DEFENSIVE BEHAVIOR
Behaviorally, V. nuchalis is a much more defensive species as compared to all the Laguna monitors I have kept, and in the several months that my observation on these two individuals have spanned, there was definitely no toning down of the said defensiveness. Their defensive repertoire includes the raising of the body by the stiffening of all four legs, accompanied by the expansion of the throat and a very audible hissing.
If I come further forward, even with no sudden movement or other threatening action, they will lash out with their tails with such force that each episode warranted enough worry of the front glass pane smashing. These animals will even ignore food offered to them, preferring instead to assume their defensive antics than eat immediately. (Feeding commences after all and any sight of a human – or even cats and dogs, for that matter – have vanished.)
Of course, drawing conclusions from observations of just two specimens are not enough, but there is no denying that these observations does say something. By contrast, captive individuals of Laguna monitors settle down rather quickly. When threatened or cornered, they resort to a fleeing response than standing their ground and assume a defensive mode. They may attempt to bite and empty out musk when handled, but this does not apply to all individuals.
This species begins to lose their fear of humans in just a matter of a few weeks, even becoming amenable to hand feeding; so strong is their feeding response that merely opening the enclosure triggers them into preparing a lunging action in anticipation of food.
Like other medium to large-sized monitors, these animals are quite adept at inflicting damage to their enclosures, particularly screens and doors, and the Sta. Maria specimen – supposedly V. dalubhasa – is no exception. But perhaps due to being a longterm captive, this animal has developed a habit of straying for only a few meters away from its enclosure upon escape. In at least three instances, it just stayed right beside its cage, giving me only casual glances and completely unperturbed as I make my approach.
Behavior-wise, the two sister species (assuming here that the Laguna population represents V. dalubhasa) are worlds apart.