Fossa (animal)
The fossa (Cryptoprocta ferox; /ˈfɒsə/ FOSS-ə or /ˈfuːsə/ FOO-sə;[3] Malagasy: [ˈfusə̥]) is a slender, long-tailed, cat-like mammal that is endemic to Madagascar. It is a member of the carnivoran family Eupleridae.
This article is about the animal with the common name fossa. For the taxonomic genus Fossa, see Malagasy civet. For other uses, see Fossa (disambiguation).
The fossa is the largest mammalian carnivore on Madagascar and has been compared to a small cougar, as it has convergently evolved many cat-like features. Adults have a head-body length of 70–80 cm (28–31 in) and weigh between 5.5 and 8.6 kg (12 and 19 lb), with the males larger than the females. It has semi-retractable claws (meaning it can extend but not retract its claws fully) and flexible ankles that allow it to climb up and down trees head-first, and also support jumping from tree to tree. A larger relative of the species, Cryptoprocta spelea, probably became extinct before 1400.
The species is widespread, although population densities are usually low. It is found solely in forested habitat, and actively hunts both by day and night. Over 50% of its diet consists of lemurs, the endemic primates found on the island; tenrecs, rodents, lizards, birds, and other animals are also documented as prey. Mating usually occurs in trees on horizontal limbs and can last for several hours. Litters range from one to six pups, which are born altricial (blind and toothless). Infants wean after 4.5 months and are independent after a year. Sexual maturity occurs around three to four years of age, and life expectancy in captivity is 20 years. The fossa is listed as a vulnerable species on the IUCN Red List. It is generally feared by the Malagasy people and is often protected by their fady taboo. The greatest threat to the fossa is habitat destruction.
Its taxonomic classification has been controversial because its physical traits resemble those of cats, yet other traits suggest a close relationship with viverrids. Its classification, along with that of the other Malagasy carnivores, influenced hypotheses about how many times mammalian carnivores have colonized Madagascar. With genetic studies demonstrating that the fossa and all other Malagasy carnivores are most closely related to each other forming a clade, recognized as the family Eupleridae, carnivorans are now thought to have colonized the island once, around 18–20 million years ago.
Etymology[edit]
The generic name Cryptoprocta refers to how the animal's anus is hidden by its anal pouch, from the Ancient Greek words crypto- "hidden", and procta "anus".[4] The species name ferox is the Latin adjective "fierce" or "wild".[5]
Its common name comes from the word fosa Malagasy pronunciation: [ˈfusə̥] in Malagasy, an Austronesian language,[4][6] and some authors have adopted the Malagasy spelling in English.[7]
The word is similar to posa (meaning "cat") in the Iban language (another Austronesian language) from Borneo, and both terms may derive from trade languages from the 1600s. However, an alternative etymology suggests a link to another word that comes from Malay: pusa refers to the Malayan weasel (Mustela nudipes). The Malay word pusa could have become posa for cats in Borneo, while in Madagascar the word could have become fosa to refer to the fossa.[6]
Habitat and distribution[edit]
The fossa has the most widespread geographical range of the Malagasy carnivores, and is generally found in low numbers throughout the island in remaining tracts of forest, preferring pristine undisturbed forest habitat. It is also encountered in some degraded forests, but in lower numbers. Although the fossa is found in all known forest habitats throughout Madagascar, including the western dry deciduous forests, the eastern rainforests, and the southern spiny forests,[22] it is seen more frequently in humid than in dry forests. This may be because the reduced canopy in dry forests provides less shade, and also because the fossa seems to travel more easily in humid forests.[9] It is absent from areas with the heaviest habitat disturbance and, like most of Madagascar's fauna, from the central high plateau of the country.[22]
The fossa has been found across several different elevational gradients in undisturbed portions of protected areas throughout Madagascar. In the Réserve Naturelle Intégrale d'Andringitra, evidence of the fossa has been reported at four different sites ranging from 810 to 1,625 m (2,657 to 5,331 ft).[23] Its highest known occurrence was reported at 2,000 m (6,600 ft);[24] its presence high on the Andringitra Massif was subsequently confirmed in 1996.[23] Similarly, evidence has been reported of the fossa at the elevational extremes of 440 m (1,440 ft) and 1,875 m (6,152 ft) in the Andohahela National Park.[25] The presence of the fossa at these locations indicates its ability to adapt to various elevations, consistent with its reported distribution in all Madagascar forest types.[22]
Human interactions[edit]
The fossa has been assessed as "Vulnerable" by the IUCN Red List since 2008, as its population size has probably declined by at least 30 percent between 1987 and 2008; previous assessments have included "Endangered" (2000) and "Insufficiently Known" (1988, 1990, 1994).[2] The species is dependent on forest and thus threatened by the widespread destruction of Madagascar's native forest but is also able to persist in disturbed areas.[9][15] A suite of microsatellite markers (short segments of DNA that have a repeated sequence) have been developed to help aid in studies of genetic health and population dynamics of both captive and wild fossas.[37] Several pathogens have been isolated from the fossa, some of which, such as anthrax and canine distemper, are thought to have been transmitted by feral dogs or cats.[15] Toxoplasma gondii was reported in a captive fossa in 2013.[38]
Although the species is widely distributed, it is locally rare in all regions, making fossas particularly vulnerable to extinction. The effects of habitat fragmentation increase the risk. For its size, the fossa has a lower than predicted population density, which is further threatened by Madagascar's rapidly disappearing forests and dwindling populations of lemurs, which make up a high proportion of its diet. The loss of the fossa, either locally or completely, could significantly impact ecosystem dynamics, possibly leading to over-grazing by some of its prey species. The total population of the fossa living within protected areas is estimated at less than 2,500 adults, but this may be an overestimate.
Only two protected areas are thought to contain 500 or more adult fossas: Masoala National Park and Midongy-Sud National Park, although these are also thought to be overestimated. Too little population information has been collected for a formal population viability analysis, but estimates suggest that none of the protected areas support a viable population. If this is correct, the extinction of the fossa may take as much as 100 years to occur as the species gradually declines. In order for the species to survive, it is estimated that at least 555 km2 (214 sq mi) is needed to maintain smaller, short-term viable populations, and at least 2,000 km2 (770 sq mi) for populations of 500 adults.[27]
Taboo, known in Madagascar as fady,[39] offers protection for the fossa and other carnivores.[40] In the Marolambo District (part of the Atsinanana region in Toamasina Province), the fossa has traditionally been hated and feared as a dangerous animal. It has been described as "greedy and aggressive", known for taking fowl and piglets, and believed to "take little children who walk alone into the forest". Some do not eat it for fear that it will transfer its undesirable qualities to anyone who consumes it.[39] However, the animal is also taken for bushmeat;[15] a study published in 2009 reported that 57 percent of villages (8 of 14 sampled) in the Makira forest consume fossa meat. The animals were typically hunted using slingshots, with dogs, or most commonly, by placing snare traps on animal paths.[41] Near Ranomafana National Park, the fossa, along with several of its smaller cousins and the introduced small Indian civet (Viverricula indica), are known to "scavenge on the bodies of ancestors", which are buried in shallow graves in the forest. For this reason, eating these animals is strictly prohibited by fady. However, if they wander into villages in search of domestic fowl, they may be killed or trapped. Small carnivore traps have been observed near chicken runs in the village of Vohiparara.[40]
Fossas are occasionally held in captivity in zoos. They first bred in captivity in 1974 in the zoo of Montpellier, France. The next year, at a time when there were only eight fossas in the world's zoos, the Duisburg Zoo in Germany acquired one; this zoo later started a successful breeding program, and most zoo fossas now descend from the Duisburg population. Research on the Duisburg fossas has provided much data about their biology.[16]
The fossa was depicted as an antagonist in the 2005 DreamWorks animated film Madagascar, being referred to as the "foosa", and accurately shown as the lemurs' most feared predator.[42]