The possible role of predator-prey dynamics as an influence on early hominin use of burned landscapes

Fire as a driver and mediator of predator-prey interactions

Both fire and predators have strong influences on the population dynamics and behaviour of animals, and the effects of predators may either be strengthened or weakened by fire. However, knowledge of how fire drives or mediates predator–prey interactions is fragmented and has not been synthesised. Here, we review and synthesise knowledge of how fire influences predator and prey behaviour and interactions. We develop a conceptual model based on predator–prey theory and empirical examples to address four key questions: (i) how and why do predators respond to fire; (ii) how and why does prey vulnerability change post‐fire; (iii) what mechanisms do prey use to reduce predation risk post‐fire; and (iv) what are the outcomes of predator–fire interactions for prey populations? We then discuss these findings in the context of wildlife conservation and ecosystem management before outlining priorities for future research. Fire‐induced changes in vegetation structure, resource availability, and animal behaviour influence predator–prey encounter rates, the amount of time prey are vulnerable during an encounter, and the conditional probability of prey death given an encounter. How a predator responds to fire depends on fire characteristics (e.g. season, severity), their hunting behaviour (ambush or pursuit predator), movement behaviour, territoriality, and intra‐guild dynamics. Prey species that rely on habitat structure for avoiding predation often experience increased predation rates and lower survival in recently burnt areas. By contrast, some prey species benefit from the opening up of habitat after fire because it makes it easier to detect predators and to modify their behaviour appropriately. Reduced prey body condition after fire can increase predation risk either through impaired ability to escape predators, or increased need to forage in risky areas due to being energetically stressed. To reduce risk of predation in the post‐fire environment, prey may change their habitat use, increase sheltering behaviour, change their movement behaviour, or use camouflage through cryptic colouring and background matching. Field experiments and population viability modelling show instances where fire either amplifies or does not amplify the impacts of predators on prey populations, and vice versa. In some instances, intense and sustained post‐fire predation may lead to local extinctions of prey populations. Human disruption of fire regimes is impacting faunal communities, with consequences for predator and prey behaviour and population dynamics. Key areas for future research include: capturing data continuously before, during and after fires; teasing out the relative importance of changes in visibility and shelter availability in different contexts; documenting changes in acoustic and olfactory cues for both predators and prey; addressing taxonomic and geographic biases in the literature; and predicting and testing how changes in fire‐regime characteristics reshape predator–prey interactions. Understanding and managing the consequences for predator–prey communities will be critical for effective ecosystem management and species conservation in this era of global change.

Chimpanzees (Pan troglodytes) in savanna landscapes

Chimpanzees (Pan troglodytes) are the only great apes that inhabit hot, dry, and open savannas. We review the environmental pressures of savannas on chimpanzees, such as food and water scarcity, and the evidence for chimpanzees' behavioral responses to these landscapes. In our analysis, savannas were generally associated with low chimpanzee population densities and large home ranges. In addition, thermoregulatory behaviors that likely reduce hyperthermia risk, such as cave use, were frequently observed in the hottest and driest savanna landscapes. We hypothesize that such responses are evidence of a "savanna landscape effect" in chimpanzees and offer pathways for future research to understand its evolutionary processes and mechanisms. We conclude by discussing the significance of research on savanna chimpanzees to modeling the evolution of early hominin traits and informing conservation programs for these endangered apes.

Fire's impact on threat detection and risk perception among vervet monkeys: Implications for hominin evolution

The spatial behavior of primates is shaped by many factors including predation risk, the distribution of food sources, and access to water. In fire-prone settings, burning is a catalyst of change, altering the distribution of both plants and animals. Recent research has shown that primates alter their behavior in response to this change. Here, we study primates' perceived threat of predation in fire-modified landscapes. We focus on the predator-related behaviors of vervet monkeys (Chlorocebus pygerythrus) after controlled burning events. We compare the occurrence of vigilance and predator-deterrent behaviors, including alarm calls, scanning, and flight across different habitats and burn conditions to test the hypothesis that subjects exhibit fewer predator-specific vigilance and predator-deterrent behaviors in burned areas. The results demonstrate that predator-related behaviors occur less often in burned habitats, suggesting that predators are less common in these areas. These results provide foundations for examining hypotheses about the use of fire-altered landscapes among extinct hominins. We set these data in the context of increasing aridity, changes in burning regimes, and the emergence of pyrophilia in the human lineage.