Evaluation of abundance indexes in open population studies: a comparison in populations of small mammals in southern Brazil.

Many manuscripts comparing populations and/or analysing the structure of animal communities use indexes of captures as synonymous of abundance. However, the basic methods more suitable to this assumption - probabilistic estimates based on equal capture probability - have not been considered. In this study, the deviations caused by different types of capture indexes are compared with a common probabilistic population estimator (Cormack-Jolly-Seber). The analyses showed that Minimum Number Known Alive (MNKA) and the number of individuals showed greater association with the population estimator than with non-probabilistic indexes based on recaptures. Therefore, none of the indexes presented the same performance to estimate population size estimation which can lead to ecological misinterpretation. Some recommendations were also described.

The role of melanism in oncillas on the temporal segregation of nocturnal activity.

The occurrence of coat colour polymorphisms in populations may promote the ecological success of species by permitting a wider spectrum of use of different subsets of available resources. We conducted an analysis of temporal segregation by comparing night brightness with nocturnal activity of spotted and melanistic oncillas (Leopardus tigrinus). Melanistic oncillas were more active during bright nights and spotted oncillas and other species were more active during dark nights. Each colour morph occupied a temporal niche outside the confidence interval of the other colour morph, demonstrating the ecological significance of polymorphic colour patterns in this felid species.

Differences in richness and composition of gastrointestinal parasites of small rodents (Cricetidae, Rodentia) in a continental and insular area of the Atlantic Forest in Santa Catarina state, Brazil.

The first and only study on gastrointestinal parasites of wild rodents in the Island of Santa Catarina was done in 1987. The aim of this study was to identify intestinal parasites from wild rodents in Santo Amaro da Imperatriz and Santa Catariana Island, and to compare the richness and composition of the gastrointestinal parasite community of both areas. Rodents were captured with live traps, and feces were screened using the sedimentation method and optical microscopy. The following species of rodents were captured in the two areas: Akodon montensis, Euryoryzomys russatus, Oligoryzomys nigripes and Nectomys squamipes. In Santo Amaro da Impetratriz, prevalent parasites were: A. montensis (51%), E. russatus (62%), O. nigripes (53%) and N. squamipes (20%). From the Island of Santa Catarina the rodent prevalence rates were: A. montensis (43%), E. russatus (59%), O. nigripes (30%) and N. squamipes (33%) and the collected parasites were: Hymenolepis sp., Longistriata sp., Strongyloides sp., Hassalstrongylus sp., Syphacia sp., Trichomonas sp., Ancylostomidae, Trichuridae, Oxyuridae and Eucoccidiorida. The species richness (10.6 ± 0.7) of the endoparasite comunity in the area located on the continent was higher (p < 0.01) and different (p = 0.001) from that of the area located on the island (6.9 ± 0.5).

Body size of commom opossum Didelphis aurita Wied-Neuwied 1826 (Didelphimorphia: Didelphidae) on southern brazilian islands.

The body size of vertebrates isolated on islands can undergo changes due to ecological features of these environments. This study aimed to compare the body size of the common opossum, Didelphis aurita, from different insular populations within the same archipelago in southern Brazil. The opossum populations showed corporal variation and different hypotheses were raised to understand the results. This study constitutes the most detailed body size comparison of a marsupial within different insular populations in the Neotropical zone and the data gathered represents an initial contribution for regional fauna biometric knowledge.

Body size of commom opossum Didelphis aurita Wied-Neuwied 1826 (Didelphimorphia: Didelphidae) on southern Brazilian islands / Tamanho corpóreo de gambás Didelphis aurita Wied-Neuwied 1826 (Didelphimorphia: Didelphidae) em ilhas no sul do Brasil

The body size of vertebrates isolated on islands can undergo changes due to ecological features of these environments. This study aimed to compare the body size of the common opossum, Didelphis aurita, from different insular populations within the same archipelago in southern Brazil. The opossum populations showed corporal variation and different hypotheses were raised to understand the results. This study constitutes the most detailed body size comparison of a marsupial within different insular populations in the Neotropical zone and the data gathered represents an initial contribution for regional fauna biometric knowledge.

O tamanho corpóreo de vertebrados isolados em ilhas pode sofrer alterações em função das particularidades ecológicas desses ambientes. O presente trabalho comparou o tamanho corpóreo de gambás, Didelphis aurita, em ilhas costeiras de um mesmo arquipélago no Sul do Brasil e encontrou diferenças de tamanho entre as localidades. Os gambás apresentaram variações para as medidas corporais e diferentes hipóteses foram consideradas para entender os resultados. Esta é a comparação mais detalhada de tamanho corpóreo entre populações insulares de um marsupial neotropical e uma contribuição inicial para o conhecimento da biometria da fauna regional.