ADOPTION OF UNRELATED YOUNG BY GREATER RHEAS

The benefits, if any, of the adoptive behavior of male Greater Rheas ( Rhea americana) towards unrelated young while leading their offspring are not known. Therefore, we quantified adoption by Rheas in an agricu ltural area of Rio Grande do Sul, Brazil, in order to quantify the pot ential benefits and the recipients of these benefits. Adult males freq uently adopted (23%), were more vigilant and protective than non-adopt ers, and ended up leading larger groups of young than non-adopting mal es. The adopted chicks were usually not more than 1-wk old and survive d in greater proportion than the adopter's own offspring.