They are omnivores and tend to be solitary, or live in small groups, unlike most other deer species. There are populations of muntjacs in Great Britain, but they were accidental transplants.
Muntjacs are territorial. Males use their large, tusk-like canine teeth and short antlers to defend territory and fight for females. Muntjacs make barking sounds when startled or when predators enter their territory. Territorial scent marking is done with liquid from the distinctive glands near their eyes.