Fire as a driver and mediator of predator–prey interactions

Abstract

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 predatorprey 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

Interactive effects of wildfires, season and predator activity shape mule deer movements

“…As researchers continue to investigate how prey such as herbivores respond to wildfire and climate change, direct measures of forage quality, snow depth and subsequent demographic impacts will improve our knowledge of wildlife dynamics in a changing world (Boelman et al, 2019; Penczykowski et al, 2017; Volkmann et al, 2020). Importantly, predicting impacts of wildfires on prey species depends not only on understanding changes to forage quality but also understanding changes to landscape structure and risk effects from the predator community (Doherty et al, 2022).…”

“…Alternatively, cursorial predators such as wolves ( Canis lupus ) favour open areas to hunt (Kauffman et al, 2007) and ungulates may use burned areas to minimize wolf predation risk. Thus, it may be necessary to account for characteristics of the predator community to predict how ungulates will respond to wildfires (Doherty et al, 2022).…”

Mammalian resilience to megafire in western U.S. woodland savannas

“…Megafire could, at least temporarily, intensify this effect, and exacerbate existing stressors on large carnivores, especially as the frequency, size, and severity of megafires continues to increase. More research is necessary to examine the impacts of megafire on these larger predators over a broader spatial and temporal context to explicitly examine how and for how long these effects may alter species interactions, such as predation (Doherty et al, 2022) and interspecies competition (Gigliotti et al, 2021).…”

Behavioral plasticity allows ungulates to balance risk and reward following megafire

“…We did not find a relaxation in the avoidance of high predation risk areas over time following wildfire as anticipated, but predator avoidance may instead be represented by the selection against fire severity and/or certain vegetation type parameters within the model. Future work that utilizes concurrent movement data from both ungulates and their predators could help fill this gap by explicitly examining how predator-prey interactions change following megafire and elucidate whether and for how long these events amplify or diminish the intensity of these interactions (Doherty et al, 2022).…”

“…trees in woodlands) (Keeley, 2009), can remove important structural resources from landscapes (Steel et al, 2021) and even cause direct mortality (Jolly et al, 2022). Changes in structural cover in these systems may alter interspecies interactions, such as predator-prey dynamics, by exposing prey species or by directly impacting the hunting success of predators (Doherty et al, 2022). At the same time, these high severity fires may also remove important vegetative food resources (i.e., forbs, grasses, seeds, etc.)…”