Rearing greater rhea (Rhea americana) chicks: is adoption more effective than the artificial intensive system?

(1) Survival and weight gain of farmed Greater Rhea (Rhea americana) chicks reared by the adult males that adopted them were compared with those of chicks reared under an artificial intensive system. (2) Both variables were periodically recorded up to the age of 3 months. Gompertz growth curves were fitted to individual growth data using the average adult weight of this population as asymptote. (3) No significant differences in survival rate were detected between systems (adoption=47%, intensive=43%). However, during the first half of the breeding season (mid-spring to mid-summer), the growth rate of adopted chicks (0.01481) was higher than that of intensively reared chicks (0.01296). (4) The adoption system may be more effective in terms of growth, and is probably more efficient in cost/effectiveness than the artificial intensive technique most frequently used. Adoption by males has additional advantages, such as a correct imprinting of the chicks and the selection of more capable individuals. Therefore, it should be used not only commercially but also in conservation projects where individuals are released to the wild.