Group size predicts feeding persistence at carcasses in scavenging wild boar (Sus scrofa)

<title>Abstract</title> <p> Scavengers play an important role in ecosystems by removing carcasses. Wild boar ( <italic>Sus scrofa</italic> ) are facultative scavengers and functionally dominant in ecosystems lacking large carnivores and obligate scavengers, yet the behavioural mechanisms underlying variation in carcass exploitation, and thus carcass removal, remain poorly understood. Due to their social nature, the sounder size – i.e. group size - may influence their scavenging behaviour. We investigated how sounder size influences behavioural transition probabilities of wild boar at carcasses with a focus on eating behaviour. Carcasses were placed in the Netherlands between 2012 and 2021, and monitored with camera traps. For each video, we extracted the primary and secondary behaviour at group-level based on cumulative duration. Behavioural transitions of the group, occurring from one video to the subsequent video, were analysed using binomial Big Additive Models (BAMs) to test the effect of sounder size on behaviour transition probabilities. Larger sounders exhibited a higher probability of remaining in a feeding state, indicating greater feeding persistence. In addition, the probability of transitioning from feeding to intraspecific interaction showed a unimodal relationship with sounder size, peaking at intermediate-sized sounders. These findings suggest that social dynamics and social facilitation influence carcass exploitation by wild boar and may contribute to variation in carcass depletion. By applying behavioural transition analysis to scavenging behaviour, this study provides new insight into the behavioural processes underlying carcass use by a socially foraging vertebrate scavenger. </p>