Supplementary Video of the Group Service Test from Proactive prosociality in a cooperatively breeding corvid, the azure-winged magpie (<i>Cyanopica cyana</i>) HornLisa ScheerClara BugnyarThomas J. M. MassenJorg 2016 Supplementary video illustrating how the birds operated the apparatus in the group service test (phase IV). The video is shot from the side, showing the receiving side (position 1) in the foreground