Fossa: Madagascar’s Top Predator Looks Like a Cat But Is Closer to a Mongoose.

Madagascar separated from the African mainland approximately 160 million years ago, and the animals that arrived on the island afterward, carried by ocean currents on floating vegetation, found a world with no large predators and no competition from the mammal groups that were diversifying across the rest of the world. What evolved in their place is unlike anything found anywhere else on Earth.

The fossa, Cryptoprocta ferox, is the largest carnivore native to Madagascar, reaching up to 80 centimeters in body length with a tail of equal length, and weighing up to 12 kilograms. It looks convincingly like a small puma. It moves like a cat, climbs like a cat, and hunts like a cat. It is not a cat. It is a member of the family Eupleridae, a group of carnivores found only in Madagascar that are most closely related to mongooses, having diverged from a mongoose-like ancestor that arrived on the island approximately 20 million years ago.

The cat-like appearance of the fossa is convergent evolution. The same ecological pressures that shaped cats on the mainland, the need to hunt agile prey in complex three-dimensional environments, shaped the fossa independently into a body plan that closely resembles a cat despite having no close relationship to one.

The Hunter

The fossa is the primary predator of lemurs in Madagascar, and its hunting behavior is adapted to the three-dimensional environment of the forest canopy where lemurs spend most of their time. Researcher Luke Dollar at National Geographic Society has studied fossa ecology and behavior in Madagascar for decades, documenting how fossas pursue lemurs through the canopy with a agility that matches their prey, using semi-retractable claws and flexible ankles that can rotate to allow head-first descent of tree trunks, a capability shared with only a few other carnivores including the margay cat of South America.

The fossa hunts both by day and by night, making it unusual among carnivores of its size. Dollar’s GPS tracking data shows fossas covering large distances during both diurnal and nocturnal activity periods, with home ranges of up to 26 square kilometers for males. The large home range relative to body size reflects the low prey density of Madagascar’s degraded forests.

Reproduction and the Mating Tree

Fossa mating behavior is one of the more unusual reproductive systems documented in any carnivore. Females select a specific tree, typically a large emergent tree with a horizontal branch at a convenient height, and remain in that tree for up to a week during their brief annual receptive period. Multiple males gather at the base of the tree and compete for access to the female, who mates with several males during her time in the tree before descending and returning to her solitary lifestyle.

Researcher Mia-Lana Lührs at the German Primate Center has studied fossa mating behavior in detail, finding that the mating tree system appears to give females control over mate choice while reducing the risk of harassment from males outside the mating period. The same trees are used by different females in successive years, suggesting that the locations are known and remembered across the fossa population.

The Forest That Is Disappearing

Madagascar has lost over 90% of its original forest cover, and the fossa’s range has contracted accordingly. The species is listed as Vulnerable on the IUCN Red List, with a population estimated at fewer than 2,500 mature individuals. The primary threat is habitat loss from slash-and-burn agriculture, charcoal production, and logging.

The fossa that evolved to fill the ecological role of a large cat in a world without cats, that hunts lemurs through the canopy with cat-like agility despite being a mongoose relative, exists in a forest that is disappearing faster than the species living in it can adapt. Madagascar’s evolutionary experiment, 160 million years in the making, is being concluded in decades.

---