Distribution of sleep and wakefulness in 24-h light-dark cycles in the juvenile and adult magpie, Pica pica.

The daily organization of sleep and wakefulness was examined electrographically under natural conditions in captive juvenile and adult magpies, Pica pica. Electrographic indices of sleep in the magpie were found to be similar to those of other avian species. The daily amount of TS in juveniles was 17% greater than in adults. The amount of paradoxical sleep (PS) in adults was one-fifth that of juveniles. In adults sleep was confined to darkness, while in juveniles it also occurred during the light period. SWS in adults was almost constant, while PS slightly increased across the night. No systematic trends were observed in juveniles. In both groups of birds, the longest sleep episodes appeared around midnight.