| |
|
Alameda Song Sparrow, photo courtesy of Peter LaTourette
Project Summary
The San Francisco Bay region has been dramatically altered in the past one hundred and fifty years. Approximately 85% of the original tidal marshes in the area have been lost due to creation of salt ponds, conversion to agricultural and industrial/urban use, and water diversion and management (Marshall & Dedrick 1994). Gold mining, which increased sediment deposition, and more recently, changes in the influx of fresh water (especially in the South Bay), have contributed to further changes in the remaining tidal marshes. The reduction in area, fragmentation and habitat degradation have all contributed to reductions in the population size of tidal marsh obligate species.
The tidal marsh bird project began in 1996 with funding from the USGS Species at Risk Program. The project seeks to assess population status and trends of the San Francisco Bay area tidal marsh bird species formerly listed as Category 2 candidates for Federal Endangered Species status and now considered Federal Special Concern species. These species are: Samuel’s Song Sparrow (Melospiza melodia samuelis), Suisun Song Sparrow (M.m. maxillaris), Alameda Song Sparrow (M. m. pusillula), Salt Marsh Common Yellowthroat (Geothlypis trichas sinuosa) and California Black Rail (Laterallus jamaicensis coturniculus). The Black Rail is listed as a Threatened species by the State of California, while the rest are California Special Concern species. Our study is the first to systematically examine the distribution and productivity of tidal marsh Song Sparrows and Common Yellowthroats on a long-term basis at a broad scale.
In addition, the project also seeks to model and predict the relative abundance and distribution of tidal marsh birds with respect to local habitat features, including vegetation and channel characteristics, as well as tidal marsh habitat configuration and surrounding landscape patterns. In recent years we have made extensive use of GIS maps and spatial analysis.
Download reports and studies from the San Francisco Bay Tidal Marsh Project.
|
Newark Slough
|
Objectives
- Estimate densities and abundance of tidal marsh birds including focal taxa: Samuel’s Song Sparrow, Suisun Song Sparrow, Alameda Song Sparrow, Salt Marsh Common Yellowthroat and California Black Rail.
- Determine how local habitat and landscape features influence the distributions and densities of tidal marsh bird populations in natural and restored tidal marshes. Variables of interest include:
- Vegetation type, height and density
- Channel density, width and shape
- Proximity to urban, natural upland and water edges
- Size, shape and isolation of marsh
- Adjacent and surrounding land use characteristics
- Assess productivity of tidal marsh Song Sparrows, Yellowthroats and Black Rails at a sample of sites in San Pablo, Suisun and San Francisco Bays. Is reproductive success sufficient to maintain populations?
|
- Determine the local habitat and landscape features that affect reproductive success.
- Determine levels of heavy metals and other toxic compounds in Samuels Song Sparrow eggs in San Pablo Bay. Examine whether levels of these compounds may be contributing to reductions in rates of egg hatchability.
- Provide information to land managers for the benefit of tidal marsh bird habitat.
|
|
Study Sites
The San Francisco Bay is composed of three smaller bays: San Francisco Bay (from the Golden Gate south), San Pablo Bay (spanning the area from the Golden Gate north and east to the Carquinez Strait), and Suisun Bay (east of Carquinez up to the Delta). Our survey study sites for the passerine taxa include approximately 50 marshes and marsh fragments in these three Bays. Of these, 7 have been selected for intensive nest monitoring studies:
- San Pablo Bay: China Camp State Park, San Rafael; Carl's Marsh (Petaluma River and Hwy. 37); Pond 2A, Napa-Sonoma Marsh; Black John Slough, Novato; and the marsh on the east side of the mouth of the Petaluma River.
- Suisun Bay: Benicia State Park, Benicia; and Rush Ranch, Grizzly Island.
|
|
| Click here for a queriable map of all study sites.
For Black Rail studies, survey plots were selected independently, and correspond with sites selected for earlier studies of Black Rails (Evens et al 1991). They include 26 marshes in San Pablo Bay, Suisun Bay and the outer coast (Tomales Bay, Bolinas Lagoon and Drake’s Estero).
|
Methods
Point Count Surveys
Marshes are surveyed using the Variable Circular Plot point count method, which involves recording the distance of the detection from the observer (Reynolds et al 1980). Detections within 100m are recorded, although for purposes of density analysis, distances are truncated to 50 or 70m. The program DISTANCE is used toestimate absolute density as a product of detection probability and encounter rate (Nur et al 1997).
Vegetation within a 50m radius around each point count location is measured. Parameters include plant species, vegetation density and height and number and size of channels.
Nest Monitoring
Nest monitoring is conducted following Martin and Geupel (1993). At each site, we establised 2 subplots of at least 9 ha. Nests are monitored at 2-4 day intervals and nestlings are banded with a unique color band combination 2 days before fledging. After nesting attempts are completed (nest failed or young fledged), measurements are taken of the nest substrate and within a 5m circular radius of the nest site (BBIRD protocol Martin & Conway 1995).
Adults and hatching year birds are captured with mist nets and color-banded in each subplot. We track the dispersal and fate of these individuals and the productivity of focal color-banded pairs. We also track birds that we color-band as nestlings and which survive to breed in subsequent years. At the time of banding, morphological measurements and a blood or feather sample of each individual are also taken for a taxonomic study (see research collaborators, listed below).
Black Rail Surveys
Study areas are surveyed by broadcasting taped Black Rail calls (Repking & Ohmart 1977). Elicited responses within 30 m are recorded and number of responses per listening station used to estimate a population density index.
| Reports
L. Liu, P. Abbaspour, M. Herzog, N. Nur, and N. Warnock. 2007. San Francisco Bay Tidal Marsh Project Annual Report 2006: Distribution, abundance, and reproductive success of tidal marsh birds. PRBO Conservation Science, Petaluma, CA.
L. Liu, M. Herzog, N. Nur, P. Abbaspour, A. Robinson, and N. Warnock. 2006. San Francisco Bay Tidal Marsh Project Annual Report 2005: Distribution, abundance, and reproductive success of tidal marsh birds. PRBO Conservation Science, Stinson Beach, CA.
Herzog, M., L. Liu, N. Nur, H. Spautz, and N. Warnock. 2004. San Francisco Bay Tidal Marsh Project Annual Report 2004: Distribution, abundance, and reproductive success of tidal marsh birds. PRBO Conservation Science, Stinson Beach, CA.
Spautz, H., J. Harley, N. Nur, and N. Warnock. 2003. San Francisco Bay Tidal Marsh Project Annual Report 2003: Distribution, abundance, and reproductive success of tidal marsh birds. PRBO Conservation Science, Stinson Beach, CA.
Spautz, H. and N. Nur. 2002. Distribution and Abundance in Relation to Habitat and Landscape Features and Nest Site Characteristics of California Black Rail (Laterallus jamaicensis coturniculus) in the San Francisco Bay Estuary.
Spautz, H., N. Nur, and J. Wood. 2001. CISNET San Pablo Bay Avian Monitoring. Annual Report. November 26, 2001.
Nur, N., S. Zack, J.G. Evens and T. Gardali. 1997. Tidal Marsh Birds of the San Francisco Bay Region: Status, Distribution, and Conservation of Five Category 2 Taxa.
Spautz, H. and N. Nur. 2004. Impacts of non-native perennial pepperweed (Lepidium latifolium) on abundance, distribution, and reproductive success of SF Bay tidal marsh birds.
|
References
Evens, J.G., G.W. Page, S.A. Laymon and R.W. Stallcup. 1991. Distribution, relative abundance and status of the California Black Rail in Western North America. Condor 93:952-966.
Martin, T.E. and C. Conway. 1995. The Breeding Biology Research and Monitoring Database (BBIRD) Field Protocol.. University of Montan Coop. Unit,
Unpublished manual.
Martin, T.E. and G.R. Geupel. 1993. Nest-monitoring plots: methods for locating nests and monitoring success. Journal of Field Ornithology 64:507-519.
Marshall, J.T. and K.G. Dedrick. 1994. Endemic Song Sparrow and Yellowthroats of San Francisco Bay. Pp316-327 in N.K. Johnson & J. Jehl (eds.), A Century of Avifaunal Change in Western North America. Studies in Avian Biology 15.
Nur, N., S. Zack, J.G. Evens and T. Gardali. 1997. Tidal marsh birds of the San Francisco Bay region: status, distribution and conservation of five Category 2 taxa. Final report to the United States Geological Survey- Biological Resources Division (Formerly National Biological Service).
Repking, C.F. and R.D. Ohmart. 1977. Distribution and density of Black Rail populations along the lower Colorado River. Condor 79:486-453.
|
Funding Sources
- Bernard Osher Foundation
- Richard Grand Foundation
- Gabilan Foundation
- Mary A. Crocker Trust
- Tides Foundation
- Rintels Charitable Trust
- National Science Foundation
- National Biological Service (now United States Geological Survey, Biological Resources Division
- U.S. Environmental Protection Agency
- U.S. Fish and Wildlife Service Coastal Program
- CalFed
Collaborators
- BREACH II San Pablo/Suisun Bay Breached Levee Wetland Study
- C. Simenstad, J. Toft, J. Cordell, University of Washington
- P. Williams, M. Orr, Phil Williams and Associates
- S. Bollens, S. Avent, T. Visintainer, A. Sanders, Romberg Tiburon SFSU
- D. Reed, University of New Orleans
- BREACH I Sacramento/San Joaquin Delta Breached Levee Wetland Study
- C. Simenstad, J. Toft, J. Cordell, H. Higgins, University of Washington
- P. Williams, M. Orr, J. Kulpa, Phil Williams and Associates
- Z. Hymanson, L. Grimaldo, Department of Water Resources
- D. Reed, University of New Orleans
- K. Kuivila, USGS
- CISNet San Pablo Bay Network of Environmental Stress Indicators
- J. Davis, J. Collins, B. Thompson, SFEI
- S. Siegel, Wetlands and Water Resources
- G. Schladow, T. M. Young, I. Werner, UC Davis
- D. Schoellhamer, USGS
- UC Berkeley
- Karl Malamud-Roam, Contra Costa Mosquito Abatement District
- Chris Kitting, CSU Hayward
- Jules Evens, Avocet Research Associates
- Stuart Siegel, Wetlands and Water Resources
- Phil Williams and Associates
- San Francisco Bay Bird Observatory
- USGS, Biological Resources Division
- U.S. Fish and Wildlife Service
- San Francisco State University
- San Francisco Estuary Institute
- University of British Columbia
- California Coastal Conservancy
- Marin Audubon Society
- Sonoma Resource Conservation District
PRBO Staff
Gary Page, Wetlands Ecology Division Co-Director
Nadav Nur, Quantitative Ecologist
Julian Wood, San Francisco Bay Program Leader
Leonard Liu, Tidal Marsh Biologist
Diana Stralberg, GIS Manager
[back to top] [Print Page]
|
|
|
