Males are expected to assist their mates whenever this behaviour raises survival of offspring with little expense in terms of mating opportunities At a more proximate level cortisol and testosterone hormones seem involved in the expression of parental care in mammals We examined the consequences to postnatal offspring development and survival of the males presence in the social rodent Octodon degus Offspring quality and quantity and maternal condition of females were contrasted among females rearing their litters in the presence of the sire females breeding in the presence of a non-breeding female and females breeding solitarily We related these differences to variation in parental behaviour and plasma levels of testosterone and cortisol Twenty two females and their litters were studied under constant conditions of adult density nest availability food availability and breeding experience Males huddled over and groomed offspring However neither the number nor the mass of pups from dams that nested with the sire differed from those recorded to breeding females that nested with a non-breeding female and females that nested solitarily Body weight loss and associated levels of plasma cortisol in dams nesting with the sire were similar to those of solitary females but higher than mothers nesting with a non-breeding female Thus male care had no consequences to offspring and seemed detrimental to breeding females Circulating levels of cortisol and total testosterone were either poor (mothers) or no (fathers non-breeding females) predictors of parental care (C) 2010 Elsevier Inc All rights reserved