brackish stream sides and marshes, associated 

 with heavy riparian and swamp vegetation (Grin- 

 nel and Miller 1944), such as alkaline cattail mar- 

 shes (Phillips et al. 1964). In general, habitat con- 

 sists of shallow-water marshes containing dense 

 stands of cattail (Typha latifolia) and big bulrush 

 or tule (Scirpus acutus), in both brackish and 

 freshwater situations. Shallow water with mud 

 flats available for feeding are selected over areas 

 where water is deep and steep banks prevalent. 

 Stands of cattail and tules dissected by narrow 

 channels of water 1.6 to 7 m wide had densest 

 populations, according to Tomlinson and Todd 

 (1973). Preferrred breeding habitat is light cattail 

 or tule stands with downed vegetation, with adja- 

 cent dry land a must (Ohmart and Smith 1973). 

 Water of breeding habitat on the Colorado River 

 Delta in Mexico is salty and growths of cattails 

 and tules appear to be limited to small fresh or 

 brackish sloughs. The vegetation is characterized 

 by an overstory of saltcedar {Tamarix sp.) and an 

 understory of iodine bush {Allenrolfia occident- 

 alis), all quite different from the habitat above 

 the delta (Tomlinson and Todd 1973). 



The rail seems to require wet mudflat or sand- 

 bar sites, covered rather densely with mostly ma- 

 ture vegetation exceeding 0.5m. Optimum condi- 

 tions are created by open ponds or channels as 

 opposed to unbroken stands of vegetation. Salt- 

 cedar {Tamarix pentandra) stands are rarely 

 utilized (Todd 1971). 



The following habitat characteristics appeared 

 in locations where clapper rail densities were 

 higher than average: 



1. Water, flowing through many small 

 channels from 0.5 to 3 m wide, either covered 

 with vegetation or appearing as small bodies 

 of open water 0.02 to 0.2 hectares in size. 



2. Extensive areas of water of depth less 

 than 0.3 m little or no daily fluctuation in 

 water level. 



3. High ground in strips or, less importantly, 

 as small islands. 



4. Emergent vegetation, cattail or bulrush, 

 with little or no Phragmites sp., which are too 

 high and have few down stems (Gould 1975). 



At Topock Marsh, the highest densities were 

 found in light cattail stands — lowest, in heavy 

 stands. Dense cattail had 0.9 rails per 10 ha; light 



light cattail 1.9 per 10 ha; dense buUrush 1.7 per 

 10 ha; light bullrush 1.8 per 10 ha. The majority 

 of rails were in the ecotone between emergent 

 vegetation and higher ground, either at the shore- 

 line or on hummocks in the marsh (Smith 1974). 

 Winter habitat probably includes mangrove 

 swamps on the Pacific coast of Sinaloa and fresh- 

 water marshes of Puebla (Banks and Tomlinson 

 1974). 



FOOD AND FORAGING BEHAVIOR 



The major food is invertebrates, with little 

 vegetable matter. Crayfish [Procambarus and 

 Oropectes) were the dominant food in 9 of 10 

 stomachs from Topock Marsh south to Imperial 

 Reservoir. Of two stomachs from the confluence 

 of the Gila and Colorado Rivers, one contained 

 primarily (98%) freshwater clams {Corbicula sp.), 

 and the other, 97% isopods. Colorado River delta 

 specimens contained a greater variety of food, but 

 the majorcomponents were water beetles and fish. 

 Of 16 stomachs, 9 had crayfish, 1 1 had insect frag- 

 ments, 4 had water beetles, 4 had fish, and 3 

 contained clams. Other insects in small amounts 

 were weevils, damselfly nymphs, dragonfly 

 nymphs, grasshoppers, and insect eggs. Spiders, 

 leeches, prawns, and a small mammal bone were 

 also found. Plant material consisted of twigs (10% 

 in one stomach), 2 legume seeds (1 stomach) and 

 18 unidentified black seeds (3 stomachs). Like 

 other subspecies of clapper rail, yumanensis seems 

 to be a selective opportunist whose variety of 

 food is limited by its availability in the particular 

 habitat (Ohmart and Tomlinson 1977). In To- 

 pock Marsh, crayfish are an important part of the 

 diet. Crayfish are found in all areas where rails 

 occurred, with the greatest number of crayfish in 

 water 8 to 15 cm deep with abundent stems and 

 leaves lying in the water. Floating and recumbent 

 vegetation is important in foraging areas, as they 

 provide habitat for crayfish and a platform to 

 walk on (Smith 1974). 



SHELTER REQUIREMENTS 



None other than mentioned in other sections. 



NESTING OR BEDDING 



In three nests, material consisted of black 



