The baylands of the San Francisco Bay estuary support a diverse assemblage of bird species. The Goals Project has divided these species into two groups: (1) shorebirds and waterfowl, and (2) other baylands birds. Representatives of the other baylands birds group include gulls, terns, grebes, pelicans, egrets, raptors, rails, and many species of songbirds. This report presents the recommendations of the Other Birds Focus Team, which was formed to address the needs of this group of birds, and the term "other birds" will be used throughout when referring to them.
The U.S. Fish and Wildlife Service's Diked Baylands Study (in preparation) and the 1992 Status and Trends Report on the Wildlife of the San Francisco Estuary identify 184 other bird species. The baylands provide important support for many of these species during migration and during the winter (warblers, grebes, and raptors), and support breeding during the summer, particularly for resident species (clapper rail and song sparrows).
The abundance and distribution of other birds using the estuary is a reflection of the habitat changes which have occurred in the baylands over the last 150 years. These changes have resulted in dramatic declines in some species (clapper rails) and increases in other species (eared grebe or meadowlark). Changes are most pronounced in species which are dependent on tidal marsh and those which have been able to exploit new habitats resulting from diking and filling of the Bay. From the historic record and inference about how species use the existing baylands, we are able to identify changes in abundance. Unfortunately, little information is available to allow us to fully understand the range of support functions provided in the historic condition.
The changes which have occurred over the last 150 years have altered the mix, abundance and distribution of habitats within the baylands and adjacent uplands significantly. The habitat most affected has been tidal marsh which has been reduce by 80 percent. Much of what remains today is recently formed, fragmented and poorly developed and does not provide the levels of support which could have been expected in the historic marshes. This can be inferred by comparing current tidal marshes to mapping of the baylands in the mid 1800s. With the exception of the Petaluma Marsh today's tidal marshes are a shadow of the historic marshes which were a diverse mixture of channels, flats, marshes, permanent ponds, salt ponds and pannes, areas of seasonal ponding and ecotones with various upland habitats.
Uplands adjacent to the bay have also been greatly altered or eliminated, particularly in the South and Central bay subregions. Based upon historic information developed as part of the EcoAtlas the uplands surrounding the baylands supported extensive areas of potential seasonal ponding. Examples of these can be seen the Warm Springs area on the South Bay and areas surrounding Suisun Bay. In many cases diking of the baylands has created habitats suitable for many upland species which historically occupied adjacent uplands (burrowing owl and meadowlark). These habitats include levees, diked marshes, managed marshes, farmed and grazed lands and areas of undeveloped fill.
Diking of the baylands has also provided for the establishment of other types of wetlands which were of limited extent or found primarily in the adjacent uplands surrounding the Bay. These include salt ponds, managed marshes and seasonal ponds. The presence of these habitats in the baylands has been beneficial for many Other bird species which prefer these habitats and have been able to exploit them (eared grebes, terns and gulls, white pelican).
These changes in the baylands have set up a natural tension between species in developing recommendations for the Goals Project. The Other Birds Focus Team selected evaluation species to represent the habitats of the entire estuary as a means of identifying needed habitat support functions. Although the recommendations for restoration of particular features of the ecosystem may benefit some evaluations species and their proxies, there will always be conflicts between the needs of the various evaluation species and management goals must seek to balance these conflicts.
The process of making recommendations for other birds focused on looking outward from the baylands. The emphasis was on making recommendations for species which depended upon the baylands for their primary support. To aid in this process an attempt was made to place evaluation species in context with their regional and flyway populations. Since the area of the baylands is limited compared to the distribution of some evaluation species, emphasis was placed on making recommendations for those species whose life requires or local occurrence depend on the support functions provided by the baylands.
The selection of evaluations species used the following criteria:
1. Requires large well developed tidal marsh habitat. 2. Uses salt pond or shallow saline pond habitat. 3. Uses higher part of tidal marsh and upland transition. 4. Representative of a particular habitat type, including: riparian, seasonal ponds, freshwater marshes, adjacent uplands, channels, open bay or rocky shores/islands. 5. Relies on a variety of baylands habitats and adjacent areas for nesting and foraging. 7. Represents a broader group of species which use the baylands. 8. Locally or regionally of limited number and distribution, (listed species, species of special concern).
Twentyseven evaluation species, were initially selected from the species identified in the Diked Baylands Study and the Status and Trends Report. The selected evaluation species represented the full range of habitats found within the baylands as well as the support functions they provided (foraging, roosting, migration, wintering, breeding).
Upon selection, the evaluation species were evaluated to look at their dependence on the baylands and their regional, statewide, and flyway populations and trends. Additionally, an evaluation was made of what their specific conservation needs were and what the limiting factors to their persistence within the baylands and the region were. This review resulted in a thinning of the evaluation species to fourteen species which provided the basis for recommendations made for the other birds.
The recommendations of the Other Birds Focus Team focused upon those species which represented habitat features present only in the baylands.
Eared Grebe (Podiceps nigricollis). This species uses the bay primarily for wintering habitat. Historically was present in the bay in low numbers, presence of salt ponds has resulted in higher wintering populations. This species represents other bird species which rely on low to mid salinity salt ponds.
Western/Clarks Grebe ( Aechmophorus occidentalis and A. clarkii). These species frequent the Bay during the fall and winter. They characteristically utilized the open bay and larger tidal channels as well as ponded habitats in the diked baylands, where fish are present.
Brown Pelican (Peleanus occidentalis). The brown pelican is a summer and fall visitor to the Bay. This species is representative primarily of the open bay habitat of the Central Bay. It requires disturbance free roost sites such as the Breakwater at the Alameda Naval Air Station.
Snowy Egret (Egretta thula). The snowy egret is a year round resident of the estuary. It is a generalist in its use of wetland habitats within the bay. The species breeds within the baylands and is used as representative for other associated species and island nesting species in the Bay. The primary limiting factor for this species is the availability of nesting sites isolated from predation and disturbance.
Northern Harrier (Circus cyaneus). The harrier is a resident raptor which inhabits the baylands. This species uses all the current habitats of the baylands and adjacent open uplands. The species is used to represent other raptor species which utilize the baylands. California Black Rail (Laterallus jamaicensis). The State listed threatened black rail is a resident of high tidal marshes of the San Pablo and Suisun bays. The species is representative of brackish tidal marsh species.
California Clapper Rail(Rallus longirostris). The State and Federally listed endangered clapper rail is a resident of the tidal marshes of the estuary. The species characteristically inhabit the more saline marshes of the bay. Highest populations are found in large tidal marshes with well developed channel systems. Forster's Tern (Sterna forsteri). Resident tern of the baylands. Uses salt ponds and managed wetlands with islands or appropriate structures for nesting. Forages in both managed wetlands and the open Bay and channels. Representative of species which rely on salt ponds for nesting habitat.
California Least Tern (Sterna antillarum browni). This State and Federally endangered species breeds in the bay, nesting on bare open sites in close proximity to areas of shallow open water. The species historically nested on beaches but has been displaced to areas of unvegetated fill adjacent to the bay. The species also relies on low salinity salt ponds for post fledging foraging.
Burrowing Owl (Speotyto cunicularia hypugaea). The burrowing owl is a species of special concern. It is characteristic of open grasslands adjacent to the Bay. Much of its historic habitat particularly in the South Bay has been lost to developed. It represents species which inhabit the upland grasslands adjacent to the baylands. In many cases the species is found in diked baylands predominated by annual grasses.
Yellow Warbler (Dendroica petechia). The yellow warbler is both a resident and migrant in the riparian habitats at the edge of the Bay. The species is used as a representative for those species which depend upon riparian and willow thicket habitats.
Salt Marsh Yellowthroat (Geothlypis trickas sinuosa). The yellowthroat is found in fresh and brackish marshes, tidal marshes, swampy riparian thickets and weedy fields and grasslands bordering wet habitats. Yellowthroat territories frequently include the ecotones between these communities.
Savannah Sparrow (Passerculus sandwichensis). The savannah sparrow is found in the transition zone between tidal marsh habitats and adjacent open uplands. This species is representative of species found in the grasslands within the baylands and transitions form marsh habitats to open uplands.
Song Sparrow (Melospiza melodia). Three subspecies of song sparrows are found in the tidal marshes of the San Francisco Bay. All are considered species of special concern due to their limited distribution and loss of habitat. These species are characteristic of tidal marshes and depend upon adjacent uplands for refugia.
Based upon the tenents identified above and the selected evaluation species, the following recommendations are made concerning future management and restoration of the baylands. From the discussion above the emphasis of the recommendations is on restoration of tidal habitats, particularly tidal marsh, due to the substantial reductions of this habitat and the number of listed or sensitive species they support. While the recommendations of the Other Birds Focus Team focus primarily on tidal habitats, it is recognized that diked habitats provide support functions for some Other bird species, but more so for Shorebird and Waterfowl. Consequently, maintenance and enhanced management of retained diked baylands will be an important feature for insuring that competing species need are balanced. Additionally for Other Bird species, it is important that upland habitats contiguous with the baylands be provided to refugia to provide a buffer from disturbance and provide habitat for bayland species which also utilize uplands.
A. Increase the amount of tidal marsh in all subregions of the Bay. Tidal wetland acreage within the Bay has been reduced by approximately 90 percent. Much of the tidal marsh that remains is recently developed and often linear with a high perimeter-to-area ratios. These tidal marshes in many cases are poorly developed, lacking topographic variation, extensive tidal channels and pannes. Consequently, they are of reduced value to many species which depend upon them. Evaluation of current tidal marshes within the Bay indicates that approximately 50 percent of the current acreage is of good habitat quality for other bird evaluation species which depend upon this habitat type.
B. Connect tidal marshes to uplands in natural gradients in all subregions of the Bay. Where possible, site marsh restorations at locations where such connections can be restored naturally. Restoration of such connections will be important for accommodating a rise in sea level.
C. Maintain low and midsalinity salt ponds in the absence of salt production, (e.g., intake ponds and adjacent evaporators), as well as other open water habitats. Several ponds operating in series are needed to provide concentration of brines to provide the array of salinities preferred by species using salt ponds. Siting of several such pond complexes around the Bay should be located so that the discharge point could be used to add salinity to large waste water discharges.
D. No special emphasis should be placed on managing for primarily upland species within the baylands (e.g., meadowlark). Protection and enhancement of transitional and adjacent uplands and seasonal and managed wetland areas will provide an appropriate habitat.
E. Development of permanent freshwater emergent wetlands should not be a priority where it would preclude restoration of tidal wetlands or convert existing wetlands within the baylands. Development of such habitats should be focused in upland areas adjacent to the bay. Development of fresh to brackish marshes using treated wastewater can provide important habitat for other bird species such as egrets and waterfowl (example at Hayward treatment marsh). Such wetlands should be carefully sited and designed to avoid direct and indirect impacts to existing wetlands.
F. Riparian and will thicket (sausal), habitats should be enhanced and developed where possible around the Bay to provide habitat migrants and resident species. These habitat should be distributed as evenly as possible around the Bay. Use of treated effluent could be used to enhance flows in streams tributary to the bay which would help to expand and maintain riparian habitats. Setback levees should be encouraged in flood control planning to restore or maintain or restore flood plain and riparian habitats where possible.
G. Within the historical extent of the Bay, farmed and grazed lands, can be maintained as long as they are in ongoing production. Farming practices which enhance wildlife and are compatible with agricultural production should be encouraged, particularly enhancement of seasonal ponding. These lands provide support to many species although the level of support varies widely depending upon the agricultural practices and climatic factors which affect the degree of ponding and quality of habitat for wildlife.
H. Opportunities to protect and enhance upland transitional habitats should be identified and given priority. Development of upland transitions should be incorporated into tidal marsh restorations where possible. They should be incorporated as they would naturally occur. For tidal marsh restorations where levees will be required, the levees should be constructed to mimic naturally occurring transition zones between tidal marshes and uplands. The levee slopes should be designed with gradual slopes. Where feasible, areas of seasonal or high tide ponding should be incorporated into the transition zone.
I. In areas now largely developed, remaining wetland parcels should be retained and/or enhanced where possible, especially where such parcels are adjacent to larger wetlands, to function as dispersal corridors for wetland birds moving between larger intact wetlands and other native habitats.
Tidal marsh = all tidal marsh types.
Salt pond = all salt pond types, inactive and crystallizer.
Diked/Farmed Baylands = diked marsh, ruderal bayland, grazed bayland, farmed bayland.
*subject to further review.
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