The tendency to roost overnight was studied in 91 juvenile "black-necked" and "ring-necked" Pheasants reared either under "semi-natural" or "commercial" pheasantry conditions. The birds were kept in cages in 4 different groups. Observations were carried out in 50 evenings. Numbers of individuals roosted per group were determined usually at four counts per evening in intervals of 10min., with the last count immediately before darkness. Data on weather parameters were recorded in each evening. All statistical tests were performed using arc-sine-transformed proportion values of roosted birds. The Pheasants started night-roosting at an age of 40-50 days. Roosting activity began approx. 40 min. before darkness and locomotory activity ceased right before darkness. Among the 4 rearing-groups considered, the tendency towards night-roosting was highest (median = 63.5%) in "black-necks" reared under "semi-natural" conditions and lowest (median = 35.0%) in "ring-necks" reared under commercial pheasantry conditions. Rainfall lowered the tendency from a median of 43% to 35%.