CONICET | Buscador de Institutos y Recursos Humanos

Territorial behaviour in female small mammals has been proposed as a mechanism to defend limited ecological resources or their pups against conspecific infanticidal or predators. Female territorial behaviour very often is associated with reproductive activity due to the fact that frequency and intensity of aggression are exhibited mainly when females are pregnant or lactating. In vole and mice species female territoriality would be a counterstrategy to prevent the killing of their pups by conspecific breeding females. In order to study if female territoriality is a strategy for pups or nest defence against infanticidal breeding females, and if time invested in nursing young affects aggressive response of mothers, we used the Pampean grassland mouse (Akodon azarae) as an ecological model species. We conducted resident-intruder tests between lactating females. Due to the fact that previous experience of females with a familiar area with critical resources to rear their pups would affect their motivation to defend this known territory, we used different residence durations prior to behavioural trials: 48 and 72 hours. In all cases, the pups of both resident and intruder mothers, were placed with the nesting material from their reproductive cages. Resident mothers were always more aggressive than intruders and they were even more aggressive when they spent more time nursing their pups. Contrarily, intruder females exhibited the greatest values of submissive behaviours. Our results suggest show that female territoriality of A. azarae would represent a strategy to protect pups from potentially infanticidal females. We discuss the extent of female intrasexual territoriality and its potential adaptive significance in relation to strategies which lead to increase their reproductive success.

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