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Western Snowy Plover

SnowyPloverKelp LeValley 512This snowy plover found something interesting amongst a shriveling strand of kelp.

Identifying Characteristics:  
The western snowy plover (Charadrius alexandrinus) is a small shorebird, about 6 inches long, with a thin dark bill, pale brown to gray upper parts, white or buff colored belly, and darker patches on its shoulders and head, white forehead and supercilium (eyebrow line). Snowy plovers also have black patches above their white forehead and behind the eye. Juvenile and basic (winter) plumages are similar to adult, but the black patches are absent. Some breeding males, especially in the southern portion of the species’ range, may exhibit a rusty or tawny cap. Their dark gray to black legs are a useful characteristic when comparing them to other plover species (Page et al. 1995).
 
Current Geographic Range:  
The Pacific coast population of the snowy plover is defined as those individuals that nest adjacent to tidal waters of the Pacific Ocean, and includes all nesting birds on the mainland coast, peninsulas, offshore islands, adjacent bays, estuaries, and coastal rivers (USDI Fish and Wildlife Service 2004). The current known breeding range of this population extends from Damon Point, Washington, to Bahia Magdelena, Baja California, Mexico (USDI Fish and Wildlife Service 2006). Snowy plovers that nest at inland sites are not considered part of the Pacific coast population, although they may migrate to coastal areas during winter months.
 
Life History:  
Pacific coast plovers typically forage for small invertebrates in wet or dry beach-sand, among tide-cast kelp, and within low foredune vegetation (USDI Fish and Wildlife Service 2004). Some plovers use dry salt ponds and river gravel bars. The breeding season in the United States extends from March 1 through September 30, although courtship activities have been observed during February. Clutches, which most commonly consist of three eggs, are laid in shallow scrapes or depressions in the sand. Pacific coast snowy plovers are polyandrous (i.e., a female may breed with more than one male), and share incubation duties. Females typically desert the brood shortly after hatching, leaving the chick rearing duties to the male. Females may renest if another male is available and if time remains in the season to do so. Snowy plover chicks are precocial, leaving the nest within hours after hatching to search for food. Males attend the young until they fledge, which takes about a month. Females generally assist the male to care for the last brood of the season. Adult plovers do not feed their chicks, rather they lead them to suitable feeding areas. Adults will present a broken-wing or tail-drag display when a predator approaches a brood or nest.
 
General Habitat Characteristics: 
The Pacific coast population of the western snowy plover breeds primarily on coastal beaches from southern Washington to southern Baja California, Mexico. The population breeds above the high tide line on coastal beaches, sand spits, dune-backed beaches, sparsely-vegetated dunes, beaches at creek and river mouths, and salt pans at lagoons and estuaries (U.S. Fish and Wildlife Service 2001). Less common nesting habitat includes bluff-backed beaches, dredged material disposal sites, salt pond levees, dry salt ponds, and river bars (U.S. Fish and Wildlife Service 2001). Suitable nesting habitat is distributed throughout the listed range, but may be widely separated by areas of rocky shoreline. 
 
Population and Habitat Status:  
Historical records indicate that nesting western snowy plovers were once more widely distributed in coastal California, Oregon, and Washington. In Washington, snowy plovers formerly nested at five coastal locations (USDI Fish and Wildlife Service 2006). Only three sites currently are known to be active, representing, a minimum 40 percent decline in Washington breeding sites. In Oregon, snowy plovers historically nested at 29 locations on the coast (USDI Fish and Wildlife Service 2006). Currently, there are only 10 nesting locations, representing a 65 percent decline in active breeding areas. In California, there has also been a significant decline in breeding locations, especially in southern California. 
 
From 2001 to 2005, the size of the breeding population of plovers in Recovery Unit 2 has ranged from 60 to 74 adults; the non-breeding population probably exceeds 100 birds (Colwell et al. 2005). Reproductive success in Recovery Unit 2 during this time period has ranged from 0.8 to 1.7 fledglings per adult male (Colwell et al. 2005). In recent years, nesting has occurred at the following locations in northern California: Gold Bluffs Beach, Big Lagoon, Clam Beach, South Spit, Eel River Wildlife Area, Centerville Beach, Eel River gravel bars, Brush Creek, Ten Mile River, and Virgin Creek.
 
Threats: 
Poor reproductive success, resulting from human disturbance, predation, and inclement weather, combined with permanent or long-term loss of nesting habitat to encroachment of non-native European beachgrass (Ammophila arenaria) and urban development has lead to a decline in active nesting, as well as an overall decline in the breeding and wintering population of the snowy plover along the Pacific coast (USDI Fish and Wildlife Service 1993). 
 
Human activities, such as walking, jogging, running pets, horseback riding, and vehicle use, are key factors in the ongoing decline in breeding sites and populations. The nesting season of the western snowy plover (March through September) coincides with the period of greatest human use (Memorial Day through Labor Day) on beaches of the west coast. Intensive beach use by humans may result in abandonment of nest sites, reductions in nest density, and reductions in nesting success.
 
Conservation Needs: 
The western snowy plover recovery plan provides a strategy for recovery of the listed population. Recovery objectives in the recovery plan include: (1) achieving well-distributed increases in numbers and productivity of breeding adult birds, and (2) providing for long-term protection of breeding and wintering plovers and their habitat. 
 
The recovery plan states that delisting will be considered when the following criteria have been met: (1) maintain for 10 years an average of 3,000 breeding adults distributed among 6 recovery units as follows: Washington and Oregon, 250 breeding adults; Del Norte to Mendocino Counties, California, 150 breeding adults; San Francisco Bay, California, 500 breeding adults; Sonoma to Monterey Counties, 400 breeding adults; San Luis Obispo to Ventura Counties, California, 1,200 breeding adults; and Los Angeles to San Diego Counties, California, 500 breeding adults; (2) maintain a 5-year average productivity of at least 1.0 fledged chick per male in each recovery unit in the last 5 years prior to delisting; and (3) have in place participation plans among cooperating agencies, landowners, and conservation organizations to ensure protection and management of breeding, wintering, and migration areas listed in Appendix B of the plan to maintain the subpopulation sizes and average productivity specified in criteria 1 and 2 above. 
 

More information about the Western Snowy Plover can be found here.

Last Updated: Feb 26, 2013
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