Wellington Hannibal

Mammal occurrence and roadkill in two adjacent ecoregions (Atlantic Forest and Cerrado) in south-western Brazil

This paper examines the frequencies of mammal roadkill in two adjacent biogeographic ecoregions (Atlantic Forest and Cerrado) of Brazil. Mammals were recorded during a seven-year period and over 3,900 km of roads, in order to obtain data for frequencies of species in habitats (sites) and frequencies of species killed by cars on roads. Sites (n = 80) within ecoregions (Cerrado, n = 57; Atlantic Forest, n = 23) were searched for records of mammals. Species surveyed in the entire region totaled 33, belonging to nine orders and 16 families. In the Cerrado, 31 species were recorded in habitats; of these, 25 were found dead on roads. In the Atlantic Forest ecoregions, however, we found 21 species in habitats, 16 of which were also found dead on roads. There was no overall significant difference between ecoregions for frequencies of occurrence in habitats or for roadkills, but there were differences between individual species. Hence, anteaters were mostly recorded in the Cerrado ecoregion, whereas caviomorph rodents tended to be more frequent in the Atlantic Forest ecoregion (seen mainly by roadkills). The greater number of species (overall and threatened) and the greater abundance of species records in the Cerrado suggest that this ecoregion has a greater biodiversity and is better conserved than the Atlantic Forest ecoregion, in the state of Mato Grosso do Sul, south-western Brazil.

Mammals in a fragmented savannah landscape in south-western Brazil

Mammal abundance, richness, and community structure were examined in fragments of savannah and in gallery forests of south-western Brazil in order to assess the influence of fragment size and habitat on the communities. Five savannah fragments and two gallery forests were sampled. Within the savannah fragments, environmental parameters such as tree and shrub densities were measured. Live-traps and pitfalls were used for trapping small mammals; larger mammals were recorded from footprints and sightings. Seventeen species of small mammal and 15 species of large mammal were recorded. Small mammals were affected by fragment size and isolation, whereas larger mammals were not. Communities of small mammals were better structured in the largest fragments, and those in smaller fragments were subsets of the communities in larger fragments. Gallery forests revealed a rather different assemblage of mammals, but also contained species common to both gallery and large savannah remnants. Data are discussed relating mammal community structure to area size and vegetation structure, in an attempt to understand the present conservation status of this fragmented landscape.

Use of vertical space by small mammals in gallery forest and woodland savannah in south-western Brazil

Abstract We examined the community composition and abundance of small mammals in the vertical strata of gallery forests and woodland savannahs in south-western Brazil. Captures were carried out during the winter and summer months of 2006/2007. Traps were set in three transect lines per habitat, with 10 capture stations on each line. Each station had three traps: on the ground, in the understorey (2–3 m in height), and in the canopy (8–10 m) in each physiognomy. With an effort of 3600 trap-nights, 11 species of small mammals were captured, which were distributed differently regarding the forest physiognomies and utilisation of vertical strata. The species showed a high degree of habitat segregation in the two physiognomies, with only the climbing-rat Rhipidomys macrurus found in both habitats. The correspondence analysis revealed that Caluromys philander occurred mostly in the canopy; Cryptonanus agricolai, Marmosa murina, and Oecomys bicolor in the understorey; and Gracilinanus agilis and Nectomys rattus on the ground. The utilisation of traps in different strata increased species richness in the Cerrado biome, showing that the small-mammal community is distributed along the vertical complexity of the forest and even in different physiognomies, enabling more species to coexist.

Differential trapping success for small mammals using pitfall and standard cage traps in a woodland savannah region of southwestern Brazil

Abstract This study aimed to compare the efficacy of different trapping methodologies for sampling small mammals, consisting of trap type (pitfall, Sherman, and wire traps) and position (ground and understorey) in the Cerrado biome of Brazil. Five fragments of woodland savannah were selected for the study. We captured a total of 364 individuals of 14 species of small mammals. Pitfall traps sampled all 14 species (100%), whereas ground cage traps sampled 8 species (57%), and arboreal traps sampled 5 species (36%). The sampling methodologies gave significantly different results, particularly between pitfall and cage traps, and between ground and arboreal cage traps. However, the comparison between Sherman and wire traps indicated no significant difference, although abundance has been higher for wire cages. Our study confirms the high success rate for pitfall traps now in the Cerrado biome and suggests combinations of trapping methodologies for surveying mammalian diversity.

Effects of altitude and vegetation on small-mammal distribution in the Urucum Mountains, western Brazil

We conducted a study on small-mammal composition, abundance and diversity across altitudinal and vegetational gradients in the Urucum Mountains (from 150 to 1000 m asl) in western Brazil, a complex biogeographic region. Small mammals were collected in 31 sampling units distributed along altitudinal and vegetational gradients (forest and grassland), totalling 18 112 trap-nights for pitfall and 3500 trap-nights for live-trap. Community variation among sampling units was assessed by randomization tests, setting altitude, vegetation, locality and time as factors, and using presence/absence data. Correlation and logistic regression analyses were run for species and diversity along gradients of altitude and vegetation, according to abundance and presence/absence data. Nineteen species (seven marsupial and 12 rodent) and 355 individuals were recorded. The species composition of small mammals differed according to altitude, vegetation type, locality and time. Species diversity varied significantly according to altitude. Species were influenced solely by altitude or vegetation, or by both vegetation and altitude concomitantly. The small-mammal community was divided in two groups according to biogeographic affinities. The grassland group is capable of invading forest habitats. The results are discussed in light of current hypotheses that attempt to explain community variation along altitudinal gradients around the world.

Biogeography and conservation of non-volant mammals from the Urucum Mountains: a Chiquitano dry forest ecoregion in western Brazil

Abstract The distributional data of mammalian fauna are important to reach a comprehensive overview of biogeographic patterns and to highlight regional conservation status, especially in a poorly known region such as the Chiquitano dry forest in western Brazil. Our aims were to survey the mammal species occurring in the Urucum Mountains, located in the southeast end of the Chiquitano forest, compare its species composition to areas elsewhere in different ecoregions, and discuss their conservation statuses. Small mammals were sampled using pitfall and live traps, and medium and large mammals were sampled by direct observation, indirect evidence (e.g. faeces and tracks), and camera traps. Patterns of species composition were compared to other surrounding areas of different ecoregions in South America using multivariate analyses. The results indicated that both faunas have similar biogeographical influences. The Urucum Mountains have an influence on the faunas from the Cerrado, Chaco and Pantanal ecoregions, and only secondarily from forested ecoregions (e.g. Amazon forest). The Urucum harbours a rich non-volant mammalian fauna with species that are widely and restrictedly distributed. The conservation of Urucum Mountains is important because these mountains harbour threatened plant, invertebrate, and vertebrate (mammals) species, which could be suffering due to the mining activity carried out in the region. We stress that the Chiquitano dry forest is unique to western Brazil, situated in a complex biogeographical region, and harbouring a rich and diversified mammal fauna.