Hearing

The only sounds commonly made by monitor lizards are a loud hiss and the occasional sneeze, but some spiny-tailed monitors can produce a rattling sound by striking the tail on a solid object, Bone (1920) record s a booming sound from a lace goanna and Ridley (1889) reported that water monitors were said to utter "the cry of the biawak", a loud, barking, laugh. Krishnan (1992) notes that Bengal monitors are reported to snore at night and claimed that they issue a call not unlike that of a bird when frightened . The ears of monitor lizards are not particularly well developed, and whilst they can hear, they do not seem to rely upon them to look for food nor to communicate with each other. Many individuals do not react even to loud noises and it is often possible to creep up on basking monitor lizards from behind if they receive neither olfactory nor visual clues of your approach.