The goal of this study was to characterize the initial growth trajectory of Epicrates assisi, 1 Epicrates cenchria, and Epicrates crassus snakes raised in captivity. An exponential model with 2 parameters for birth weight (A) and growth rate (k) was fitted for each animal. There was a significant 3 difference A and k among the three species, the means (standard error) for A and k parameters were 4 31 (0.3) g and 0.0027 (0.00006) for E. assisi, 27.6 (0.6) g and 0.0046 (0.00013) for E. cenchria and 25.9 5 (1.4) g and 0.0033 (0.00027) for E. crassus. We showed a significative variability between species for 6 initial growth trajectory. In addition, we also demonstrated the existence of variability within species, 7 which can be used to change the growth trajectory of snakes, being a tool for selection and genetic 8 improvement.9