Title
Seasonal variation in the age and sex structure of Rousettus madagascariensis (Yinpterochiroptera: Pteropodidae) in Ankarana, northern Madagascar.
Author(s)
Noroalintseheno Lalarivoniaina, Oliva S.;Rajemison, Faneva I.;Andrianarimisa, Aristide;Goodman, Steven M.
Published
2018
Publisher
Revue D Ecologie-La Terre Et La Vie
Abstract
In this study, the adjustment and homogeneity tests were used to determine whether the sex ratio deviates from equilibrium (1:1) and whether the age and sex structure of the population varies seasonally. According to the animals captured, juveniles and adults are more numerous in the dry season than in the wet season. The proportion of adults is always higher than that of juveniles. Newborns are only counted during the wet season and their sex ratio is in balance. In juveniles, the sex ratio is skewed in favor of males in the wet season (January 2015: SR = 4, January 2016: SR = 1.66), in favor of females in the dry season (September 2014: SR = 0.67; September 2015: SR = 0.30; September 2016: SR = 0.13). In adults, the sex ratio is skewed toward females in the wet season (January 2015: SR = 0.56; January 2016: SR = 0.22), toward males in the dry season (September 2014: SR = 1.77; September 2015: SR = 1.70; September 2016: SR = 2.50). The seasonal pattern in Rousettus madagascariensis show the existence of two forms of segregation at the site level: 1) ages (juveniles and adults) and 2) sex (males and females).
Keywords
ratio variation;bats;segregation;patterns
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