16. CROTALIDM 



three miles south from Lovic, Oro Grande, and Needles, 

 San Bernardino County; Indio, Torres, Mecca, and Blythe 

 Junction, Riverside County j and on Echo Island in the 

 Salton Sea, at New River near the Salton Sea, Holtville, 

 Coyote Wells, Laguna Station, and Pilot Knob, Imperial 

 County, and in La Puerta Valley, San Diego County. 



Habits. — In certain parts of its range, as in the Colorado 

 and Mohave deserts, this species is very numerous, but owing 

 to its coloring and habits individuals seldom are seen. The 

 name "side-winder" is derived from its peculiar mode of 

 progression: "when disturbed it moves away sideways, keep- 

 ing its broadside toward the observer instead of proceeding 

 in the usual serpentine manner. * * * One was shot con- 

 taining a kangaroo rat (Dipodomys) and two pocket mice 

 (Perognathus). * * * During the latter part of April and 

 the early part of May these rattlesnakes were often found 

 in pairs and were doubtless mating. At such times they re- 

 mained out in plain sight over night instead of retreating to 

 holes or shelter under desert brush, and on two occasions they 

 were found by us on cold mornings so early that they 

 were too chilled to move until considerably disturbed."* 



Heller is quoted by Meek as stating that it is strictly 

 nocturnal. I have found it to be not entirely inactive in the 

 daytime. Two were found coiled in the mouths of rodent 

 holes in clumps of cactus where they were lying in the sun. 

 One was found crawling under a bush, and one hidden under 

 a tin can. One was found out on the desert at night, and 

 it is probable that most rattlesnakes are most active at that 

 time. Camp states that both at Needles and near Blythe 

 Junction individuals were traced by the characteristic tracks 

 in the sand. Each was found closely coiled in a symmetrical 

 pad and partly buried flush with the surface in the hot sand 



•Merriam, N. Amer. Fauna No. 7, 1893, p. 217. 



