sábado, 29 de outubro de 2011

Scale-dependent habitat selection in three didelphid marsupials using the spool-and-line technique in the Atlantic forest of Brazil

MOURA, M.C.; CAPARELLI, A.C.; FREITAS, S.R.; VIEIRA, M.V. 2005. Scale-dependent habitat selection in three didelphid marsupials using the spool-and-line technique in the Atlantic forest of Brazil. Journal of Tropical Ecology 21:337-342.

Abstract. Habitat selection can be detected at different scales. For small mammals, habitat studies normally evaluate micro- or meso-habitat selection, but rarely are multiple scales analysed simultaneously. These studies use quantitative data of structural characteristics around the trap stations to evaluate selection. We test an alternative method to evaluate habitat selection in three didelphid marsupials (Didelphis aurita, Philander frenatus and Metachirus nudicaudatus), using a spool-and-line device, and measure habitat selection at two spatial scales. Habitat was characterized by seven habitat variables measured at ten points of direction change along the path traversed by each individual, and at 25 trap stations distributed in a 1-ha area. Micro-habitat selection was estimated at each point by comparing habitat measures between the direction selected against other directions. Meso-habitat selection was estimated by comparing habitat measurements on the whole path of an individual against habitat measures on the 25 trap stations. Patterns of selection for each species could only be detected at the meso-habitat scale, although a few individuals in each species were selective at the micro-habitat scale. Studies of habitat selection need to address the scale of study quantitatively, if possible comparing two or more scales to determine the scale of selection.

sábado, 22 de outubro de 2011

Coexistence of temporal partitioned spiny mice: roles of habitat structure and foraging behaviour

JONES, M.; MANDELIK, Y.; DAYAN, T. 2001. Coexistence of temporal partitioned spiny mice: roles of habitat structure and foraging behaviour. Ecology 82(8):2164-2176.

Abstract. Two coexisting species of spiny mice in rocky deserts in Israel temporally partition activity in opposite parts of the diel cycle. Acomys cahirinus is nocturnal and A. russatus is diurnal, although it becomes nocturnal if its congener is experimentally removed, suggesting that the temporal partitioning is driven by interspecific competition. Such extreme temporal partitioning within the diel cycle has not previously been recorded elsewhere among mammals. Using artificial food patches, we studied microhabitat use and foraging efficiencies under seasonally variable predator regimes and physiological pressures to assess the roles that habitat structure and foraging behavior might play in coexistence. The two species showed trade-offs in foraging efficiency leading to different strategies of microhabitat use that may help promote coexistence. A. cahirinus is a "cream skimmer," a relatively inefficient forager that gives up at relatively high giving-up densities, and a habitat generalist; whereas A. russatus is a habitat specialist, perhaps compensating for this restricted niche by foraging very efficiently to low giving-up densities. Seasonal shifts in foraging microhabitat suggest that the response to predation risk from snakes in summer overrides and opposes the effects of physiological costs and risk from owls and diurnal raptors, leading to increased predatory risk and foraging microhabitat overlap in summer. Temporal partitioning of the food resource may compensate for decreased partitioning of the habitat resource in summer. Provision of cover was more important than escape distance in determining habitat and microhabitat use. Boulder fields in rocky deserts provide a physical structure that is more complex and provides more continuous cover than is available in open deserts, where most research on community structure of desert rodents has been carried out. We propose that this physical structure of rocky deserts, in conjunction with the desert adaptations of A. russatus, may enable the extreme temporal partitioning to opposite parts of the diel cycle and, therefore, contributes to coexistence in this community.

quinta-feira, 20 de outubro de 2011

PPG em Ecologia e Conservação pela UNEMAT - Edital

Esta aberto o edital de processo seletivo para ingresso no curso de Mestrado em Ecologia e Conservação para 2012 da Universidade do Estado de Mato Grosso. São ofertadas 12 vagas nas seguintes linhas de pesquisa: Ecologia de Sistemas e Comunidades Terrestres e Ecologia de Sistemas e Comunidades de Áreas Úmidas.
Maiores informações no edital.

sábado, 15 de outubro de 2011

Diet of crab-eating fox, Cerdocyon thous (Linnaeus) (Carnivora, Canidae), in a suburban area of southern Brazil

PEDÓ, E.; TOMAZZONI, A.C.; HARTZ, S.M.; CHRISTOFF, A.U. 2006. Diet of crab-eating fox, Cerdocyon thous (Linnaeus) (Carnivora, Canidae), in a suburban area of southern Brazil. Revista Brasileira de Zoologia 23(3):637-641.

Abstract. The crab-eating fox, Cerdocyon thous (Linnaeus, 1766), is a small canid with twilight and nocturnal habits from savanna and forests of South America. In this study, we seasonally determined and quantified the diet of C. thous in Lami Biological Reserve, a conservation unit with 179.78 ha situated in a suburban area in the municipality of Porto Alegre, southern Brazil. During the year 2000, we colected 80 fecal samples - 20 for each season - in two or three week sampling intervals, along trails inside the Reserve. Samples were dried in an oven for 24h at 60ºC, immersed in 70% alcohol, and prey items were identified using a stereomicroscope. The diet of the crab-eating fox was essentially carnivorous (87.62% composed by vertebrates), with seasonal variation (p = 0.0009) and absence of fruits. Small non-flying mammals and birds were the most frequent prey, being proportionally more preyed in autumn and summer, respectively. Arthropods were more preyed in winter and spring and bird/respile eggs only in summer and spring, in the reproduction period of these groups.

sábado, 8 de outubro de 2011

Area de acción, actividad y uso de hábitat del zorro patas negras, Cerdocyon thous, en un bosque seco

MAFFEI, L.; TABER, A.B. 2003. Area de acción, actividad y uso de hábitat del zorro patas negras, Cerdocyon thous, en un bosque seco. Mastozoologia Neotropical 10(1):154-160.

Abstract. Home range, activity, and habitat use of the crab-eating fox (Cerdocyon thous) in a dry forest. The ranging behaviour of three crab-eating foxes in a dry forest in Santa Cruz, Bolivia was studied using radiotracking. Animals occupied an area between 110 and 280 ha estimated with Minimum Convex Polygon and has a small overlap (27 ha) between ranges. The foxes were principally active at night between 17:00 and 08:00 hours. They preferred riparian forest over chacoan and montane forest habitats, althought the former was less available than the others.

quarta-feira, 5 de outubro de 2011

Fotos: Dasypus novemcinctus

Esse é o Zeca. Na verdade era pra ser "Jeca Tatu", mas eu me confundi na hora e acabou ficando Zeca mesmo. Esse tatu ciu em uma pitfall para roedores e estava quase morto quando encontramos. Ficamos o dia inteiro cuidando dela, aquecendo e tentando dar comida, e no fim do dia conseguimos fazer ele ir embora e seguir seu rumo sozinho.
Espécie: Dasypus novemcinctus (tatu-galinha, armadillo de nueve bandas, nine-banded armadillo).
Fotógrafo: Maury S.L. Abreu
Contato: maury.abreu@gmail.com

sábado, 1 de outubro de 2011

Evolution of nakedness in Homo sapiens

RANTALA, M.J. 2007. Evolution of nakedness in Homo sapiens. Journal of Zoology 273:1-7.

Abstract. Homo sapiens L. is the only existing primate species lacking in functionally effective thermally insulating fur. As all other primates have considerable hair covering, it has always been accepted that our ancestors must once have had a respectable amount of body hair. Unfortunately, fossils cannot help us when it comes to differences in skin and hair. Recent DNA analysis, however, has given us some idea of when and where the great denudation took place. A number of hypotheses have been proposed to account for this feature, but none of these has gained general acceptance. In this paper, I present these hypotheses in the light of current empirical evidence and discussion.