A Long-Term Dietary Assessment Of Invasive Boa Constrictor On Aruba

Invasive Boa Constrictors (Boa constrictor) have established a reproductive population on Aruba. High B. constrictor densities could stress prey populations on this small, faunally simplistic island. We examined diet, size, and condition of 501 B. constrictor at three periods over nearly 15 y: during early invasion, approaching the peak in encounters, and after 5 y of declining encounters. The 401 prey identified consisted of 32.9% mammals, 37.4% lizards, and 29.7% birds. Dietary proportion of these categories was consistent across sampling periods. Non-native prey were consumed in relatively high proportions. Despite a positive relationship between snake snout-vent length and prey mass, even the largest snakes consumed small prey. During the high encounter period, many snakes had empty digestive tracts, little abdominal fat, and low body mass, possibly due to a decline in prey availability; however, snakes from residential/agricultural areas had better body condition than those from natural areas. High population densities of the native Aruban Whiptail Lizard (Cnemidophorus arubensis) may provide a consistent food supply for B. constrictor in both natural and residential/agricultural areas, and domesticated prey near human habitation may subsidize the population in residential/agricultural areas. Improved body condition in the last sampling period suggests that the population is either stabilizing or poised for an increase. The endemic Aruba Island Rattlesnake (Crotalus durissus unicolor) and B. constrictor had similar, broad diets that overlapped heavily. Eradication of B. constrictor from Aruba is unlikely, but integration may be possible if the population can be stabilized at low densities. We recommend continued control efforts and systematic monitoring of prey populations.