Survival and growth rates of pups in common vole (Microtus arvalis) litters depending on the presence of sire

Two groups of litters obtained from individuals captured in natural environments have been monitored under laboratory conditions. The females of one group reared the offspring in the absence of sires; the litters of the other group are raised by both parents. It is ascertained that the presence of sires, especially those who are characterized by higher levels of aggression, has a negative effect on the survival and growth rates of the pups. Therefore, the reproductive success of common vole males can decrease if they enter the family-group composition and depends on the specificity of their behavior, first and foremost, an inclination toward exhibiting aggression.