One of the main threats to the survival of the endangered maned sloth (Bradypus torquatus) is its relatively restricted geographic range, especially in comparison with the other mainland species of the genus (Aguiar and Fonseca, 2008; Chiarello, 2008). This range is basically restricted to the coastal Atlantic Forest between eastern Rio de Janeiro and southern Sergipe (Fonseca and Aguiar, 2004; Lara-Ruiz and Chiarello, 2005), and thus also coincides with the region of Brazil with the longest history of European colonization and deforestation (Dean, 1995). Furthermore, there is some evidence of the existence of three geographically and genetically distinct populations in Bahia, Espírito Santo, and Rio de Janeiro (Lara-Ruiz et al., 2008) which may even represent separate taxa (Fonseca and Aguiar, 2004).
There are recent records of the species from southern Bahia (Prado, 2001), where a few large tracts of Atlantic Forest still remain. On the other hand, Fonseca and Aguiar (2004: p. 7) affirm that the species is absent from Sergipe, where “the forest is gone”. Deforestation has reached critical levels in this state (Siqueira and Ribeiro, 2001), but many relatively small fragments, of up to 900 hectares, still persist. Some of these forests harbor a surprisingly diverse fauna of mammals, including the endangered primates Callicebus coimbrai and Cebus xanthosternos, and even pumas, Puma concolor (Jerusalinsky et al., 2006; Santos Junior, 2007). Recent surveys have confirmed that Callicebus coimbrai occurs in dozens of fragments statewide, including in some of less than ten hectares.
Unexpectedly, ongoing fieldwork—which is directed primarily at the local primate populations—has also resulted in the observation of maned sloths at two sites in the south of the state. These observations not only confirm that the species still occurs as far north as Sergipe, but also suggest that B. torquatus may be relatively abundant in this region. It is clear, however, that additional research is needed to confirm the size and status of these populations.
The first record of B. torquatus was collected on August 1st, 2004, at the Fazenda Riacho Seco (11°18′S, 37°33′W), in the municipality of Arauá (Figure 1), during a survey of local Callicebus populations (Jerusalinsky et al., 2006). The adult sloth was seen at 14-14:30 h moving and feeding approximately 10 m above the ground in the crown of a jitaí tree (Apuleia leiocarpd) in a relatively small, disturbed fragment of less than 25 hectares. While local residents indicated that Callicebus was also present in the fragment, this was not confirmed during the survey.
Bradypus torquatus was also observed during mammal surveys at the Fazenda Trapsa (11°12′S, 37°14′W), an abandoned farm in the municipality of Itaporanga d'Ajuda, just south of the state capital Aracaju (Figure 1). This site encompasses a mosaic of Atlantic Forest fragments that vary in size from a few dozen to more than a hundred hectares, with a total cover of more than 500 ha. Maned sloths were observed in three of these fragments, denominated Alagado (118 ha.), Viveiro (62 ha.) and Camboinha (15 ha.), in June and July of 2008, and in April and August of 2009.
Alagado is characterized by relatively well-preserved hilltop forest with an open understorey, and canopy height of five to 15 m. By contrast, much of the smaller Viveiro fragment caught fire approximately ten years ago, and the forest is now characterized by dense undergrowth and a mostly discontinuous canopy. The much smaller Camboinha fragment was also extensively damaged by fire in early 2009. Nevertheless, much of the vegetation is still well-preserved, with trees of up to 15 m in height and a relatively open understorey.
One adult B. torquatus (Figure 2) was observed at Alagado on June 1st, 2008, at 13:50 h, moving up a vertical trunk at approximately 10 m height. As soon as it perceived the presence of human observers, the animal remained motionless for a few moments, but then continued its upward movement. At 06:44 h on April 17, 2009, an adult was observed at a height of 9 m in a Dalbergia sp. tree.
At the Viveiro forest, sloths were observed on the mornings of July 16 and 21, 2008, at 11:30 h and 09:30 h, respectively. On the first occasion, an adult individual was observed at a height of approximately 7 m in an “açoita-cavalo” (Luehea divaricata) tree, close to the area regenerating from the fire. This individual had a head-body length of 570 mm, but its sex was not recorded given the difficulties of identifying the gender in this species (Pinder, 1993; Chiarello, 1998a).
On the second occasion, a female carrying an infant dorsally was observed moving, apparently seeking shelter, in a lapachillo tree (Poecilanthe parviflora) in a part of the forest that is still in the initial stages of regeneration. The adult female had a head-body length of 609 mm (length of: head =100 mm, right arm = 390 mm, right leg = 209 mm, hand = 75 mm, and foot = 79 mm). The infant was about a third the size of the adult, with a head-body length of 209 mm. The body length of the female is typical of the species, considering the values recorded by Pinder (1993: 520–672 mm; see also Lara-Ruiz and Chiarello, 2005).
Finally, one individual was observed at Camboinha on August 22, 2009, at 07:43 h. The animal was apparently a subadult, but its sex was not determined. It was at rest at a height of approximately 10 m.
Additionally, at least two sloths are known to have been captured by local residents during the past year (pers. obs.; E. M. Santos Junior, pers. comm.). Overall, the observations from the Fazenda Trapsa appear to indicate that B. torquatus is relatively abundant at this site. These records, together with the one from Riacho Seco, seem to support the assumption that the species is present in at least some of the regions other fragments. In fact, A. Cunha and R. Beltrão-Mendes (pers. comm.) have recently observed the species at two other sites in southern Sergipe, in the municipalities of Santa Luzia do Itanhi and Indiaroba.
The few ecological data available for the species (Chiarello, 1998a; 1998b) indicate that its diet consists almost exclusively of leaves, and that individuals occupy home ranges of a few hectares. A priori, then, it seems likely that the species would be able to survive in most fragments. A series of factors ranging from historical processes and ecological constraints, to habitat quality and hunting pressure may, however, determine its presence or absence from a given site.
The answer to the question of why the species had not been recorded in Sergipe in recent decades is probably a simple one—a combination of the lack of specific surveys and the cryptic habits of the animal. With the exception of general observations of terrestrial mammals in the Serra de Itabaiana National Park (Oliveira et al., 2006), most recent fieldwork in the state has been directed specifically at the primate fauna (Sousa, 2003; Jerusalinsky et al., 2006; Santos Junior, 2007; Chagas, 2008). The fact that the observations recorded here were an indirect result of the latter fieldwork might be indicative of the possible relative abundance of B. torquatus in this region.
Good knowledge of a species' geographic distribution is key to the reliable assessment of its conservation status (IUCN, 2008) and the planning of conservation strategies (Primack and Rodrigues, 2001). The records presented here not only extend the known range of B. torquatus northwards by a number of hundred kilometers, but also suggest that it may still be present in at least some of the Atlantic Forest fragments that remain in the intervening area in Bahia and Sergipe. It is also possible that the species may still range as far north as the São Francisco River, although there is less forest cover and fewer fragments in Sergipe further north and east of Fazenda Trapsa (Jerusalinsky et al., 2006).
Overall, the main hindrance to the identification of B. torquatus populations, such as those reported here, may simply have been the lack of expectations based on the available literature (e.g. Eisenberg and Redford, 2000; Prado, 2001; Fonseca and Aguiar, 2004; Chiarello, 2008). In the light of the evidence presented here, it is clear that such expectations need to be revised, and it would seem recommendable to include the identification of sites at which B. torquatus may occur in the aims of any survey conducted within the Northern Atlantic Forest. The species could easily be included in the standardized interviews used to survey primate populations (Jerusalinsky et al., 2006) or even in the objectives of ecological studies.
We are especially grateful to Mr. Ary Ferreira, owner of Fazenda Trapsa, and José Elias “Bóia”. The Sergipe State Environment Ministry (SEMARH) and CNPq (process no. 476064/2008-2) provided logistic support. RRDC and JPSA receive graduate stipends from the Deutscher Akademischer Austauschdienst (DAAD), and SFF a CNPq research grant (process no. 307506/2003-7). We are also grateful to Marcelo Xavier Filho for the map, Elisio Marinho dos Santos Neto for the identification of plants from Fazenda Trapsa, and André Cunha and Raone Beltrão-Mendes for their unpublished observations. The fieldwork reported here was authorized by the Brazilian Federal Environment Institute (IBAMA) and the National Research Council (CNPq).