sábado, 28 de abril de 2012

Camera trapping for jaguar (Panthera onca) in the Tuichi Valleys, Bolivia

WALLACE, R.B.; GOMEZ, H.; AYALA, G.; ESPINOZA, F. 2003. Camera trapping for jaguar (Panthera onca) in the Tuichi Valleys, Bolivia. Mastozoología Neotropical 10(1):133-139.

Abstract. Camera trapping techniques, in combination with robust mark-recapture statistics, have been used extensively in Asia to provide tiger population density estimates and relative abundance information. Here we present the results of a first attempt to use these methodologies to determine jaguar abundance. Results suggest a relatively low jaguar population density. Nevertheless, it is hypothesized that previous human disturbance at the site may be responsible for this situation, thereby underlining the need for further studies of this nature.

sábado, 21 de abril de 2012

Population ecology and reproduction of the white-eared opossum Didelphis albiventris (Mammalia, Marsupialia) in an urban environment of Brazil

CÁCERES, N.C. 2000. Population ecology and reproduction of the white-eared opossum Didelphis albiventris (Mammalia, Marsupialia) in an urban environment of Brazil. Ciência e Cultura Journal of the Brazilian Association for the Advanced of Science 52(3):171-174.

Abstract. The seasonal variation in numbers of individuals, causes for death, breeding season and litter size of the white-eared opossum, Didelphis albiventris, were studied in two small urban forest fragments of southern Brazil. In order to trap opossums, 30 live traps were used once a weak in a forest fragment (5 ha) between February 1995 and January 1996. In addition, 10 traps were used twice a month in another area (2.5 ha) between Novemeber 1996 and February 1997. Individuals trapped were sexed, aged, and released. Females with litter had their pouch young counted. The bait used was banana with codfish liver oil. As results after an effort of 1770 traps set, 37 opossums were captured (20 females and 17 males) with the sex ratio being significantly equal (p > 0.40). Juvenile individuals were captured seasonally during the wet season (spring and summer). Since juveniles represented the most common individuals trapped, total abundances were heigher during the wet season. Immigrations (plus births) rather than emigrations were thought to be the main factor for abundance variations. Moreover, road kill by cars and fights with dogs were the main causes for death of opossums. Based on time of captures of recently weaned opossums and females with litters, the breeding season showed mainly two periods of births (between August and November), though two litters were seen in April of two years. The mean litter size was 9.0 young (N = 14 litters). The white-eared opossum revealed a great potential to colonize urban environments where there are forest fragments, with its higher numbers of juveniles compensating adult deaths mainly by anthropical factors.

sábado, 14 de abril de 2012

Coexistence of jaguar (Panthera onca) and puma (Puma concolor) in a mosaic landscape in the Venezuelan llanos

SCOGNAMILLO, D.; MAXIT, I.E.; SUNQUIST, M.; POLISAR, J. 2003. Coexistence of jaguar (Panthera onca) and puma (Puma concolor) in a mosaic landscape in the Venezuelan llanos. Journal of Zoology, London 259:269-279.

Abstract. Jaguar Panthera onca and puma Puma concolor are sympatric throughout the jaguar’s distribution. Although several studies have focused on the interactions between these two predators, the ecological and behavioural factors that promote their coexistence remain unclear. The goal of this study was to identify those factors that facilitate the coexistence of these cats in a mosaic landscape in the Venezuelan llanos. The study was conducted from January 1996 until November 1998. Five jaguars and six pumas were captured and radio-collared. A high degree of spatial overlap was observed between jaguars and pumas, which may be related to the abundance and distribution of prey species. At a fine scale, there was little overlap of puma locations with jaguar locations. Both species were more active at night than during daytime, but seasonal differences were detected in the activity levels of these predators. Major segregation was found in food habits. Jaguars selected for large prey and pumas for medium-sized prey. Jaguars selected for capybara Hydrochaeris hydrochaeris and collared peccary Tayassu tajacu and consumed caiman Caiman crocodilus and white-tailed deer Odocoileus virginianus less than expected. Pumas selected just for collared peccary and also killed caiman less than expected. It is suggested that the abundance of medium-sized prey is an ecological factor that is facilitating the coexistence of jaguar and puma in the study area. Habitat heterogeneity may be another influential factor leading to the coexistence. Seasonal differences in activity levels probably reflect differences in the size and species of prey taken by these cats.

segunda-feira, 9 de abril de 2012

Concurso Professor Substituto UFERSA

A Universidade Federal Rural do Semi-Árido abriu processo seletivo para professor substituto. Para biólogos há vagas para as discuplinas Ecologia da Poluição, Ecologia Marinha, Estudos de Impacto Ambiental, Nanobiotecnologia e Biotecnologia e Patentes. Maiores informações no site http://www2.ufersa.edu.br/sistemas/concursos/publico/exibir_concurso/35. As inscrições vão até esta quinta-feira, portanto é bom se apressar.

sábado, 7 de abril de 2012

Movement distances of five rodents and two marsupial species in forest fragments of the coastal Atlantic Rainforest, Brazil

PÜTTKER, T.; MEYER-LUCHT, Y.; SOMMER, S. 2006. Movement distances of five rodents and two marsupial species in forest fragments of the coastal Atlantic Rainforest, Brazil. Ecotropica 12:131-139.

Abstract. Movement distances provide information on diverse population biological parameters and are essential in understanding the ecology of a species. Mean distances moved between successive captures (SD), distribution of movement distances, and the mean maximum distances moved (MMDM) were investigated in five rodent and two marsupial species in forest fragments of the coastal Atlantic rainforest (Mata Atlântica) in the state of São Paulo, Brazil. The investigated species were the rodents Akodon montensis (Thomas, 1902), Oligoryzomys nigripes (Olfers, 1818), Delomys sublineatus (Thomas, 1903), Oryzomys russatus (Wagner, 1848), and Thaptomys nigrita (Lichtenstein, 1829), and the marsupials Marmosops incanus (Lund 1840), and Gracilinanus microtarsus (Wagner, 1842). Akodon montensis differed significantly from all other species and moved the lowest SD and MMDM. The marsupials differed significantly from most of the rodents and moved the largest SDs. All species showed the highest frequency of movements in a distance class of 0–20 m. Differences between sexes in SD was detected for O. nigripes, O. russatus, and G. microtarsus, males moving significantly longer distances than females. The different study sites had no influence on SD in any of the investigated species. Only the males of G. microtarsus showed a seasonal variation in SD, moving longer distances during reproductive activity.

terça-feira, 3 de abril de 2012

Concurso Petrobás

Já estão abertas as inscrições para o processo seletivo da Petrobás S.A., com provas para serem realizadas no dia 06 de maio de 2012. Há duas vagas para biólogos (de qualquer área), e as inscrições vão até o dia 11 de abril de 2012. Visite o site da cesgranrio (http://www.cesgranrio.org.br/) para maiores informações e para fazer download do edital.
Não é uma notícia diretamente ligada a mamíferos, mas que pode interessar a muitos biólogos que visitam o blog.