Mammalian Biology 76 (2011) 243–250
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Mammalian Biology
journal homepage: www.elsevier.de/mambio
Original Investigation
The cacao agroforests of the Brazilian Atlantic forest as habitat for the
endangered maned sloth Bradypus torquatus
Camila Righetto Cassano a,b , Maria Cecília Martins Kierulff c , Adriano G. Chiarello d,∗
a
Instituto de Estudos Socioambientais do Sul da Bahia – IESB, Rua Araujo Pinho, 72/3, Ilhéus, BA, Brazil
Programa de Pós-graduação em Zoologia, Universidade Estadual de Santa Cruz, km 16, Rodovia Ilhéus-Itabuna, Ilhéus, CEP:45.662-900 BA, Brazil
Instituto Pri-Matas para a Conservação da Biodiversidade, Caixa Postal 3304, Belo Horizonte, CEP: 30.112-970, MG, Brazil
d
Programa de Pós-graduação em Zoologia de Vertebrados, Pontifícia Universidade Católica de Minas Gerais – PUC-MG, Av. Dom José Gaspar 500,
Prédio 41, Belo Horizonte, CEP: 30.353-610, MG, Brazil
b
c
a r t i c l e
i n f o
Article history:
Received 7 December 2009
Accepted 21 June 2010
Keywords:
Xenarthra
Pilosa
Cocoa plantation
Home range
Radio telemetry
Theobroma cacao
a b s t r a c t
Sloths are arboreal mammals strictly dependent upon forested habitats. The southern part of the state of
Bahia in northeastern Brazil harbors important forest remnants and the highest genetic diversity known
for the maned sloth (Bradypus torquatus), an endangered species endemic to the Atlantic forest. Large
extents of cacao agroforests (cabrucas) connected to forest patches mitigate the effects of fragmentation
in this region. We radio-tracked three maned sloths during 40 months in a cabruca at the vicinity of
Una Biological Reserve, southern Bahia, and estimated their home range using two commonly employed
estimators (minimum convex polygon (MCP) and kernel). Overall cabrucas comprised a significant portion
of the home range of the three study animals (MCP: 7–100%) and at least a third of the areas of more
intensive use (kernel: 27–99%). The tagged sloths used cabrucas more than expected according to the
availability of this habitat in their home range and in the surrounding landscape. In addition to the
tagged individuals, maned sloths were observed five times in the study area, twice in cabrucas. Eleven tree
species present in cabrucas were used as food sources by maned sloths. Results indicate that biologically
rich cacao agroforests immersed in a landscape still largely composed of native forests, as is the case
here, can provide habitat for the maned sloth. This finding spells good news for the conservation of
this species, as southern Bahia is one of the most important strongholds for the maned sloth. However,
further actions are necessary to protect the species from local extinction, including active management
of protected areas, forest fragments, cabrucas and pastures in an integrated, landscape-level manner.
© 2010 Deutsche Gesellschaft für Säugetierkunde. Published by Elsevier GmbH. All rights reserved.
Introduction
Land use change is one of the major forces leading to a decrease
in wildlife population, reduction of species distribution, and disruption of ecosystem function (Gutzwiller 2002). In recent years,
a large number of studies have focused on the importance of
the mosaic of habitats to preserve biodiversity, and some studies
have suggested that managed environments such as agroforestry
systems may play an important role in sustaining vertebrate biodiversity in human-modified landscapes (Rice and Greenberg, 2000;
Ricketts, 2001; Schroth and Harvey 2007; Cassano et al. 2009).
The Brazilian Atlantic forest is a biodiversity hotspot that has
been severely fragmented. It is currently reduced to less than 12%
of its original extent (Ribeiro et al. 2009). Southern Bahia is a relatively well-preserved part of this biome where over 50% of the land
∗ Corresponding author. Tel.: +55 31 33194967; fax: +55 31 33194967.
E-mail address: [email protected] (A.G. Chiarello).
is covered by “forested environments”, mainly traditional cacao
plantations (26% of the landscape), secondary growth forest (19%)
and primary forests (9%) (Landau et al. 2008); the remaining 46% is
covered mainly by pastures and agriculture. In the 1990s, approximately 70% of the 700,000 ha planted with cacao (Theobroma cacao)
in this region was cabrucas, traditional plantations established in
the shade of native canopy trees (Araújo et al. 1998). However, as a
result of the cocoa economic crisis of the late 1980s associated with
the infection of a fungus disease (witches’ broom, Moniliophthora
perniciosa), traditional cabrucas have increasingly been replaced
by pasture or cacao plantations shaded by exotic trees or simply
unshaded cacao. At the same time, some cabrucas have been abandoned or received little management. In these cases, tree recovery
has resulted in a dense canopy layer (Sambuichi and Haridasan
2007) that, while beneficial for native wildlife, negatively impacts
cacao production, making it a non-viable management strategy.
Oliver and Santos (1991) proposed that sloths and other threatened mammals from the Atlantic Forest make use of cabrucas to
some extent, and more recent research has shown the importance
1616-5047/$ – see front matter © 2010 Deutsche Gesellschaft für Säugetierkunde. Published by Elsevier GmbH. All rights reserved.
doi:10.1016/j.mambio.2010.06.008
244
C.R. Cassano et al. / Mammalian Biology 76 (2011) 243–250
Fig. 1. Land cover in the region of the Una Biological Reserve and Ecoparque de Una (insert, right), northeastern Brazil (left, lines indicate state borders). The study site is
located to the east of Una Biological Reserve (circle).
of those areas as corridors or as additional habitat for some mammal species (Moura 1999; Pardini, 2004; Raboy et al. 2004; Pardini
et al. 2009). The maned sloth (Bradypus torquatus) is one of the six
extant species of sloths and is listed as “endangered” by the IUCN
(IUCN 2008). The maned sloth is endemic to the coastal rain forest of eastern Brazil, occurring from the state of Sergipe to Rio de
Janeiro (Wetzel and Avila-Pires 1980; Oliver and Santos 1991). The
species is separated into three functionally isolated populations,
each genetically homogeneous but strongly differentiated from the
others, to the extent that the northernmost population in Bahia is
considered a distinct evolutionary unit requiring separate management from the southern populations (Lara-Ruiz et al. 2008). Habitat
destruction is by far the main threat to the conservation of the
maned sloth (Machado et al. 2005; IUCN 2008).
Given the great reduction and fragmentation of mature forest
remnants in southern Bahia, a better understanding of the capacity of maned sloths to use agroforests as permanent or temporary
habitat has critical implications for assessing the conditions under
which the species can persist. Given that agroforests comprise such
a large proportion of the matrix, we investigate the use of a cabruca
by three maned sloths in the vicinity of Una Biological Reserve in
southern Bahia. Additionally, we describe the tree species found in
cabrucas that can be used as a source of food by maned sloths.
Material and methods
Study site
The maned sloths were monitored in a cabruca located at the
Cabana da Serra Farm (15◦ 11 20 S; 39◦ 2 33 W) in the municipality
of Una, in the lowlands of southern Bahia, Brazil. The study site is
located near the Una Biological Reserve and the Private Reserve
Ecoparque de Una, and is crossed by the Maruim River (Fig. 1).
Approximately 67% of the land encompassed by Una Biological
Reserve and its buffer zone (extending 10 km beyond the Reserve’s
borders) is covered by primary and secondary forests (Instituto
de Estudos Socioambientais do Sul da Bahia, unpublished data).
Shaded cacao plantations and rubber tree plantations account for
60% of the cultivated land and represent the main crops in the Una
Biological Reserve buffer zone (Araújo et al. 1998).
Average annual temperature is 24–25 ◦ C, and annual precipitation is 1600–2000 mm (Gouvêa 1969). The vegetation in the study
area is tropical lowland rainforest (Oliveira-Filho and Fontes 2000).
The mature humid forest at Una Biological Reserve is characterized
by a canopy 25–30 m tall, high abundance of epiphytes and vines,
and clearly defined strata (Amorim et al. 2008). In the cabrucas,
the understory of original forest is replaced by cacao shrubs, tree
canopy density is lower than in mature forests, epiphytes are usually reduced to canopy layer and vines are minimal (Alves 1990,
2005; Sambuichi 2006; Sambuichi and Haridasan 2007; Cassano
et al. 2009). Traditional cacao agroforests exhibit great variation
in vegetation diversity and structure as a consequence of both
tree diversity of the original forest and the agroforest management
(Sambuichi 2006). The cabruca where the study was conducted has
well-developed canopy strata, although it is lower and thinner than
that of mature forests. Barreto and Cassano (2007) found 30 trees
(11 species) with a DBH > 10 cm in 0.1 ha, most were early successional species. Inga edulis, Tapirira guianensis and Senna multijuga,
for example, together comprised over 50% of the trees. The cacao
plantation where the study was conducted received little manage-
C.R. Cassano et al. / Mammalian Biology 76 (2011) 243–250
ment: weeding happened only twice during the four years of the
study, tree epiphytes were neither pruned nor removed from cacao
plants, and agrochemicals were not used.
Data collection
Three maned sloths inhabiting the cabruca, an adult female and
two of its infants, were tracked with telemetry equipment (radio
collars model TW-3 from Biotrack Ltd., a Telonics TR-4 receiver
and a three-element Yagi antenna from Wildlife Material) between
October 2004 and February 2008. These radio collars weigh less
than 80 g (<2% of the adult body weight) and have not caused
injuries, scars, or any other known problems to tagged individuals
in the 10+ years we have been studying these animals (Chiarello
1998a,b; Chiarello et al. 2004; Lara-Ruiz and Chiarello 2005; LaraRuiz et al. 2008). The two cubs were tagged while they were still
carried by the adult female, but data on home range were collected for these individuals only after they separated (i.e., became
independent) from the mother.
The sloths were located two to three times a month; consecutive
sightings were separated by at least 1 week. Every tree in which
the animals were seen was mapped. To minimize location errors
two methods were used for mapping trees. When used trees were
between 10 and 50 m to each other the position of these trees were
mapped using compass and measuring tapes. We avoided using
the GPS in these circumstances as distances were generally smaller
than the GPS error. Later the geographic coordinates (recorded by a
Garmim Etrex 12 channel GPS) of at least three trees located at the
periphery of the area used by each animal were used as a geographic
reference to plot these trees on a map using ArcMap 9.2 Program.
Trees located more than 50 m from the nearest used tree had their
coordinates recorded directly by the GPS.
Information on sloth diet was collected during observations of
feeding behavior of the three individuals inhabiting the cabruca
(Correia et al. 2006 and C.R. Cassano, personal observation) and also
from previous research developed in a mature forest remnant at
Ecoparque de Una (Cassano 2006 and C.R. Cassano, personal observation). We searched botanical inventories carried out in southern
Bahia and compile information on plant species present in cabrucas
of this region that are known to be used as source of food by maned
sloths.
Data analysis
Home ranges were estimated using HawthsTools, for ArcMap
9.2. For comparative purposes, home ranges were calculated using
two methods: the minimum convex polygon (MCP) using 100% of
locations, and fixed kernel using 95% of locations. Because of its
ease of calculation, many investigators use MCP to describe home
ranges, and we therefore present these analyses to facilitate comparison with other studies. However, the kernel method provides a
more detailed home range map, identifying areas of intensive use
(Powell 2000) through concentric contour lines (95, 50, 20, 10 and
5%) indicating the probability of finding an animal in a given region
245
of its range (i.e., the utility density distribution, Powell (2000)). The
bandwidth (h) chosen for fixed kernel was 15 m, which we considered as a good approximation of the perception radius (Powell
2000) of this species (see also Montgomery and Sunquist 1975).
Scaling factor used was 108 and raster cell size was 10 due to the
small areas under analysis.
Interpretation of aerial photographs provided by Instituto de
Estudos Socioambientais do Sul da Bahia (unpublished data) was
used as an initial source for the land cover of the region. However,
this method did not discriminate cabrucas from secondary logged
forest, due to similarities in canopy structure between these two
vegetation types. We therefore modified the original maps using
field observations in order to delimitate more accurately the extent
of cabrucas in the study site. The home ranges (MCP and kernel)
were clipped from the land cover map using the intersect function from ArcMap 9.2. We then calculate the proportion of cabruca
falling within each home range using the resulting shape file.
We used contingency tables (Chi-square goodness-of-fit-tests)
complemented by residual analysis to assess if the radio-collared
sloths used the habitats according to their availabilities. First, we
contrasted the number of location fixes on each major habitat type
inside the MCPs (swamp/pasture, cabruca, early secondary forest and late secondary forest) with the expected frequencies of
fixes based on the availability of these habitats in the MCPs. We
pooled the swamp with pasture as all fixes falling in pasture were
in fact in the very edge between pasture and swamp vegetation.
In a second Chi-square we contrasted the observed frequency of
fixes with the expected value based on habitat availability in a
buffer area surrounding the home ranges of the three sloths. To
calculate the width of this buffer area we measured the largest
distances between fixes inside each individual home range and
averaged them. The resulting width (487 m) encompassed an area
of 214.7 ha (6.8 times larger than the combined area of the three
MCPs). Although this wide buffer may include land-use types differing from the immediate study area, a narrower band would not
be representative of the larger landscape context. These tests were
performed using BioEstat version 5.0, a free statistical software
available at Instituto de Desenvolvimento Sustentável Mamirauá
(http://www.mamiraua.org.br).
Results
Monitoring time for individual sloths ranged from 12 to 40
months. A total of 199 locations of the three radio-collared maned
sloths were recorded (Table 1). Both MCP and kernel methods
indicated that the adult female (BT464) had the smallest home
range, followed by the male juvenile (BT162) and the female
juvenile (BT065) (Fig. 2). The cabrucas comprised the majority of home range of the mother and the male juvenile and a
significant proportion of the home range of the female juvenile (Table 1). The latter individual stayed in the cabruca tract
where it was born during the first year of study. Subsequently,
it used a mix of land-use types including secondary forest, the
border of a swamp vegetation and another tract of cabruca
Table 1
Estimates of home range size (in hectares, ha) of the three radio-collared maned sloths based on minimum convex polygon (MCP) and kernel methods and the corresponding
percentage of the home range comprising cabruca (in parenthesis). See Methods for details.
Study animal
BT464
BT065
BT162
a
b
Sex/age
Female/adult
Female/juvenile
Male/juvenile
Number of fixes
116
58
25
MCP (ha)
Kernel (ha)
Year 1
Year 2
Year 3
Total
0.44 (90)
0.72 (70)
2.28 (100)
0.49 (86)
17.59 (7)
0.45 (83)
0.56 (83)a
29.33 (7)b
2.28 (100)
1.00 (76)a
4.04 (27)b
1.64 (99)
Based on the total number of fixes (years 1, 2 and 3, plus nine fixes from the forth year). Annual number of fixes were year 1 = 47; year 2 = 31 and year 3 = 29.
Based on the total number of fixes (years 1 and 2). Annual number of fixes were year 1 = 31 and year 2 = 27.
246
C.R. Cassano et al. / Mammalian Biology 76 (2011) 243–250
Fig. 2. Minimum convex polygon (MCP) home ranges of the tree radio-tracked animals showing the main land cover types as well as opportunist sightings of other maned
sloths (dotted circles).
(Fig. 2). The female juvenile moved continuously northwards in
what seems to be a dispersal movement (Fig. 2). Areas of more
intensive use (kernel contours) corresponded to groves or individual trees used repeatedly by the sloths (Fig. 3). These include
Ficus clusiaefolia, Inga edulis, Tapirira guianensis, Cecropia hololeuca,
Ocotea pretiosa and one individual from the Olacaceae Family covered by an unusually high number of vines. Leaves of all these
species were consumed by maned sloths, except the Olacaceae
tree and the vines. The kernels in cabrucas indicated that sloths
are using this habitat both for resting and for feeding. In addition to the two tagged juveniles, the mother gave birth to two
other infants during the study. One was seen when the adult
female was first tagged, in October 2004, and the second when
the mother was last captured for removal of the radio collar in
February 2008. Besides the tagged individuals, five opportunistic
observations of other maned sloths were recorded in the study
cabruca or in adjacent areas, two of which within areas of cabruca
(Fig. 2).
The frequency with which the three sloths were located in
each vegetation type was significantly different from expected
(Chi-square goodness-of-fit test; 2 = 111.517; d.f. = 3; p < 0.0001).
The residuals showed that swamp/pastures and early secondary
forests were used less than expected, cabrucas were used more
than expected and the late secondary forests were used according to their availability within the home range’s area (Table 2).
Similarly, the frequency of fixes differed significantly from the
expected value based on availability of habitat in the buffer area
(Chi-square goodness-of-fit test; 2 = 119.001; d.f. = 3; p < 0.0001)
and the residuals showed the same pattern found in the previous
analysis (Table 2).
Sloths were observed feeding on leaves of six tree species from
cabrucas and on 11 plant species (10 trees and one vine) from
mature forests at the Ecoparque de Una (Table 3). Five of the 10 tree
species found in mature forests and four of the six species found in
cabrucas at Una have also been previously recorded in other cabru-
cas from southern Bahia by Sambuichi (2002, 2006) and Sambuichi
and Haridasan (2007). Most trees used as food in the mature forest are considered shade tolerant, i.e., indicative of late succesional
phases, while the opposite was observed for tree species consumed
solely in cabrucas (Table 3).
Discussion
This is the first unequivocal confirmation of the use of a cacao
agroforest by maned sloths based on field observation of wild individuals. Both kernel and residual analyses suggested that cabruca
was actively selected by maned sloth, providing both feeding and
resting trees. Indeed, the range of the adult female (BT464) was
relatively small, and was comprised almost entirely of cabruca. Nevertheless she was actively reproducing, indicating the availability
of both sufficient food resources and sexually mature males in her
home range. Our limited sample of 199 observations in a single
cabruca limits our ability to conclude that maned sloths area able
to exploit cabruca throughout their range. However, we observed
no evidence that using cabruca was detrimental to the sloths, and
we believe that these areas potentially represent high-quality sloth
habitat. Sloths have been reported in cabruca region of Uruçuca,
Santa Maria Eterna (Oliver and Santos 1991) and Una municipalities (C.R. Cassano, personal observation) suggesting that cabrucas
in a wider area of southern Bahia might similarly represent usable
habitat for maned sloths.
Because the plant species consumed by maned sloths are found
in a wider sample of cabrucas in the region (Sambuichi 2002, 2006;
Sambuichi and Haridasan 2007) sloths should be able to forage in
many of southern Bahia’s cabrucas. Although they feed from many
abundant trees (Inga edulis, Tapirira guianensis and Senna multijuga) the kernel analysis demonstrates that the availability of many
relatively rare species (Ficus clusiaefolia, Cecropia hololeuca, Ocotea
pretiosa) may be the key to the survival of maned sloths in these
habitats. That single trees have significant influences on patterns of
C.R. Cassano et al. / Mammalian Biology 76 (2011) 243–250
247
Fig. 3. Home range (kernel method) of the three tagged animals showing the land cover types. The concentric contours (kernels) represent from outside in, 95, 50, and 5%
of the utility density distribution. See Methods for details.
Table 2
Results of two residual analyses on habitat preferences of the three radio-collared maned sloths. In the first analysis (“MCP”), the number of fixes found inside the home ranges
(minimum convex polygons – MCP) (“observed”) was contrasted with the expected number based on the proportion of vegetation types available in the MPCs (“expected”).
In the second analysis (“Buffer”), the frequency of fixes was contrasted with the expected number based on habitat availability in the buffer surrounding the MCPs (buffer
area). See Methods for details.
Vegetation
MCP
Observed
Residual p
Expected
Swamp/pasture
Cabruca
Early secondary forest
Late secondary forest
12
123
7
57
62
30
36
71
Total
199
199
a
ns: not significant (p > 0.05).
Buffer
Observed
<0.01
<0.01
<0.01
nsa
Residual p
Expected
12
123
7
57
58
26
40
75
199
199
<0.01
<0.01
<0.01
nsa
248
C.R. Cassano et al. / Mammalian Biology 76 (2011) 243–250
Table 3
Tree species from mature forest or cabruca where maned sloths have been found feeding at Ecoparque Una (“feeding trees”). We also indicate which of these species were
recorded in other cabrucas sampled in the study region (“other cabrucas”) and the tree sucessional phases: shade intolerant (SI) and shade tolerant (ST).
Family
Species
Anacardiaceae
Burceraceae
Cecropiaceae
Fabaceae
Tapirira guianensis
Tetragastris catuaba
Cecropia hololeuca
Dalbergia frutencens
Dialium guianense
Inga edulis
Machaerium sp. (vine)
Macrolobium latifolium
Senna multijuga
Ocotea pretiosa
Eriotheca globosa
Ficus clusiifolia
Brosimum guianense
Brosimum rubescens
Virola gardneri
Myrcia fallax
Coussapoa pachyphilla
Mature foresta
Lauraceae
Malvaceae
Moraceae
Myristicaceae
Myrtaceae
Urticaceae
Total
a
b
c
d
Other cabrucasc
Sucessional phased
x
x
x
x
SI
ST
SI
SI
ST
SI
Feeding trees
Cabrucab
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
6
9
x
x
x
x
x
11
ST
SI
ST
ST
ST
SI
SI
SI
ST
ST
Cassano (2006).
This study and Correia et al. (2006).
Sambuichi (2002, 2006) and Sambuichi and Haridasan (2007).
Classified by expert taxonomists with experience in the region (Eduardo Mariano Neto, André Amorim, Jomar Gomes Jardim and André Mauricio de Carvalho).
habitat use by sloths (Vaughan et al. 2007) and primates (WilliamsGuillén et al. 2006; Oliveira et al. 2010) in similar agroforestry
systems suggest that our results may be generalized beyond our
study population.
Most tree species eaten by maned sloths in cabruca are shade
intolerant species, a probable consequence of the tree species
composition of these systems in general. In cacao plantations
established under the shade of native trees, climax trees of the
canopy layer undergo gradual loss, being replaced by pioneer, early
secondary growth or exotic species (Rolim and Chiarello 2004;
Sambuichi and Haridasan 2007). On the other hand, the majority of trees consumed by maned sloths in forest remnants are
shade tolerant species, which are probably more abundant there
than in cabrucas (Sambuichi and Haridasan 2007; Pardini et al.
2009). Although detailed dietary studies comparing maned sloths
in cabrucas with native forests are still lacking, this finding suggest that maned sloths might be able to adapt its diet according
to local differences in tree species composition and abundance.
This corroborates previous studies on feeding preferences of maned
sloths carried out in other region of the Atlantic forest (Chiarello
1998a) and suggests that this endangered sloth might thrive in a
broader diversity of habitats than was previously thought. In fact
the maned sloths do not seem to be different from the other sloths
in this respect. Such adaptability may result in part for the apparent ability of sloths to tolerate a variety of plant feeding deterrents
(Cork and Foley 1991), from trees found in primary and secondary
forests (Chiarello 1998a), a trait other sloth species apparently
share (Montgomery and Sunquist 1975; Chiarello 2008).
As more information on habitat and diet preferences accumulates, the more it appears that sloths in general are flexible species
(Vaughan et al. 2007; Chiarello 2008). A recent study in Costa Rica
demonstrated, for example, that two other sloth species, the threetoed sloth (Bradypus variegatus) and the two-toed sloth (Choloepus
hoffmanni), are also able to use cocoa landscape as habitat (Vaughan
et al. 2007). Vaughan et al. (2007) also observed that sloths (mainly
Choloepus hoffmanni) can routinely venture into relatively open
pastures in search of preferred food trees. Although this fact doubtless stress the behavioral plasticity of sloths and their high capacity
of adaptation to disturbed places, it should be regarded as exceptional in the light of what is known about the natural history of
sloths (Montgomery and Sunquist 1975; see Chiarello 2008, for a
recent review) which, in turn, derives from its anatomy strongly
adapted to arboreal life (Goffart 1971). Further, sloths are very vulnerable to predation by mammalian carnivores when on the ground
(Vaughan et al. 2007, pers. obs.). Being a strictly arboreal species,
maned sloths need high densities of shade and, perhaps more
importantly, uninterrupted connectivity between trees crowns of
the canopy layer. We have observed that maned sloths might cross
small canopy gaps, but mainly when adjacent tree crowns are sufficiently close to each other. Larger gaps might hamper movements
because sloths never jump as primates do and are very reluctant to
use the ground as a substrate to pass from tree to tree (Chiarello
et al., 2004; Chiarello 1998b). We strongly believe therefore that
low canopy connectivity might be a major hindrance for maned
sloths in cabrucas. The tree densities in cabrucas from southern
Bahia are at least half that found in forest remnants of this region,
although it is generally much lower than that. Sambuichi (2006)
recorded, for example, densities varying from 47 to 355 individuals/ha in cabrucas of southern Bahia as compared to 596 to 988
individuals/ha in native forests of the region (Martini et al. 2007).
Tree densities approaching 300 trees/ha are characteristics of littlemanaged cabrucas but much lower tree densities are recommended
to increase cacao productivity in traditional agroforests (25–30
tree/ha according to Alvim (1972)). It is therefore critically important to investigate what is the maximum tolerance to tree thinning
for maned sloths.
Very likely, the survival of maned sloth is also dependent upon
the existence and proximity of forests tracts, as has been observed
in other forest specialists (Faria et al. 2006, 2007; Moura 2008;
Raboy et al. 2008; Pardini et al. 2009), including the golden-headedlion-tamarin (Leontopithecus chrysomelas) (Dietz et al. 1996; Raboy
et al. 2004). In agricultural landscapes, the distribution and richness of large mammals is affected by the presence of forest tracts,
for example, through the gradual loss of species with increasing
distance from forest (Bali et al. 2007), or through the availability
of more species in forest fragments (Daily et al., 2003; Harvey et
al. 2006). What if these native forest tracts provide feeding trees
in lean times of the year, or function as source habitats for surplus individuals for sloths? These and other possibilities should be
investigated in future studies to better frame our results.
C.R. Cassano et al. / Mammalian Biology 76 (2011) 243–250
Given the severe reduction in the original extent of the Brazilian Atlantic forest (Ribeiro et al. 2009), understanding how maned
sloth use human-modified landscape is essential to prioritize areas
and actions for the conservation of this endangered species. Our
results, although limited in scope, suggest that existing habitat for
this species in southern Bahia is, in fact, greater than the area covered solely by primary and late secondary forest remnants, which
together account for approximately 28% of southern Bahia (“Litoral
Sul da Bahia” – Landau et al. 2008). Since cabrucas cover a quarter
of the landscape, the area available to maned sloth in this landscape could exceed 50%, but only if cabrucas are managed with both
productivity and wildlife conservation in mind. However cabrucas
vary widely in the diversity and density of tree cover (Sambuichi
2006; Schroth and Harvey 2007). Moreover, the presence of large
tracts of primary forest, certainly contributes for the existence of
a relatively healthy wildlife in cabrucas of southern Bahia (Faria
et al. 2007; Cassano et al. 2009), making them very different from
biologically poorer cabrucas of eastern Brazil, such as those found,
for example, in the state of Espírito Santo (Rolim and Chiarello
2004).
Southern Bahia likely harbors the largest and genetically most
diverse population of maned sloths (Chiarello and Lara-Ruiz 2004;
Lara-Ruiz et al. 2008). This, alongside the findings presented here,
indicate that the cacao region of southern Bahia has great potential
to support perhaps the most viable populations of maned sloth.
Nevertheless, deforestation, selective logging, the thinning and
impoverishment of trees in the cabrucas, as well as their conversion
into non-agroforest systems (Johns 1999; Sambuichi and Haridasan
2007), might undermine the expectation of long term survival of
this species. These practices must be reverted or at least better
controlled particularly in the buffer zones of forest reserves and
corridors. Canopy shade management within the cabrucas should,
for example, consider the maintenance of canopy connectivity, tree
species of conservation interest as well as key tree species for fauna
(see Cassano et al. (2009) and Oliveira et al. (2010) for species recommendation). Additionally, forest cover in private lands should
achieve at least the minimum amount mandated by the Brazilian
environmental legislation (20% of the property’s area). Otherwise
the policy makers and society as a whole must be aware that not
all cocoa plantations can be regarded as a “green” economic alternative.
Acknowledgements
We would like to thank the Instituto de Estudos Socioambientais do Sul da Bahia for the logistic support. Fundação O Boticário de
Proteção à Natureza, Conservation International Brazil and Seeds of
Change for financial support. We also thank the Brazilian Program
CAPES for the MSc scholarship to Camila R. Cassano at the Universidade de Santa Cruz, and the Brazilian Environmental Agency for the
research permits (IBAMA # 02001.007588/2002-18). Rubens Vieira
Lopes, Rebeca M. Fonseca Barreto and Tâmara L Correia helped
during the field work and Rebeca Mascarenhas Fonseca Barreto collected data on tree species from cabruca. Adriano G. Chiarello has
a research Grant from the Brazilian Science Council (CNPq grant
# 303273/2008-9). One anonymous referee made a careful and
thorough revision.
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