Forest elephants modulate their behaviour to adapt to sounds of danger

The African forest elephant (Loxodonta cyclotis) plays a critical role in upholding the Congo Basin's structure and function, a vital area that supports global carbon sequestration. However, between 1990 and 2021, the species' numbers declined by 86%, mainly because of ivory hunting. Owing to their elusive nature in the region's dense rainforests, their responses to human disturbances, such as gun hunting, are not well understood, though the limited studies that have been completed suggest that forest elephants may respond by altering their abundance, distribution and nocturnal activity. Using passive acoustic monitoring (PAM) in and around Nouabalé-Ndoki National Park, Republic of Congo, we assess how gun hunting impacts forest elephant occupancy and night-time vocal activity. Findings reveal that elephant occupancy drops from 0.54 to 0.52 following a gunfire event, a change sustained over 8 days. Additionally, increased gunshots led to a significant rise in the proportion of night-time vocal activity. These behavioural changes can affect forest elephant foraging and reproductive success and their interactions with vegetation, impacting forest growth and function. This study highlights the need for effective conservation strategies to protect the species and their habitats and demonstrates PAMs effectiveness in studying cryptic species in our world's dense, highly biodiverse and life-sustaining tropical forests.This article is part of the theme issue 'Acoustic monitoring for tropical ecology and conservation'.