abundant in south San Francisco Bay, while being 

 less numerous in similar marshes in northern San 

 Francisco Bay and the south end of Tomales Bay 

 and apparently absent from Suisun Bay, where 

 extensive pickleweed marshes exist. He noted that 

 the latter area has lower salinity, which may pre- 

 vent occurrence of organisms on which rails de- 

 pend for food. Wilbur (pers. coram.) adds that 

 habitat in northern San Francisco Bay is almost 

 pure pickleweed while in the southern part, where 

 rails are more numerous, it is mixed pickleweed- 

 cordgrass with cordgrass predominating. 



Fall wanderers from the salt marshes have 

 been observed feeding in a city park, on the edges 

 of lawns next to shrubbery into which they re- 

 treated (Orr 1939). 



FOOD AND FORAGING BEHAVIOR 



Food consists almost entirely of animal mat- 

 ter, such as worms and crustaceans available in 

 salt marshes. Several stomachs taken in Alameda 

 county contained only parts of crabs (Grinnell, 

 et al. 1918). Rails may feed on molluscs obtained 

 by probing in mud-bottomed sloughs (Williams 

 1929, Moffitt 1941, Test and Test 1942). Fall 

 wanderers away from salt marshes have been noted 

 feeding on earthworms in a city park. One was 

 seen to swallow 5 worms in 5 minutes (Orr 1939). 

 Most feeding done in marshes is at low tide when 

 the most food is available. Volumetric content of 

 stomachs of 18 rails taken near Palo Alto, Calif. 

 4 February 1939 averaged 85% animal matter and 

 14.5% vegetable matter, all of which consisted of 

 Spartina seeds. No gravel was found in any stom- 

 ach. Plaited horse-mussel {Modiolus demissus) 

 amounted to 66% of the animal food. Spiders of 

 the family Lycosidae, common inhabitants of 

 marshes, made up 17.5% of animal matter (Moffitt 

 1944). Williams (1929) found the little macoma 

 clam {Macoma baltica) to be a principal item of 

 food near Palo Alto. Grinnell, et al. (1918) found 

 parts of the yellow shore-crab or mud crab {Hemi- 

 grapts oregonensis) were almost the only food in 

 clapper rails in Alameda County. Emerson 

 (1885) found that worms and insects made up 

 most of the food. Moffitt (1944) comments that 

 the relative amounts of plant and animal matter 

 in the rail's diet varies with the time of year, stage 

 of tide, and geographic locality. 



Rails often wash their food before swallowing 

 it. They swallow small clams whole and peck larger 



ones open with their bills and eat only the con- 

 tents. Crabs are dismembered and pecked open 

 before being eaten (Cohen 1895, Grinnell et al. 

 1918, Tomlinson and Wilbur 1976). 



SHELTER REQUIREMENTS 



Dense marsh vegetation for concealment and 

 nesting. 



NESTING OR BEDDING 



Rails nest on or near ground, usually on a 

 slight rise near a tidal slough; many well defined 

 trails lead from them to the water (Bryant 1880; 

 Taylor 1894, Cohen 1895, DeGroot 1927). Nest 

 sites are in dense patches of pickleweed {Sali- 

 cornia) or cordgrass {Spartina), or at the base of 

 gumweed {Grindelia) plants (Grinnell et al. 1918, 

 Zucca 1954, Gill 1972, Bent 1926, Wilbur and 

 Tomlinson 1976). 



The nest is a platform or heap of material of 

 cordgrass and dead plants buUt up 8 to 15 cm 

 above ground, sometimes deeply cupped and 

 securely woven to surrounding vegetation (Bryant 

 1880, Cohen 1895, DeGroot 1927, Emerson 

 1885, Taylor 1894). Rails frequently build several 

 nests but use only one (Adams 1900, Gill 1972, 

 Grinnell et al., Bent 1926, Tomlinson and Wilbur 

 1976). 



RITUAL REQUIREMENTS 



Rails exhibit intraspecific hostility indicating 

 territoriality (Williams 1929). 



OTHER CRITICAL ENVIRONMENTAL 

 REQUIREMENTS 



An unobstructed tidal flow of clean saltwater, 

 saltmarsh vegetation, and mudbanks for suitable 

 food organisms are environmental requirements 

 of/?. /. obsolete. 



POPULATION NUMBERS AND TRENDS 



No estimate of the total California clapper rail 

 population has been made (Wilbur and Tomlinson 

 1976). At least 100 were noted in an area of less 

 than 2.5 km^ of salt marsh near Palo Alto on 

 Feb. 1939 (Moffitt 1941). Gill (1972), by dragging 

 a rope, found densities ranging from 0.34 to 0.43 

 rails per ha in primary habitat (pure cordgrass) to 

 0.13 to 0.17 per ha in secondary habitat (mixed 

 cordgrass, pickleweed and other marsh vegetation) 



