The Fossa: A Cat-Like Mongoose Relative in Madagascar
An Interesting Animal
The fossa (pronounced "FOO-sa") is the largest predator in Madagascar. It lives in forests, both in trees and on the ground, and is active in the day or at night. The animal is an excellent hunter and a great tree climber. It travels up and down trees and along branches with ease. It can also move rapidly over land.
The fossa was once thought to be a type of cat. Researchers have now concluded that it’s related to mongooses, despite having a body with several cat-like features and a dog-like muzzle. Its scientific name is Cryptoprocta ferox. "Crypto" comes from the Ancient Greek word for hidden and "procta" from the word for anus. The name refers to the fact that the animal's anus is hidden inside a pouch, which opens to the outside via a slit. "Ferox" comes from the Latin word for fierce.
Madagascar is the fossa’s only home in the wild. The IUCN (International Union for Conservation of Nature) classifies the animal's population as vulnerable due to the loss and fragmentation of its habitat. Animals in the vulnerable category are likely to become endangered if the factors hurting their population size aren’t changed.
Approximately 95 percent of Madagascar’s reptiles, 89 percent of its plant life, and 92 percent of its mammals exist nowhere else on Earth.— World Wildlife Fund
Physical Appearance and Body Dimensions
A fossa is a slender animal with a highly elongated body and a long tail. Its hair is short and dense. Its coat is usually reddish or golden brown in colour but is occasionally black. In contrast, its belly is generally cream or light tan.
The animal's head is quite small. It has a projecting muzzle, rounded ears, and long whiskers. The nose is bulbous and often especially noticeable. The large eyes of a fossa help it to see at night. Its sharp canine teeth are helpful for attacking its prey.
The fossa's head and body have a total length of around twenty-four to thirty-one inches. The long tail is about the same length as the head and body. The animal is between fourteen and fifteen inches high at the shoulder.
Fossas weigh around fifteen to twenty-four pounds. Females are generally shorter and lighter than males. The size of one fossa in relation to a human is shown in the second video below.
The fossa belongs to the order Carnivora, like cats, dogs, and mongooses. At one time it was placed in the cat family (Felidae), but it's now placed in the family Eupleridae. It's thought to be more closely related to the African and Asian mongooses than to cats.
The fossa's hind legs are longer than its front ones, which enables it to leap from branch to branch in the trees. Its long tail helps it to balance as it jumps. The animal has semi-retractable claws, like those of a cat. It also has flexible ankles that can bend through an angle of 180 degrees. This ability helps the fossa to cling to tree branches and walk head first down tree trunks. Fossas in captivity have been observed hanging upside down from ropes with just their hind feet attached to the rope.
Fossas walk on the soles of their feet, as we do, which is known as a plantigrade method of locomotion. Cats and dogs walk on their toes and are said to have digitigrade locomotion.
The fossa in the following video was temporarily anesthetized so that biologists could examine it. The animal was then released unharmed.
The fossa is a carnivorous animal. Its favourite food seems to be lemurs, which may be almost as large as the fossa. According to some reports, lemurs make up over half of the animal's diet. Lemurs are primates, like us. As far as scientists know, the fossa is the only animal whose primary food is a primate (if this is actually the case).
The biologist in the video above says that although fossas do eat lemurs, they also eat many other animals and are an "equal opportunity predator." The animals also eat rodents and other small mammals, birds, reptiles, amphibians, and sometimes insects. They drink water from the small pools that they find on their travels.
Animals are categorized based on the time when they are most active. Nocturnal animals are active during the night, diurnal animals during the day, crepuscular animals at dawn and dusk, and cathemeral animals—such as the fossa—at any time. The fossa is most active at night, however.
Fossas are often hard to observe because they move rapidly through the tree canopy, leaping from branch to branch. This makes it difficult for biologists to learn about their lives in the wild and to get a reasonably accurate assessment of their population status. The animal is the largest carnivore in Madagascar, yet there is much to learn about it.
Some facts about the animal are known. Fossas are usually solitary. They have sometimes been observed in pairs or small groups and have occasionally been seen engaging in cooperative hunting, however. They are ambush hunters and catch prey both in the trees and on the ground.
Researchers know that the animals maintain a territory, which they mark with a secretion from their anal glands and, at least in males, from glands on their chest.
The animals communicate vocally as well as by scent. They make yelping, chirping, purring, snoring, and mewing sounds at different times, depending on the situation. They sleep in a den on the ground or in a hole in a tree.
In the wild, fossas breed in September and October. Mating usually takes place in specific trees that are used each year, although it has also been observed taking place on the ground. A female may stay in her mating tree for up to a week and attract many males. The mating process may last for up to an hour or more per male. The female usually mates with multiple males before she descends from her tree.
The youngsters are born in a ground den. A hollow in a tree, a rock crevice, an old termite mound, or a hole in the ground are favourite sites for dens. The babies are known as pups or cubs. Between two and four pups are born after a gestation period of around two months. The reported time is variable.
The pups are helpless at birth and are unable to move around. Their eyes are closed and they have no teeth. Due to these characteristics, fossas are said to be an altricial species. The youngsters of a precocial species have relatively mature features at birth and can move around almost immediately.
The pups are weaned at about four months old. They stay with their mother for at least twelve months and are ready to mate at around four years of age. Fossas in captivity live for about twenty years. Their lifespan in the wild may be shorter.
Masculinization in Juvenile Females
One interesting feature of the fossa's development is the transient masculinization shown by a juvenile female when she is between eight and eighteen months old. Her clitoris temporarily becomes elongated and spiny, making her look like a male. She also releases an orange or red secretion on her undersurface like a mature male. By the time she reaches adulthood these features have disappeared. The reason for the female's temporary masculinization is unknown.
From left to right, the meaning of the IUCN Red List categories shown above is as follows.
EW - Extinct
EW - Extinct in the Wild (but still exists in captivity)
CR - Critically Endangered
EN - Endangered
VU - Vulnerable
NT - Near Threatened
LC - Least Concern
Often two additional categories are added on the right—DD, or Data Deficient, and NE, or Not Evaluated.
Population Status of the Fossa
The IUCN maintains a “Red List” of threatened animal species. Each species that has been assessed is assigned to a Red List category based on its nearness to extinction. The latest assessment of the fossa population took place in 2015. The animal was placed in the "Vulnerable" category, since its numbers are decreasing. Though it seems to have quite a wide range, it appears to have a low population throughout the range.
The main reason for the population decline is the destruction of forests in Madagascar. The land is being cleared for agriculture and logging. As a result, it has become harder for fossas to find food. They sometimes prey on livestock, especially chickens, and risk being killed by farmers. In some areas, they have a bad and perhaps undeserved reputation as a nuisance or even a dangerous animal. They are sometimes hunted as a pest or killed for bushmeat.
The IUCN predicts that the fossa population will drop by around thirty percent over the next three generations. The animals can be seen at zoos in both Europe and North America and have bred in captivity. The wild population needs help, however.
The fossa is a distinctive and very interesting animal, just like much of the other wildlife of Madagascar. I hope that ways can be found to balance both the needs of humans and the needs of wildlife on the island.
Questions & Answers
© 2011 Linda Crampton