Goal: Protect, enhance, and restore California least tern occupied and historically occupied habitat to create resilient, self-sustaining populations that provide for persistence over the long-term (>100 years).
Management units: 1, 7
From 2017-2021, annually conduct predator control at breeding least tern colonies before and during the nesting season to improve fledgling success. Include tracking of predator-tern interactions to provide real-time data to improve control efforts during the breeding season.
|IMP-1||Conduct predator control prior to breeding and during the breeding season to control the various taxa (e.g. mammals, reptiles, birds, inverebrates) that prey on adult, nestling, and fledgling least terns.||in progress|
|IMP-2||Submit data and reports to MSP web portal.||in progress|
|Predator Control Implemented and Reports Completed Annually||2021|
Management units: 1, 7
From 2017-2021, monitor the effectiveness of predator control at least tern colonies and monitor overall tern predator status and trend to identify larger issues potentially affecting other MSP species and to improve management effectiveness.
|IMP-1||Submit monitoring data and reports to MSP web portal||available for implementation|
|Monitoring completed and data and report submitted within 1 year of management actions being completed.||2021|
Management units: 1, 7
From 2017 to 2021, continue the existing survey efforts for California least tern implemented by the wildlife agencies and military.
|SURV-1||Submit monitoring data and management recommendations to MSP web portal||In progress|
|Least Tern Surveys and Reports Completed Annually||2021|
Management units: 1, 7
From 2017 to 2021, annually inspect the existing nest sites for California least tern, taking precautions to avoid disturbance during the nesting season, to identify necessary management actions in order to support the expansion of the occurrence to self sustaining levels.
|IMP-1||Conduct regional IMG monitoring protocol survey locations and habitat, assess status, and quantify potential threats.||Available for implementation|
|IMP-2||Based upon threat evaluation, determine if routine management or more intensive management is warranted.||Available for implementation|
|IMP-3||Submit monitoring data and management recommendations to MSP web portal||Available for implementation|
|Surveys Completed Annually with management recommendations||2021|
Management units: 1, 7
From 2017-2021, perform routine management activities such as invasives removal, sand replenishment, nest prep, and protecting occurrences from disturbance through fencing, signage, and enforcement.
|IMP-1||Perform management activities protecting occurrences from disturbance through fencing, signage, and enforcement.||Available for implementation||Adaptive Management of Coastal Sand Dunes in Mission Bay to Benefit Native Plants and the CA Least Tern|
|IMP-2||Submit project metadata and management data to MSP web portal.||Available for implementation||Adaptive Management of Coastal Sand Dunes in Mission Bay to Benefit Native Plants and the CA Least Tern|
|Management Completed as Needed Based Upon Monitoring Recommendations||2021|
Adaptive Management of Coastal Sand Dunes in Mission Bay to Benefit Native Plants and the CA Least Tern
San Diego Audubon has been leading efforts to restore coastal sand dunes in Mission Bay for decades, largely focused on supporting nesting California Least Terns (Sternula antillarum browni), and rare and endangered sand dune plants such as Nuttall's Lotus (Acmispon prostratus) and Coast Wooly Head (Nemacaulis denudata). The primary threat to these species is the presence of fast-growing, nonnative vegetation, which takes up space that Least Terns require for nesting, and outcompetes native dune plants. Volunteer-led hand management of these sites has resulted in a dramatic reduction in invasive cover, and bi-annual vegetation monitoring has revealed that hand management is a more effective strategy in reducing nonnative growth than the more traditional mechanized scraping and broadcast herbicide application strategies. These results are being used to inform year-to-year site management, and to create longterm strategies for managing coastal dunes in Mission Bay.
California Least Tern Predator Monitoring (Ternwatchers)
Volunteer-based predator monitoring program at the nesting sites in Mission Bay. Citizen scientists are trained to monitor nesting sites for predators from mid-April through late May, with the program concluding the end of September.
North County Dunes Restoration
Phase I of this project focused on surveys and restoration activities at potential dune habitat between northern Carlsbad and northern La Jolla. This was in order to extend the range and increase the population of dune-dependent species, such as the California least tern, Western snowy plover, and Nuttall's lotus. Phase 2 will focus on the completion and implementation of the following site-specific restoration plan that was developed during the first phase of the project: the Cardiff State Beach Living Shorelines Draft Habitat Restoration Plan. In addition, SELC proposes to conduct invasive species management and support existing populations of special-status/native coastal dune and bluff plant species at South Carlsbad State Beach Campground.
|File name||Lead Author||Year||Type|
|CALIFORNIA LEAST TERN BREEDING SURVEY 1993 Season||Caffrey, Carolee||1994||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 1994 SEASON||Caffrey, Carolee||1995||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 1995 Season||Caffrey, Carolee||1997||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 1996 Season||Caffrey, Carolee||1998||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 1997 Season||Keane, Kathy||1998||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 1998 Season||Keane, Kathy||1999||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 1999 Season||Keane, Kathy||2001||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 2000 SEASON||Patton, Robert T.||2001||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 2004 Season||Marschalek, Dan||2005||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 2005 Season||Marschalek, Dan||2006||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 2006 Season||Marschalek, Dan||2007||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 2007 Season||Marschalek, Dan||2008||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 2008 Season||Marschalek, Dan||2009||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 2009 Season||Marschalek, Dan||2010||report|
|California Least Tern Breeding Survey 2010 Season||Marschalek, Dan||2011||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 2011 Season||Marschalek, Dan||2012||report|
|CALIFORNIA LEAST TERN BREEDING SURVEY 2012 Season||Frost, Nancy||2013||report|
|California least Tern Breeding Survey 2014 Season||Frost, Nancy||2015||report|
|California Least Tern Breeding Survey 2015 Season||Frost, Nancy||2016||report|
|California Least Tern Breeding Survey 2016 Survey||Frost, Nancy||2017||report|
|California Least Tern Breeding Survey 2017 Season||Sin, Hans||2021||report|
|City of Carlsbad Habitat Management Plan Annual Report and Monitoring Summary Year 7, Nov. 2010 - October 2011||2012||report|
|Final Mission Bay Park Natural Resource Management Plan||1990||report|
|Final Report for Grant Agreement #5001768 – North County Dunes Restoration (Coastal Species)||Gibson, Doug||2016||report|
|Final Report Mission Bay Park||Redfern, Chris||2015||report|
|Final Report: SD Bay National Wildlife Refuge: California Least Tern and Western Snowy /plover Recovery at D Street Nesting Site||2015||report|
|Final Report: Threatened and Endangered Species Stewardship at D Street Fill||Kramp, Heather; Maher, Eileen||2020||report|
|Maps of treatment and monitoring sites for California least tern on Mission Bay||2012||other|
|Mission Bay IBA Conservation Planning Quarterly Report||2012||report|
|Mission Bay IBA Conservation Planning Workshop Summary||2012||workshop summary|
|Mission Bay Park Conservation Program: Habitat Assessment, Invasive Control, and Community-Based Habitat Restoration||Redfern, Chris||2013||powerpoint presentation|
|Nuttall's Lotus: Final Report||Redfern, Chris; Flaherty, Megan||2018||report|
|Recording - September 2020 SDMMP Management and Monitoring Coordination Meeting||Sin, Hans; Merlos, KariLyn||2020||recording|
|Revised California Least Tern Recovery Plan||1985||other|
|Saltwork Nest History||2008||other|
|San Diego Association of Governments CA least tern predator monitoring by SDAS Final Report||2017||report|
|San Diego Audubon Society Research Study: Project proposal and methods||2012||report|
|STATUS OF THE ENDANGERED CALIFORNIA LEAST TERN: POPULATION TRENDS AND INDICATORS FOR THE FUTURE||Keane, Kathy; Langdon, Spencer; Mudry, Nathan||2010||fact sheet|
|Ternwatchers, San Diego Audubon||2016||powerpoint presentation|
|Updates on California Least Tern Management at SDIA||Merlos, KariLyn||2020||powerpoint presentation|
|Venice Beach Least Tern Colony Habitat Improvement and Restoration Study, 2006-2009||Ryan, Thomas; Vigallon, Stacey; Dunno, Glenn; Magier, Shelly; Delnevo, Adrian||2010||report|
Found along the Pacific Coast of California, from San Francisco southward to Baja California, and in Chiapas, and Jalisco during the breeding season [1;2]. Wintering likely from Baja California to southern Mexico or along the Pacific coast of Central America and north to at least Colima, Mexico [3 cited from 2].
Occurrences found in Camp Pendleton, Borderfield State Park, San Diego Bay National Wildlife Refuge, Fiesta Island, Flood Control Channel Southern Wildlife Preserve, Mariner's Point, Mission Bay Park, Silver Strand State Beach, Agua Hedionda Lagoon Ecological Reserve, San Luis Rey River Park, Tijuana Slough National Wildlife Refuge, Torrey Pines State Natural Reserve, Batiquitos Lagoon Ecological Reserve, Buena Vista Lagoon Ecological Reserve, Agua Hedionda-SDGE, San Elijo Lagoon Ecological Reserve, Cardiff State Beach, James Scripps Bluffs Preserve, and San Dieguito Lagoon.
Nest in colonies on relatively open, flat beaches kept free of vegetation by natural scouring from tidal action and along lagoon or estuary margins [1;3 cited from 2]. Forages along seacoasts, beaches, bays, estuaries, lagoons, lakes, and rivers [5 cited from 2]. Rests and loafs on sandy beaches, mudflats, and salt-pond dikes [6 cited from 2].
A subspecies of least terns where two other subspecies, Interior (S. a. athalassos) and Eastern (S. a. antillarum), are recognized in the United States [7 cited from 4]; however, there is little genetic variation among the subspecies which questions the validity of this division [8 cited from 4]. A taxonomic change by the American Ornithologists' Union (AOU) [9 cited from 4] resurrected the genus Sternula for the least tern based on genetic studies.
Fall migration commences the last week of July and first week of August. Several weeks before the Fall Migration, adults and young wander along marine coastlines, congregating at prime fishing sites. In the autumn, adults move south along the california coast with their fledglings stopping to rest and feed along the migration route [2;10 cited from 1].
Arrive at California nesting sites in late April, where courtship and pair formation activities last into early May [10 cited from 11]. Typical colony size is 25 pairs . Egg-laying and incubation generally begins in mid-May, and pairs may renest following loss of their first clutch . Nests are simple scrapes made on non-vegetated substrates, usually consisting of one to three eggs, and are incubated for 19-25 days by both parents [1;10 cited from 11;13 cited from 4]. Chicks are mobile and leave the nest at only two days after hatching, the semi-precocial young are tended by both parents, and first flight happens at approximately 20 days after hatching [10 cited from 11;13 cited from 4]. Usually start breeding in their third year, but it is not uncommon to start in their second year. Can re-nest up to two times if eggs or chicks are lost early in the breeding season [1;12]. Usually nests in same area in successsive years; tends to return to natal site to nest . Very gregarious and forage, roost, nest and migrate in colonies . A long-lived species and banded birds have been recovered after 24 years .
Prey species captured and consumed are remarkably similar across a broad geographic range including the San Fransisco Bay, southern California, and the Gulf of California off Baja Mexico [11;15;16]. Most abundant prey species selected in California are northern anchovies (Engraulis mordax), topsmelt (Atherinops affinis), jacksmelt (Atherinopsis californiensis), deepbody anchovies (Anchoa compressa), and slough anchovies (Anchoa delicatissima). For coastal birds, preference for nearshore foraging habitats is apparently related to prey species selection as northern anchovies, topsmelt, and jacksmelt (all marine species) comprise 92% of captured fish .
Threats to tern colonies include predation, human disturbance, and nonnative plants. Other threats to terns are food shortage and environmental contamination .
 U.S. Fish and Wildlife Service. 2006. California Least Tern (Sternula antillarum browni) 5-Year Review Summary and Evaluation. Carlsbad Fish and Wildlife Office, Carlsbad, California, USA.
 NatureServe. 2015. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available from ttp://explorer.natureserve.org. Accessed: September 28, 2016.
 Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1992. Birds in Jeopardy: the Imperiled and Extinct Birds of the United States and Canada, Including Hawaii and Puerto Rico. Stanford University Press, Stanford, California. 259 pp.
 California Department of Fish and Wildlife. 2016. California Least Tern Breeding Survey 2015 Season. South Coast Region, San Diego, California, USA.
 American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.
 Stiles, F. G. and A. F. Skutch. 1989. Guide to the birds of Costa Rica. Comistock.
 American Ornithologists’ Union (AOU). 1957. Check-list of North American Birds, 5th Ed. American Ornithologists’ Union, Ithaca.
 Whittier, J. B., D. M. Leslie Jr., and R. A. Van Den Bussche. 2006. Genetic variation among subspecies of Least Tern (Sterna antillarum): implications for conservation. Waterbirds 29, no. 2: 176-184.
 Banks, R. C., C. Cicero, J. L. Dunn, A. W. Kratter, P. C. Rasmussen, J. V. Remsen Jr, J. D. Rising, and D. F. Stotz. 2006. Forty-Seventh Supplement To The American Ornithologists' Union Check-List Of North American Birds. The Auk 123, no. 3: 926-936.
 Thompson, B. C., J. A. Jackson, J. Burger, L. A. Hill, E. M. Kirsch and J. A. Atwood. 1997. Least Tern (Sterna antillarum). In Birds of North America, No. 290 (A. Poole and F. Gill, Eds.). The Academy of Natural Sci- ences, Philadelphia, PA, and The American Ornithologists' Union, Washington, DC.
 Elliott, M. L., R. Hurt, and W. J. Sydeman. 2007. Breeding biology and status of the California least tern Sterna antillarum browni at Alameda Point, San Francisco Bay, California. Waterbirds 30, no. 3: 317-325.
 Massey, B. W. and J. L. Atwood. 1981. Second-wave nesting of the California Least Tern: age composition and reproductive success. The Auk: 596-605.
 U.S. Fish and Wildlife Service. 1985. Recovery plan for the California least tern, Sterna antillarum browni.
 Atwood, J. L. and B. W. Massey. 1988. Site fidelity of least terns in California. Condor: 389-394.
 Atwood, J. L. and P. R. Kelly. 1984. Fish dropped on breeding olonies as indicators of Least Tern food habits. The Wilson Bulletin: 34-47.
 Zuria, I. and E. Mellink. 2005. Fish abundance and the 1995 nesting season of the Least Tern at Bahia de San Jorge, northern Gulf of California, Mexico. Waterbirds 28, no. 2: 172-180.