quarta-feira, 30 de novembro de 2011

Fotos: Juliomys sp.

Juliomys é um gênero de roedor arborícola neotropical com três espécies reconhecidas (J. pictipes, J. rimmofrons e J. ossitenuis). O gênero foi descrito recentemente, sendo que antigamente as espécies conhecidas eram parte do gênero Wilfredomys (hoje este gênero inclui apenas a espécie W. oenax). É um roedor muito pouco conhecido e pouco abundante nas áreas onde ocorre. O nome comum de cada espécie utiliza o termo "juliomys", portanto o nome comum do gênero seria pronunciado de maneira idêntica ao gênero.
Espécie: Juliomys sp.
Fotógrafo: Maury S.L. Abreu
Contato: maury.abreu@gmail.com

sábado, 26 de novembro de 2011

Differences in population density and energy use between birds and mammals: a macroecological perspective

SILVA, M.; BROWN, J.H.; DOWNING, J.A. 1997. Differences in population density and energy use between birds and mammals: a macroecological perspective. Journal of Animal Ecology 66(3):327-340.

Abstract.

1. Data from 364 mammal and 564 bird species were used to compare these two taxa in the patterns of variation in population density and energy use as a function of body mass.
2. This study demonstrates previously unappreciated quantitative differences between mammals and birds. Over a wide range of sizes, population densities and rates of energy use are at least one order of magnitude higher in mammals than in birds of similar size. The highest population densities are found in species that weigh about 100 g in mammals and 30 g in birds.
3. Comparisons between mammals and birds from the same dietary category indicate that mammals maintain higher densities and use more energy than birds. Insectivorous mammals and birds maintain the lowest densities.
4. Flying mammals and birds reach lower densities and use more energy than nonflying forms.
5. These findings reveal relationships between the morphology, physiology and behaviour of individual organisms and the ecological performance of these endothermic vertebrates in populations, communities and ecosystems: relationships that have not previously been appreciated.

quarta-feira, 23 de novembro de 2011

Fotos: Gracilinanus microtarsus

O nome gracilinanus vem do latim gracilis (delgado, fino) e do grego nanos (anão), enquanto o epíteto microtarsus vem do prefixo grego micro (pequeno) e o substantivo grego tarsos (tornozelo, sola do pé) (PIRES et al., 2010 - Mammalian Species 42(851):33-40).
Espécie: Gracilinanus microtarsus (cuíca graciosa, guaiquica, Brazilian gracile mouse opossum).
Fotógrafo: Maury S.L. Abreu
Contato: maury.abreu@gmail.com

sábado, 19 de novembro de 2011

The Brazilian Caatinga in South American zoogeography: tropical mammals in a dry region

MARES, M.A.; WILLIG, M.R.; LACHER JR., T.E. 1985. The Brazilian Caatinga in South American zoogeography: tropical mammals in a dry region. Journal of Biogeography 12:57-69.

Abstract. Recent research in South American biogeography on groups other than mammals suggests that the semi-arid Caatinga of northeastern Brazil provided xeric refugia during mesic phases of the Pleistocene climatic cycles. If this supposition is correct, the Caatinga mammal fauna might be expected to contain numerous species showing a pronounced level of adaptation to aridity and the origins of a substantial segment of the fauna slr~ould be traceable to the diversification and eventual speciation that would be expected to have resulted from extended isolation in a xeric environment. An analysis of the extant mammal fauna fails to corroborate these predictions; only one endemic mammal species is found in the Caatinga, and the fauna lacks the expected physiological and morphological adaptations. Other vertebrate groups also exhibit low levels of endemism. The high degree of climatic unpredictability that is characteristic of the Caatinga may preclude the development of a unique fauna adapted to xeric conditions. It appears that the present inhabitants of the region avoid the environmental effects of aridity and climatic unpredictability during harsh periods by utilizing the numerous mesic enclaves scattered throughout the Northeast. Indeed, even during periods of elevated precipitation, most mammal species reach their highest density in these relatively restricted areas. Although the Caatinga contains a xeric-adapted flora, it harbours an anomalous mammal fauna that is more characteristic of a mesic tropical biome in terms of both species composition and overall adaptation. The development of an assemblage of vertebrates whose adaptations do not parallel those of the dominant flora in a region is an unusual situation which should be of particular interest to palaeontologists attempting to reconstruct ancient environments.

sexta-feira, 11 de novembro de 2011

The looming crisis: interactions between marine mammals and fisheries

READ, A.J. 2008. The looming crisis: interactions between marine mammals and fisheries. Journal of Mammalogy 89(3):541-548.

Abstract. Direct fisheries interactions pose a serious threat to the conservation of many populations and some species of marine mammals. The most acute problem is bycatch, unintended mortality in fishing gear, although this can transition into unregulated harvest under some circumstances. A growing issue in some fisheries is depredation, in which marine mammals remove captured fish from nets or lines. Depredation reduces the value of catch and may lead to a greater risk of entanglement and the potential for retaliatory measures taken by fishermen. The conservation threat caused by direct fisheries interactions is most dire for small populations of cetaceans and dugongs. Immediate action is needed to assess the magnitude of bycatch, particularly in many areas of Africa and Asia where little work has been conducted. New and innovative solutions to this problem are required that take account of the socioeconomic conditions experienced by fishermen and allow for efficient transfer of mitigation technology to fisheries of the developing world.

sábado, 5 de novembro de 2011

Feeding habits of the crab-eating fox, Cerdocyon thous (Carnivoria: Canidae), in a mosaic area with native and exotic vegetation in Southern Brazil

ROCHA, V.J.; AGUIAR, L.M.; SILVA-PEREIRA, J.E.; MORO-RIOS, R.F.; PASSOS, F.C. 2008. Feeding habits of the crab-eating fox, Cerdocyon thous (Carnivoria: Canidae), in a mosaic area with native and exotic vegetation in Southern Brazil. Revista Brasileira de Zoologia 25(4):594-600.

Abstract. Cerdocyon thous (Linnaeus, 1766) is the most widespread neotropical canid, most commonly inhabiting forested areas. This animal is a generalist omnivore that is able to use environments disturbed by human activities. The aim of this study was to describe its diet through the stomach content analysis of 30 samples obtained from specimens that were run over in a mosaic composed by Araucaria Pine Forest, Smidecidual Seasonal Forest, natural grasslands, and exotic vegetation. The items were quantified by frequency of occurrence (F.O.) and percentage of occurrence (P.O.). A total of 64 food items were found among 171 occurrences. According to F.O. method, plant items corresponded to 93.3% of the occurrences, followed by animal items (86.7%) and human rejects (16.6%) Among plants, fruits accounted for 92.9% of the occurrences, followed by leaves (53.6%) and flowers (10.7%). Syagrus romanzoffianum (Cham.) Glassman, 1968 and the exotic Hovenia dulcis Thunberg were the most consumed fruits (30% each), and the most consumed leaves were Poaceae. Among preyed animals, the F.O. was 73.3% for invertebrates (mostly Orthoptera and Coleoptera, 36.7% each) and 63.3% for vertebrates (mostly mammals, 33.3%). Regarding the P.O. method, there was an overestimation of invertebrates (98.1%) due to the preference of ants and termites in the stomach of a single individual. In general, C. thous presented its usual diet. Its generalistic feeding habits can positively influence its survival in altered environments. This study also compares different methods for dietary analysis and discusses some opportunistic behaviours of C. thous, such as the consumption of exotic species and the use of silviculture areas as hunting sites.