Passive acoustic monitoring reveals behavioural response of African forest elephants to gunfire events

African forest elephants (Loxodonta cyclotis) are a critically endangered and visually cryptic species that inhabits Central African rainforests. Using a 1250 sq-km grid of 50 acoustic sensors in Republic of Congo, we investigated the landscape-scale behavioural response of forest elephants to poaching events. We detected eight automatic weapon fire events over 1.5 years of recording (2017-2019). We examined detections of elephant vocalisations across grid sites within 10 km of the gunfire events in the 48 h surrounding the gunfire, and in paired 48-h control periods free of gunfire. Fewer vocalisations were detected before gunfire events than during control periods, suggesting elephants show behavioural responses to poacher presence before any shots are fired. Immediately following the gunfire events, a significant increase in elephant calls was detected, which may indicate increased communication to facilitate group cohesion and movement. Elevated call levels dropped to lower-than-baseline rates after several hours, suggestive of a sustained response. These patterns indicate forest elephants respond to both poacher presence and to gunfire events themselves. As these patterns may reflect behaviours that mediate population processes, conservation strategies should account for the potential of poaching to impact populations via indirect effects on nontarget elephants in the area.