134 Neotropical Primates 14(3), December 2007 Schneider, E. C., Hunter, L. F. and Horwich, R. H. 1999. 13–15 species and 33 recognized forms (Hershkovitz, Adoption of a young juvenile in black howler monkeys 1977; Rylands et al., 2000). Defler (2003a) recognizes the (Alouatta pigra). Neotrop. Primates 7: 47–51. presence of six species of Saguinus in Colombia (40–46% Siegel, S. and Castellan Jr., N. J. 1988. Nonparametric Sta- of the total species in the genus), three of them exclusively tistics for the Behavioral Sciences. McGraw-Hill, Boston. distributed in the Colombian Amazon: S. fuscicollis (Spix, Silver, S. C., Ostro, L. E. T., Yeager, C. P. and Horwich, 1823), S. nigricollis (Spix, 1823), and S. inustus (Schwartz, R. 1998. Feeding ecology of the black howler monkey 1951). Saguinus inustus, the mottled-face tamarin, is dis- (Alouatta pigra) in northern Belize. Am. J. Primatol. 45: tributed in southeastern Colombia, west of the Andes, 263–279. between the Guayabero-Guaviare rivers and the Caquetá Stevenson, P. R., Quinones, M. J. and Ahumada, J. A. River, and between the Mesay River and the border with 1998. Effects of fruit patch availability on feeding sub- Brazil; however, accurate eastern and western boundar- group size and spacing patterns in four primate species ies of its geographical range within the country are still at Tinigua National Park, Colombia. Int. J. Primatol. 19: unknown (Defler, 2003a). The species is also present in 313–324. western Brazil, between the Rio Negro and the Colombian Strier, K. B. 1994. Brotherhoods among Atelins: Kinship, border. affiliation, and competition. Behaviour 130: 151–167. Strier, K. B. 1999. Why is female kin bonding so rare? Saguinus inustus is one of the least-studied species of Comparative sociality of neotropical primates. In: Com- Neotropical primates; preliminary information on its ecol- parative Primate Socioecology, P. C. Lee (ed.), pp.300–319. ogy (ranging and diet) comes from only two short studies Cambridge University Press, Cambridge, UK. carried out near La Pedrera, at Comeyafú Indigenous Re- Strier, K. B., Dib, L. T. and Figueira, J. E. C. 2002. Social serve, an interfluvial area between the Caquetá and Apapo- dynamics of male muriquis (Brachyteles arachnoides hy- ris rivers (Palacios et al., 2004; Defler, unpublished data), poxanthus). Behaviour 139: 315–342. and from occasional observations of foraging groups in Treves, A. and Baguma, P. 2002. Interindividual proxim- the Amanã Sustainable Development Reserve in Brazil (de ity and surveillance of associates in comparative perspec- Souza et al., 2004). Here we present the first data on the tive. In: The Guenons: Diversity and Adaptation in African density of S. inustus. We collected this information during Monkeys, M. E. Glenn and M. Cords (eds.), pp.161–172. a primate survey in the lower Caquetá River as part of a Kluwer Academic/Plenum Publishers, New York. larger effort started six years ago to document and monitor Treves, A., Drescher, A. and Ingrisano, N. 2001. Vigi- the densities of primates and 15 other large vertebrate spe- lance and aggregation in black howler monkeys (Alouatta cies in eastern Colombian Amazonia (Palacios et al., 2003; pigra). Behav. Ecol. Sociobiol. 50: 90–95. Palacios and Peres, 2005; Peres and Palacios, 2007). Wang, E. and Milton, K. 2003. Intragroup social relation- ships of male Alouatta palliata on Barro Colorado Island, Methods Republic of Panama. Int. J. Primatol. 24: 1227–1243. White, F. J. and Chapman, C. A. 1994. Contrasting chim- Study area panzees and bonobos: Nearest neighbor distances and Censuses were carried out in the interfluvial area between choices. Folia Primatol. 63: 181–191. the lower Caquetá and Apaporis Rivers, Amazonas, near Zucker, E. L. and Clarke, M. R. 1998. Agonistic and affili- Loma Linda indigenous community (01°16'S, 69°44'W, ative relationships of adult female howlers (Alouatta pal- 101 m a.s.l.; Fig. 1), Córdoba Indigenous Reserve. Prima- liata) in Costa Rica over a 4-year period. Int. J. Primatol. ry terra firme and várzea forests represented the majority 19: 433–449. of the forested matrix in the study site. An area of second- ary terra firme forest (locally called rastrojo) located around the indigenous settlement comprised a small proportion Density of SAGUINUS INUSTUS (Schwartz, of such matrix. There were also patches of what is locally 1951) in the Interfluvium of the Caquetá– known as savanna forest or varillal, which corresponds to Apaporis Rivers, Colombian Amazonia primary forest with a mean height of 17–18 m, and a very sparse understory growing on rocky outcrops and white Claudia Idaly Castillo-Ayala sands; and another savanna type known as sabana capo- Erwin Palacios tuda, with a mean canopy height of 8 m, deep soil litter and a very dense understory with intermingled vines and Introduction lianas. The Amazon bioregion is considered one of the highest bio- Linear transects diversity areas in the world. Primates are important com- We used the line transect method (Burnham et al., 1980) ponents of this biodiversity, and with 15 genera, 81 species to estimate S. inustus densities. From a zero point lo- and 134 taxa, they are the most emblematic faunal group cated ca. 100 m away from the community secondary of Amazonia (Mittermeier et al., 2002). Saguinus is per- forest area, two transects (4.6 and 4.9 km long, oriented haps the most diverse of Neotropical primate genera, with 40° NW and 40° NE respectively) were cut; they were Neotropical Primates 14(3), December 2007 135 Figure 1. The lower Caquetá region in Eastern Colombian Amazonia. Black square shows the area where censuses were carried out. marked with flagging tape every 50 m to facilitate ac- Results and Discussion curate location of sightings. Transects were cut a month before we started the censuses, so at the time of the study, A total census effort of 380 km was achieved, during local fauna were already habituated to the transect paths. which groups of S. inustus were sighted 33 times. Six ad- The shortest transect crossed nearly 2 km of rastrojo, ditional primate species are sympatric with S. inustus in 1.1 km of varillal, and 1.5 km of primary terra firme ter- the lower Caquetá and Apaporis interfluvial area:Alouatta race forest. The second transect crossed hilly primary seniculus, Aotus cf. vociferans, Callicebus torquatus, Cebus terra firme forest with sandy soils in the first half of its albifrons, Cebus apella, and Saimiri sciureus. Although the length and clay soils in the second, as well as patches of study site is included in the distribution range of Lago- sabana capotuda. thrix lagothricha, this species was not recorded during the survey period. People from Loma Linda said they have Censuses were carried out during 10 days each month never seen woolly monkeys in that area, and this is likely between October 2005 and February 2006. Independent to be a consequence of a long history of human settlement observers walked the transects during days without rain at and subsistence hunting in the region. L. lagothricha has a mean speed of 1.2 km/h, between 0630 and 1130 hrs. not been recorded recently in the lower interfluvium of Community members previously trained and able to accu- the Caquetá and Apaporis Rivers, east of the mouth of the rately detect and identify local primate species participated Mirití River (Palacios, pers. obs.), and the species is likely in the surveys. Every time we encountered groups of S. in- to be locally extinct. ustus, we recorded the date, time, number of individuals, perpendicular distance from the transect, distance walked, We estimated a S. inustus density of 3.8 groups / km² height and type of forest. After each encounter, a maxi- and 19.6 individuals / km². Mean group size was 5.2 in- mum of 15 minutes were spent to obtain accurate counts dividuals (sd = 1.87). The mottled-face tamarin was one of groups. Data were analyzed using DISTANCE 5.0 Beta of the primate species most frequently encountered after 5 software (Thomas et al., 2005). C. torquatus and S. sciureus (Castillo-Ayala, in prep.). 136 Neotropical Primates 14(3), December 2007 Mottled-faced tamarin density at Loma Linda is in the in secondary forest corresponded to rastrojo alto with a very range of that reported for other Saguinus species in nine dense understory. These preferences have been reported for different localities in western Amazonia (Soini, 1981; other species of Saguinus; for example, Emmons and Feer Freese et al., 1982; Pook and Pook, 1982; Terborgh, 1983; (1999) mention that S. fuscicollis, S. nigricollis and S. bicolor Peres, 1997), but high compared with those reported for often can be seen in habitats with high densities of lianas. S. fuscicollis at some sites in eastern Colombian Amazonia (3.4–16.9 individuals / km²: Palacios et al., 2003; Palacios This first density estimate of S. inustus provides important y Peres, 2005; Palacios, unpublished data). In contrast, data, but supplemental information from other areas of S. fuscicollis densities in three other sites in eastern Co- the Caquetá–Apaporis interfluvium will be necessary in lombian Amazonia (Caño Arapa and Caño Esperanza, order to assess the conservation status of the species in this Puré National Park, and Caño Curare) were much higher region. The forests around the community of Loma Linda (21.5, 26.5, and 30.3 individuals /km² respectively; Pala- still offer appropriate habitats for the conservation of the cios, unpubl. data) than those found for S. inustus at Loma species, including secondary forests at different succes- Linda. Mean group size is in the range recorded for other sional stages, and a large proportion of primary forest. The species of Amazonian Saguinus; for example, S.