In adult male Coturnix coturnix japonica neither norepinephrine (NE) nor serotonin (5HT) in various brain regions were affected by caging density (174 cm2-8/cage; 348 cm2-4/cage; 696 cm2-2/cage). Dopamine (DA) in diencephalon was elevated in high density cages. 2. Peck order rank was assigned on the basis of feather distribution on head, neck and back and lesions on head and back. 3. Upper strata peck order rank was associated with significantly lower levels of brain regional NE and DA compared to lower strata peck order rank. 4. Peck order rank did not affect brain regional 5HT. 5. The results indicate significant individual behavioral-neuroendocrine interaction leading to reproductive dysfunction.