To volunteer to count shorebirds as part of PRBO's Pacific Flyway Shorebird Survey project, click here to be re-directed!

Next Count - SF Bay, November 2011 (more details to come).

Current Project Summary

The PFSS is a continuation project of PRBO's Pacific Flyway Project, which spanned 1988-1995, the first ever attempt to establish baseline data on shorebirds using the Pacific Flyway.  It spanned from Alaska to Baja California, and provided a basis for management recommendations and conservation efforts of shorebirds throughout the Flyway.

Every November and December, hundreds of volunteer scientists will be scouring the San Francisco Bay and Central Valley to count shorebirds. This study will help elucidate the importance of San Francisco Bay and Central Valley wetlands as wintering grounds for shorebirds and other waterbirds along the Pacific Flyway. 

Past Project Summary

PUBLICATIONS

Patterns of shorebird use of the Salton Sea and adjacent Imperial Valley, California

Abundance and distribution of shorebirds in the San Francisco Bay Area

Patterns of distribution and abundance of migratory shorebirds in the intermountain west of the United States

Overview of shorebird abundance and distribution in wetlands of the Pacific Coast of the contiguous United States
- Includes four graphics

Patterns and dynamics of shorebird use of California's Central Valley

Patterns and Dynamics of Shorebird Use of California's Central Valley
Shuford, D. W., G. W. Page, and J. E. Kelmyr. 1998. The Condor 100:227 - 244

Abstract. Surveys of California's Central Valley between 1992-1995 document it as one of the most important regions in western North America to migratory and wintering shorebirds. Populations averaged 134,000 individuals in August, 211,000 in November, 303,000 in January, and 335,000 in April. Of 33 species, the 10 or 11 that averaged over 1,000 individuals each season accounted for 99% of total numbers. Managed wetlands, agricultural fields (especially rice), and agricultural evaporation ponds held the most shorebirds. Species varied their seasonal, geographic, and habitat use of the Central Valley, primarily in response to changes in water availability from rainfall or management practices and latitudinal variation in habitat availability mediated, in part, by climate. In the record rainfall year of 1994-1995, shorebird numbers increased 74% between November and January, primarily from coast-to-interior movements of the Dunlin (Calidris alpina) and Long-billed Dowitcher (Limnodromus scolopaceus) and local habitat shifts of Killdeer (Charadrius vociferus). Although the Valley's shorebirds face threats from poor or toxic water quality, changing agricultural practices, and habitat loss to urbanization, they should benefit from current efforts to increase flooding of rice fields and to secure a stable high quality water supply for wetlands. Development of a sound conservation strategy is crucial for the preservation of shorebird populations in the Central Valley, as this agriculturally-dominated landscape is among the most altered in North America and remains vulnerable to strong economic and population growth pressures that may impact shorebird habitats in the future.

Overview of Shorebird Abundance and Distribution in Wetlands of the Pacific Coast of the Contiguous United States
Page, G. W., L. E. Stenzel, and J. E. Kjelmyr. 1999. The Condor 101:461-471

Abstract. We coordinated censuses from April 1988 to April 1995 to obtain an overview of shorebird abundance and distribution in Pacific Coast wetlands of the contiguous United States. We attempted to acquire at least 3 years of data for all major wetlands from counts within a short time window each fall, winter, and spring. Fourteen abundant, 8 moderately abundant, and 21 rare-to-uncommon species were recorded. For temperate-zone breeders, peak periods of abundance were fall or winter and, when discernible for arctic breeders, mostly fall or spring. Arctic breeders were relatively more abundant than temperate-zone breeders in Oregon and Washington wetlands. All five of the most abundant temperate breeders were limited primarily to California wetlands in all seasons. Only for Western Sandpiper (Calidris mauri) and Dunlin (C. alpina) did the estimated total individuals present simultaneously in all wetlands exceed 100,000. Fifty-six of 66 sites surveyed had at least four counts and at least 100 shorebirds on one or more counts; 38 of the 56 sites held at least 1% of 1 of 13 key species during at least one season. San Francisco Bay accounted for 24-96% of the estimated totals for key species; Grays Harbor, Willapa Bay, Humboldt Bay, Tomales Bay,, Point Reyes Esteros, Bolinas Lagoon, Elkhorn Slough, Morro Bay, Mugu Lagoon, Bolsa Chica, Mission Bay, and San Diego Bay held at least 1% of at least half the key species in at least one season. The usefulness of five criteria for selecting key wetlands for shorebird conservation are examined and potential threats are discussed.

Distribution and Abundance of Migratory Shorebirds in the Intermountain West of the United States
Shuford, D.W., G. W. Page, and L. E. Stenzel. 2002. Western Birds 33:134-174

Abstract. From 1989 to 1995, we coordinated shorebird surveys in wetlands throughout the Intermountain West. Of 39 species, the American Avocet was the most numerous (280,000 in fall). Population estimates also exceeded 50,000 birds for the Black-necked Stilt (fall), American Avocet (spring), Western Sandpiper (fall and spring), and Long-billed Dowitcher (fall) and 10,000 for the Black-necked Stilt (spring), Marbled Godwit (fall and spring), Least Sandpiper (fall and spring), and Long-billed Dowitcher (spring). Great Salt Lake, Utah, held the greatest numbers of shorebirds (380,000 in fall) followed by the Salton Sea, California (88,000 in fall). Eight other sites held >10,000 shorebirds in spring or fall: Harney Basin, Summer Lake, and Lake Abert, Oregon; Lake Lowell, Idaho; Goose Lake, Oregon/California; Mono Lake, California; and Humboldt Wildlife Management Area and the Lahontan Valley, Nevada. An additional 29 sites held >1000. Shorebirds distribution varied among sub-regions and habitats of the Intermountain West. Species also varied from being highly concentrated in large numbers at a few sites (e.g., Marbled Godwit) to being spread in small numbers among many sites (e.g., Killdeer). The single greatest threat to intermountain shorebirds is the scarcity of high quality water for wetlands. The U.S. Shorebird Conservation Plan shows great promise, but it will require vigorous regional implementation to stem and reverse the ongoing loss and degradation of wetland and upland habitats used by shorebirds.

Abundance And Distribution Of Shorebirds In The San Francisco Area.
L. E. Stenzel, C. M. Hickey, J. E. Kjelmyr, and G. W. Page. 2002. Western Birds 33: 69-98

Abstract - On 13 comprehensive censuses of the San Francisco-San Pablo Bay System we found between 325,000 and 396,000 shorebirds (Charadrii) in mid-August to mid-September and in November, 225,000 in late January to Feburary, and between 589,000 and 932,000 shorebirds in late April. We recorded 38 species on the censuses, of which 23 occurred on all fall, early-winter, and spring counts. Median totals in one or more seasons exceeded 10,000 for 10 of the 23 species, were 1,000-10,000 for 4 of the species, and were less than 1,000 for 9 of the species. Under rising tide census conditions when tidal flats were exposed, tidal habitat held the majority of totals for 12 species groups (including 19 species); salt ponds usually held the majority of the totals for 5 species groups (including 7 species); and 1 species was primarily in tidal habitat and other wetland types. Most species groups tended to concentrate either: 1) in the geographic center of the Bay System, or 2) in increasing proportion, relative to the extent of tidal flat, from San Pablo Bay south to the southern end of San Francisco Bay. The density of total shorebird biomass varied among 14 tidal divisions of the unvegetated tidal habitat in the study area, with tracts of highest biomass along the Napa River, which flows into San Pablo Bay, and on the east and south shores of central and south San Francisco Bay. Those tracts that supported the highest total shorebird biomass were also the ones to most frequently support high count densities for species groups. Most species groups consistently occurred in higher count densities in some tidal tracts than others; however, most tidal tracts held relatively high densities for one or more of the 18 species group in at least one season. The tidal tracts distinguished by most frequent high biomass or count densities were adjacent to systems of active salt ponds along Napa River and in South San Francisco Bay. The San Francisco-San Pablo Bay System is critical to large numbers of wintering, migrating, and breeding shorebirds, despite extensive loss and alteration of natural wetlands in the area. The geographic limitations of species' distributions in the Bay System should be considered when planning wetland restoration activities. Mitigation for important shorebird habitat lost in one part of the Bay System may not be possible in another part and the impact of habitat loss in areas of high density (or of high reproductive success for breeding shorebirds) will be far higher than in lower "quality" areas of the same habitat type.

See Figures Below:

SURVEY TIDAL TRACTS OF THE BAY, INCLUDING SAN PABLO BAY AND THREE REGIONS OF SAN FRANCISCO BAY.

	Tidal tracts in San Pablo Bay Region include P1, the west shore between Point San Pedro (reference point a) and Petaluma River mouth (b); P2, the northwest shore between b and Sonoma Creek (c); P3, the northeast shore between c and Napa River mouth (d); P4, Napa River flats north of d; P5, the east shore between the Carquinez Bridge (e) and Point Pinole (f); and the southeast shore between f and Point San Pablo (g). Tidal tracts in North (San Francisco) Bay include N1, the west shore between a and the Golden Gate (h); and N2, the east shore between g and the Bay Bridge (i). Tidal tracts in Central (San Francisco) Bay include C1, the west shore between i and the Hayward-San Mateo Bridge (j); C2, San Leandro Bay and the south shore of Alameda (k); C3, Hayward Shoreline between Bay Farm Island (l) and j. Tidal tracts in South (San Francisco) Bay include S1, the west shore between j and the Dumbarton Bridge (m); S2 the east shore between j and m; and S3, the shore south of m. Base map from the EcoAtlas, version 1.5003, July 1998, San Francisco Estuary Institute.
FALL SHOREBIRD BIOMASS BY REGION
	Median fall shorebird biomass on 14 tidal tracts of the Bay (see previous map for description of tracts). Base map from the EcoAtlas, version 1.5003, July 1998, San Francisco Estuary Institute.
SPRING SHOREBIRD BIOMASS BY REGION
	Median spring shorebird biomass on 14 tidal tracts of the Bay (see first figure for description of tracts). Base map from the EcoAtlas, version 1.5003, July 1998, San Francisco Estuary Institute.
Patterns of Shorebird Use of the Salton Sea and Adjacent Imperial Valley, California. 2003. Shuford, D. W., N. Warnock, and R. L. McKernan. In Press, Studies in Avian Biology Abstract. From 1989-1995 and in 1999, we recorded 34 species on shorebird surveys at the Salton Sea and adjacent Imperial Valley, California. Of 27 regularly occurring species, 4 were primarily year-round residents and breeders, 12 winter residents, and 11 migrants. Median shorebird totals were 78,835 in fall, 68,281 in spring, and 27,796 in winter; maximum counts on single surveys exceeded 100,000 in spring and fall. The only taxa exceeding 10,000 individuals in spring or fall were the Black-necked Stilt (Himantopus mexicanus, fall), American Avocet (Recurvirostra americana, fall), Western Sandpiper (Calidris mauri, spring and fall), and dowitchers (Limnodromus spp., spring). The American Avocet and Long-billed Dowitcher (L. scolopaceus) were the only species exceeding 5,000 in winter. The Salton Sea remains an important breeding and wintering area for the Snowy Plover (Charadrius alexandinus). Increased coverage of agricultural fields in 1999 revealed 2,486-3,758 Mountain Plovers (C. montanus), representing 30% to 38% of the species' estimated world population. At all seasons, shorebirds concentrated primarily along the south and secondarily along the north and west shorelines. Still, distribution patterns around the Sea varied greatly among species, and several relied extensively on freshwater and brackish ponds. The Mountain Plover, Whimbrel (Numenius phaeopus), and Long-billed Curlew (N. americanus), primarily used agricultural fields of the Imperial Valley. The shorebird community at the Salton Sea shows affinities with coastal sites in California and west Mexico. Despite many similarities, the Salton Sea contrasts with other intermountain sites by serving as a stopover for several primarily coastal species, hosting large numbers of Whimbrels (spring) and Mountain Plovers (winter), and, for many species, acting mainly as a wintering area rather than a breeding area or migratory stopover. Shorebirds at the Salton Sea face potential threats from high salinity, disease outbreaks, contaminants, and eutrophication. Large restoration projects proposed to reduce salinity may have negative impacts if placed in shallow water or alkali flat habitats where large numbers of shorebirds or sensitive species concentrated.