When rat populations are large, a hierarchy develops within a burrow. Stronger individuals become dominant, while weaker ones are subordinate. Males no longer protect female burrows. When a female is estrous, several males mate with her sequentially, in the order of their social dominance.
Rats exhibit aggressive behavior when threatened. They may fight, chase, bite and box. Rats also display some behaviors such as sidling and belly-up defensive postures.
Rats dwell in cities, suburbs and rural areas. They are capable of thriving in human environments are therefore are considered a commensal rodent. Rats are known to travel great distances and are wary of unknown objects in their established foraging paths. This skepticism can make trapping a rat particularly difficult for a homeowner.