Megapodes meet conspecifics at an unpredictable age, and it is unknown how their social behavior develops under such conditions. The authors induced encounters between 2-day-old socially ive hatchlings and up to 49-day-old chicks of the Australian brush-turkey (Alectura lathami) in a large outdoor aviary. All social behavior patterns found in older chicks were present in hatchlings and did not change in form or the frequency in which they occurred thereafter; the frequency of calling was the only feature that changed significantly with age. Chicks stayed only 0.3-2.0 m (medians) apart and synchronized their feeding activity from the age of 20 days. These results indicate that megapode chicks show social behavior without social experience and that this requires no posttal learning.