[A comparative study of diurnal patterns of activity and diurnal changes of body weight in caged and free-living warblers (sylvia)].

1. In Sylvia atricapilla und S. borin the pattern of locomotor activity in caged birds and the temporal distribution of capture of free-living birds are concurrent, as are also the body-weight curves of the two groups. 2. This agreement leads to the conclusion that the diurnal distribution of captures accurately reflects the diurnal pattern of activity of the typical individual bird, and that the averaged curve of body weight represents the diel cycle of body weight of a typical individual. 3. Our results show that it is possible to extrapolate accurately from the diurnal pattern of activity and from the diurnal cycle of body weight of caged birds to the patterns and cycles of free-living birds and vice versa.