Maximum brood size for the Yucatán Neotropical Rattlesnake (Crotalus tzabcan Klauber 1952)

R esearch on reproductive biology and life history of ver- tebrates (e.g., ages and sizes at first reproduction, litter sizes) is essential to understanding the evolution and ecology of species, and rattlesnakes (Crotalinae: Crotalus spp.and Sistrurus spp.) are excellent model organisms for reproductive studies in nature (Taylor and Booth 2017).However, field observations of breeding female rattlesnakes remain relatively scarce, particularly for species outside the United States, in part because they usually are smaller than male counterparts and likely also because males are easier to find than females in some populations (Taylor and Booth 2017).The Yucatn Neotropical Rattlesnake (Crotalus tzabcan Klauber 1952) is a crotaline endemic to the Yucatn Peninsula Biotic Province, where it inhabits mostly open and dry environments (Heimes 2016;Carbajal-Mrquez et al. 2020).Although it is widely distributed in this region, it is elusive, and thus knowledge on its natural history is scarce.As with other crotalines, C. tzabcan is viviparous, with mating usually occurring during the dry season, and birthing during the rainy season from July to September (Armstrong and