Leadership and information transfer in groups escaping a (simulated) threat in the wild

Collective motion in many species is believed to be driven by predation, which is considered a crucial evolutionary force. However, there are limited studies on how information about predators spreads through a group, particularly in natural settings. Here, using high-resolution drone-based recordings, we analyze the collective escape dynamics of a group living species - blackbuck (Antilope cervicara), an Indian antelope - under the conditions of a simulated threat in their natural grassland habitat. Our analysis reveals that, in response to the simulated threat, group cohesion first increases, followed by a simultaneous increase in median speed and polarization. We also observe the emergence of a temporary leader-follower relationship during the collective escape. Interestingly, we found that the distance of individuals from the "predator" affected only their response time, not their influence on the group movement. The individuals furthest from the threat were the least likely to initiate movement and were uncoordinated with the groups speed. Additionally, we discovered that the most influential individuals during the collective escape were the least likely to occupy front positions during group movement. Instead, our results indicate that individuals at the rear "push" individuals at the front during collective escape events. This contrasts with the typical notion of individuals at the front determining group movement and those at the back trying to catch up.