Singapore is very sunny, except when it rains out of nowhere, so the lizards are very happy to make use of the hot cement or brick walls to lie on in the afternoon. In this way they are modern lizards, adapting to an increasingly human environment.
Grabbing the lizards or stepping on them (clearly) can hurt the lizards quite badly, but if you make sure to be careful and watch your step, you won’t run over them. They are also very fast and will probably get away in time anyway!
