Western Snowy Plover Charadrius alexandrinus nivosus,

 Federal Threatened Species (58 FR12864)

Female Snowy Plover by nest. J.Fancher

The is a sparrow-sized, white and tan colored shorebird with dark patches on either side of the neck, behind the eyes, and on the forehead. The coastal western snowy plover population is defined as those individuals that nest adjacent to or near tidal waters and includes all nesting colonies on the mainland coast, peninsulas, offshore islands, adjacent bays, and estuaries. The breeding range of the western snowy plover extends along coastal beaches from the southern portion of Washington State to southern Baja California, Mexico.

The breeding season of the western snowy plover extends from March 1 through September 15. Generally, 3 eggs are laid in a nest which consists of a shallow depression scraped in sandy or saline substrates. Some nests are lined with plant parts, small pebbles, or shell fragments. The female usually incubates the eggs for an average of 27 days. Snowy plovers will renest after loss of a clutch or brood. Snowy plover chicks are precocial and leave the nest within hours of hatching in search of food. The tending adult provides danger warnings, thermoregulation assistance, and guides the chicks to foraging areas, but does not provide food to their chicks. Broods rarely stay in the immediate area of the nest. Young birds are able to fly within approximately 31 days of hatching. Double brooding and polyandry have been observed and snowy plover females may leave very young chicks to find another mate, leaving the male to care for the brood. Western snowy plover adults and young forage on invertebrates along intertidal areas, along beaches in wet sand and surf cast kelp, in foredune areas of dry sand above the high tide, on salt pans, and along the edges of salt marshes and salt ponds. The snowy plover is primarily a run and glean type of forager.

Poor reproductive success resulting from human disturbance, predation, and inclement weather, combined with permanent or long-term loss of nesting habitat to urban development and the encroachment of introduced beachgrass, has led to the decline in active nesting colonies as well as an overall decline in the breeding and wintering population of the western snowy plover along the Pacific coast of the United States. In southern California, the very large human population and the resultant beach recreation activities by humans have precluded the western snowy plover from breeding on historically used beach strand habitat. As a result of these factors, the Pacific coast population of the western snowy plover was Federally listed as a Threatened with extinction in 1993.

There are only a handful of snowy plover breeding locations currently used in southern California. The more well used locations include Bolsa Chica (Orange County), Camp Pendleton, Batiquitos Lagoon, Naval Amphibious Base-Coronado, and Tijauna Estuary in San Diego County. Snowy plover nesting use at Bolsa Chica is reported in detail in annual reports spanning the years 1997-2003.

At Bolsa Chica, the western snowy plover reproductive success has varied between poor and very good. Typically, between 30 and 40 adults are present during breeding season. In some years, half or more nests were destroyed by egg stealing predators, such as crows which are very abundant in the adjacent urban area. The use of mini-exclosures on nests reduced nest loss. However, plover chicks are very vulnerable to avian chick predators found at Bolsa Chica, such as American kestrel and loggerhead shrike. Bolsa Chica continues to be an important snowy plover breeding area in southern California.