In North America, the Snowy Plover (Charadrius alexandrinus) is found along the west coast from southern Washington to southern Baja California; around the Gulf of California to southern Mexico; along the Gulf coast from Florida to the Yucatan Peninsula; and inland during summer at saline lakes, reservoirs and river bars in California, Oregon, Nevada, Utah, Arizona, New Mexico, Colorado, Kansas, Oklahoma, Texas, and central Mexico (Figure 1).³

The western subspecies (Charadrius alexandrinus nivosus) breeds on coastal beaches from southern Washington to southern Baja California, Mexico, and in interior areas of Oregon, California, Nevada, Utah, New Mexico, Colorado, Kansas, Oklahoma and north central Texas.² A distinct population unit of the Western Snowy Plover (WSP), called the Pacific coast population, is comprised of nesting birds on the mainland coast, offshore islands, bays, estuaries, lagoons, and river mouths of the Pacific coast of the U.S. and Baja California, Mexico (Figure 1).^2,4 Extensive breeding data confirm that Pacific Coast WSP are largely reproductively isolated from those breeding in interior areas.⁵ The draft recovery plan for the Pacific coast population has identified 157 current or historical breeding/wintering locations in the U.S.: 5 in Washington, 19 in Oregon, and 133 in California.² In Baja California, the Pacific coast population breeds as far south as Bahia Magdelena, Mexico.⁶

Snowy Plovers belonging to the Pacific coast population breed at multiple coastal sites within the longitudinal extent of the MBNMS (Table 1, Figure 2). These sites are located in two of the six Recovery Units identified in the draft recovery plan: 1) Recovery Unit 4 - including the entire outer coast of Sonoma, Marin, San Francisco, San Mateo, Santa Cruz and Monterey counties); and 2) Recovery Unit 5 including San Luis Obispo, Santa Barbara and Ventura counties).²

Figure 2. Sites in the Monterey Bay National Marine Sanctuary where Western Snowy Plover have been observed during one or more breeding season monitoring surveys since 2000 (breeding season window survey data, G. Page and K. Neuman, PRBO Conservation Science).

On the Pacific coast Snowy Plovers are found at beaches, lagoons, estuaries, salt evaporation ponds, and on river islands and gravel river bars near the ocean. Types of habitats used include sandy beaches, dunes (mainly foredunes just inland from the active beach face), sand spits, tidal flats, gravel bars, dredge spoils, salt pans, and salt pond levees. Nests are typically in flat, open areas with sandy or saline substrates above the high tide line. This species often nests or roosts beside objects, such as stones, wrack or driftwood; these structures are usually sparsely distributed throughout the habitat. Nests are usually within 100 m of the water. Nesting habitat should be relatively undisturbed by humans, pets, vehicles, and predators. Winter habitat consists primarily of coastal beaches, tidal flats, lagoon margins and salt-evaporation ponds.³ Many sites are used as both nesting and wintering habitat, while others are only used in the winter. For example, some urban and bluff-backed beaches that are not used for nesting may be used in the winter.

In the MBNMS, this species breeds on sand spits (e.g., Pajaro and Salinas River mouths), on pocket beaches at creek mouths (e.g., Wilder and Laguna creek mouths), on dune backed beaches (e.g., Salinas River State Beach, Morro Bay sand spit), bluff-backed beaches (e.g., southern Marina State Beach and Fort Ord), former salt evaporation ponds (ponds at Moss Landing Wildlife Area), and irregularly on river islands (e.g., islands at mouth of Salinas River). Winter habitat is typically sand spits, dune-backed beaches, and estuarine tidal flats.

Some individuals remain in their coastal breeding areas year-round, while others disperse up or down the coast to wintering locations. Many individuals return to the same nesting and wintering sites year after year, but some move between sites and may disperse in some years, but not in other years.⁷ Movement between sites can occur both within a season and between years. In the winter, many individuals will move between adjacent sites in the same region.⁸ Coastal plovers that disperse for the winter tend to leave nesting sites in late summer and early fall and return to nesting sites from late winter to early spring.

Many WSP that breed inland in the Central Valley of California and the western Great Basin (i.e., are not members of the Pacific coast population) migrate to the coast of California and Baja California for the winter.⁹ These inland breeders begin arriving on the central California coast in early July and then depart in March and April.³ Interbreeding between coastal and interior colonies appears to be very uncommon.

Studies of birds at Pajaro River found that 41% of nesting males and 24% of females are consistent year-round residents.¹⁰ The remaining birds leave nesting sites to winter at other locations along the Pacific coast. This dispersal to wintering locations occurs from late-June to late-October. Some birds that nest along the central California coast have been observed wintering as far north as Bandon, OR and as far south as Laguna Ojo de Liebre, Baja Mexico.³ Some birds that nest in Oregon have been sighted during the winter in Monterey Bay.³ WSP that disperse during winter begin to return to nesting beaches in central California as early as January, but most arrive between early March and late April.³ However, because some individuals nest at multiple locations in a given season, some birds will continue to arrive until late June and some early arrivals may leave for another nesting beach as early as late April.³

Many individuals move within the Monterey Bay area during nesting season (typically females). For example a female may nest in the Fort Ord area and then move north a few miles for her next nest at the Salinas River National Wildlife Refuge. Many birds remain or return to the Monterey Bay region to breed in consecutive years. Banding studies between Waddell Creek and Del Monte Beach revealed that on average 70% of males and 64% of females that nested in the study area between 1999 and 2004 returned to breed in consecutive years.¹¹

In the winter, many birds also remain in the Monterey Bay region, but may move between nearby sites.⁸ For example, some birds wintering in Santa Cruz County moved between Scott, Waddell and Laguna creeks. Birds also move between Sunset State Beach, the Pajaro River mouth, and the beach at Jetty Road.

Migrants from inland nesting areas arrive at wintering sites in the MBNMS starting in July and remain in the area until March or April. Banded individuals from the San Joaquin Valley, California, and the western Great Basin have been sighted at wintering locations in central California.³

In 2006, available information suggests 16,000 breeding Snowy Plovers for the entire United States with most occurring west of the Rocky Mountains.^3,12 A continent-wide survey to estimate breeding Snowy Plovers is planned by the FWS for 2007 and will provide more current information on population size¹²

The Pacific coast population of WSP is estimated to contain approximately 2,400 breeding adults in the United States (extrapolated from a 2006 coast-wide survey which detected 1,879 adults and 1,900 adults in Baja (extrapolated from a 1991-92 survey which detected 1344 adults).^6,12 The 2006 survey of the U.S. Pacific coast detected 67 adults in Washington, 93 in Oregon, and 1,719 in California.¹² These population sizes are likely to be substantially smaller than historic levels. Increasing human density and associated development along the Pacific coast over the last century has fragmented and degraded Pacific coast WSP habitat. Many locations with historic records of breeding activity do not currently support nesting populations. In the late 1970s, Snowy Plovers were absent from 33 of 53 locations in coastal California where nesting had been documented prior to 1970.¹⁴

The number of adults breeding in Monterey Bay and northern Santa Cruz County has shown an increasing trend since 1999 (Figure 3). In 2005, 210 male breeders and 174 female breeders were identified in the area - a small decrease over the 235 males and 197 females estimated for 2004.¹⁵ The number of breeding birds over the last three seasons (384 in 2005, 432 in 2004 and 350 in 2003) has exceeded the recovery plan target of 338 birds for the Monterey Bay area (from Waddell Creek to Carmel River mouth).¹⁵ The 229 verified fledglings for 2005 compares to an average of 217 (SE = 33.9) from 1997-2004; the highest total was 364 fledged young in 2003.¹⁵ The contributions of different areas within Monterey Bay to reproductive success vary over time as indicated by changes tracked from 1984-2002 (Figure 4).

At nesting sites in the Monterey Bay area, high reproductive success can be attributed to active conservation and management programs. Reproductive success has improved at the Moss Landing Wildlife Area salt ponds since intensive management began in 1995 (Figure 5). With management the salt ponds can support 70-80 nests during the nesting season compared to 10-20 nests prior to the start of management efforts.^15,16,17 Recently, Snowy Plovers have re-colonized the beaches of Fort Ord (south of Reservation Road) where nesting had not been seen since 1998 (representing a 4-year hiatus). One nesting pair was present in 2003; in 2004 six males and at least four different females initiated eight nests.¹⁸

Habitat loss and modification: Increased development along coastal beaches has led to loss of suitable nesting habitat. Activities that degrade nesting habitats include urban development, beach stabilization projects, sand mining/removal, and beach raking. Salt ponds provide valuable nesting habitat, especially if operated to accommodate plovers. In the Monterey Bay area, some large nesting populations are located on private property. If these lands are developed, it will lead to loss or degradation of essential nesting habitat.¹⁸

Human disturbance/harassment: Recreational activities that disturb nesting and wintering Snowy Plovers include horseback riding, beach walking and jogging, dog walking, fishing, camping, and off-road vehicle use. Negative effects include trampling of eggs or nestlings, preventing birds from incubating their eggs, separating adults from their young, and disrupting foraging and roosting birds. Kites, low flying aircraft, and model planes resemble avian predators and sometimes disturb Snowy Plovers. Driftwood removal or relocation can disturb valuable habitat features for nesting and roosting birds. Driftwood structures provide perches for predators. Fireworks, bright lighting and loud noises near nesting beaches can cause nest abandonment. High levels of disturbance may cause Snowy Plovers to abandon otherwise suitable nesting/wintering sites.

Introduced species: The spread of European beachgrass and iceplant and other non-native plant species has reduced the amount of nesting habitat along the coast. It may also cause a decrease in available food resources. The non-native red foxes can be a substantial source of mortality for eggs and also the cause of mortality of some chicks and adults. This species has been actively controlled in parts of the Monterey Bay area since 1993.

Predation: Urban development near nesting areas can increase numbers of domestic cats that may prey on chicks and adults. Increased amounts of garbage on the beach attract predators such as gulls, coyotes, foxes, raccoons, crows and ravens. Twelve nests at the Pajaro River mouth were depredated by ravens in 2002.¹⁹ Signs, telephone poles, fences, non-native landscape trees and other structures near nesting beaches can provide nesting sites and perches for predatory birds, including Loggerhead Shrikes, American Kestrels, Merlin, Peregrine Falcon, Coopers Hawk and Northern Harrier.

Pollution: Oil from offshore spills can be swept into coastal habitats by tidal exchange and wave action. Oil coating beaches and other foraging habitats can decrease food availability. Ingested oil can have harmful physiological effects. Debris along the coast can harm Snowy Plovers. Some individuals have been entangled in abandoned monofilament fishing line.

No threats are unique to the MBNMS, but all the “general” threats listed above may impact breeding or wintering birds in the Sanctuary.

In 1993 the Pacific Coast WSP was listed as “threatened” under the Endangered Species Act (ESA).²⁰ Under the ESA, the U.S. Fish and Wildlife Service (FWS) is responsible for the management and recovery of this population. As required under the ESA, the FWS is in the process of creating a recovery plan for the Pacific Coast WSP. A recovery team was created and a draft recovery plan became available for public review in 2001.² The draft recovery plan recommends actions including protection, enhancement, and restoration of all habitats deemed important for recovery, as well as monitoring, research, and public outreach. The recovery team also established the following recovery criteria for delisting the species:

1. Maintain for 10 years an average of 3,000 breeding adults distributed among 6 recovery units between Washington and southern California.
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.
3. Have in place participation plans among cooperating agencies, landowners, and conservation organizations to assure protection and management of breeding and wintering areas and maintain the population sizes and productivity levels specified in criteria 1 and 2 above.

In 2002, the FWS received a petition from the Surf-Ocean Beach Commission of Lompoc, California, to delist the Pacific Coast WSP. On March 22, 2004, FWS announced that it found that the petition presented substantial information that delisting may be warranted and that a review of the listing status should be initiated.²¹ In 2006, FWS released a status review of the Pacific Coast WSP and issued a 12-month finding on the petition to delist.⁵ The FWS found that the Pacific Coast WSP remains at risk from habitat loss, human disturbances and other perils and should retain its status as threatened under the Endangered Species Act (ESA).

In September 2005 the FWS designated 32 critical habitat units along the coast of California (24 units), Oregon (5 units), and Washington (3 units) for the Pacific Coast WSP.²² The critical habitat units total 12,145 acres. Under the ESA, critical habitat identifies geographic areas that contain features essential for the conservation of a threatened or endangered species and may require special management considerations.

All WSP are protected in the U.S. and Mexico by the Federal Migratory Bird Treaty Act (MBTA) of 1918, which prohibits pursuing, hunting, shooting, wounding, killing, trapping, capturing, or collecting any migratory bird, nest, or eggs without a permit from the FWS. The MBTA does not protect nesting or wintering habitat. This species is also recognized by the FWS as being a “bird of conservation concern” and a “migratory non-game bird of management concern”.

Specific actions taken by federal agencies to protect and enhance Snowy Plover nesting and wintering populations in the MBNMS include:¹²

• Year-round closure of upper beach nesting habitat at Salinas River National Wildlife Refuge by FWS.
• Signed and seasonally closed upper beach nesting areas on several State Beaches in Santa Cruz and Monterey counties.
• Fenced exclosures around single nests at some beach sites and in the Moss Landing Wildlife Area (by multiple agencies).
• Mammalian predator removal and limited avian predator relocation by the Wildlife Services Division of U.S. Department of Agriculture on Monterey Bay beaches and at the Moss Landing Wildlife Area.

The Western Snowy Plover is classified by the California Department of Fish and Game (CDFG) as a “species of special concern”. This status is assigned to species determined to be in decline and possibly in need of listing under the California Endangered Species Act (CESA). The species of special concern designation is intended to alert agencies, land managers, biologists, and academia about the declining status of a species and to encourage research and special management efforts that may help avert the need for listing under CESA in the future. State agencies are involved in a number of projects intended protect habitat and increase Snowy Plover populations.

Moss Landing Habitat Enhancement Project (Lead Agency: CDFG). The project consisted of reconfiguring existing salt ponds and accompanying water distribution systems at the Moss Landing Wildlife Area to provide maximum wildlife and habitat values using minimal personnel and a minimal amount of water manipulation.²³ The primary emphasis was to enhance nesting habitat for the Western Snowy Plover in the salt ponds, which is considered to be an extremely important nesting area for the Monterey Bay population. The project was completed in 2006.²⁴

The California Public Resources Code (Section 5019.71) allows designation of natural preserves. The purpose of natural preserves is to maintain such features as rare or endangered plant and animal species and their supporting ecosystems. The Wilder Creek Natural Preserve, Pajaro River Mouth Natural Preserve, and Salinas River Mouth Natural Preserve were designated by the California State Park and Recreation Commission in recognition of the need to protect Snowy Plovers.

Special management actions for Snowy Plovers are conducted at many coastal sites owned by state agencies (usually the California Department of Parks and Recreation). Management actions to improve conditions for this species include: 1) resource management actions include monitoring, predator trapping, and use of symbolic fencing and exclosures; 2) public outreach programs such as informational signage or brochures; and 3) enforcement of rules and restrictions.

The American Bird Conservancy and the Audubon Society have placed the WSP on their Watch Lists. These lists identify species that are considered to be of the greatest conservation concern in the U.S. The lists are intended to raise public awareness of species with declining populations and focus conservation efforts on Watch List species.

Monterey Bay Snowy Plover Conservation Project (Principal Investigator: Gary Page, PRBO Conservation Science). The objectives of this project are: 1) to determine the annual breeding population size, nesting success, first-year and adult survivorship, and dispersal patterns of Snowy Plovers nesting in coastal habitats of Santa Cruz and Monterey counties; 2) to assist county, state, and federal agencies in identifying and protecting nesting and brood-rearing areas used each year; and 3) to develop and examine the effect of management actions on breeding population size, and 4) work with partner government agencies to develop an effective management program for Snowy Plover population in the Monterey Bay Area. Monitoring has occurred at seven beach segments around Monterey Bay and at the Moss Landing Wildlife Area since 1984 and at small pocket beaches in northern Santa Cruz County since 1988. Since 1995, PRBO has been managing the former salt ponds at the Moss Landing Wildlife area for Snowy Plovers. Actions include predator control, removal of excessive vegetation, and operation of water control structures. Partners: CDFG, CDPR, FWS Salinas River Refuge, FWS Endangered Species Office.

Point Reyes Snowy Plover Recovery Project (Contact: Gary Page, PRBO Conservation Science). Started in 1996, this project protects and monitors nesting Snowy Plovers within the Point Reyes National Seashore. The geographic area covered by this project includes beaches in the northern portion of the MBNMS (e.g. Marin and San Mateo counties). Partners: Point Reyes National Seashore, National Park Service, Point Reyes National Seashore Association, FWS Endangered Species Office.

The Draft Recovery Plan identified information gaps and recommended research and monitoring programs to fill those gaps.² In the MBNMS, research and management programs directed by PRBO Conservation Science, CDFG, CDPR and FWS are addressing most of the gaps. Additional research is needed in the following area:

• Determine cost-effective and efficient methods to remove introduced plant species (e.g., beachgrass and iceplant) and restore native dune plant communities.

• Enforce Sanctuary regulations that help prevent disturbance to Snowy Plovers and degradation of nesting and wintering habitat:
  • Existing “Restricted Overflight” zones prohibit low flying aircraft (<1,000 ft) over some Snowy Plover habitat in the Sanctuary. Use education outreach efforts to decrease low flying aircraft over important Snowy Plover habitat that is not located in a restricted overflight zone.²⁵
  • Prohibitions on discharging or depositing any material in or near Sanctuary boundaries that injures a Sanctuary resource (e.g. garbage, oil, abandoned fishing gear).²⁶
  • Prohibitions on take or injury to seabirds protected under the MBTA*.
  • Prohibitions on dredge material disposal and beach replenishment except at sites already designated for this purpose. However, beach replenishment and dredge material disposal, if properly planned and implement, can be used to restore suitable nesting habitat and should be considered in such cases.
• Develop and implement education outreach programs to supplement existing efforts. Focus on ways to minimize human-caused disturbance to nesting and wintering Snowy Plovers and to prevent human activities that attract predators and degrade habitats.^2,27
• Regulate/minimize beach alteration or development activities that can lead to loss of suitable habitat. Work to maintain natural coastal processes that perpetuate high quality breeding habitat.²⁸
• Support habitat restoration efforts including the removal of invasive vegetation and control of non-native and anthropogenically enhanced predator populations.
• Support efforts to maintain nesting habitat on private property. Encourage conservation management of these properties (possible strategies including conservation easements or acquisition and management by appropriate federal or state management agencies).

*Sanctuary regulations use the term “seabird”, but this regulation applies to all birds that occur within the boundaries of the MBNMS including the beach below mean high water.

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Thank you to Gary Page and Kriss Neuman for reviewing this report and providing helpful comments and corrections.