| A Successful Breeding Season for California Least Terns
and Western Snowy Plovers at Bolsa Chica By Kelly O’Reilly, Associate Marine Fisheries Biologist, California Department of Fish and Game Thanks to the dedication and hard work of Fish and Game staff, fledgling success for two listed species, California least tern (CLT) and western snowy plover (WSP), increased significantly at the Bolsa Chica Ecological Reserve (BCER) during 2008. This season, CLT produced a total of 242 nests at BCER and 184 of these were on Nest Site 1 (NS1) which was created during the restoration and is visible through the fence just past the footbridge. Of the 67 WSP nests at BCER, 37 were on NS1. In addition to CLT and WSP, Caspian tern, elegant tern, royal tern, and black skimmers also nested on NS1 this year. Because this nest site is so large and is used by multiple species, determining a total count of CLT and WSP fledglings posses quite a challenge to our threatened/endangered species monitor, Peter Knapp. This explains why the range of estimated fledglings for 2008 is so wide. Out of a total of 371 CLT chicks, as many as 100-150 fledged this year; compared to only 15 chicks during 2007. WSP only had 15 chicks fledge during 2007 as well, yet out of 159 chicks born at BCER during 2008, 42-144 survived to fledge. Compared to 2007, the total number of CLT nests at BCER increased by 7% and WSP nests increased by 25%, this year. The decline in chick mortality during 2008 is likely due to several management measures taken by Fish and Game prior to nesting season. For example, palm trees along PCH that harbored American kestrels that had preyed upon chicks during 2007 were felled by Ecological Reserve Botanist, John Ekhoff. In addition, John treated non-native plants on both nesting islands and NS1 with herbicides. This was an efficient means of removing non-native vegetation to provide more nesting space on the islands and facilitate the growth of native plants on NS1 to provide refuge for chicks. Another strategy to provide refuge for chicks on Nest Sites 1 and 3 was the addition of curved clay roofing tiles. Finally, in order to protect CLT eggs from being trampled by larger birds on NS1, Peter encircled CLT nests with circular wire fences. The combination of these measures along with the watchful eye of Peter Knapp and those who assisted him, paved the way for a significant increase in the breeding success of these two listed species. |