Seasonal patterns and influence of temperature on the daily activity of the diurnal neotropical rodent Necromys lasiurus.

Vieira, E. M.; Baumgarten, L. C.; Paise, G.; Becker, R. G.

We investigated the relation between temperature and diel activity patterns of Necromys lasiurus (Lund, 1841) in 10 sites of open vegetation (grassland fields) in the Cerrado (savanna-like vegetation) of central Brazil. We used live traps equipped with timing devices during two trapping sessions: in the end of the dry season (session 1, October 2001) and in the wet season (session 2, January-February 2002). Necromys lasiurus is basically a diurnal rodent with more pronounced crepuscular and nocturnal activity in the dry season than in the wet season. Only in the wet season did we detect significant between-gender differences, with males being less active than females in the first hours after sunrise but more active between 0900 and 1200. There was no significant activity-temperature relation in the dry season, but in the wet season, both genders showed a positive relation between ambient temperature and activity. Individuals might be avoiding hot midday hours in the end of the dry season to minimize time exposure to a physiologically stressful condition caused by the joint action of high temperatures and extremely low relative humidity (<15%). In the rainy season, the high relative humidity (80%-90%) might allow the animals to show a positive relation between activity and ambient temperature.

LATIN America; BRAZIL; GRASSLAND animals; HAIRY-tailed bats; ANIMAL populations; VEGETATION boundaries; SEX differences (Biology); SUNRISE & sunset; HUMIDITY

Canadian Journal of Zoology, 2010, Vol 88, Issue 3, p259

0008-4301

Academic Journal

10.1139/Z09-142