Why budgerigars breed in continuous darkness

Budgerigars ( Melopsittacus ) exposed to male vocalizations will breed in total darkness, and the possibility arises that darkness is stimulatory. The present experiments showed that the availability of a nest-box accelerates egg-laying, and that relative darkness is an important property of a nest-box. Furthermore in the absence of a nest-box breeding occurs sooner in continuous darkness than on 14 L: 10 D. Intermittent periods of darkness imposed in the light period of a 14 L: 10 D regime accelerate egg-laying somewhat.