Type: report

Article abstract: Monitoring of nesting sites in 2000 resulted in an estimate of 4521 to 4790 breeding pairs of California least terns establishing 5301 nests at 37 locations. This represents a 31 percent increase in the minimum estimated number of breeding pairs from 1999. An estimated 3710 to 4013 fledglings were produced, or 0.77 to 0.89 fledglings per pair. This represents a 453 percent increase over productivity of the 1999 season, and 38 percent over that of 1998. Depredation was the primary limiting factor to reproductive success. Other reported causes of mortality included a heat wave in the San Francisco Bay area, nest abandonment, and human activity, including loss of chicks to vehicles. The nesting colony at Camp Pendleton continues to be the largest in the state, accounting for 22.8 percent of breeding pairs and producing 27.6 percent of this season's fledglings. Other colonies numbering over 200 nests included Alameda Point, Point Mugu, Venice Beach, L.A. Harbor, Huntington State Beach, Mariner's Point, Naval Amphibious Base Coronado North Delta Beach and ocean beach, and Tijuana Estuary. The nesting site first documented in 1998 at Tulare Lake bed evaporation ponds outside of Kettleman City in Kings County was used again in 2000, and newly created Caltrans mitigation islands in Albany in Alameda County were colonized and produced at least one fledgling.