A variety of infectious and noninfectious causes may contribute to feather-damaging behavior (FDB) in birds. This paper describes an episode of FDB behavior related to an isosexual group composition in a group of 20 golden conures (Guaruba guarouba) kept in a collective aviary. After ruling out infectious causative agents and analyzing the social bird group composition over a period of 10 yr, the male to female ratio of the group was reduced from 1.7 to 1.0. This intervention resulted in a significant improvement of the feather condition and improved reproduction. Further analysis revealed that FDB was not correlated to age, gender, or origin. In addition, FDB was associated with stress, as reflected by an elevated heterophil : lymphocyte ratio that decreased significantly following social restructuring. This study stresses the importance of an appropriate male to female ratio when golden conures are kept in aviaries.