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29 result(s) for "Hilário, Renato R."
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The Density of Callicebus coimbrai is Better Predicted by Vegetation Structure Variables than by Surrounding Landscape
Primate population density often varies considerably between sites, reflecting differences in site conditions and resource availability. Understanding these differences may provide important insights for habitat management. We identified environmental variables that affect the population density of Callicebus coimbrai in forest patches throughout its geographic distribution in northeastern Brazil. We sampled the vegetation structure of 19 forest patches and assessed the composition of the surrounding landscape and the resistance of the surrounding matrix to the movement of C. coimbrai. We used the number of responses of C. coimbrai to playback to estimate the species density in each patch. The density of C. coimbrai was positively related to understory vegetation density, and tree diameter and density, but not to the surrounding landscape composition. The sites with the highest densities were concentrated in the center of the species geographic range and only one of the forest patches may be large enough to host a viable population of C. coimbrai over the long term. Denser understories and larger and closed-spaced trees were related to food availability, and possibly also to predator avoidance, although most predators were extirpated from the region. C. coimbrai tolerate and may even benefit from forest disturbance, depending on how the process has changed the vegetation structure. Our results emphasize the need to enhance the connectivity of the forest patches, particularly in the central portion of the species distribution. Our findings suggest that a whole-range approach is effective to identify the drivers of species density, and priority areas and conservation strategies.
Drivers of primate richness and occurrence in a naturally patchy landscape in the Brazilian Amazon
We assessed the spatial extent at which the species-landscape relationship is strongest (i.e. the scale of effect—SE) on primate occurrence (Alouatta belzebul, Saguinus midas, Saimiri sciureus, and Sapajus apella and Cebus olivaceus, the last two considered together in the analysis) and species richness and evaluated which landscape, patch, and human variables influence primate distribution in a savanna ecosystem in Brazil. We used nested buffers to measure the landscape attributes, and used these data to assess the SE of the species-landscape relationships. We explored the relative contributions of landscape, patch, and human variables to species richness and occurrences by using Generalized Linear Mixed Models and logistic regression. We found that the SE did not differ between primates, but did between two regions with different matrix composition. At the landscape level, occurrence of all species was higher as the distance to the nearest block of continuous forest decreased, but was lower as the amount of water bodies and anthropogenic cover in the matrix increased. The occurrence of S. apella, C. olivaceus and A. belzebul was positively related to forest cover, and all species but A. belzebul had higher occurrence in taller forest. The occurrence of S. apella, C. olivaceus and A. belzebul decreased closer to the city, and S. apella and C. olivaceus presence increased with the number of residents. Richness was negatively related to the number of residents and anthropogenic cover, but positively to forest height. We concluded that conservation planning for primates should follow a “functional landscape” perspective, by maintaining higher forest cover and minimizing the anthropogenic alterations in the matrix.
Influence of life-history traits on the occurrence of carnivores within exotic Eucalyptus plantations
Aim The world's forested area has been declining, especially in developing countries. In contrast, forest plantations are increasing, particularly exotic Eucalyptus plantations, which cover nowadays over 20 million ha worldwide. This global landscape change affects native communities, especially those at higher trophic levels that are affected by bottom–up cascading effects, such as carnivores. We seek to identify the general life‐history traits of mammalian carnivore species that use exotic Eucalyptus plantations. Location We reviewed 55 studies reporting carnivore presence in Eucalyptus plantations worldwide. Methods We consider seven species life‐history traits (generation length, social behaviour, body mass, energetic trophic level, diet diversity, habitat generalist/specialist and locomotion mode) as candidate drivers. We used generalized linear mixed models, with life‐history traits as fixed factors, and study as well as carnivore species as random factors. We obtained the carnivore occurrence data from the literature (detection of 42 different species, from seven families). We considered non‐detected species those with an IUCN Red List of Threatened Species estimated distribution range overlapping with the study areas, but not recorded by the studies. Results While we found no evidence of an effect of any of the other life‐history traits tested, our modelling procedure indicated that habitat generalist species are more likely to use Eucalyptus forests than specialist species. Main conclusions Our results, therefore, confirm an impoverishment of predator communities in disturbed environments, with the exclusion of the most specialist predators, leading to fragmentation of their populations and, ultimately contributing to their local extinction. The local extinction of specialist carnivores may lead to “functional homogenization” of communities within plantations, modifying ecosystem functioning with a negative impact on plantations’ productivity, profitability and services.
Direct links between resource availability and activity budget better reveal ecological patterns of endangered Coimbra-Filho’s titi monkey
Many primatological studies do not assess direct indexes of food availability to make inferences about behavioral strategies. We related the diet and behavior of a group of Callicebus coimbrai in northeastern Brazil to fruit availability indexes and compared this pattern between seasons (direct and indirect assessment of food availability) to assess whether direct and indirect approaches detect similar ecological patterns. We monitored the study group for 33 months (5 days/month) via scan sampling. The monthly availability of fruits and new leaves was recorded in phenological transects. Fruit availability varied across years based on fruit prevalence, and timing and duration of the abundant seasons. We did not find evidence of a time-minimizing strategy, since C. coimbrai did not change its activity levels according to food availability. However, the negative relationship between foraging and fruit availability indicates that C. coimbrai can compensate for the lower fruit availability by increasing the search for alternative food sources. Monthly fruit consumption was positively correlated to fruit availability and negatively related to the consumption of other food items. However, the behavioral and feeding profiles did not vary between seasons and were not related to rainfall levels. Primate studies should directly relate behavioral and feeding profiles to fruit availability indices, thus avoiding using seasons as proxies of food availability.
Correlates of plant β-diversity in Atlantic Forest patches in the Pernambuco Endemism Centre, Northeastern Brazil
Understanding how vegetation structure and floristic composition vary across landscapes is fundamental to understand ecological patterns and for designing conservation actions. In a patch-landscape approach, we assessed the β-diversity (q0 order – rare species, q1 order – common species, and q2 order – dominant species) of plants between forest patches and surveyed plots in Atlantic Forest patches located in the Pernambuco Endemism Centre, northeastern Brazil. Furthermore, we tested the influence of predictor variables linked to landscape (forest cover and edge density) and habitat (basal area), as well as the geographical distance between forest patches and plots on the β-diversity in each forest patch and plot. We measured and identified a total of 1,682 individuals (trees and lianas), corresponding to 248 species, 116 genera, and 56 families in 10 plots (50 × 2 m) from each forest patch. The β-diversity presented lower values for the Mata de Água Azul patch at a landscape scale (i.e., between forest patches) and Mata dos Macacos patch at a site scale (i.e., between plots) for all orders. Geographical distance positively influenced the β-diversity at the landscape scale, and higher turnover between plots (e.g., within forest patches) was positively associated with differences in geographical distance, edge density, forest cover, and basal area. Our results indicate the need to conserve forest patches distributed across a wide area (distant sites) that encompass different landscape contexts with different vegetation structures, in order to conserve greater floristic diversity.
Drivers of hunting in the savannahs of Amapá: implications for conservation
Although overhunting is amongst the main threats to biodiversity, wild meat is culturally and nutritionally important for many communities. Conservation initiatives should therefore address the drivers of hunting, rather than its practice alone. Here we gathered information from structured interviews with 68 local households to assess the drivers of hunting in a highly threatened Amazonian savannah complex, the Cerrado of Amapá in Brazil. We used regression models to evaluate the influence of socio-economic parameters and spatial variables on hunting prevalence and frequency. The only identified driver of hunting prevalence was forest cover, whereas five variables had significant effects on hunting frequency. The positive effect of forest cover and the negative effect of hunter's age on hunting frequency suggest that logistical and physical feasibility are important drivers of hunting frequency. Furthermore, we suggest that the negative effect of distance to urban centres may be related to the profitability of hunting. We base this on the negative effect of river length in the vicinity of households and per capita monthly income on hunting frequency, which corroborates the tendency of hunting frequency to decrease when alternatives to wild meat are more readily available. We argue that to reduce unsustainable hunting it is necessary both to raise awareness amongst local communities and involve them in the creation of management plans that conserve biodiversity and meet economic and social needs.
Effect of Site Attributes and Matrix Composition on Neotropical Primate Species Richness and Functional Traits: A Comparison Among Regions
Fragmentation threatens biodiversity and forest-dwelling animals can be especially vulnerable. Neotropical primates inhabit forests and play ecological roles in maintaining forest biodiversity. Currently, many primate communities are restricted to forest fragments. We (1) evaluated the influence of environmental, matrix, and site attributes on species richness and functional traits of primates in the Neotropics; and (2) evaluated the effect of the sub-region on the relationships between primates and environmental, matrix, and site attributes. We conducted literature searches to find published data on primate communities in forest fragments throughout the Neotropics. Each fragment was assigned to 1 of 11 sub-regions: Mesoamerica, Tumbes-Chocó-Magdalena, Caribbean, Orinoco, Amazon, Atlantic Forest, Cerrado, Chaco, Andes, Caatinga, and Pampa. Based on actual and expected species occurrences, we calculated the proportion of primate species retained in the fragments, the mass retained, and dietary items retained considering reproductive and vegetative plant parts and prey. We used linear mixed models to correlate primate variables with environmental, matrix, and site attributes. Fragment area was more important for primate retention than environmental, matrix, and site attributes, with primate retention being higher in larger fragments. Fragment size was positively correlated with all primate variables, except for retention of prey consumption, whose retention decreased as water bodies and density of buildings in the matrix increased. Fragments within protected areas retained larger species than unprotected fragments. The proportion of extant mass retained and vegetative plant parts in the diet were highest in Mesoamerica and lowest in the Atlantic Forest. Conservation planning of Neotropical primates should consider both the differences among sub-regions, forest restoration to increase fragment size, and the creation of new protected areas, even in fragmented landscapes.
Vulnerability of mammals to land-use changes in Colombia’s post-conflict era
Colombia, one of the most biodiverse countries in the world, is entering a peaceful period after more than fifty years of armed conflict. Due to land use changes resulting from this new situation, negative effects on biodiversity, including mammals are expected. We think that mammal populations will be more sensitive in municipalities where activities related to post-conflict will be carried out. In that order, we aim to: 1) identify which mammal species would be more sensitive and 2) identify the critical regions where there is higher richness of sensitive mammals. We used the distributions of 95 mammal taxa and calculated a sensitivity index by combining four factors: 1) the proportion of each species distribution within protected areas in relation to their proposed extinction thresholds, 2) the proportion within post-conflict municipalities, 3) the proportion of five types of potential land use in post-conflict municipalities and 4) the threat status of each species. Using this index, we drew a map of species richness for mammals classified at high-risk and very high-risk categories. Primates were the most sensitive group to post-conflict changes. Urabá and the region near to the Serranía de San Lucas were the areas with the highest richness of sensitive species. We suggest using primates as flagship species to carry out conservation schemes in the post-conflict era in programmes led by local farmers and former fighters who have been reintegrated into civilian life.
A primate at risk in Northeast Brazil: local extinctions of Coimbra Filho’s titi (Callicebus coimbrai)
Identifying the factors that determine local extinction of populations is crucial to ensure species conservation. Forest-dwelling primates are especially vulnerable to habitat fragmentation, although few studies have provided systematic evidence of local extinctions. Over an 11-year period, approximately 100 remnant populations of the endangered Coimbra Filho’s titi monkey ( Callicebus coimbrai ) have been found within the geographic range of the species in Bahia and Sergipe, Northeast Brazil. During the present study, extinction of 13 of these populations was recorded through intensive surveys. These extinctions were detected from evidence of intensive logging and clear-cutting, interviews with local residents and systematic searches of the sites where occurrence of the species had been confirmed in previous surveys. These local extinctions represent approximately 10 % of the known populations of C. coimbrai and up to 28.3 % of the area occupied by the species. Comparison of the vegetation structure in fragments where extinction was recorded and where the species still occurs indicated that sparser understorey may be a correlate of extinction, combined with the fact that extinctions occurred within fragments characterised by relatively high levels of anthropogenic disturbance. These findings reinforce the Endangered status of the species and the urgent need for intensification of conservation measures within the most impacted areas of the geographic distribution of C. coimbrai .
Taxonomic, functional and phylogenetic bat diversity decrease from more to less complex natural habitats in the Amazon
The high levels of biodiversity in the Amazon are maintained mostly due to its composition as a natural mosaic of different habitats, including both unflooded and flooded forests, campinaranas, and savannahs. Here, we compared multiple dimensions of α- and β- bat biodiversity between four natural Amazonian habitats (savannah, campinarana, forest patches, and continuous forest). In addition, we explored the extent to which bat communities in the different habitats are nested within one another, and compared the community-level functional uniqueness and community-weighted mean traits between habitats. Our results show that taxonomic, functional and phylogenetic a-diversity of bats is higher in continuous forest than in any of the other habitat types. The continuous forest also harbours more unique species, and indeed, the bat community assemblages in the less-complex habitats, including forest patches, campinarana and savannahs, are taxonomic, functional and phylogenetic sub-sets of the assemblage found in the continuous forest. By examining β-diversity partitions and species composition, we are able to shed light on the mechanisms behind the variation in diversity between the four habitat types, which reflect a process of environmental sorting along a habitat gradient going from a more complex to a less complex habitat. We conclude that nesting patterns along the mosaic of habitats are determined by differences in complexity between habitats and that taxonomic and functional uniqueness contribute to overall regional bat diversity and functionality. Ongoing human-induced disturbances of these habitats could provoke an unprecedented loss of bat diversity and functionality with negative consequences for biodiversity and ecosystem services.