The fossa is the largest carnivore and most formidable predator on the island of Madagascar. It is acrobatic, agile, and relentless in its pursuit of lemurs. Superficially, the fossa resembles a cat or weasel, but DNA studies have revealed that it is most closely related to the mongoose. The fossa’s ancestors arrived on Madagascar 21 million years ago.
Fossas are expert tree climbers. Sharp, protractile claws and flexible ankles allow them to climb up and down trees headfirst. Their tails are nearly as long as their bodies and provide balance while leaping from tree to tree. They hunt both day and night, traveling up to 16 miles in search of prey, more than 50 percent of which is lemurs. The balance of their diet is rodents, lizards, and birds. Fossas rest in tree hollows, caves, or abandoned termite mounds, usually choosing a different sleeping place each night. Fossas emit a foul odor when frightened and scent-mark their territories with a substance produced by glands on their chests and hind ends.
Fossas are solitary except during the mating season. A female fossa may mate with multiple males, often in trees. After a gestation period of six to eight weeks, the female gives birth to two to four cubs. The cubs are raised by the mother alone and are weaned at about four months. They will remain with the mother for up to two years. The threat to these unusual animals is humans. About 90 percent of the fossa’s native range has been deforested for lumber, oil palm plantations, and other agricultural use. Additionally, farmers sometimes kill fossas because they are perceived as a threat to livestock. There may be as few as 2,500 fossas left in the wild in Madagascar.
The fossa prefers the densely forested savannas of the coastal plains and the mountains that run along the edges of the island. It avoids the treeless areas of the central highlands.
Well more than half of this carnivore’s diet consists of lemurs. It will also feed opportunistically on birds, baby bush pigs, civet cats, fish, rats, eggs, snakes, frogs, and insects. Occasionally, the fossa will raid domestic chickens, small sheep, and goats.
Standing about 15 inches tall, its long slender body can reach up to 32 inches in length (with an equally long tail). They weigh between 15 and 22 pounds. Lifespan is estimated at 15 to 20 years.