Keyword: Atlantic Forest

Jumping ability in the arboreal locomotion of didelphid marsupials

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Didelphid marsupials are considered to cross discontinuities between arboreal supports using a cautious locomotion, using the prehensile tail as fifth limb. However, this ability was only described for Caluromys philander. We describe and compare the locomotory performance and postural behavior of seven species of didelphid marsupials crossing discontinuities between artificial supports representing arboreal gaps. Individuals were captured in areas of Atlantic Forest in Rio de Janeiro State, Brazil. Animals were stimulated to jump from a fixed horizontal support one meter above the ground to an inclined support of same diameter. We measured the maximum distance of jump (40, 60, 80 or 100 cm) and reach or distance actually reached by the jump. Arboreal species (Marmosops incanus, Gracilinanus microtarsus, Micoureus paraguayanus, and C. philander) jumped longer distances and had longer relative reach in jumps than semi-terrestrial species (Didelphis aurita and Philander frenatus). Only the specialized terrestrial Metachirus nudicaudatus did not jump in the tests. The relation between absolute reach and body size was weak and non significant. This study did not corroborate the view that didelphid marsupials cross discontinuities between arboreal supports only through a cautious locomotion, without jumping. On the contrary, we identified patterns of jumping performance and behavior of didelphid marsupials related to their use of the vertical strata.

Habilidade de salto na locomoção arborícola de marsupiais didelfídeos. Os marsupiais didelfídeos são tidos como animais que cruzam descontinuidades entre suportes arbóreos através de uma locomoção cautelosa, utilizando a cauda preênsil como quinto membro. Entretanto, esta habilidade somente foi descrita para Caluromys philander. O objetivo desse estudo foi descrever e comparar o desempenho e comportamento de sete espécies de marsupiais didelfídeos na transposição de descontinuidades entre suportes artificiais representando descontinuidades arbóreas. Indivíduos capturados em áreas de Mata Atlântica no Estado do Rio de Janeiro, Brasil, foram submetidos a testes que consistiam em estimulá-los a saltarem de um suporte horizontal fixo a um metro do chão para um suporte inclinado de mesmo diâmetro. Foram medidas a distância máxima de salto (40, 60, 80 ou 100 cm) e o alcance ou distância efetiva atingida com o salto. As espécies arborícolas (Marmosops incanus, Gracilinanus microtarsus, Micoureus paraguayanus e C. philander) saltaram prontamente maiores distâncias e tiveram maiores alcances relativos no salto do que as semiterrestres (Didelphis aurita e Philander frenatus). Apenas a especializada terrestre Metachirus nudicaudatus não realizou saltos. A relação entre alcance e peso corporal foi fraca e não significativa. Esse estudo não corroborou a visão de que os marsupiais didelfídeos cruzam descontinuidades entre suportes arbóreos somente através de uma locomoção cautelosa, sem saltar. Ao contrário, identificamos diferentes padrões de desempenho e comportamento no salto relacionados ao uso dos estratos verticais da mata pelos marsupiais didelfídeos estudados.

Dinâmica populacional de marsupiais e roedores no Parque Municipal da Lagoa do Peri, Ilha de Santa Catarina, sul do Brasil

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Population dynamics of marsupials and rodents in Parque Municipal da Lagoa do Peri, Santa Catarina Island, southern Brazil. A two-year mark-recapture study of small mammals was conducted in an area of Atlantic Forest hillside in the state of Santa Catarina, Brazil. Four species of marsupial and seven species of rodent were captured during 12132 trap nights. Aspects of population dynamics and natural history are discussed for each common species. The sex ratio was biased toward males for all species. Oryzomys russatus, Didelphis aurita and Akodon montensis had the highest population densities, the least amount of variation in population density and an inverse relationship between survivorship rates and population densities. Micoureus paraguayanus, Nectomys squamipes and O. angouya registered the higher population densities after continual survivorship rates. The recruitment rates were low for most species (< 50%), with some, M. paraguayanus, Lutreolina crassicaudata, Oligoryzomys nigripes, O. angouya and Oxymycterus aff. judex, disappearing occasionally from the study area. The survivorship rates were high for most species (> 50%). Population densities of D. aurita, O. nigripes and O. aff. judex increased in cold and dry periods. The marsupials reproduced seasonally from late winter until the end of the summer, whereas rodents reproduced throughout the year. No species were long-lived, with average life-span < six months.

Padrão de atividade de Akodon montensis e Oryzomys russatus na reserva Volta Velha, Santa Catarina, sul do Brasil

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Padrão de atividade de Akodon montensis e Oryzomys russatus na Reserva Volta Velha, Santa Catarina, sul do Brasil. São apresentadas informações preliminares sobre o padrão de atividade de duas espécies de roedores em uma área de Floresta Atlântica do sul do Brasil. Sistemas com relógios analógicos foram usados para determinar o horário de captura de pequenos mamíferos e um modelo exponencial negativo foi usado para transformar o número de capturas no padrão de atividade de cada espécie. Foram capturadas três espécies de roedores e três de marsupiais em armadilhas com estes sistemas, porém, analisou-se apenas o padrão de atividade das duas espécies mais abundantes, A. montensis e O. russatus. Os padrões de atividade destas duas espécies foram significativamente diferentes (p < 0.05). A primeira espécie foi caracterizada como possuindo padrão de atividade bicrepuscular enquanto a segunda como noturna. Os padrões de atividade registrados para estas espécies simpátricas podem ter um importante papel na partição de recursos.

Activity patterns of Akodon montensis and Oryzomys russatus in Volta Velha Reserve, Santa Catarina, southern Brazil. The results of this paper give preliminary information on activity patterns of two rodents in an Atlantic Forest area in southern Brazil. Analogical watches were used to determine the capture time of small mammals and a negative exponential model was used to transform the number of captures in each activity period. Three rodents and three marsupials were captured in traps with systems, but activity patterns were determined for only two rodents species, A. montensis and O. russatus. The activity patterns of these two species were significantly different (p < 0.05). The first species had activity characterized as a twilight pattern and the second species had activity characterized as a nocturnal pattern. These activity patterns may have an important role in resource partitioning of the sympatric species.

Patrón de actividad de Akodon montensis y Oryzomys russatus en la
Reserva Volta Velha, Santa Catarina, sur de Brasil. Son presentadas informaciones preliminares sobre el patrón de actividad de dos especies de roedores en una selva Atlántica del sur de Brasil. Sistemas con relojes analógicos fueron usados para determinar el horario de captura de pequeños mamíferos y un modelo exponencial negativo fue usado para transformar el número de capturas en el patrón de actividad de las dos especies más abundantes, A. montensis y O. russatus. Los patrones de actividad de estas dos especies fueron significativamente diferentes (p < 0.05). La primera especie fue caracterizada como poseedora de un patrón de actividad bicrepuscular y la segunda como nocturna. Los patrones de actividad registrados para estas especies simpátricas pueden tener un importande papel en la repartición de recursos.

Sprainting sites of the Neotropical otter, Lontra longicaudis, in an Atlantic Forest area of southern Brazil

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This work was carried out in Reserva Volta Velha, an Atlantic Forest area in Itapoá, Santa Catarina State, in southern Brazil, from September 95 to March 97. The objectives were to tipify holts of the Neotropical otter [Lontra longicaudis (Olfers, 1818)] and determine the use of sprainting sites. Monthly, we went by boat along Saí-Mirim, Braço do Norte, and Volta Velha rivers looking for otter holts, scats and footprints. The results obtained indicate that on the studied rivers, characterized by presence of silty and/or sandy bottom and absence of rocks, otters use holts among tree roots, mainly where river banks are high. In this type of environment, dense vegetation protects holt structure against erosion and high banks represent a protection against flooding. The present work corroborates the importance of the alluvial dense ombrophyllous forest to keep habitat conditions favorable to the Neotropical otter.

Fruit occurrence in the diet of the Neotropical Otter, Lontra longicaudis, in southern Brazilian Atlantic Forest and its implication for seed dispersion

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The Neotropical otter has been described as insectivorous and piscivorous-cancrivorous. We registered the presence of fruit remains in the scats of the Neotropical otter and developed an analysis about the occurrence and importance of fruits in its diet. This study was carried out from September 1995 to March 1997 in Reserva Volta Velha, an Atlantic Forest area in south Brazil. Otter scats were collected along rivers, washed, dried and analyzed. Seeds found in scats were identified by comparison with a reference collection and their viability was tested in germination ground plots. Fruit collectors helped studying the availability of these fruit species during seven months. A total of 202 scats were collected but only six (3%) presented fruit remains. Identified seeds from only four scats indicated that otters ate three fruit species: Marlierea tomentosa (Myrtaceae), Manilkara subsericea (Sapotaceae) and Pouteria lasiocarpa (Rubiaceae). The availability results indicate that all three are abundant fruit species in the study area, specially the former. In the germination experiments all seeds of M. tomentosa germinated (n = 16). Considering the daily movement pattern of the Neotropical otter, and the high germination rate of M. tomentosa, it is possible that the Neotropical otter is a seed disperser for this plant species in the study site.

Presencia de frutos en la dieta de la nutria, Lontra longicaudis, en la Mata Atlántica del sur de Brasil y su implicancia en la dispersión de semillas. La nutria, Lontra longicaudis, ha sido descrita como insectívora y piscívora/cancrívora. Constatamos la presencia de restos de frutos en esta especie y analizamos la importancia de los frutos en su dieta. Este estudio fue realizado entre septiembre 1998 a marzo 1997 en la Reserva Volta Velha, una zona de Mata Atlántica en el sur de Brasil. Los excrementos de la nutria fueran recolectados a lo largo de diferentes ríos y posteriormente limpiados, secados y analizados. Las semillas encontradas fueron identificadas por comparación con una colección de referencia; su viabilidad fue probada por germinación. Recolectores de frutos estudiaron la disponibilidad de los diferentes frutos durante siete meses. Solo seis (3%) de 202 muestras recolectadas contenían restos de frutos. Las semillas identificadas de cuatro muestras indican que las nutrias se alimentan de los frutos de tres especies: Marlierea tomentosa (Myrtaceae), Manilkara subsericea (Sapotaceae) y Pouteria lasiocarpa (Rubiaceae). Los resultados de disponibilidad indican que las tres especies de frutos encontradas son abundantes en el área de estudio, en especial la primera de ellas. En los estudios de germinación, todas las semillas de M. tomentosa germinaron (n = 16). Considerando los patrones de movimiento diario de la nutria y el alto grado de germinación de M. tomentosa, es posible que esta especie sea un dispersor de semillas de estas plantas en el área de estudio.

Patterns of space use by Micoureus demerarae (Marsupialia: Didelphidae) in a fragment of Atlantic Forest in Brazil

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Space use by the marsupial Micoureus demerarae was studied through mark-recapture trapping in a seven hectare Atlantic Forest fragment, from March 1995 to September 1996. Captures of this species were slightly aggregated within the fragment, and aboveground traps were more successful than the ones placed on the ground. Males had larger home ranges and moved further between successive captures than did females. Two adult males moved between the study area and a nearby forest fragment, crossing 300 m of open vegetation. Home ranges of males overlapped extensively with each other and with those of females. Female home ranges, on the other hand, showed no overlap with each other, with only one exception. These patterns are consistent with the hypothesis that M. demerarae has a promiscuous mating system.

Patrones de uso del espacio de Micoureus demerarae (Marsupialia: Didelphidae) en un fragmento de Selva Atlántica en Brasil. El uso del espacio del marsupial Micoureus demerarae fue estudiado a través de la captura, marcado y recaptura de ejemplares en un fragmento de 7 ha de Selva Atlántica, entre marzo 1995 y setiembre 1996. La captura de ejemplares de esta especie fue levemente agregada dentro del fragmento y las trampas elevadas fueron más efectivas que las colocadas a ras del suelo. Los machos tuvieron un área de actividad mayor que las hembras y se desplazaron mayores distancias que estas entre capturas. Dos machos adultos recorrieron 300 m de vegetación abierta entre el área de estudio y un fragmento de selva cercano. Las áreas de actividad de los machos se superpusieron ampliamente entre sí y con las de las hembras. Por otra parte, las áreas de actividad de las hembras no se superpusieron, con una sola excepción. Estos patrones concuerdan con la hipótesis de que M. demerarae tiene un sistema de apareamiento promiscuo.