Climate-driven animal mass mortality events: is there a role for scavengers?

Abstract

Summary Animal mass mortality events (MMEs) will increase with weather and climate extremes. MMEs can add significant stress to ecosystems through extraordinary nutrient pulses or contribute to potential disease transmission risks. Given their efficient removal of carrion biomass from landscapes, we argue here for the potential of scavenger guilds to be a key nature-based solution to mitigating MME effects. However, we caution that scavenger guilds alone will not be a silver bullet. It is critical for further research to identify how the composition of scavenger guilds and the magnitude of MMEs will determine when scavengers will buffer the impacts of such events on ecosystems and when intervention might be required. Some MMEs are too large for scavengers to remove efficiently, and there is a risk of MMEs subsidizing pest species, altering nutrient cycling or leading to disease spread. Prioritizing native scavenger taxa in conservation management policies may help to boost ecosystem resilience through preserving their key ecological services. This should be part of a multi-pronged approach to MME mitigation that combines scavenger conservation with practices such as carcass dispersal or removal when exceeding a threshold quantity. Policymakers are urged to identify such thresholds and to recognize both the insects and the vertebrate scavengers that could act as allies for mitigating the emerging problem of climate-driven MMEs.

Carrion ecology in inland aquatic ecosystems: a systematic review

“…Mass‐mortality events are increasing in occurrence and magnitude in aquatic ecosystems due to increased disease emergence, biotoxicity, and events produced by multiple interacting stressors (Fey et al ., 2015). Scavengers are likely to play a key role in disease mitigation and nutrient cycling by consuming large amounts of carrion in these ecosystems (Barton et al ., 2023). In most aquatic ecosystems, especially in lentic systems, a large part of carrion is generated as large pulses, i.e.…”

“…In addition, mass‐mortality events, mostly associated with biotoxicity and emerging diseases, may add large amounts of nutrients to terrestrial ecosystems (Fey et al ., 2015; Ulloa et al ., 2023). As these events are expected to increase in frequency, the relevance of scavenging and its related consumption and recirculation of nutrients from large carrion pulses may also grow (Barton et al ., 2023).…”

Not All Mass Mortality Events are Equal

“…Due to the rise in reports of MMEs, there is ongoing discussion of how scavengers hinder or exacerbate secondary effects of large carrion biomass (such as pathogen spread) (36), highlighting the need to understanding population growth for purposes of conservation and understanding overall ecological outcomes. Scavenger communities (e.g., microbial and invertebrate) often rely on carrion as a portion or all of their diet (37,38), the logistic growth model can be used as a basis to predict population growth of carrion feeders after a mortality event, assuming carrion resources are incorporated in the population's carrying capacity.…”

Scavenger and herbivore functional role impairment modulates changes in plant communities following mass mortality events

“…Mass mortality events (MMEs) are wildlife die‐offs that generate a substantial input of carrion into the ecosystem (Barton et al, 2022), and can simultaneously impair or remove the functional role of the species affected depending on the number of individuals involved and the degree of functional complementarity (e.g. Bogdziewicz et al, 2022; Holdo et al, 2009; for a theoretical framework see Fey et al, 2019).…”