Up, Down, or Stable: Populations of Endangered Birds in Beach and Estuarine Areas in Southern California

The coastal beach-dune ecosystem in California supports two federally listed threatened or endangered species: California least tern (Sterna antillarum browni) and western snowy plover (Charadrius alexandrinus nivosus). This ecosystem has become highly stressed due to shoreline development, invasion of exotic plants, beach stabilization, and heavy recreational use. Least tern populations have increased significantly since the 1980s. Snowy plover populations, however, show continued decline along California’s coast. Management practices to protect least tern nesting colonies appear to be successful for terns but do not offer protection for plovers. More research is needed to monitor reproductive success and survival of snowy plovers in order to improve management practices and preservation of nesting areas. Impacts to estuarine ecosystems have been severe and include loss, degradation, and fragmentation. The most imperiled species within this system is the endangered lightfooted clapper rail (Rallus longirostrus levipes). Rail populations have ranged from a low of 142 pairs in 1985 to a high of 325 pairs in 1996 during the 22-year period they have been monitored. Most alarming is that only one estuary consistently supports more than 50 percent of California’s rails, and only three sites support more than 80 percent. Although Belding’s savannah sparrow (Passerculus sandwichensis beldingi) is not federally listed as endangered, populations in estuaries are stable or declining, but monitoring is erratic at best. Belding’s savannah sparrows are area-sensitive, and reproductive success appears to be low in fragmented marshes. Research on productivity and survival of rails and sparrows is needed. Habitat enhancement and creation should be the highest priority for beach and estuarine birds as well as migratory shorebirds, but predator management and restrictions on recreation beach use are also necessary.