Sumatran rhinoceroses are typically solitary animals, and they are not known to live in large social groups. They are generally reclusive and prefer a solitary lifestyle. Adult males and females typically have separate home ranges and only come together during the breeding season when a female is receptive to mating. After mating, they go their separate ways.
The only time Sumatran rhinos are found in groups is when a mother is caring for her calf. The mother-calf bond is relatively strong, and the calf may stay with its mother for an extended period before becoming independent.
This solitary behavior is in contrast to some other rhino species, like the white rhinoceros, which is known to form loose groupings.