The fossa (Cryptoprocta ferox) is the largest native carnivore of Madagascar and the sole member of the genus Cryptoprocta within the family Eupleridae, order Carnivora. Endemic to the island, it occupies a range of forested habitats from lowland rainforests to montane and dry deciduous forests, often preferring dense canopy cover that facilitates its arboreal hunting style. Morphologically, the fossa resembles a small cougar: it has a sleek, elongated body, muscular limbs, semi‑retractable claws, and a long, thick tail that provides balance during rapid climbs and leaps. Its flexible ankle joints allow it to descend trees head‑first, a unique adaptation among Malagasy mammals. The species is listed as Vulnerable by the IUCN due to ongoing habitat loss and hunting pressure, with an estimated 2,500–10,000 mature individuals remaining. Conservation efforts focus on protecting remaining forest blocks, mitigating hunting, and promoting community‑based stewardship to ensure the fossa’s continued ecological role as a top predator on Madagascar.

Fossas are primarily solitary, with individuals maintaining exclusive home ranges that may overlap with those of the opposite sex. Males hold larger territories that encompass several female ranges, and they use scent marking, vocalizations, and visual cues to communicate. Activity peaks at dusk and during the night, though they are also active during daylight in areas with low human disturbance. Territorial disputes are settled through vocal growls, hisses, and occasional physical confrontations. During the breeding season, males increase their movements to locate receptive females, and they may temporarily tolerate each other’s presence. Communication includes a repertoire of whines, clicks, and a distinctive “purring” sound used between mother and offspring. The fossa’s agility enables it to patrol both ground and canopy, making it an effective ambush predator.

The fossa is a strict carnivore, preying on a wide array of vertebrates. Its diet is dominated by lemurs, especially the diurnal Propithecus and the nocturnal Microcebus species, which together can comprise up to 70 % of stomach contents in some studies. It also hunts tenrecs, rodents, birds, reptiles (including chameleons and geckos), and occasionally scavenges carrion. Hunting strategy combines stealthy stalking with rapid bursts of speed; the fossa can sprint up to 20 km/h on the ground and can climb trees with equal agility, allowing it to ambush arboreal prey from above. It uses powerful jaws and sharp carnassial teeth to dispatch prey quickly, often delivering a fatal bite to the neck. Daily food intake varies with prey availability but averages 300–500 g of meat for an adult male.

Sexual maturity is reached at about 2–3 years for both sexes. Breeding occurs opportunistically throughout the year, with a peak during the rainy season (November to March) when prey is abundant. After a gestation period of 84–90 days, females give birth to litters of 1–4 young, most commonly two or three. Neonates are born blind and hairless, weighing roughly 150 g, and are hidden in a secure nest within a hollow tree or dense vegetation. The mother nurses the kits for approximately four months, during which she teaches them hunting techniques and climbing skills. Juveniles become independent at 6–8 months but may remain near the mother’s range for several additional months before establishing their own territories. Parental care is solely provided by the female; males play no role in rearing.

The IUCN classifies the fossa as Vulnerable, with a declining population trend. Primary threats include extensive deforestation driven by slash‑and‑burn agriculture, illegal logging, and expanding mining operations, which fragment the forest habitat essential for hunting and breeding. Hunting for bushmeat and traditional medicine further reduces numbers, especially in remote communities where the fossa is prized for its meat and fur. Road development increases mortality from vehicle collisions and facilitates access for hunters. Introduced species such as feral dogs and cats may compete for prey and transmit diseases. Current estimates suggest only 2,500–10,000 mature individuals remain, scattered across protected areas and unprotected forest fragments. Conservation actions focus on expanding and effectively managing protected reserves, enforcing anti‑poaching laws, and engaging local communities in sustainable livelihood programs that reduce reliance on forest resources.

• The fossa can rotate its hind ankles up to 180°, allowing it to descend trees head‑first.
• It is the only Malagasy carnivore capable of sustained high‑speed pursuit on the ground.
• Fossas have a semi‑retractable claw system similar to felids, despite being more closely related to mongooses.
• Genetic studies show the fossa diverged from other Eupleridae about 18 million years ago.
• In some regions, local folklore regards the fossa as a guardian spirit of the forest.