San Francisco Bay Tidal Marsh Project Annual Report

2007

San Francisco Estuary and Watershed Science, 2012

Extensive habitat loss and degradation have resulted in decreases in populations of tidal marsh breeding birds in the San Francisco Estuary in the past 150 years. We conducted point count surveys and nest monitoring in tidal marsh habitat at China Camp State Park from 1996 through 2007 to assess bird abundance, species richness and reproductive success over time. We found overall species richness at China Camp to be significantly lower than that of other San Pablo Bay tidal marshes, but also to be increasing during the study period. We present relative density indices and confirm breeding for three focal species that are of conservation concern: San Pablo song sparrow (Melospiza melodia samuelis), California black rail (Laterallus jamaicensis coturniculus), and California clapper rail (Rallus longirostris obsoletus). Song sparrows were observed at higher densities at China Camp than at other San Pablo Bay sites. There was no apparent trend in song sparrow density during the study period at China Camp, in contrast with the rest of San Pablo Bay, which displayed a significant decline. We determined song sparrow nest survival probability using the method described by Mayfield (1975) and found that nest survival at China Camp varied markedly among years, from >30% in 1996 to 6% in 2006, with no discernible trend. The main causes of nest failure were predation and tidal flooding. Song sparrow nests were found predominantly in gumplant (Grindelia stricta) and pickleweed (Sarcocornia pacifica) and less commonly in saltgrass (Distichlis spicata). Clapper rails nested exclusively in pickleweed and black rail nests were found mainly in gumplant and less commonly in saltgrass. China Camp's expansive ancient marsh supports endemic and bird species of conservation concern, while serving as a reference site for tidal marsh studies in San Francisco Bay. The long-term monitoring of tidal marsh bird breeding parameters at China Camp has the potential to provide early detection of declining population trends before local populations become imperiled.

San Francisco Estuary and Watershed Science, 2023

The South Bay Salt Pond Restoration Project aims to restore many former salt production ponds, now managed for wildlife and water quality, to tidal marsh. However, because managed ponds support large densities of breeding waterbirds, reduction of pond habitat may influence breeding waterbird distribution and abundance. We investigated habitat use associated with breeding, feeding, and roosting behaviors during the breeding season for American Avocets (Recurvirostra americana), Black-necked Stilts (Himantopus mexicanus), Forster's Terns (Sterna forsteri), and Caspian Terns (Hydroprogne caspia) in south San Francisco Bay in 2019 after substantial tidal marsh restoration, and compared results to a 2001 survey (before restoration). In 2019, managed ponds (26% of currently available habitat) were selected by waterbirds engaged in breeding behaviors (> 39% of observations), foraging (> 42%), and roosting (> 73%). Waterbirds avoided tidal habitats (43% of available habitat), comprising < 17% of observations of breeding behavior, < 28% of foraging observations, and < 13% of roosting observations. Waterbird densities increased in managed ponds between 2001 and 2019, and decreased in active salt ponds, especially among feeding Avocets (92% decrease) and Stilts (100% decrease). Islands were important for waterbirds observed breeding and roosting (45% of Avocet and 53% of Tern observations). Avocets and Stilts fed primarily on wet bare ground (65% and 58%, respectively), whereas feeding Forster's Terns and Caspian Terns used mostly open water (82% and 93%, respectively). Within ponds, Avocets were associated with islands (131 m closer than expected). Stilts and Forster's Terns were also associated with islands (68 m and 161 m closer than expected), except when feeding (1 m closer and 90 m farther than expected). Avocets and Stilts were associated with pond levees (39 m and 41 m closer than expected), but Forster's Terns were not (9 m closer than

2006

We modeled the abundance or probability of occurrence of several tidal-marsh-dependent birds found in the San Francisco Bay estuary-the San Pablo Song Sparrow (Melospiza melodia samuelis), Alameda Song Sparrow (M. m. pusillula), Suisun Song Sparrow (M. m. maxillaris), Salt Marsh Common Yellowthroat (Geothlypis trichas sinuosa), California Black Rail (Laterallus jamaicensis coturniculus), and Marsh Wren (Cistothorus palustris)-based on marsh characteristics at several scales. Local habitat variables included vegetation type, structure, and height, and tidal-channel characteristics. Landscape variables included marsh size and confi guration, distance to edge, and type of surrounding land use. For each species considered, both landscape and local habitat factors were signifi cant predictors in multi-variable, multi-scale, linear or logistic regression models. While the best models contained both local and landscape variables, all four bird species were also well predicted by local habitat or landscape variables alone. Predictor variables differed by species, but each species responded strongly to vegetation composition (specifi c plant species) as well as the overall structure (height or complexity) of the vegetation. Scale effects also differed by species. For Song Sparrows, land-use variables were most important at a relatively small spatial scale (500 m) while for Marsh Wrens and Common Yellowthroats they were important at the largest scale examined (2,000 m). Certain elements of vegetation type and structure, as well as marsh size and confi guration (perimeter to area ratio) and surrounding land use, were important across several species, suggesting a suite of habitat and landscape characteristics that may be useful in identifying sites important to multiple bird species.

2011

Wetlands, 2009

Human-induced and natural processes continue to act upon the estuaries of the northern Gulf of Mexico. Predictive models have been applied to project the interactions between habitat modification and population estimates for some estuarine species. However, these assessments may be furthered by focusing on a suite of species, such as a subset of the marsh birds that inhabit these ecosystems. During 2004 and 2005, we conducted point count surveys within the estuarine systems of Alabama and Mississippi, USA to assess whether small-scale wetland characteristics and a broader scale metric of habitat modification influenced the distributions of several marsh bird species: clapper rail (Rallus longirostris), common yellowthroat (Geothlypis trichas), least bittern (Ixobrychus exilis), marsh wren (Cistothorus palustris), and seaside sparrow (Ammodramus maritimus). On the basis of current habitat, we project change in species occupancy through several scenarios. Projections suggest that habitat alteration through loss of emergent marsh and increased cover of the halophyte Juncus roemerianus may be most influential to the distribution of these marsh bird species. Thus, continued alteration of existing conditions coupled with sea-level rise will likely have a significant impact on the distribution of this group of marsh bird species as well as the integrity of their habitat.

Contract, 2006

Waterbirds, 2007

Emergent tidal marshes are a dominant feature of the Chesapeake Bay's estuarine environment and account for an approximate 123,100 ha of the 185,870 ha (66%) of classified wetlands. Tidal marshes vary in salinity, structure, and plant composition according to their geographic position in the Bay. Chesapeake Bay marshes support breeding bird populations that are of regional or national conservation significance. Marsh bird communities vary with marsh type, geographic position, salinity, patch size, and landscape context. Marsh loss has been significant over the past two hundred years primarily as a result of urban, industrial, and agricultural development. Protective legislation enacted in the 1970s has slowed the rate of loss but marshes continue to be degraded and population of marsh birds continue to decline from the invasion of exotic species, ground predators, poor management practices, encroachment by development, and sea-level rise. Despite these concerns, there is still relatively little information on the population trends of most marsh birds or on the distribution of some of the Bay's highest species of concern such as Black Rails ( Laterallus jamaicensis ), King Rails ( Rallus elegans ), Saltmarsh Sharp-tailed Sparrows ( Ammospiza caudacuta ), and Henslow's Sparrows ( Ammodramus henslowii ). Marshes along the bay's fringe, tributaries, and islands that currently support species at risk of extinction in the Bay are in immediate need of identification and protection. High marshes on the Delmarva peninsula, support greatest concentrations of species at risk and are marshes among the most at risk of loss and degradation. Management to reduce or abate threats to marsh birds is critical to their long term survival.

1997

Levees: No levees. Channelization: One large channel with a few lateral ones. Very few small channels. Vegetation: Again dominated by Pickleweed, but with patches of Tule throughout and on the marsh fringes. Site Name: Pt. Edith. Bay: Suisun. County: Contra Costa Location: On south side of Suisun Bay. Crossing the Interstate 780 bridge to south after Benicia, turn on first exit and head east on Waterfront Road. Obtain permission to bird watch at the entrance kiosk at the site of the Port of Chicago. Park at the small parking lot created for Pt. Edith. The marsh we censused was to the east of the main north-south levee. Marsh History: The marsh was affected by the Shell Oil spill of 1988. Abundance oil residue remains today. Logistics: All points were accessed from the main levee, with one point on an old levee. Most all points were within 200 m of main levee. Levees: Many perpendicular levees come off main levee. Channelization: Some large channels exist, but much channelization occurs adjacent to levees. Vegetation: Tule vegetation and common cattail vegetation dominates. Patches of Pickleweed and Saltgrass are common as well.

2000