BLACK SKIMMER (RYNCHOPS NIGER) BREEDING SUCCESS IN THE EAST BAY REGIONAL PARK DISTRICT, CALIFORNIA

David L Riensche; driensche@ebparks.org; Meredith L. Elliott

The Black Skimmer (Rynchops niger), one of our most distinctive colonial waterbirds, is listed as a California Species of Special Concern. Factors affecting their breeding population include limited suitable open nesting habitat, human disturbance, varied food availability, predation (feral animals and gulls), extreme weather, and environment pollutants. It is projected that by the year 2050, due to climate change, this coastal bird will have its habitat reduced by 50%. Typically, islet-breeding skimmers are in close proximately to nesting tern species which provide early warning and defensive behaviors against intruders. Since 2001, the East Bay Regional Park District has been working to establish and enhance a California Least Tern (Sterna antillarum browni) colony at Hayward Regional Shoreline located along the eastern shore of the San Francisco Bay. These efforts are to assist in the recovery of this State and Federally listed endangered species and resulted in the attraction of breeding Black Skimmers to the site in 2015. For a total of eight breeding seasons (2015 to 2024), the Black Skimmer, California Least Tern, the threatened Western Snowy Plover (Anarhynchus nivosus nivosus) have nested successfully, in association with American Avocet (Recurvirostra americana) and Black-necked Stilt (Himantopus mexicanus). The results presented on Black Skimmer breeding chronology, hatching and fledging success, and diet in the northern portion of the species range answers data gaps that may help inform future research, protection, and management measures for this special status bird species.

Poster Session