SLOTHS
Maned sloth
Bradypus torquatus
RANGE

B. torquatus is restricted to the coastal Atlantic forests of eastern Brazil. Historically, it possibly occurred throughout the coastal forest of Bahia through to the state of Pernambuco. At present, the southern part of the state of Bahia is the primary stronghold for the species. Maned sloths were recently reported from the state of Sergipe (Chagas et al., 2009) but thus far no records have been collected in the adjacent state of Alagoas. The extensive deforestation of suitable habitat in this state suggests that it is unlikely to survive there. A natural biogeographic gap occurs in northern Espírito Santo, perhaps due to a higher degree of deciduity in the forests of this region (Hirsh and Chiarello, in press). The species does not occur from the left bank of Doce River to the vicinity of Mucuri River. It has been reported from extreme northern Minas Gerais on the left bank of Jequitinhonha River. Bradypus torquatus has been introduced to some National Parks in Espírito Santo (Caparaó National Park) and Rio de Janeiro (Tijuca National Park), among other areas, although it is not known if the species is still present at these sites. It ranges from sea level to 1,290 m asl.


DESCRIPTION

As its common name implies, this three-toed sloth bears a long, black mane on the base of the neck that projects over its shoulders. This mane is only present in adult individuals; it is usually larger and darker in males than in females. The rest of its body is covered by pale brown hair. The head is round with short ears. The long forelimbs bear three digits with large claws; one of them being considerably shorter than the other two. The hindlimbs also have three digits and are short when compared to the forelimbs. The tail is very short and stumplike. Adults weigh approximately 4kg.

HABITAT

This largely arboreal species is found in wet tropical forest, most typically in areas with an annual precipitation of 1,200 mm or higher and lacking a dry season. Most records are from evergreen forests, and just a handful of sightings are from semi-deciduous forests (Hirsch and Chiarello, in press). It can be found in secondary forest habitats, including “cabrucas” (cocoa plantations under native forests in southern Bahia; Cassano et al., in press). Some animals have been sighted in forest fragments as small as 20 ha, although the long-term persistence of populations at these sites is unknown.

BIOLOGY

The maned sloth is a strict folivore that feeds on a relatively small number of food plants (Chiarello, 2008). Chiarello (1998) found that leaves from 21 species formed 99% of the diet of three animals. Like other congeneric sloths, animals descend from trees periodically to urinate and defecate. The females give birth to one young per year, predominantly at the end of the wet season and beginning of the dry season (February-April), and copulation concentrates in the late dry and early wet seasons (August-October; Dias et al., 2009). Sexual maturity is probably reached between the second and third year and longevity in the wild is over 12 years (Lara-Ruiz and Chiarello, 2005).
In some parts of Bahia and Espírito Santo, the animals are locally abundant in forest fragments although the population density is not well known. Genetic studies indicate no gene flow between the populations of southern Bahia (Ilhéus) and Espiríto Santo (Santa Teresa), and those of Poço das Antas (Rio de Janeiro). It appears that these populations have been isolated before the anthropogenic fragmentation of habitat, possibly beginning in the Pleistocene (Moraes-Barros et al., 2006; Lara-Ruiz et al., 2008). In general, little genetic diversity is exhibited within individual populations, but the northernmost population (Bahia) is the genetically more diverse (Moraes-Barros et al., 2006; Lara-Ruiz et al., 2008). Overall, the global population of B. torquatus is assumed to be decreasing in response to the continuing loss and fragmentation of suitable habitat, the Atlantic Forest (Ribeiro et al., 2009).

THREATS

The rate of deforestation in the Atlantic forest of eastern Brazil has decreased dramatically in the last three decades but has not stopped (Ribeiro et al., 2009), so the pressure on habitat continues. In southern Bahia the economic crisis of the cocoa plantation (Theobroma cacao) puts a pressure on farmers of this product to clear their forest to make room for other economic alternatives, mainly pastures. In other areas, native forests are cleared for other reasons, including coal production, agriculture and city sprawl. The genetic integrity of distinct populations is threatened by the release of confiscated animals at different sites without knowledge or understanding of their origins. Additional threats include subsistence hunting and accidental mortality of B. torquatus on roads. Sloths attract the attention when spotted and might be killed just for the sake of curiosity. Although the species is not actively pursued by hunters, individuals might sometimes fall victims of subsistence hunting when spotted by local people. Although hunting is legally forbidden in Brazil, enforcement is ineffective and practically inexistent.

CONSERVATION

The maned sloth was previously listed as Endangered based on its very restricted extent of occurrence. However, new data and a detailed range analysis based on all confirmed locations and habitat preferences revealed that the extent of occurrence is larger than previously thought. Recent analyses of the available habitat left for Bradypus torquatus suggest that this species has an area of occupancy less than 1,000 km? (based on remaining forest within its highly fragmented range). Nevertheless, its range, area of occupancy, and habitat are in continuing decline due to ongoing habitat loss and degradation in the Brazilian Atlantic Forest. Furthermore, it is threatened by hunting. Bradypus torquatus is therefore listed as Vulnerable, with the caveat that a re-assessment should be performed as soon as more data on the wild populations become available.
B. torquatus is present in a number of protected areas, such as the Biological Reserves of Una (Bahia), Augusto Ruschi (Espírito Santo) and Poço das Antas (Rio de Janeiro), among others. The low genetic diversity within fragmented populations indicates a need to develop corridors of suitable habitat between these populations. Confiscated animals should be genetically characterized to determine the most appropriate release site. Data on dispersal ability, sex ratio, mating system, and population density are virtually unknown but important for conservation planning and monitoring. The species has been successfully translocated (Chiarello et al., 2004). Awareness programs are in place in Espírito Santo, Brazil.

REFERENCES

Additional information and a complete list of references can be found in: Superina, M., T. Plese, N. Moraes-Barros and A.M. Abba (2010): The 2010 Sloth Red List Assessment. Edentata 11(2): 115-134. This article is available here.

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