Ricardo B. Machado

Sampling bias and the use of ecological niche modeling in conservation planning: a field evaluation in a biodiversity hotspot

Ecological niche modeling (ENM) has become an important tool in conservation biology. Despite its recent success, several basic issues related to algorithm performance are still being debated. We assess the ability of two of the most popular algorithms, GARP and Maxent, to predict distributions when sampling is geographically biased. We use an extensive data set collected in the Brazilian Cerrado, a biodiversity hotspot in South America. We found that both algorithms give richness predictions that are very similar to other traditionally used richness estimators. Also, both algorithms correctly predicted the presence of most species collected during fieldwork, and failed to predict species collected only in very few cases (usually species with very few known localities, i.e., <5). We also found that Maxent tends to be more sensitive to sampling bias than GARP. However, Maxent performs better when sampling is poor (e.g., low number of data points). Our results indicates that ENM, even when provided with limited and geographically biased localities, is a very useful technique to estimate richness and composition of unsampled areas. We conclude that data generated by ENM maximize the utility of existing biodiversity data, providing a very useful first evaluation. However, for reliable conservation decisions ENM data must be followed by well-designed field inventories, especially for the detection of restricted range, rare species.

Effectiveness of Scat-Detection Dogs in Determining Species Presence in a Tropical Savanna Landscape

Most protected areas are too small to sustain populations of wide-ranging mammals; thus, identification and conservation of high-quality habitat for those animals outside parks is often a high priority, particularly for regions where extensive land conversion is occurring. This is the case in the vicinity of Emas National Park, a small protected area in the Brazilian Cerrado. Over the last 40 years the native vegetation surrounding the park has been converted to agriculture, but the region still supports virtually all of the animals native to the area. We determined the effectiveness of scat-detection dogs in detecting presence of five species of mammals threatened with extinction by habitat loss: maned wolf (Chrysocyon brachyurus), puma (Puma concolor), jaguar (Panthera onca), giant anteater (Myrmecophaga tridactyla), and giant armadillo (Priodontes maximus). The probability of scat detection varied among the five species and among survey quadrats of different size, but was consistent across team, season, and year. The probability of occurrence, determined from the presence of scat, in a randomly selected site within the study area ranged from 0.14 for jaguars, which occur primarily in the forested areas of the park, to 0.91 for maned wolves, the most widely distributed species in our study area. Most occurrences of giant armadillos in the park were in open grasslands, but in the agricultural matrix they tended to occur in riparian woodlands. At least one target species occurred in every survey quadrat, and giant armadillos, jaguars, and maned wolves were more likely to be present in quadrats located inside than outside the park. The effort required for detection of scats was highest for the two felids. We were able to detect the presence for each of five wide-ranging species inside and outside the park and to assign occurrence probabilities to specific survey sites. Thus, scat dogs provide an effective survey tool for rare species even when accurate detection likelihoods are required. We believe the way we used scat-detection dogs to determine the presence of species can be applied to the detection of other mammalian species in other ecosystems.

Severe Loss of Suitable Climatic Conditions for Marsupial Species in Brazil: Challenges and Opportunities for Conservation

A wide range of evidences indicate climate change as one the greatest threats to biodiversity in the 21st century. The impacts of these changes, which may have already resulted in several recent species extinction, are species-specific and produce shifts in species phenology, ecological interactions, and geographical distributions. Here we used cutting-edge methods of species distribution models combining thousands of model projections to generate a complete and comprehensive ensemble of forecasts that shows the likely impacts of climate change in the distribution of all 55 marsupial species that occur in Brazil. Consensus projections forecasted range shifts that culminate with high species richness in the southeast of Brazil, both for the current time and for 2050. Most species had a significant range contraction and lost climate space. Turnover rates were relatively high, but vary across the country. We also mapped sites retaining climatic suitability. They can be found in all Brazilian biomes, especially in the pampas region, in the southern part of the Brazilian Atlantic Forest, in the north of the Cerrado and Caatinga, and in the northwest of the Amazon. Our results provide a general overview on the likely effects of global climate change on the distribution of marsupials in the country as well as in the patterns of species richness and turnover found in regional marsupial assemblages.

Resource Selection and Its Implications for Wide-Ranging Mammals of the Brazilian Cerrado

Conserving animals beyond protected areas is critical because even the largest reserves may be too small to maintain viable populations for many wide-ranging species. Identification of landscape features that will promote persistence of a diverse array of species is a high priority, particularly, for protected areas that reside in regions of otherwise extensive habitat loss. This is the case for Emas National Park, a small but important protected area located in the Brazilian Cerrado, the worlds most biologically diverse savanna. Emas Park is a large-mammal global conservation priority area but is too small to protect wide-ranging mammals for the long-term and conserving these populations will depend on the landscape surrounding the park. We employed novel, noninvasive methods to determine the relative importance of resources found within the park, as well as identify landscape features that promote persistence of wide-ranging mammals outside reserve borders. We used scat detection dogs to survey for five large mammals of conservation concern: giant armadillo (Priodontes maximus), giant anteater (Myrmecophaga tridactyla), maned wolf (Chrysocyon brachyurus), jaguar (Panthera onca), and puma (Puma concolor). We estimated resource selection probability functions for each species from 1,572 scat locations and 434 giant armadillo burrow locations. Results indicate that giant armadillos and jaguars are highly selective of natural habitats, which makes both species sensitive to landscape change from agricultural development. Due to the high amount of such development outside of the Emas Park boundary, the park provides rare resource conditions that are particularly important for these two species. We also reveal that both woodland and forest vegetation remnants enable use of the agricultural landscape as a whole for maned wolves, pumas, and giant anteaters. We identify those features and their landscape compositions that should be prioritized for conservation, arguing that a multi-faceted approach is required to protect these species.

Climatic factors influencing triatomine occurrence in Central-West Brazil

We estimated the geographic distributions of triatomine species in Central-West Region of Brazil (CW) and analysed the climatic factors influencing their occurrence. A total of 3,396 records of 27 triatomine species were analysed. Using the maximum entropy method, ecological niche models were produced for eight species occurring in at least 20 municipalities based on 13 climatic variables and elevation. Triatoma sordida and Rhodnius neglectus were the species with the broadest geographic distributions in CW Brazil. The Cerrado areas in the state of Goiás were found to be more suitable for the occurrence of synanthropic triatomines than the Amazon forest areas in the northern part of the state of Mato Grosso. The variable that best explains the evaluated models is temperature seasonality. The results indicate that almost the entire region presents climatic conditions that are appropriate for at least one triatomine species. Therefore, it is recommended that entomological surveillance be reinforced in CW Brazil.

A systematic evaluation of the conservation plans for the Pantanal wetland in Brazil

The Pantanal is the world’s largest contiguous freshwater wetland spanning Brazil, Bolivia, and Paraguay. It contains the greatest wildlife densities in the Neotropics and was enlisted by all three countries in the Ramsar convention on wetland conservation. The Brazilian government, together the UNESCO’s Man and the Biosphere Program, declared a biosphere reserve in the Pantanal in 2000. Other plans to protect the region include expansion of existing reserves and land use regulations following recommendations from the Cerrado-Pantanal priority setting workshop. Here we evaluated how four conservation scenarios complied with the principles of systematic conservation planning and analyzed their representativeness, efficiency, and complementarity using 17 vegetation classes as surrogates for regional biodiversity. We used MARXAN (systematic conservation planning software) to determine the value of the habitat types protected by each conservation scenario. We found that none of the four conservation scenarios met preferred areal targets for protection of habitats, nor did any protect all 17 biodiversity surrogates. The Pantanal Biosphere Reserve provided the best compromise in conservation planning.

Habitat use and movements of Glossophaga soricina and Lonchophylla dekeyseri (Chiroptera : Phyllostomidae) in a Neotropical savannah

The greatest current threat to terrestrial fauna is continuous and severe landscape modification that destroys and degrades animal habitats. This rapid and severe modification has threatened species, local biological communities, and the ecological services that they provide, such as seed dispersal, insect predation, and pollination. Bats are important pollinators of the Cerrado (woodland savanna) because of their role in the life cycles of many plant species. However, there is little information about how these bat species are being affected by habitat loss and fragmentation. We used radio-tracking to estimate the home ranges of Glossophaga soricina (Pallas, 1776) and Lonchophylla dekeyseri Taddei, Vizotto & Sazima, 1983. The home range of G. soricina varies from 430 to 890 ha. They combine shortrange flights of up to 500 m to nearby areas with longer flights of 2 to 3 km that take them away from their core areas. The maximum flight distance tracked for L. dekeyseri was 3.8 km, and its home range varies from 564 to 640 ha. The average distance travelled by this species was 1.3 km. Our data suggest that G. soricina and L. dekeyseri are able to explore the fragmented landscape of the Central Brazilian Cerrado and that they are likely to survive in the short- to medium-term. The natural dispersal ability of these two species may enable them to compensate for continued human disturbance in the region.

Do Current Vampire Bat (Desmodus rotundus) Population Control Practices Pose a Threat to Dekeyser's Nectar Bat's (Lonchophylla dekeyseri) Long-Term Persistence in the Cerrado?

The Cerrado is rapidly losing space to agriculture, pastures and urbanization. Current management practices to control rabies outbreaks through the eradication of vampire bat populations may put other bat species in peril. Our objective is to evaluate if the current vampire bat population control practices could pose a threat to Lonchophylla dekeyseris persistence, an endemic bat of the Cerrado. We used the VORTEX program to model different vampire bat management scenarios, causing low (25%), medium (50%) or high (75%) incidental mortality to L. dekeyseri populations. Inbreeding depression has been identified as a threat to the species, therefore we also modeled scenarios evaluating such effects. Results show that current vampire bat management practices have serious impacts on populations of L. dekeyseri. In all cases marked declines in population sizes were observed (even when there was no decline in survival probabilities). For medium and high incidental mortality management scenarios, we also observed decreases in survival probability and in genetic diversity. In those scenarios evaluating vampire bat management and inbreeding depression together, the models suggest that such interaction results in more pronounced declines. Habitat loss and fragmentation in the Cerrado are severe threats and have already negatively impacted L. dekeyseri. Unfortunately, if currentpopulation control practices dealing with vampire bats are not changed, inappropriate rabies management may be the coup de grace to the long-term persistence of this species.

The impact of habitat fragmentation on the ecology of xenarthrans (Mammalia) in the Brazilian Cerrado

The impact of deforestation and fragmentation upon ecologically important and poorly known groups is currently an important issue for conservation biology. Herein we describe xenathran communities across the Brazilian Cerrado and study the effects of habitat fragmentation on occupancy and activity patterns on these assemblages. Our hypothesis was that larger and specialized species would be more ecologically sensitive, and likely to exhibit shifts in their activity patterns in more deforested areas as a way of dealing with the myriad of effects involved in the fragmentation process. The study was conducted by camera trapping in ten Cerrado sites. Five species were analyzed: Priodontes maximus, Euphractus sexcinctus, Dasypus novemcintus (Order Cingulata), Tamandua tetradactyla and Myrmecophaga tridactyla (Order Pilosa). Fragmentation was quantified by landscape metrics, calculated on scales that matched the species’ home ranges. Occupancy and detection probability analyses were conducted to test for shifts in occupancy under different fragmentation conditions. A mixed-effects model analysis was conducted to test for shifts in species’ frequency of records related to time of day, controlling for spatial autocorrelation by means of eigenvector-based spatial filters for the models’ residuals. There were no changes in activity pattern between more and less fragmented areas, so that our behavioural plasticity hypothesis was not corroborated for this group. The lack of changes in the patterns could be explained by a species’ time-lag response, or by the lack of a wide enough fragmentation gradient in our study.

How may agricultural matrix intensification affect understory birds in an Atlantic Forest landscape? A qualitative model on stochasticity and immigration

Abstract Understanding how different approaches of matrix management affect organisms that inhabit natural patches is crucial for biological conservation. Considering that great part of the tropical area is composed of agricultural land and that most of the land use is either intensified or on the verge to be, a relevant question is: how may agricultural intensification of the landscape matrix affect the population dynamics of understory birds? This paper describes a qualitative model based on the Qualitative Process Theory and implemented in Garp3 to provide answers to this question. We built a model using four species of endemic passerine birds in order to evaluate the case in an Atlantic Forest area, a biodiversity hotspot. The model describes a landscape composed of an extinction-resistant source patch and one target forest patch where stochastic events occur. If permeability of the matrix exceeds a given species-specific threshold, propagules coming from the source reach the target patch. Agriculture intensification affects the matrix spatial structure and reduces permeability to forest birds, thus reduces rescue effect. Additionally, we assume that some species may use the matrix as a supplementary habitat for feeding and that matrix management may affect the resource base for those species. Simulation results suggest that, if agriculture intensification continues to threat the Atlantic Forest biome, populations of sensitive species ( Xiphorhynchus fuscus and Sclerurus scansor ) that exist in the small forest patches (which is true for most forest remnants) will be highly susceptible to local extinctions and without further re-colonization.