dowitchers); others go on to Central and 

 South America. May and June are the 

 months of least abundance of birds in 

 southern California wetlands (Collier 

 1975; Figure 46); at this time most of the 

 migrants have moved north toward their 

 breeding grounds. 



The role of the salt marsh in 

 supporting these bird communities is not 

 well understood. Most of the birds seem 

 to prefer intertidal flats to marsh 

 canopies for feeding and other activities. 

 The intertidal flat community profile of 

 Nybakken and Oliver (in prep.) for central 

 California includes many of the bird 

 species which also use southern California 

 wetlands. In addition, Boland (1981) 

 describes habitat utilization of Tijuana 

 Estuary by shorebirds, Dawes (1975) 

 discusses bird use of Los Penasquitos 

 Lagoon, and Quammen (1980) examines the 

 shorebird-invertebrate interactions at 

 Upper Newport Bay and Mugu Lagoon. While 

 the details of marsh and bird relation- 

 ships are unclear, we can at least 

 identify four ways in which marshes 

 contribute to the support of wetland birds 

 and suggest some ways in which birds in 

 turn influence salt marsh communities. 

 Marshes provide (1) bird food--either 

 directly as animals, plants, and plant 

 seeds which grow in the marsh or 

 indirectly by releasing organic matter to 

 tidal creeks which support food chains 

 leading to carnivorous birds, (2) cover 

 for protection against predators, (3) 

 habitat for nesting, and (4) habitat for 

 roosting. From the opposite perspective, 

 birds affect marsh communities by (1) 

 reducing densities of prey species and (2) 

 returning nutrients to tidal waters or 

 directly to the marsh in the form of 

 guano. Birds provide one of the few links 

 in the nutrient cycle which reverses the 

 net flow of materials to the sea. Their 

 feeding on marine fishes and defecation on 

 land provides the potential for continuous 

 recycling of elements which are essential 

 for marsh plant growth, Katsuo Nishikawa 

 of the Centre de Investigacion Cientifica 

 y Educacion Superior de Ensenada, Baja 

 California, is currently determining the 

 magnitude of nutrient return via pelicans. 



cormorants, and other fish- eating birds. 

 His data should suggest some interesting 

 differences in nutrient availability for 

 marshes adjacent to large bird- feeding 

 areas compared to isolated marshes with 

 little nutrient input. Perhaps we will 

 someday understand how the artificial 

 cormorant perches (power lines) across the 

 San Diego River channel contribute to the 

 high algal productivity of the upstream 

 mudflat and marsh communities. Since 

 cormorants release their wastes at their 

 roosts instead of in flight, substantial 

 nutrient additions may derive from the 

 hundreds of birds that rest over the river 

 channel each night. 



Because birds are of great interest 



to the general public, they have been a 



major consideration in the preservation 



and conservation of coastal wetland 



habitat. Using the southern California 



wetlands are our Federally listed 



endangered birds: the California least 



tern ( Sterna albif rons browni ) , the brown 



pelican ( Pelecanus occidentalis 



californicus ) , the peregrine falcon ( Falco 



peregrinus anatum ) , the light-footed 



clapper rail ( Rallus longirostris levipes ) , 



and the State listed (endangered) Belding's 



savannah sparrow ( Passerculus sandwichensis 



beldingl ) . The latter two species are 



residents of the salt marsh, and hence 



will be discussed in detail. Uther species 



which are commonly seen feeding within the 



marsh are long billed curlews ( Numenius 



americanus ) and willets ( Catoptrophorus 



semipalmatus ). Their habitat requirements 



are fairly broad, whereas the rail and 



sparrow are closely associated with only a 



portion of the marsh and absolutely depend 



on it for survival. 



The light-footed clapper rail (Figure 

 47) is restricted to coastal salt marshes 

 of southern California and northern Baja 

 California. Its Federal endangered status 

 is linked to the widespread habitat 

 destruction and modification which has 

 occurred in the region. Two other 

 subspecies of clapper rail are found in 

 the western United States, Rallus 

 longirostrus obsoletus in the San 

 Francisco Bay area and R. 1. yumanensis 



77 



