Belén Fresnillo, Josabel Belliure, José Javier Cuervo. Animal Behaviour, Volume 102, April 2015, Pages 59-67. The presence of red coloration in juveniles caused the reduction in adult aggression, while small natural variations in this red colour did not seem to have any further effect. Juvenile red coloration in this species might indicate age or sexual immaturity to adults. Leer más.