carlos peres - Academia.edu (original) (raw)

Papers by carlos peres

Voices from the Tropics, 2013

South American Primates, 2009

Evolutionary Anthropology, 2001

Conservation Biology for All, 2010

American Journal of Primatology, 1997

In this paper we describe the use of space and feeding ecology of seven groups of golden lion tam... more In this paper we describe the use of space and feeding ecology of seven groups of golden lion tamarins observed for a total of 2,164 hr in Poço das Antas Reserve, Rio de Janeiro, Brazil. Relative to habitat availability in the home ranges of these groups, lion tamarins spent more time than expected in relatively undisturbed swamp forests and less time than expected in more degraded hillside and pasture habitats. Home range area was correlated with group biomass but not group size. Golden lion tamarins fed primarily on fruits and small animal prey, but relied heavily on floral nectar during seasonal periods of relatively low fruit availability. Compared to other New World monkeys, lion tamarins used larger home range areas and exhibited longer daily path lengths than would be predicted by group biomass alone. We suggest that this pattern of foraging and use of space may be explained by the relatively greater availability of cryptic prey and their microhabitats in forests that are flooded and/or have closed canopies than in forests that are in earlier stages of succession where prey may be more susceptible to desiccation during the dry season.

Primates, 2009

Stable associations between two or more primate species are a prominent feature of neotropical fo... more Stable associations between two or more primate species are a prominent feature of neotropical forest vertebrate communities and many studies have addressed their prevalence, and their costs and benefits. However, little is known about the influence of different habitat types on the frequency, seasonality, and composition of mixedspecies groups in Amazonian forest primates. Here we examine the features of interspecific primate groups in a large mosaic of flooded (várzea and igapó) and unflooded (terra firme) forest in central Amazonia. In total, 12 primate species occurred in the study area, nine of which were observed in mixed-species associations. Primates were more than twice as likely to form associations in várzea forest than in terra firme forest. Squirrel monkeys were most frequently found in mixed-species groups in all forest types, most commonly in association with brown capuchins. Another frequent member of interspecific associations was the buffy saki, which often formed mixedspecies groups with tamarins or brown capuchins. There was no seasonality in the frequency of associations in terra firme forest whereas associations in várzea forest were twice as frequent during the late-dry and early-wet seasons than in the late-wet and early-dry seasons. Interspecific primate associations were common in all forest types, but the degrees to which different species associate varied between these environments. We suggest that the temporal variation of várzea forest associations is connected with seasonal changes in habitat structure and resource abundance. However, more work is needed to pinpoint the underlying causes of mixed-species associations in all forest types and their strong seasonality in várzea forest.

Primates, 2008

Little information exists on mixed-species groups between primates and other mammals in Neotropic... more Little information exists on mixed-species groups between primates and other mammals in Neotropical forests. In this paper, we describe three such associations observed during an extensive large-vertebrate survey in central Amazonia, Brazil. Mixed-species groups between a primate species and another mammal were observed on seven occasions between squirrel monkeys (Saimiri cf. ustus) and either South American coatis (Nasua nasua) or tayras (Eira barbara) and between brown capuchins (Cebus apella) and coatis. All associations were restricted to floodplain forest during its dry stage. We suggest that the associations involving the coatis are connected to foraging and vigilance but may be induced by a common alternative food resource at a time of food shortage.

PLoS ONE, 2012

Tropical deforestation and forest fragmentation are among the most important biodiversity conserv... more Tropical deforestation and forest fragmentation are among the most important biodiversity conservation issues worldwide, yet local extinctions of millions of animal and plant populations stranded in unprotected forest remnants remain poorly explained. Here, we report unprecedented rates of local extinctions of medium to large-bodied mammals in one of the world's most important tropical biodiversity hotspots. We scrutinized 8,846 person-years of local knowledge to derive patch occupancy data for 18 mammal species within 196 forest patches across a 252,669-km 2 study region of the Brazilian Atlantic Forest. We uncovered a staggering rate of local extinctions in the mammal fauna, with only 767 from a possible 3,528 populations still persisting. On average, forest patches retained 3.9 out of 18 potential species occupancies, and geographic ranges had contracted to 0-14.4% of their former distributions, including five large-bodied species that had been extirpated at a regional scale. Forest fragments were highly accessible to hunters and exposed to edge effects and fires, thereby severely diminishing the predictive power of species-area relationships, with the power model explaining only ,9% of the variation in species richness per patch. Hence, conventional species-area curves provided over-optimistic estimates of species persistence in that most forest fragments had lost species at a much faster rate than predicted by habitat loss alone.

mammalia, 2000

Examining edge effects is imperative to developing effective conservation and management strategi... more Examining edge effects is imperative to developing effective conservation and management strategies in fragmented landscapes as they are a key component of how landscape change influences habitat quality. Although medium-to large-bodied mammals are recognised as key components of tropical forests, their responses to forest edges remain poorly documented. Here, we describe how five species of medium-to large-bodied terrestrial neotropical mammals respond to forest-pasture edges along 17 forest patches (ranging in size from 5-4714 ha) and two continuous areas of Amazonian forest in Alta Floresta, Brazil. Tracks from two rodent (Dasyprocta agouti and Agouti paca) and three ungulate species (Tayassu tajacu, Mazama gouazoubira and Tapirus terrestris) were recorded over 4900 sand track station nights during a 4-month study period. When species occurrences were compared between patch size classes we found a significant interaction between patch size and distance from the nearest forest edge only for ungulates. We discuss the cost-effectiveness of monitoring protocols for large terrestrial mammals in tropical forests based on sand track stations, and how edge effects and patch size can modulate species abundance and distribution.

International Journal of Primatology, 1994

Conservation Biology, 1995

Many tropical nature reserves are woefully understaffed or exist only on paper. Without effective... more Many tropical nature reserves are woefully understaffed or exist only on paper. Without effective implementation, tropical reserves cannot count on in situ enforcement and consequently are subject to a wide range of invasive threats. Weak institutional structures are aggravated by reserve designs that facilitate rather than discourage unlawful human activities. Taking into account severe financial and institutional constraints, we consider the current status of forest reserves in lowland Amazonia. We ask how the criteria by which reserves are delimited may affect the efficiency with which the contained areas are defended. In a GIS analysis, we found that 40 to 100% of the area of all existing nature reserves in Brazilian Amazonia are directly accessible via navigable rivers and/or functional roads. Such access greatly facilitates the illegal harvest and conversion of forest resources in a region where each guard is responsible for protecting an area larger than the State of Delaware. Cost-effective defense of large areas can be achieved through appropriate delimitation of reserves along watershed divides and by efficient deployment of limited infrastructure and personnel. Given current and probable future levels of financial resources allocated to reserve maintenance in Amazonia, any new nature reserves in this region should be designed and situated so that their defensibility is maximized. Defensibility criteria should complement site considerations based on biological criteria, such as presumed centers of diversity and endemism.Muchas reservas naturales tropicales se encuentran desastrosamente atendidas o existen sólamente en papeles. Sin una implementación efectiva, las reservas tropicales no pueden contar con una implementación in situ de la ley y en consecuencia estan sujetas a un amplio espectro de amenazas invasoras. Las estructuras institucionales débiles se ven agravadas por diseños de reservas que facilitan más que desalientan las actividades humanas fuera de la ley. En este estudio, consideramos el estado actual de las reservas de bosques en las tierras bajas de la Amazonía, tomando en cuenta las severas restricciones financieras e institucionales. Nos preguntamos cómo el criterio por el cual las reservas son delimitadas puede afectar la eficiencia con la cual las áreas contenidas son defendidas. A través de un análisis de SIG, encontramos que entre un 40 y un 100% del área de todas las reservas naturales existentes en la Amazonía Brasileña resulta directamente accesible por medio de ríos navegables y/o rutas funcionales. Este tipo de acceso facilita la recolección ilegal y la conversión de recursos forestales en una región dónde cada guardia es responsable de proteger un área mayor que el Estado de Delaware. Una defensa de grandes áreas, eficiente desde un punto de vista de costos, se puede lograr a través de una delimitación adecuada de las reservas a lo largo de las lineas divisorias de aguas y mediante un empleo eficiente de los limitados recursos de infraestructura y personal. Dados los niveles de los recursos financieros presentes y probablemente futuros, dedicados al mantenimiento de las reservas en Amazonía; cada nueva reserva natural en esta región debe ser diseñada y localizada de tal forma que su defensa sea maximizada. Los criterios de defensa deben complementar las consideraciones del sitio basadas en criterios biológicos, tales como presumibles centros de diversidad y endemismo.

Unregulated hunting of large-bodied frugivores is ubiquitous in tropical forests. Due to their lo... more Unregulated hunting of large-bodied frugivores is ubiquitous in tropical forests. Due to their low fecundity and complex social organization, large primates are often the first tropical forest vertebrates to be extirpated by hunting. Large primates are important seed dispersers and the only dispersal vectors of many large-seeded plants, leading to concerns that primate-dispersed trees will succumb to large-scale recruitment failure wherever they co-occur with overhunting. We used a field experiment in a remote, nonhunted region of the western Brazilian Amazon to test how the seedling recruitment success of a primate-dispersed Sapotaceae tree (Manilkara bidentata) is affected by distance from parent trees, protection from vertebrate seed predators, and gastro-intestinal seed cleaning associated with passage through frugivorous vertebrates. Only seed cleaning significantly increased the rate of seedling recruitment. Janzen-Connell effects have been widely purported as the central mechanism for recruitment failure, but our results suggest that for many tropical forest plant species Janzen-Connell effects are a second-order effect that acts once seeds have been successfully cleaned of fruit pulp by gut treatment. As an illustration of the relative importance of the sheer quantity of seeds ingested by woolly monkeys (Lagothrix cana), we further estimate the density and dispersal services provided by a complete primate assemblage to show that L. cana cleans and disperses nearly one million seeds per km 2 per 24-day Manilkara fruiting season, amounting to over 71% of the seed dispersal services provided by the entire primate assemblage. The disperser vacuum in the absence of L. cana greatly reduces the quantity of cleaned seeds deposited on the forest floor. For similar fleshy-fruited species where gut passage greatly increases survival, a simple lack of redundancy in seed consumption may be the primary driver of recruitment failure resulting from large-primate extirpation due to overhunting, with Janzen-Connell effects secondarily influencing recruitment success as a function of either dispersal distance or seed density.

Conservation Biology, 2003

Extractive activities targeting a wide range of nontimber forest products (NTFPs) are ubiquitous ... more Extractive activities targeting a wide range of nontimber forest products (NTFPs) are ubiquitous in tropical forests, yet the extent of structurally intact forests in a given region affected by this form of cryptic disturbance is poorly documented. We conducted a basin-wide geographic information system analysis of the nonmotorized accessibility of Amazonian NTFP extraction and estimated the proportion of the Amazon drainage basin within Brazil (3.74 million km 2 ) that can be accessed on foot from the nearest navigable river or functional road. We use a long-term series of standardized line-transect vertebrate censuses conducted throughout the region to illustrate the effects of physical accessibility on wildlife densities in terms of hunting pressure as a function of distance from the nearest point of access. Population abundance in largebodied, prime-target species preferred by game hunters tended to increase at greater distances from the access matrix, whereas small-bodied species ignored by hunters usually showed the reverse trend. In addition, we estimated the proportion of presumably inviolate core areas within nature, extractive, and indigenous reserves of Brazilian Amazonia that are prohibitively remote and unlikely to be overhunted; for instance, only 1.16% of the basin-wide area is strictly protected on paper and is reasonably safe from extractive activities targeted to game vertebrates and other valuable NTFPs. Finally, we discuss the concept of truly undisturbed wildlands in the last major tropical forest regions by distinguishing potentially overharvested areas from those that remain largely or entirely pristine and that maintain viable populations of a full complement of harvest-sensitive species.

Folia Primatologica, 1997

This large-scale geographic comparison examines the effects of subsistence hunting pressure and s... more This large-scale geographic comparison examines the effects of subsistence hunting pressure and several indirect indicators of habitat quality on the abundance of howler monkeys {Alouatta spp.), the best studied and the most folivorous of all platyrrhine primates. Alouatta population densities were obtained from a standardized series of line-transect censuses undertaken at 23 Amazonian forest sites (1987–1995), including annually flooded (várzea),

Biological Conservation, 1999

Habitat fragmentation is a major cause of biodiversity erosion in tropical forests. The Brazilian... more Habitat fragmentation is a major cause of biodiversity erosion in tropical forests. The Brazilian Atlantic forest has both high species richness and a long history of anthropogenic disturbance, beginning with colonial agriculture in the sixteenth century. Here we examine the species composition and guild structure of woody plants within five montane Atlantic forest fragments of the Tiet River basin, State of São Paulo, southeastern Brazil, ranging from 5 to 7900 ha in area. We found a negative relationship between fragment size and the relative importance of tree and shrub species that (1) depend on abiotic modes of seed dispersal, (2) are shade-intolerant, and (3) occupy the forest canopy. As fragment size decreased, there was a marked rise in the relative importance of ruderal species, primarily in the Compositae, Euphorbiaceae, Solanaceae, and Leguminosae. There also was a 9% average decline in smaller fragments in relative importance of Myrtaceae, Lauraceae, Sapotaceae, and Rubiaceae, which are the main sources of fleshy fruits for vertebrate frugivores in these forests. Our results suggest that predictable shifts in plant guild structure occur as tropical forest fragments are reduced in size, and that small fragments may become dominated by edges and the surrounding habitat matrix. We suggest that small forest fragments will be unlikely to preserve intact plant and animal assemblages of Brazil's Atlantic coastal forest

Summary 1 Islands formed upstream of mega hydroelectric dams are excellent experimental landscape... more Summary 1 Islands formed upstream of mega hydroelectric dams are excellent experimental landscapes to assess the impacts of habitat fragmentation on biodiversity. We examined the effects of plot-, patch- and landscape-scale variables on the patterns of floristic diversity across 34 forest islands that had experienced 26 years of isolation since the creation of the 4,437 km2 Balbina Hydroelectric Reservoir of central Brazilian Amazonia. In addition, three undisturbed continuous forest sites in neighbouring mainland areas were also sampled across a comparable elevational gradient. 2 We identified all live trees ≥10 cm DBH at species level within a total of 87 quarter-hectare forest plots and conducted a comprehensive compilation of functional attributes of each tree species. We then examined species-area relationships (SARs) and the additional effects of patch and landscape scale metrics on patterns of tree assemblage heterogeneity, both in terms of taxonomic and functional diversity. 3 Despite a clearly positive SAR, edge-mediated forest disturbance was the single most important driver of species composition and abundance within islands. Our results suggest that non-random floristic transitions within island plots followed a predictable pattern, with different life-history traits either penalizing or rewarding local persistence of different functional groups. Distance to edges mediated the probability of tree mortality induced by windfalls and episodic surface fires, clearly resulting in faster species turnover and unidirectional changes in guild structure within small islands where light-wooded fast-growing pioneers largely replaced heavy-wooded species of the old-growth flora. 4 Synthesis ─ Following a simultaneous 26-year post-isolation history, we disentangle the effects of habitat loss and insularization on tree assemblages within a large set of Amazonian ‘true’ forest islands, of variable sizes, sharing a uniform open-water matrix. Area effects are expressed via a response to edge effects, with trees in smaller islands being more vulnerable to edge-related surface fires and windthrows. Additionally, forest edge effects can be a powerful driver of non-random floristic transitions across islands within the Balbina archipelago via a process of rapid pioneer proliferation, drastically affecting both the taxonomic and functional composition of insular tree communities. Finally, our results indicate that detrimental effects of forest fragmentation induced by hydroelectric dams are considerably stronger than those of forest patches embedded within a terrestrial vegetation matrix.