California Least Tern & Western Snowy Plover (Oceano Dunes SVRA)
- maintaining an approximate 300-acre fenced exclosure seasonally from March to October,
- extensive seasonal habitat enhancement,
- intensive daily monitoring of nests and chicks by Park staff and contractor
- color banding of all chicks,
- predator management,
- educating Park visitors, and
- enforcement of resource protection regulations.
From 1991 to 1996, Oceano Dunes had a very small least tern colony of 0-5 breeding pairs. From 1997 to 2002, with management efforts, the number of breeding pairs in the colony slowly increased to an average of 19-21 (range=4-37). Continued efforts resulted in an average of 42-48 (range=23-66) breeding pairs at the Park for the 15-year period from 2003-17. During the same 15-year period from 2003-17, the average nest hatching rate was 82%. From 2006-17, the average chick fledging rate was 73% (580 fledglings produced), and the average fledglings per pair was 1.12-1.19. For all least tern colonies in California, the average number of fledglings per pair was 0.35-0.50 for 2016 (Frost 2017). Although the colony is small, Oceano Dunes has been one of the top contributors to the number of juveniles produced each year in California.
The number of breeding snowy plover adults at Oceano Dunes has steadily increased over the years. In 2002, the minimum breeding number of adults was 32. With increased management the number of breeding adults jumped to 84 in 2003 and the average for the 14-year period 2004-17 was 150 (range=79-226). The average has continued to increase to 197 minimum adults for the 5-year period 2013-17 (range=163-226) and 199 minimum adults for the 3-year period 2015-17 (range 183-209). For the 16-year period 2002-17, there were an average of 161 nests (range=35-281), the average hatch rate was 75%, and the average chick fledgling rate was 39%. For the 5-year period 2013-17, breeding results have improved to an average of 232 nests (range=178-281), a 78% average hatch rate (range=63-86%), and a 44% fledge rate (range=34-55%). One chick fledged per breeding male is the estimated number needed to prevent the population from declining and 1.2 chicks fledgling per male will allow for moderate population growth (US Fish & Wildlife Service 2007). For the 16-year period 2002-17, average productivity was 1.49 chicks fledged per breeding male. This average has also improved in recent years to 1.88 and 1.92 chicks fledged per male for the 5-year period 2013-17 and for the 3-year period 2015-17, respectively (California Department of Parks and Recreation 2016).
California Department of Parks and Recreation, 2017. Nesting of the California least tern and western snowy plover at the Oceano Dunes State Vehicular Recreation Area, San Luis Obispo County, California 2017 Season. Unpublished Report, CDPR, Off-Highway Motor Vehicular Recreation Division.
Frost, N. 2017. California least tern breeding survey, 2016 season. California Department of Fish and Wildlife, Wildlife Branch, Nongame Wildlife Program Report, 2017-03. Sacramento, CA. 20 pp + Appendices.US Fish & Wildlife Service, 2007. Recovery Plan for the Pacific Coast Population of the Western Snowy Plover (Charadrius alexandrinus nivosus). In two volumes. Sacramento, CA. xiv+751pp.