摘要 : the benefits, if any, of the adoptive behavior of mal Greater Rheas (Rhea amer- icana) towards unrelated young while leading their offspring are not known. Therefore, we quantified adoption by Rheas in an agricultural area of Rio ... 展开 the benefits, if any, of the adoptive behavior of mal Greater Rheas (Rhea amer- icana) towards unrelated young while leading their offspring are not known. Therefore, we quantified adoption by Rheas in an agricultural area of Rio Grande do Sul, Brazil, in order to quantify the potential benefits and the recipients of these benefits. Adult males frequently adopted (23/100), were more vigilant and protective than non-adopters, and ended up leading larger groups of young than non-adopting males. The adopted chicks were usually not more than 1-wk old and survived in greater proportion than the adopter's own offspring. 收起