The fossa (Cryptoprocta ferox; pronounced "FOSS-ə" or "FOO-sə"; Malagasy: [ˈfusə̥]) is a thin, long-tailed, cat-like mammal that lives only in Madagascar. It belongs to the carnivore family Eupleridae.
The fossa is the largest meat-eating mammal in Madagascar. It is sometimes compared to a small cougar because it has developed many cat-like traits over time. Adult fossas measure 70–80 cm (28–31 in) from head to body and weigh 5.5–8.6 kg (12–19 lb), with males being larger than females. They have claws that can be extended but not fully retracted, and flexible ankles that allow them to climb trees head-first and jump between trees. A larger relative, Cryptoprocta spelea, likely became extinct before 1400.
The fossa lives in forests and hunts during both day and night. More than half of its diet includes lemurs, which are primates found only in Madagascar. It also eats tenrecs, rodents, lizards, birds, and other animals. Mating often happens on tree branches and can last several hours. Fossa litters have one to six young, which are born blind and toothless. These young are weaned after 4.5 months and become independent after one year. They reach sexual maturity at three to four years old, and in captivity, they can live up to 20 years. The fossa is listed as vulnerable on the IUCN Red List. It is feared by many Malagasy people and is sometimes protected by traditional beliefs called fady. The main threat to the fossa is the destruction of its forest habitat.
The classification of the fossa has been debated because its physical traits resemble those of cats, but other traits suggest it is closely related to viverrids. Studies of its genetics show that the fossa and other Malagasy carnivores are closely related, forming a group called the family Eupleridae. These findings suggest that carnivores colonized Madagascar only once, about 18–20 million years ago.
Etymology
The scientific name Cryptoprocta comes from the Ancient Greek words crypto- meaning "hidden" and procta meaning "anus," referring to how the animal's anus is covered by a pouch. The species name ferox is a Latin word meaning "fierce" or "wild." Its common name, fosa, is taken from the Malagasy word for the animal, pronounced [ˈfusə̥] in Malagasy, an Austronesian language. Some English writers use the Malagasy spelling for the name.
The word fosa is similar to posa, which means "cat" in the Iban language, another Austronesian language spoken in Borneo. Both terms may have originated from trade languages used in the 1600s. Another possible origin suggests a connection to the Malay word pusa, which refers to the Malayan weasel (Mustela nudipes). The Malay word pusa may have changed to posa for cats in Borneo and to fosa for the fossa in Madagascar.
Taxonomy
The fossa was first officially described by Edward Turner Bennett in 1833, based on a specimen from Madagascar sent by Charles Telfair. Its common name is the same as the Malagasy civet (Fossa fossana), but these are two different species. Scientists have debated the fossa’s classification because it shares physical traits with viverrids, mongooses, and cats. Bennett originally classified the fossa as a type of civet in the family Viverridae, a view that remained popular for many years. Features such as its small braincase, large eye sockets, retractable claws, and teeth adapted for eating meat have also led some scientists to link it to cats (Felidae). In 1939, William King Gregory and Milo Hellman placed the fossa in its own subfamily within Felidae, called Cryptoproctinae. In 1945, George Gaylord Simpson moved the fossa back to Viverridae, still in its own subfamily, but noted its cat-like traits.
In 1993, Géraldine Veron and François Catzeflis used DNA analysis to suggest the fossa is more closely related to mongooses (family Herpestidae) than to cats or civets. However, in 1995, Veron’s study of physical traits again grouped the fossa with Felidae. In 2003, Anne Yoder and colleagues used genetic data to show that all native Malagasy carnivores share a common ancestor not found in other carnivores, making them a group (clade) with a single origin (monophyletic). These findings led scientists to place all Malagasy carnivores in a single family, Eupleridae. Within Eupleridae, the fossa is grouped with the falanouc (Eupleres goudoti) and Malagasy civet in the subfamily Euplerinae, though its exact relationships remain unclear.
An extinct relative of the fossa, Cryptoprocta spelea, was identified in 1902 from ancient remains and classified as a separate species in 1935. This species was larger than the modern fossa, with an estimated body mass about twice as great, but otherwise similar. In Madagascar, people often describe two types of fossa: a larger "black fossa" (fosa mainty) and a smaller "reddish fossa" (fosa mena). A white form has also been reported in the southwest. It is unclear whether these differences are due to folklore, natural variation related to age, sex, or rare color traits like melanism or leucism, or if they represent separate species.
Description
The fossa looks like a small version of a large cat, such as a cougar, but has a thin body and strong legs, with a tail almost as long as its body. It has a head similar to a mongoose, which is longer than a cat's head, but with a wide and short muzzle and large, rounded ears. Its eyes are medium brown, spaced apart, and its pupils narrow into slits. Like many night-hunting animals, its eyes reflect light, which appears orange. The length of its body is 70–80 cm (28–31 in), and its tail is 65–70 cm (26–28 in) long. Males are larger than females, with adult males weighing 6.2–8.6 kg (14–19 lb) and females weighing 5.5–6.8 kg (12–15 lb). Smaller individuals are usually found in the north and east of Madagascar, while larger ones are found in the south and west. Some reports mention unusually large individuals weighing up to 20 kg (44 lb), but these measurements are not always reliable. The fossa has good senses of smell, hearing, and sight. It is a strong animal, and illnesses are rare in captivity.
Both males and females have short, straight fur that is thick and has no spots or patterns. They are generally reddish-brown on the back and dirty cream on the belly. During mating season, their abdomen may turn orange due to a reddish substance from a chest gland, though this has not been consistently observed. The tail is lighter in color than the sides. Juveniles are gray or nearly white.
Several features of the fossa help it climb trees. It uses its tail for balance and has claws that can be partially retracted to climb. Its feet can switch between walking on the soles (when climbing trees) and on the toes (when walking on the ground). The soles of its paws are nearly bare and covered with strong pads. Its ankles are very flexible, allowing it to grasp tree trunks and climb headfirst or leap between trees. Captive juveniles have been seen swinging upside down by their hindfeet from ropes.
The fossa has several scent glands, though these are less developed in females. Like some mongoose species, it has a skin gland near the anus inside a sac that opens with a slit below the tail. Other glands are near the penis or vagina, with the male's glands emitting a strong odor. Unlike some other animals, the fossa does not have glands near the scrotum.
A unique feature of the fossa is its external genitalia. Its genital shape is unusual for its family, sharing traits with cats and hyenas. The male has a long penis and a bone inside the penis (baculum) that extends between its forelegs when erect, with an average thickness of 20 mm (0.79 in). The tip of the penis is spiny except at the end. In comparison, cats have short, spiny penises, and other animals have smooth, long ones. Female fossas develop a temporary, spiny clitoris resembling a male's penis starting at 1–2 years old. This clitoris is supported by a small bone that shrinks as the animal grows. Unlike some other species, female fossas do not have a pseudo-scrotum but secrete an orange substance that colors their underparts, similar to males.
Hormone levels such as testosterone do not seem to influence this temporary change in females. Scientists believe this change may help reduce harassment from adult males or aggression from other females. Unlike some other mammals, such as hyenas, no other species is known to reduce the size of this feature as it grows.
The fossa shares traits with three different carnivore families, leading scientists to classify it in different groups, including Herpestidae, Viverridae, and Felidae. Features related to eating and digestion, such as tooth shape, the skull, tongue, and digestive system, are similar to cats. The rest of the skull resembles that of the viverra genus, and the body structure is similar to some mongoose species. The fossa has 3 incisors, 1 canine, 3 or 4 premolars, and 1 molar on each side of the upper and lower jaws. Its baby teeth follow a similar pattern but lack the fourth premolar and molar.
The fossa has a large, noticeable nose like viverrids but has larger, round ears similar to a cat of the same size. Its whiskers are long, with the longest ones longer than its head. Like some mongoose species, it has whiskers on its wrists. Its claws can be retracted but are not hidden in skin sheaths like in cats. It has three pairs of nipples: one in the groin area, one on the belly, and one on the
Habitat and distribution
The fossa has the largest area of land where it lives among Madagascar's carnivores. It is usually found in small numbers in the island's remaining forest areas, especially in forests that are not disturbed. It is also found in some forests that have been damaged, but in fewer numbers. Even though the fossa lives in all types of forests across Madagascar, such as the western dry forests, the eastern rainforests, and the southern spiny forests, it is more often seen in wet forests than in dry ones. This may be because dry forests have less tree cover, which provides less shade, and the fossa moves more easily in wet forests. It does not live in areas with the most habitat damage, and like many other animals in Madagascar, it is not found in the central high plateau of the country.
The fossa has been found at different heights in protected areas of Madagascar. In the Réserve Naturelle Intégrale d'Andringitra, signs of the fossa have been found at four locations between 810 and 1,625 meters (2,657 to 5,331 feet). Its highest known location was reported at 2,000 meters (6,600 feet), and its presence at this height on the Andringitra Massif was confirmed in 1996. In the Andohahela National Park, signs of the fossa have been found at heights ranging from 440 meters (1,440 feet) to 1,875 meters (6,152 feet). The fossa's presence at these different heights shows that it can live in various elevations, which matches its known range in all types of forests in Madagascar.
Behavior
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The fossa is active during both the day and the night and is considered cathemeral; activity peaks may occur early in the morning, late in the afternoon, and late in the night. The animal generally does not reuse sleeping sites, but females with young do return to the same den. The home ranges of male fossas in Kirindy Forest are up to 26 km (10 sq mi) large, compared to 13 km (5.0 sq mi) for females. These ranges overlap—by about 30 percent according to data from the eastern forests—but females usually have separated ranges. Home ranges grow during the dry season, perhaps because less food and water is available. In general, radio-collared fossas travel between 2 and 5 kilometres (1.2 and 3.1 mi) per day, although in one reported case a fossa was observed moving a straight-line distance of 7 km (4.3 mi) in 16 hours.
The animal's population density appears to be low: in Kirindy Forest, where it is thought to be common, its density has been estimated at one animal per 4 km (1.5 sq mi) in 1998. Another study in the same forest between 1994 and 1996 using the mark and recapture method indicated a population density of one animal per 3.8 km (1.5 sq mi) and one adult per 5.6 km (2.2 sq mi).
Except for mothers with young and occasional observations of pairs of males, animals are usually found alone, so that the species is considered solitary. A 2009 publication, however, reported a detailed observation of cooperative hunting, wherein three male fossas hunted a 3 kg (6.6 lb) sifaka (Propithecus verreauxi) for 45 minutes, and subsequently shared the prey. This behavior may be a vestige of cooperative hunting that would have been required to take down larger recently extinct lemurs.
Fossas communicate using sounds, scents, and visual signals. Vocalizations include purring, a threatening call, and a call of fear, consisting of "repeated loud, coarse inhalations and gasps of breath". A long, high yelp may function to attract other fossas. Females mew during mating and males produce a sigh when they have found a female. Throughout the year, animals produce long-lasting scent marks on rocks, trees, and the ground using glands in the anal region and on the chest. They also communicate using face and body expression, but the significance of these signals is uncertain. The animal is aggressive only during mating, and males in particular fight boldly. After a short fight, the loser flees and is followed by the winner for a short distance. In captivity, fossas are usually not aggressive and sometimes even allow themselves to be stroked by a zookeeper, but adult males in particular may try to bite.
The fossa is a carnivore that hunts small to medium-sized animals. One of eight carnivorous species endemic to Madagascar, the fossa is the island's largest surviving endemic terrestrial mammal and the only predator capable of preying upon adults of all extant lemur species, the largest of which can weigh as much as 90 percent of the weight of the average fossa. Although it is the predominant predator of lemurs, reports of its dietary habits demonstrate a wide variety of prey selectivity and specialization depending on habitat and season; diet does not vary by sex. While the fossa is thought to be a lemur specialist in Ranomafana National Park, its diet is more variable in other rain forest habitats.
The diet of the fossa in the wild has been studied by analyzing their distinctive scats, which resemble gray cylinders with twisted ends and measure 10–14 cm (3.9–5.5 in) long by 1.5–2.5 cm (0.6–1.0 in) thick. Scat collected and analyzed from both Andohahela and Andringitra contained lemur matter and rodents. Eastern populations in Andringitra incorporate the widest recorded variety of prey, including both vertebrates and invertebrates. Vertebrates consumed ranged from reptiles to a wide variety of birds, including both understory and ground birds, and mammals, including insectivores, rodents, and lemurs. Invertebrates eaten by the fossa in the high mountain zone of Andringitra include insects and crabs. One study found that vertebrates comprised 94% of the diet of fossas, with lemurs comprising over 50%, followed by tenrecs (9%), lizards (9%), and birds (2%). Seeds, which comprised 5% of the diet, may have been in the stomachs of the lemurs eaten, or may have been consumed with fruit taken for water, as seeds were more common in the stomach in the dry season. The average prey size varies geographically; it is only 40 grams (1.4 oz) in the high mountains of Andringitra, in contrast to 480 grams (17 oz) in humid forests and over 1,000 grams (35 oz) in dry deciduous forests. In a study of fossa diet in the dry deciduous forest of western Madagascar, more than 90% of prey items were vertebrates, and more than 50% were lemurs. The primary diet consisted of approximately six lemur species and two or three spiny tenrec species, along with snakes and small mammals. Generally, the fossa preys upon larger lemurs and rodents in preference to smaller ones.
Prey is obtained by hunting either on the ground or in the trees. During the non-breeding season the fossa hunts individually, but during the breeding season hunting parties may be seen, and these may be pairs or later on mothers and young. One member of the group scales a tree and chases the lemurs from tree to tree, forcing them down to the ground where the other is easily able to capture them. The fossa is known to eviscerate its larger lemur prey, a trait that, along with its distinct scat, helps identify its kills. Long-term observations of the fossa's predation patterns on rainforest sifakas suggest that the fossa hunts in a subsection of their range until prey density is decreased, then moves on. The fossa has been reported to prey on domestic animals, such as goats and small calves, and especially chickens. Food taken in captivity includes amphibians, birds, insects, reptiles, and small- to medium-sized mammals.
This wide variety of prey items taken in various rainforest habitats is similar to the varied dietary composition noted occurring in the dry forests of western Madagascar, as well. As the largest endemic predator on Madagascar, this dietary flexibility combined with a flexible activity pattern has allowed it to exploit a wide variety of niches available throughout the island, making it a potential keystone species for the Madagascar ecosystems.
Fossas have a polyandrous mating system. Most of the details of reproduction in wild populations are from the western dry deciduous forests; determining whether certain of these details are applicable to eastern populations will require further field research. Mating typically occurs during September and October, although there are reports of its occurring as late as December, and can be highly conspicuous. In captivity in the Northern Hemisphere, fossas instead mate in the northern spring, from March to July. Intromission usually occurs in trees on horizontal limbs about 20 m (66 ft) off the ground. Frequently the same tree is used year after year, with remarkable precision as to the date the season commences. Trees are often near a water source, and have limbs strong enough and wide enough to support the mating pair, about 20 cm (7.9 in) wide. Some mating has been reported on the ground as well.
As many as eight males will be at a mating site, staying in close vicinity to the receptive female. The female seems to choose the male she mates with, and the males compete for the attention of the female with a significant amount of vocalization and antagonistic interactions. The female may choose to mate with several of the males, and her choice of mate does not seem to have any correlation to the physical appearance of the males. To stimulate the male to mount her, she gives a series of mewling vocalizations. The male mounts from behind, resting his body on her slightly off-center, a position requiring delicate balance; if the female were to stand, the male would fall.
Human interactions
The fossa is listed as "Vulnerable" by the IUCN Red List since 2008 because its population likely decreased by at least 30% between 1987 and 2008. Earlier assessments included "Endangered" (2000) and "Insufficiently Known" (1988, 1990, 1994). The species depends on forests and is threatened by the destruction of Madagascar's native forests. However, it can survive in areas that have been disturbed. Scientists have created microsatellite markers (short DNA segments with repeated sequences) to study the genetic health and population changes of both wild and captive fossas. Some diseases, such as anthrax and canine distemper, have been found in fossas and may have been spread by feral dogs or cats. In 2013, Toxoplasma gondii was reported in a captive fossa.
Although the fossa is found in many areas, it is rare in all regions, making it vulnerable to extinction. Habitat fragmentation increases this risk. For its size, the fossa has a lower population density than expected, which is further threatened by the loss of Madagascar's forests and the decline of lemurs, a major part of its diet. Losing the fossa could disrupt ecosystems, possibly leading to over-grazing by some prey species. The total number of fossas in protected areas is estimated to be fewer than 2,500 adults, but this number may be too high.
Only two protected areas, Masoala National Park and Midongy-Sud National Park, are thought to have 500 or more adult fossas, though these numbers may also be overestimated. Insufficient data prevents a formal analysis of population viability, but estimates suggest that no protected areas support a viable population. If true, the fossa may take up to 100 years to go extinct as its numbers slowly decline. To survive, the species needs at least 555 km² (214 sq mi) to maintain small, short-term viable populations and at least 2,000 km² (770 sq mi) for 500 adults.
In Madagascar, a cultural tradition called "fady" protects some animals, including the fossa. In the Marolambo District, the fossa is feared as dangerous, described as "greedy and aggressive," and believed to attack livestock and children. Some people avoid eating it, fearing it might transfer bad traits to those who consume it. However, fossa meat is also hunted for bushmeat; a 2009 study found that 57% of villages in the Makira forest consume it. Hunting methods include slingshots, dogs, and snares. Near Ranomafana National Park, fossas and other animals are sometimes seen scavenging on bodies of ancestors buried in shallow graves, which makes eating them taboo. If fossas enter villages, they may be killed or trapped. Small carnivore traps have been found near chicken coops in the village of Vohiparara. People who dislike fossas are more likely to kill them, especially if they attack livestock.
Fossas are sometimes kept in zoos. The first successful breeding in captivity occurred in 1974 at Montpellier Zoo in France. The next year, Duisburg Zoo in Germany acquired one of the eight fossas in zoos worldwide. This zoo started a successful breeding program, and most zoo fossas today are descendants of that population. Research on these animals has provided valuable information about their biology.
The fossa appeared as an antagonist in the 2005 DreamWorks film Madagascar, where it was called "foosa" and shown as the lemurs' most feared predator.