The California Least Tern is an endangered migratory shorebird that nests on our beaches within a limited range from northern Baja California to San Francisco Bay. The Least Tern needs cleared, sandy areas for nesting and depends on estuaries, lagoons, and other open water areas for hunting small fish. Terns nest in colonies which helps them work together to defend nests and chicks from predators such as American Crows, Gulls, cats, and snakes. San Diego County supports 60% of the breeding population of this bird at 12 sites including the Tijuana Estuary, the Sweetwater Marsh National Wildlife Refuge, Mission Bay, and our coastal lagoons.
Fun Fact: Least Terns defend their nesting colony against a predator by flying up, calling loudly, and pooping on their target!
How we're helping
SDAS is working in Mission Bay and San Diego Bay to restore Least Tern nesting habitat. We currently have active projects at the D-Street Fill in the Sweetwater Marsh National Wildlife Refuge and at Mariner’s Point in Mission Bay. This year, we plan to focus our conservation efforts on additional nesting sites in Mission Bay through habitat restoration and citizen science projects.
The Western Snowy Plover is a threatened shorebird that is found on flat, open coastal beaches, in dunes, and near stream mouths. Similar to the Least Tern, the Snowy Plover nests in a shallow scrape in sand, usually lined with small pebbles and shells. Snowy Plovers are year round residents of San Diego County and nest along our coastline with breeding concentrations in Camp Pendleton and the Silver Strand. The plovers nest in loose colonies from early spring to mid-fall. Incubation duties are shared by both parents – the male keeps the eggs warm at night, while the female is responsible for day duty. Similar to other nesting shorebirds such as the Least Tern, Snowy Plovers are threatened due to human disturbance, predation, and habitat loss.
Fun Fact: Snowy Plover chicks are precocial, meaning they are able to walk just hours after birth!
How we’re helping:
SDAS has collaborated with California State Parks to carry out a children’s signage and education program called Share the Shore. This program engaged local schoolchildren in the creation of educational signage while teaching them about the plover. Signage is currently displayed at Silver Strand State Beach and the Tijuana Slough and has proved to be quite effective in deterring human disturbances near nesting areas.
The Coastal Cactus Wren is a resident, non-migratory subspecies of Cactus Wren that is listed as a Species of Special Concern. Habitat loss, degradation, and fragmentation are the most critical management issues facing this species, which have been more recently exacerbated by the 2007 wildfires which burned much of the cactus scrub that they depend on. The wrens nest in stands of prickly pear or cholla cactus throughout coastal San Diego County, with concentrations in southern Camp Pendleton/Fallbrook Naval Weapons Station, Lake Hodges/San Pasqual, Lake Jennings, and Sweetwater/Otay.
Fun Fact: Coastal Cactus Wrens are home bodies, maintaining their nests in stands of prickly pear or cholla cactus year-round.
How we’re helping:
SDAS is coordinating volunteers to assist with cactus wren habitat assessments in the San Dieguito River Valley and other locations throughout the County. These assessments will support the prioritization of cactus scrub restoration and a USGS study that will examine dispersal of cactus wrens.
The Light-footed Clapper Rail is a year round resident of San Diego County’s coastal salt marshes. As a result of the loss of over 90% of southern California’s coastal wetlands, this species has been listed as federally-endangered for over 40 years. Clapper Rails prefer to nest in tidal marshes dominated by cordgrass. There are an estimated 100 pairs in San Diego County with breeding populations scattered throughout coastal lagoons and estuaries. The Tijuana River estuary is an especially critical site, supporting a record 80 pairs in 1999.
Fun Fact: The Clapper Rail’s nest is constructed from hollow cordgrass stems which are weaved around upright cordgrass stems – this allows the nest to float, while secured in place, with the changing tides.
How we’re helping:
SDAS has collaborated with the UC Natural Reserve System and the Ocean Discovery Institute to carry out an invasive mangrove removal project at the Northern Wildlife Preserve in Mission Bay. This invasive plant posed a threat to the Clapper Rail by displacing native cordgrass and negatively impacting the quality of the salt marsh habitat. SDAS has also partnered with the Tijuana National Estuarine Research Reserve, California State Parks, and the US Fish & Wildlife Service to carry out a vegetation monitoring program that established baseline data to evaluate changes in habitat, including salt marsh, to inform future management actions.