The Amphibians and Reptiles of Sinaloa, Mexico - Smithsonian ...

AMPHIBIANS AND REPTILES OF SINALOA, Mixico 183
are similar to the race of bilineatus purported to be restricted to the
Ajo Mountains, Arizona (Hensley, 1950:344). The subspecies of
M. bilineatus presently are being reviewed.
Although most specimens were collected during the day, there
are indications that the species may be partially nocturnal in habit.
A specimen was found alive at 2220 hours on the road south of
Acaponeta, Nayarit, with a large Drymarchon. A second individual
(LACM 6989) was found dead on the road at midnight on August
3. This snake was active between 2315 hours and midnight, for the
same stretch of highway was carefully searched at about 2315 hours.
Several other large colubrid snakes were seen on the highway at
night, but due to their speed they eluded capture. Judging from
their size the snakes might well have been Masticophis blineatus.
Certain ecological factors, such as competition from other large
diurnal predatory snakes, may explain the apparent nocturnal activity
of this species in Sinaloa.
Distribution in Sinaloa.—Lowlands and foothills below about 550
meters throughout the state. See Fig. 74.
Specimens examined.—6.5 km. S Casa Blanca, 520 m. (* KU 83406); 1.9
km. NE Chupaderos, 350 m. (" KU 78949); 0.2 mi. W Concordia (LACM
6992); 16 km. W Concordia