry
- Vernal Pool Fairy Shrimp
8th Graders and older
- See also our regular species accounts.
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Last updated: November 29, 2017