Showing papers by "Milton Cezar Ribeiro published in 2016"

Space Use and Movement of a Neotropical Top Predator: The Endangered Jaguar

Abstract: Accurately estimating home range and understanding movement behavior can provide important information on ecological processes. Advances in data collection and analysis have improved our ability to estimate home range and movement parameters, both of which have the potential to impact species conservation. Fitting continuous-time movement model to data and incorporating the autocorrelated kernel density estimator (AKDE), we investigated range residency of forty-four jaguars fit with GPS collars across five biomes in Brazil and Argentina. We assessed home range and movement parameters of range resident animals and compared AKDE estimates with kernel density estimates (KDE). We accounted for differential space use and movement among individuals, sex, region, and habitat quality. Thirty-three (80%) of collared jaguars were range resident. Home range estimates using AKDE were 1.02 to 4.80 times larger than KDE estimates that did not consider autocorrelation. Males exhibited larger home ranges, more directional movement paths, and a trend towards larger distances traveled per day. Jaguars with the largest home ranges occupied the Atlantic Forest, a biome with high levels of deforestation and high human population density. Our results fill a gap in the knowledge of the species’ ecology with an aim towards better conservation of this endangered/critically endangered carnivore—the top predator in the Neotropics.

Threshold effect of habitat loss on bat richness in cerrado-forest landscapes

Abstract: Understanding how animal groups respond to contemporary habitat loss and fragmentation is essential for development of strategies for species conservation. Until now, there has been no consensus about how landscape degradation affects the diversity and distribution of Neotropical bats. Some studies demonstrate population declines and species loss in impacted areas, although the magnitude and generality of these effects on bat community structure are unclear. Empirical fragmentation thresholds predict an accentuated drop in biodiversity, and species richness in particular, when less than 30% of the original amount of habitat in the landscape remains. In this study, we tested whether bat species richness demonstrates this threshold response, based on 48 sites distributed across 12 landscapes with 9-88% remaining forest in Brazilian cerrado-forest formations. We also examined the degree to which abundance was similarly affected within four different feeding guilds. The threshold value for richness, below which bat diversity declines precipitously, was estimated at 47% of remaining forest. To verify if the response of bat abundance to habitat loss differed among feeding guilds, we used a model selection approach based on Akaike's information criterion. Models accounted for the amount of riparian forest, semideciduous forest, cerrado, tree plantations, secondary forest, and the total amount of forest in the landscape. We demonstrate a nonlinear effect of the contribution of tree plantations to frugivores, and a positive effect of the amount of cerrado to nectarivores and animalivores, the groups that responded most to decreases in amount of forest. We suggest that bat assemblages in interior Atlantic Forest and cerrado regions of southeastern Brazil are impoverished, since we found lower richness and abundance of different groups in landscapes with lower amounts of forest. The relatively higher threshold value of 47% suggests that bat communities have a relatively lower resistance to habitat degradation than other animal groups. Accordingly, conservation and restoration strategies should focus on increasing the amount of native vegetation of landscapes so as to enhance species richness of bats.

Ecosystem Services Modeling as a Tool for Defining Priority Areas for Conservation

Abstract: Conservationists often have difficulty obtaining financial and social support for protected areas that do not demonstrate their benefits for society. Therefore, ecosystem services have gained importance in conservation science in the last decade, as these services provide further justification for appropriate management and conservation of natural systems. We used InVEST software and a set of GIS procedures to quantify, spatialize and evaluated the overlap between ecosystem services-carbon stock and sediment retention-and a biodiversity proxy-habitat quality. In addition, we proposed a method that serves as an initial approach of a priority areas selection process. The method considers the synergism between ecosystem services and biodiversity conservation. Our study region is the Iron Quadrangle, an important Brazilian mining province and a conservation priority area located in the interface of two biodiversity hotspots, the Cerrado and Atlantic Forest biomes. The resultant priority area for the maintenance of the highest values of ecosystem services and habitat quality was about 13% of the study area. Among those priority areas, 30% are already within established strictly protected areas, and 12% are in sustainable use protected areas. Following the transparent and highly replicable method we proposed in this study, conservation planners can better determine which areas fulfill multiple goals and can locate the trade-offs in the landscape. We also gave a step towards the improvement of the habitat quality model with a topography parameter. In areas of very rugged topography, we have to consider geomorfometric barriers for anthropogenic impacts and for species movement and we must think beyond the linear distances. Moreover, we used a model that considers the tree mortality caused by edge effects in the estimation of carbon stock. We found low spatial congruence among the modeled services, mostly because of the pattern of sediment retention distribution.

Connectivity maintain mammal assemblages functional diversity within agricultural and fragmented landscapes

Abstract: Despite major advances in mammal research, there are knowledge gaps regarding distribution, composition, and the functional role of mammal species within agricultural and fragmented landscapes. Also, there is a lack of knowledge about which factors influence mammal assemblages within agricultural ecosystems. Therefore, this study aimed to estimate the contribution of forest cover, functional connectivity, drainage, and amount of sugar cane toward explaining the functional diversity of terrestrial mammals. We made an inventory of terrestrial mammals in an agricultural and fragmented landscape in an Atlantic Forest-Cerrado ecotone in southeastern Brazil, assessed the functional diversity of mammal assemblages, and proposed conservation strategies at the landscape level. Data collection occurred from September/2011 to August/2012 through a combination of complementary methods: active search; trapping stations; collection of fecal samples, which were identified by hair cuticle and fecal DNA analysis; and data from the literature. Functional diversity (FD) was calculated using a set of ecological traits including body mass, locomotion form, behavioral and dietary traits, and the environmental sensitivity of species. Akaike information criterion was used to compare generalized linear models between FD values and landscape metrics. Our results reveal a surprising insight about the role exerted by agricultural and fragmented landscapes, which still sustain impressively high biodiversity levels and a meaningful amount of ecological functions, indicating some resistance of species to pressure from the agricultural matrix and advancing urbanization. The amount of ecological functions performed by mammal species within agricultural and fragmented landscapes was similar to pristine areas and more preserved landscapes. Functional connectivity (amount of area assessed for species able to cross 200 m of matrix) was the most plausible model (wAICc = 0.873). Thus, we concluded that improving functional connectivity guarantees high FD values, and we demonstrate the importance of maintaining and restoring structural connections between fragment patches within these landscapes for species conservation and the maintenance of populations over time.

Effects of Land Cover on the Movement of Frugivorous Birds in a Heterogeneous Landscape.

Abstract: Movement is a key spatiotemporal process that enables interactions between animals and other elements of nature. The understanding of animal trajectories and the mechanisms that influence them at the landscape level can yield insight into ecological processes and potential solutions to specific ecological problems. Based upon optimal foraging models and empirical evidence, we hypothesized that movement by thrushes is highly tortuous (low average movement speeds and homogeneous distribution of turning angles) inside forests, moderately tortuous in urban areas, which present intermediary levels of resources, and minimally tortuous (high movement speeds and turning angles next to 0 radians) in open matrix types (e.g., crops and pasture). We used data on the trajectories of two common thrush species (Turdus rufiventris and Turdus leucomelas) collected by radio telemetry in a fragmented region in Brazil. Using a maximum likelihood model selection approach we fit four probability distribution models to average speed data, considering short-tailed, long-tailed, and scale-free distributions (to represent different regimes of movement variation), and one distribution to relative angle data. Models included land cover type and distance from forest-matrix edges as explanatory variables. Speed was greater farther away from forest edges and increased faster inside forest habitat compared to urban and open matrices. However, turning angle was not influenced by land cover. Thrushes presented a very tortuous trajectory, with many displacements followed by turns near 180 degrees. Thrush trajectories resembled habitat and edge dependent, tortuous random walks, with a well-defined movement scale inside each land cover type. Although thrushes are habitat generalists, they showed a greater preference for forest edges, and thus may be considered edge specialists. Our results reinforce the importance of studying animal movement patterns in order to understand ecological processes such as seed dispersal in fragmented areas, where the percentage of remaining habitat is dwindling.

Edge and land use effects on dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) in Brazilian cerrado vegetation

Abstract: The Edge Influence is one of the most pervasive effects of habitat fragmentation, as many forest remnants in anthropogenic landscapes are within 100 m of edges. Forest remnants may also affect the surrounding anthropogenic matrix, possibly resulting in a matrix–edge–remnant diversity gradient for some species groups. We sampled dung beetles in 15 agricultural landscapes using pitfall traps placed along transects in matrix–edge–remnant gradients. The remnants were a native savanna-like vegetation, the cerrado, and the matrix was composed of three human-dominated environments (sugarcane, eucalyptus, pasture). More species were observed in cerrado remnants than in adjacent land uses. Dung beetles were also more abundant in the cerrado than in the landscape matrix of sugarcane and eucalypt, but not of pasture. Dung beetles were severely affected by anthropogenic land uses, and notwithstanding their high abundance in some land uses such as pasture, the species richness in these areas tended to be smaller than in the cerrado remnants. We also found that the influence of the edge was evident only for abundance, particularly in landscapes with a pasture matrix. However, this land use disrupts the species composition of communities, indicating that communities located in cerrado and pasture have a distinct species composition, and that both communities are affected by edge distance. Thus, anthropogenic land uses may severely affect dung beetles, and this impact can extend to communities located in cerrado remnants as well as to those in matrices, with possible consequences for ecological processes such as decomposition and nutrient cycling.

Patch size, shape and edge distance influence seed predation on a palm species in the Atlantic forest

Abstract: Seed predation is an important ecological process that aff ects the abundance, diversity and distribution of plant species, and it is known to be infl uenced by defaunation and forest fragmentation. Most studies on seed predation in humanmodifi ed landscapes do not take into account the diff erent spatial scales in which this process operates. In this study, we evaluated how variables at three distinct spatial scales aff ected the seed predation of a palm that provides a keystone resource to the frugivore community, the queen palm Syagrus romanzoffi ana . Th irteen landscapes that vary in forest cover, number of fragments and patch sizes were sampled in the Brazilian Atlantic forest. We also evaluated the contribution of the three main groups of seed predators: squirrels, terrestrial rodents and invertebrates. Our results indicate that seed predation is more aff ected by fragment and local variables than by landscape infl uences. In addition, the size of the fragment, its shape and the distance from the nearest forest edge were the main predictors of the proportion of predated seeds. Moreover, the two main seed predators (squirrels and invertebrates) responded to the same fragment and local variables. Because most of the Atlantic forest consists of small fragments, we expect that the seed predation of this keystone palm should be high in most of its distribution, with potential consequences for the frugivore community.

Beauty before age: landscape factors influence bird functional diversity in naturally regenerating fragments, but regeneration age does not

Abstract: Effective ecological restoration actions should be able to recover ecosystem processes that influence community development in the long term. However, there is scarce information on how landscape factors promote or accelerate fauna recovery. We used a landscape framework to evaluate how functional groups respond to natural regeneration in a highly fragmented region of Atlantic Forest. Using bird functional groups sampled in 15 regenerating forest fragments, we built and ranked models using a model selection approach to test the relative effect of landscape variables on each group. Our results showed that bird community recovery is not determined by the duration of the regeneration process (i.e. forest age), but by how the species responds to the landscape context. Functional diversity and the abundance of the functional groups were mainly related to composition metrics, whereas the functional metric affected only specific groups. Our findings highlight the importance of considering the landscape level to ensure both the colonization of fauna and the restoration of ecological functions.

Importance of waterholes for white-lipped peccary (Tayassu pecari) in the Selva Maya, Guatemala

Abstract: Water is considered an essential nutrient for wildlife and, when not in the proper proportion, can be a limiting factor to populations. Differences in water dependency among ungulate species can arise through a variety of physiological, morphological and behavioral mechanisms employed in maintaining the balance of temperature and water. The white-lipped peccary forms large and cohesive groups of 10 to over 300 individuals inhabiting dense tropical forests. Our objectives were to describe the use of waterholes by white-lipped peccaries groups in a humid site of the Selva Maya and evaluate the effect of humidity may have on the visit frequency, group size and activity patterns. From June to August 2014 and February to April 2015 seven waterholes were monitored using digital camera traps. The visit frequency was estimated by dividing the number of events between 1,000 sampling effort traps night. The minimum group size and age structure were estimated for each separate event. Activity patterns were estimated at one-hour intervals for the dry and rainy seasons. Forty-seven and 185 separate events for the rainy and dry season respectively were obtained. The sampling effort in each period was 630 traps night. For the rainy and dry season we obtained a visit frequency of 74.6 and 293.7 respectively. For the rainy and dry season an average group size of 17 (± 9.5) and 25.5 (± 12.6) were estimated respectively. The groups are mainly composed of adults. The presence of newborns was mainly in August and April. Activity patterns were mainly recorded between 10:00 h and 16:00 h. The visit frequency estimated is higher compared to other protected areas in the Selva Maya. The minimum group size estimated is similar to those reported in dry areas within the Selva Maya. The presence of newborns was reported during all months of the study, existing peaks during August, March and April. The white-lipped peccary visited the waterholes mainly during the day between 10:00 h and 16:00 h. Waterholes in the Laguna del Tigre National Park can be called “sanctuaries” for white-lipped peccaries because are extremely important in the ecology of this social ungulate.

Landscape effects on the occurrence of ichthyofauna in first-order streams of southeastern Brazil

Abstract: Objective In this study we aimed to understand how extrinsic environmental factors measured in the watercourses and the surrounding landscape influence the ichthyofauna of first-order streams. Methods Data were collected within the Corumbatai River Basin, Sao Paulo, southeastern Brazil, during the dry season of 2012. We sampled the ichthyofauna in 13 stretches of streams distributed across four river sub-basins. The stretches differed in relation to the presence/absence of riparian forest, the predominant type of matrix and the percentage of forest. Response variables were species richness and the occurrence of functional groups and explanatory variables include both local and landscape structures from the surrounding environment. Local variables comprised the following water quality and structural attributes: pH, temperature, conductivity, turbidity, flow rate, depth, width, type of substrate. Landscape variables included presence/absence of riparian vegetation, type of vegetation, type of matrix, percentage of forest and canopy cover. Results A total of 268 individuals were recorded, which were distributed among 12 species. The landscape structure influenced the occurrence of functional groups in first-order streams, especially allochthonous-feeders, nektonic and hypoxia-intolerant species. The presence of riparian forest was the most important predictor. Species richness was negatively related to the presence of riparian vegetation, supporting the hypothesis that degraded landscapes lead to a reduction in diversity. Conclusion The protection of riparian vegetation is critical to the maintenance of ichthyofauna diversity in first-order streams. The presence or absence of riparian vegetation differently affected the occurrence of species depending on their functional characteristics, particularly those related to the tolerance to hypoxia, source of alimentary items and the position in the water column.