Aggressive behavior of pregnant females of Akodon azarae: ¿a strategy to reduce infanticide risk of their youngs next to be born?

BONATTO FLORENCIA; STEINMANN, ANDREA; PRIOTTO JOSÉ

Mastozoología Neotropical

UNIDAD DE ZOOLOGÍA Y ECOLOGÍA ANIMAL, INSTITUTO ARGENTINO DE INVESTIGACIÓN DE LAS ZONAS ARIDAS, CRICYT, CONICET

Año: 2019 vol. 25 p. 255 - 262

1666-0536

Infanticide by males is an adaptive behavioral strategy to improve the reproductive success of the perpetrator reproductive success of perpetrator by increasing their chances to reproduce with the victim female by shortening the inter-birth interval. Thus, females are expected to evolve dierent ounterstrategies towards infanticide by males. We study nest site defense, or future ospring protection, through the direct attack of pregnant females close to give birth against potentially infanticidal males in the Pampean grasslandmouse (Akodon azarae). We experimentally test the prediction that pregnant females are more aggressive against unfamiliar intruder males than non-pregnant females, and that the intensity of this aggressive response is independent of females residence durations in their home territory. We conducted 46 behavioral trials between resident females (pregnant or non-pregnant) and unfamiliar intruder males, considering dierent residence durations of females in their own individual enclosure (48 and 72 hours). We found that pregnantfemales were always more aggressive than non-pregnant females, independently of residence duration. Our research provides evidence that aggressive behavior of future mothers of A. azarae to defend the nest site would reduce infanticide risk of their youngs next to be born; keeping away potential infanticidal males could reduce the greater cost of avoiding infanticide of their vulnerable ospring (i.e., when they become lactating females). In this way, even though aggression is risky, it would be advantageous for pregnant females to useaggression even when there are not yet any pups to protect.