Wyniki wyszukiwania

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Age, season, and arboreal movements of the opossum Didelphis aurita in an Atlantic rain forest of Brasil

100%

Cunha A. A., Vieira M. V.

Acta Theriologica

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2005

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tom 50

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nr 4

551-560

The common opossum of the Atlantic forest,Didelphis aurita Wied-Neuwied, 1826 is predominantly terrestrial, but uses the vertical space of the forest regularly. It is the didelphid that most frequently uses large supports in vertical movements. Here we test the influence of age and seasonality in fruit production on the vertical movements ofD. aurita. Animals were trapped in Serra dos Órgăos, state of Rio de Janeiro, and equipped with a spool-and-line device before release. The paths were tracked, and variables related to support incline, diameter, distances and heights moved above ground were measured and compared between age classes and seasons. There were no significant differences between seasons. Individuals of all ages used the vertical space of the forest but the young opossums did it more intensively along their paths.

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Stride lengths and frequencies of arboreal walking in seven species of didelphid marsupials

100%

Delciellos A. C., Vieira M. V.

Acta Theriologica

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2007

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tom 52

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nr 1

Didelphid marsupials differ in their use of the forest strata, with corresponding differences in morphology and arboreal walking performances. Similar performances may be reached by different combinations of stride length and frequency, but it has been suggested that arboreal walkers increase velocity by longer strides. Our objective was to determine how stride length and frequency contribute to the velocity in the arboreal walking of seven species of didelphid marsupials of the Atlantic Forest of Brazil. Animals were stimulated to cross five 3-m long horizontal supports of different diameters. The cycle of maximum velocity was chosen to measure relative stride length, frequency, and relative velocity. Except forCaluromys philander, the more arboreal species were faster than the terrestrial species, but maximum velocity of arboreal species was reached by two strategies, increasing stride frequency (Gracilinanus microtarsus, Micoureus demerarae, andDidelphis aurita), or reducing frequency and increasing stride length (Marmosops incanus andC. philander). Increasing velocity in arboreal walking by more frequent strides may reduce oscillations of the body, whereas longer strides may reduce branch swaying. Among the terrestrial species,Philander frenatus performed similarly to more arboreal species, suggesting a potential ability to use the canopy, undetected in field observations.

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Movement distances and density estimation of small mammals using the spool-and-line technique

100%

Mendel S. M., Vieira M. V.

Acta Theriologica

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2003

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tom 48

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nr 3

Edge effect is an inherent problem when using trapping grids to estimate density of small mammals, resulting in a sampling area larger than the area of the grid. Distances between captures of individuals are used to estimate A(W), the effective sampling area of a trapping grid, but grid size sets a limit for the largest detectable distance. The spool-and-line technique is proposed here as a new method to estimate A(W). Movement distances based on the spool-and-line technique were compared to similar movement distances based on capture-recapture of three species of marsupials of the Atlantic Forest of Brazil. Distances based on the two methods were uncorrelated, and only ln-transformed distances based on the spool-and-line were normally distributed. The maximum distance moved (MaxD) estimated by the spool-and-line was chosen as the more accurate and practical distance to estimate edge effect. Estimates of the effective sampling area and densities for the common opossum Didelphis aurita (Wied-Neuwied, 1826), were compared using MaxD based on spool-and-line (MaxDspool), capture-recapture (MaxDcap), and also the distance between traps (DT). MaxDspool reflected more accurately density variation between seasons. Movement distances of small mammals based on the spool-and-line technique permit more accurate estimates of density and its dynamics.

4

Nests and nesting sites of Brazilian forest rodents [Nectomys aquamipes and Oryzomys intermedius as revealed by a spool-and-line device

80%

Briani D. C., Vieira E. M., Vieira M. V.

Acta Theriologica

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2001

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tom 46

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nr 3

Patterns of nest construction and nest site selection of two murid rodents of the Brazilian Atlantic rainforest were described. The animals were captured in an area of about 1.5 ha of primary forest, marked, equipped with a spool-and-line device and released at the capture point. The next day we followed the thread to find their nests. In total 11 nests of Nectomys squamipes (Brants, 1827) and 13 of Oryzomys intermedius (Leche, 1886) were found. They were all egg-shaped, about 15 cm long and 10 cm wide, without any apparent entrance and consisted of dry leaves and grass. The two species differed in the selection of nest sites. The nests of N. squamipes were close to streams and built inside decomposed fallen logs or using natural entrances between the soil and tangled roots or rocky crevices. Nests of O. intermedius were built under or inside fallen logs and inside aerial root systems of palms. The spool-and-line technique used here is useful to provide detailed information on several aspects of the ecology and natural history of small mammals.

Ograniczanie wyników

4 Acta Theriologica

4 Vieira M. V.

1 Briani D. C.

1 Cunha A. A.

1 Delciellos A. C.

1 Mendel S. M.

1 Vieira E. M.

1 2007

1 2005

1 2003

1 2001

Age, season, and arboreal movements of the opossum Didelphis aurita in an Atlantic rain forest of Brasil

Stride lengths and frequencies of arboreal walking in seven species of didelphid marsupials

Movement distances and density estimation of small mammals using the spool-and-line technique

Nests and nesting sites of Brazilian forest rodents [Nectomys aquamipes and Oryzomys intermedius as revealed by a spool-and-line device