Social Behaviour

Monitor lizards are not usually sociable animals. Congregations of monitor lizards have been reponed amongst juveniles, around carrion and on riverbanks but most are solitary creatures that shun company except during the breeding season. They are not territorial in any strict sense and the activity areas of many animals may overlap. However most have activity ranges that are large enough to make accidental encounters unlikely, The lizards are certainly able to detect the presence of other monitors by the smells they leave behind them. Quite often, when two monitor lizards meet one will attempt to eat the other. They are well equipped to deliver savage bites and grievous scratches and so every encounter is potentially dangerous. When face to face with each, other monitor lizards engage in a series of distinctive behaviours, some of wh.ich are highly ritualised (e.g. Auffenberg 1978, Daltry 1991). All involve a series of visual and probably scent oriented cues and they playa very important role in preventing the lizards' social occasions from degenerating into a cannibalistic orgy.

Rirualised fights have been recorded for many species of monitor lizard (e.g. Ali 1944, Deraniyagala 1958a, Murphy & Mitchell 1974, Carpenter et al 1976, Auffenberg 1981a&b, 1988, Tsellarius 1994 and particularly Hom 1985 & Hom et al 1994). The most dramatic are those of the larger species in wh.ich the animals stand bipedally, gripping their opponents around the shoulders and attempt to wrestle each other to the ground. In dwarf monitors and some larger species the wrestling matches only occur in a horizontal position, with the lizards grasping each other with all four legs and sometimes supporting themselves only with their heads and tails. Again the object is to overpower and get on top of the opponent. In all cases these ritualised fights allow the lizards to test their strength against each other without incurring serious injuries, particularly bites. Only rarely does one lizard break the rules and tear the other to pieces. Success in combat seems to be determined largely by strength and the winners tend to be the heavier animals, at least in bipedal contests. The fights are often presumed to occur only between males but there is evidence that they are practised by both sexes (Gaulke 1992a, Hom et al 1994). However males appear to engage in engage in ritual combat more often, as is evidenced by the large numbers of scars on the backs of old specimens. In the wild the fights are often observed to occur around carrion and are most common during the breeding season. Once dominance has been established the losers may avoid having to fight rematches by displaying appeasing behaviours when they encounter the dominant animal (Auffenberg 1981 , Daltry 1991). It is presumed that animals which habitually win in bouts of combat have access to better resources (food, shelter, basking sites, nest sites) than the losers, and that amongst males, the dominant animals would be more likely to be successful with females, although this is not always the case (Carter 1990).

Attribution / Courtesy: Daniel Bennett. 1995. A Little Book of Monitor Lizards. Viper Press U.K.