Fig. 6. Abrupt orientation changes following a turn of the polarizer were observed in a few butterflies, although this behavior also occurred in other situations. (A,B) Tracks of two of the three individual butterflies (out of a total of 50 monarchs tested) that changed their orientation by 90° after the polarizer was turned by 90°. (A) 44° polarizer. (B) 85° polarizer. (C,D) Examples of what might be transient orientation responses towards the polarizer being turned by 90°. (E) However, one out of 10 monarchs showed a distinct 90° shift in orientation when the lid with an opening exposing the blue sky instead of a polarizer was turned. (F) A 90° turn observed in the same experimental condition (see E) but occurring before the turn of the lid. (G,H) Spontaneous 90° changes in orientation of monarchs flying under the artificial polarizer. Note that the animal in G altered its mean flight direction before the polarizer was turned and not in response to the turn. In H, the butterfly abruptly changed its orientation by 90° although the polarizer was never turned. In two-colored tracks, the orange parts indicate the virtual flight paths of the monarchs before the polarizer and/or the lid was turned. The blue parts indicate the tracks flown after the turn.