Autor: Emygdio L.A. Monteiro-Filho

Emygdio Leite de Araújo Monteiro-Filho

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.

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.