Compensatory behaviour following displacement in migratory birds A meta-analysis of cage-experiments

Using a meta-analysis approach we re-analysed orientation cage experiments with displaced migrants found in the literature. A rather large proportion of the orientation experiments showed directional shifts after displacements, indicating ability for birds to detect and react on such displacements. There was a clear difference between overcast and experiments where birds had a view of the starry sky. In experiments under a starry sky, the birds compensated the displacements, whilst under overcast unaltered or reverse orientations were generally displayed. This indicates a role for the stars to be involved in detection of the changes in position. Such a role of celestial cues is further stressed by the results of several studies manipulating a planetarium sky.