Geographic distribution and population characteristics of the endangered white-fronted spider monkey (Ateles marginatus) on the lower Tapajós River in central Brazilian Amazonia

Abstract

The white-fronted spider monkey, Ateles marginatus, is endemic to Brazilian Amazon between the Tapajós and Xingu Rivers, and is classified as endangered due primarily to habitat loss. This study presents data on the distribution and relative abundance of the species in the northwestern corner of its distribution, on the lower Tapajós River, centered on the 545,000 ha Tapajós National Forest (Flona Tapajós). Quantitative data were collected in line transect surveys at 14 sites, and confirmatory interviews were conducted at these, and a further four sites. The results indicate that A. marginatus is extinct or extremely rare at sites in the northern extreme of the study area, but is relatively widespread further south, except in very small fragments (<100 ha). While the present-day occurrence of A. marginatus is clearly affected by habitat fragmentation, the species' original distribution appears to have been characterized by local lacunas, determined by factors relating to habitat quality. While hunting pressure does not seem to be a major threat at the present time, competition with a second atelid, Alouatta discolor, may have reinforced the effects of habitat disturbance in some areas, especially smaller fragments. Grouping patterns were typical of the genus, including an apparent female bias in the sex ratio of adults. Overall, the results indicate an ongoing decline in the occurrence of A. marginatus within the study area, local extinction, especially in smaller fragments, and an urgent need for the establishment of effective conservation measures.

Long-term persistence of midsized to large-bodied mammals in Amazonian landscapes under varying contexts of forest cover

“…However, all interviews with local residents indicate that white-fronted spider monkeys (Ateles marginatus; but see Ravetta and Ferrari 2009), white-nosed bearded saki-monkeys (Chiropotes albinasus) and small-eared dogs (Atelocynus microtis) no longer occurred in any of the three landscapes and had been likely extirpated on a regional scale. White-lipped peccary (Tayassu pecari), lowland tapir (Tapirus terrestris), greater long-nosed armadillo (Dasypus kappleri) and giant armadillo (Priodontes maximus) had long been absent from the two least forested landscapes (L2 and L3) and giant anteater (Myrmecophaga tridactyla) had been absent from the forest fragments in L3 (Table 2).…”

Resource availability and diet in Harpy Eagle breeding territories on the Xingu River, Brazilian Amazon

“…The Xingu basin harbors great species diversity (Pacheco and Olmos, 2005), and many species, such as the larger primates and birds of prey, are vulnerable or threatened due to advancing deforestation (Ravetta and Ferrari, 2009;Trinca et al, 2008). Conservation plans are being developed for several of these species, and specifically, the Conservation Plan of Lower and Mid-Xingu River (PAN Xingu) includes two bird of prey species, Harpy Eagle Harpia harpyja (Linnaeus) and Crested Eagle Morphnus guianensis (Linnaeus) (Brasil, 2012(Brasil, , 2014a.…”

Distribution and Abundance of White-Fronted Spider Monkeys, Ateles belzebuth (Atelidae), and Threats to Their Survival in Peruvian Amazonia

“…We currently lack an explanation for this 'lacuna' in the distribution of A. belzebuth . Such 'lacunae' have also been reported for Ateles marginatus and Lagothrix cana from Brazilian Amazonia [Iwanaga and Ferrari, 2002;Ravetta and Ferrari, 2009] and may be more common than appreciated so far in the geographic distribution of many New World primates [Palminteri, 2010;Palminteri et al, 2011]. While local absence can often be explained by extinction due to excessive hunting [Peres, 1990;Nuñez-Iturri and Howe, 2007], local and regional lack of a species may also relate to fine-grained and often unrecognized habitat factors [Ravetta and Ferrari, 2009;Palminteri, 2010].…”