PRIORITY INDEX 



8 



DESCRIPTION 



R. I. yumanensis is a chicken-size bird, gray- 

 brown above with cinnamon brown breast, flanks 

 barred gray and white, and a white patch under 

 the upturned tail. Bill, legs, and toes are long. 

 Similar to R. I. levipes but paler underparts, 

 duller and more olivaceous upper parts. More 

 slender tarsus and bill (Dickey 1923). Very simi- 

 lar to levipes of southern coastal California, 

 differing only in more slender proportions and 

 paler coloration (Van Rossem 1929). Similar to 

 rhizophorae (of Sonora) in paleness but, in gen- 

 eral, more brownish (less grayish) and has more 

 pointed wings because of difference in length of 

 primaries. Compared with levipes, it is paler on 

 breast and throat, has grayer flanks, duller wing 

 coverts and more extensive brown in the crown 

 (Banks and Tomlinson 1974). Ripley (1977), 

 although noting the above differences, is dubious 

 about the validity of yumanensis as a subspecies. 



Measurements — Male: Wing 143.1-160.1 mm 

 (av. 149.8 mm); tail 60.3-69.0 (av. 64.2); exposed 

 culmen 55.4-61.8 (av. 59.2); tarsus 47.9-55.0 

 (av. 50.3); middle toe without claw 50.3-54.6 

 (av. 52.7); weight 222-307 g (av. 256g). Female: 

 wing 135.6-148.5 mm (av. 141.8mm); tail 57.8- 

 62.6 (av. 59.9); exposed culmen 51.9-58.2 (55.5); 

 tarsus 43.0-49.5 (45.4); middle toe without claw 

 46.5-51.1 (49.0); weight 192-268g (219g). Banks 

 and Tomlinson 1974). 



Eggs are oval, glossy, pale pinkish buff and 

 cartridge buff, with sparse spots of varying brown 

 shades;41.8 by 28.8mm (Bent 1926). 



RANGE 



This rail breeds, at present, in marshes along 

 the Colorado River in California and Arizona, 

 from Needles to the Topock marsh south to the 

 Colorado River delta in Sonora; west to marshes 

 along the southeastern Salton Sea, California; 

 east, locally, to the Gila River near Tacna, Ari- 

 zona, and possibly the Salt River near Phoenix 

 (Tomlinson and Todd 1973, Ohmart and Smith 



1973). It is thought to winter, at least in part, in 

 coastal and interior marshes and coastal mangrove 

 swamps in Mexico, including Estero Mescales, 

 8 km north of Teacapan, and Castillo, 11km east 

 of Mazatlan, Sinaloa; also at Laguna San Felipe, 

 Puebla (Banks and Tomlinson 1974). 



The former more restricted range is documen- 

 ted by Dickey (1923), Bent (1926, Van Rossem 

 (1929), Moffitt (1932), Abbott (1940), and 

 Grinnell and Miller (1944). 



Lack of authentic winter records in the north- 

 em breeding areas is noted by Phillips et al. 

 (1964), Todd (1971), and Tomlinson and Todd 

 (1973). Winter records of clapper rails (presum- 

 ably yumanesis but possibly wanderers of other 

 subspecies) at Salton Sea appearing on two 1976 

 Christmas bird counts published in American 

 Birds 31 (4):880, 1977 and confirmed by R. Guy 

 McCaskie (pers. comm.) ; and also at Topock Marsh 

 in January 1974 (Smith 1974), suggest that some 

 individuals do not migrate. 



Breeding populations along the Colorado Riv- 

 er, the Colorado River delta and at Salton Sea have 

 been identified from specimens as yumanensis 

 (Banks and Tomlinson 1974). No specimens rep- 

 resentative of the small, isolated populations 

 along the Gila and Salt Rivers in Arizona, nor any 

 winter specimens from the Colorado River or 

 Salton Sea have been critically examined. 



RANGE MAP: 



The following map depicts breeding range 

 (from Tomlinson and Todd 1973) and winter re- 

 cords (from Banks and TomHnson, 1974). 



STATES/COUNTIES: 



California: Imperial, Riverside, San Bernardino. 

 Arizona: Maricopa, Mohave, Yuma. 



HABITAT 



The Yuma clapper rail requires freshwater or 



