NATURAL HISTORY OF THE TWIN-SPOTTED RATTLESNAKE (CRoTALUs pRICEI) IN THE SOUTHERNMOST RANGE OF ITS DISTRIBUTION

The Twin-Spotted Rattlesnake (Crotalus pricei) is a small-bodied rattlesnake that inhabits mountain systems from the southwestern tip of the USA to central Mexico. Despite its wide distributional range, there is scarce information about its natural history in many localities where it is found, including the population occurring in Aguascalientes, Mexico, where fewer than 10 individuals have been reported since 1953. The goal of this study was to describe ecological and morphological aspects of C. pricei in the southernmost portion of its distributional range and compare them with what we currently know for this species. We conducted field surveys in 2019 and 2020 searching for individuals of C. pricei and we found 19 individuals. General characteristics of this population did not vary from what we know for C. pricei, although we found some morphological differences at the subspecies level. Crotalus pricei was more easily found in July, August, and September, and it was commonly associated with Pine and Oak Forest leaf litter. Its main activity periods during the day were from 1100 to 1600. Two females gave birth while they were held captive; one gave birth to four neonates, and the other just six unfertilized ova. The information presented here increases the ecological knowledge of the population of this species occurring in Aguascalientes, Mexico.