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Architecture of Ctenomys mendocinus [Rodentia] burrows from two habitats differing in abundance and complexity of vegetation

100%

Rosi M. I., Cona M. I., Videla F., Puig S., Roig V. G.

Acta Theriologica

2000

tom 45

nr 4

Burrow systems of the fossorial rodent Ctenomys mendocinus Philippi, 1869 were studied in the Andean Precordillera. These burrows were linear, with laterals and branches forked off the main tunnel. Their size and architecture did not differ between sexes. Burrows showed a constant heading along the main tunnel, with a mean directional angle close to 0°, Most forks of the main tunnel were originated more than expected at plants, indicating a change of search pattern where plants were encountered. This behaviour suggests a tactic consistent with area-restricted search. These systems were compared with others of the same species located in a habitat with higher cover and structural complexity of vegetation, at the Mendoza Piedmont. Female burrows were larger and male burrows more bifurcated in the Precordillera. These burrows were more complex than those from the Piedmont, owing to the presence of secondary tunnels. The mean directional angle close to 0°, orthogonal branches and angles of ascent of laterals close to 40° were attributes shared by the systems of both habitats. C. mendocinus maintains a basic search pattern as an optimal forager, and increases the systems size and complexity probably as an adaptive strategy to optimize the foraging efficiency and minimize the prédation risk.

Diet of a Piedmont population of Ctenomys mendocinus [Rodentia, Ctenomyidae]: seasonal patterns and variations according sex and relative age

80%

Puig S., Rosi M. I., Cona M. I., Roig V. G., Monge S. A.

Acta Theriologica

1999

tom 44

nr 1

Dietary composition was determined seasonally in males and females of Ctenomys mendocinus Philippi, 1869 from the Andean Piedmont (Mendoza, Argentina) during the reproductive and non-reproductive period. Reproductive condition and relative age of each animal was determined. Stomach contents were individually analyzed with the microhistological technique, Dietary generalism is supported by the high proportion of available genera eaten, but the intensity and continuity of use suggested specialization on grasses. Prédation risk induces minimization of the exposure time out of the burrow, and could justify the specialization in grasses, considering that other rodents showed lower harvest and handling times for grasses than for shrubs. Males had a more varied diet than females in winter, and the opposite occurred in spring. Since males have been found to dig longer burrow systems than females in winter, searching for mates might cause males to intersect a higher number of food items during that season. Higher energetic and nutritional requirements associated with pregnancy and nursing may lead to the inclusion of more food items in the spring diet of females, and their higher specialization on grasses. Dietary similarities between immature and mature individuals suggested that age did not affect selection of diet items. Seasonal variation in dietary diversity suggested a foraging strategy adaptive to environmental seasonal variations and to the subterranean life style.

Ograniczanie wyników

2 Acta Theriologica

2 Cona M. I.

2 Puig S.

2 Roig V. G.

2 Rosi M. I.

1 Monge S. A.

1 Videla F.

1 2000

1 1999

Wyniki wyszukiwania

Architecture of Ctenomys mendocinus [Rodentia] burrows from two habitats differing in abundance and complexity of vegetation

Diet of a Piedmont population of Ctenomys mendocinus [Rodentia, Ctenomyidae]: seasonal patterns and variations according sex and relative age