A preliminary study of the effects of enrichment on the activity and spatial distribution of captive monitor lizards in Nakhon Ratchasima Zoo, Thailand

The monitor lizard (Varanus salvator) has the widest distribution among all extant varanids found across South and Southeast Asia. However, behavioral studies on captive monitor lizard have not been well-documented. The objective of this research was to investigate the effects of enrichment items on the activity and spatial distribution of captive monitor lizards. The study involved three adult captive Black water monitors (Hiea dam), three adult Roughnecked monitors (Ngu-hao Chang), and two adult Dumeril’s monitors (Tut-too) in outdoor enclosures. Three treatments were administered: control (no enrichment item), cone (enrichment item), and takraw (enrichment item: a rattan ball). The frequency of activity and spatial distribution of three species of monitor lizards were recorded. The results showed that the percentages of activity and spatial distribution of three species of monitor lizards were not significantly affected by the enrichment items (P > 0.05). However, there were significant differences only in lying behavior between the Hiea dam, Ngu-hao Chang, and Tut-too monitors (P < 0.05). In conclusion, the general behaviors of captive Hiea dam, Ngu-hao chang, and Tut-too monitor lizards were similar, and their spatial distribution was also similar. The behavior and spatial distribution of captive monitor lizards were not affected by the enrichment items.