Fossas are mostly solitary animals, but they have been observed forming small groups for short periods of time, especially during mating season or when a mother is taking care of her young.
FOSSAS ARE GENERALLY SOLITARY ANIMALS AND DO NOT LIVE IN SOCIAL GROUPS OR PACKS. THEY ARE KNOWN TO BE TERRITORIAL AND MAINTAIN EXCLUSIVE TERRITORIES THAT THEY DEFEND AGAINST INTRUDERS, INCLUDING OTHER FOSSAS.