Fear the reaper: ungulate carcasses may generate an ephemeral landscape of fear for rodents

Abstract

Animal carcasses provide an ephemeral pulse of nutrients for scavengers that use them. Carcass sites can increase species interactions and/or ephemeral, localized landscapes of fear for prey within the vicinity. Few studies have applied the landscape of fear to carcasses. Here, we use a mass die-off of reindeer caused by lightning in Norway to test whether rodents avoided larger scavengers (e.g. corvids and fox). We used the presence and abundance of faeces as a proxy for carcass use over the course of 2 years and found that rodents showed the strongest avoidance towards changes in raven abundance ( β = −0.469, s.e. = 0.231, p -value = 0.0429), but not fox, presumably due to greater predation risk imposed by large droves of raven. Moreover, the emergence of rodent occurrence within the carcass area corresponded well with the disappearance of raven during the second year of the study. We suggest that carcasses have the potential to shape the landscape of fear for prey, but that the overall effects of carcasses on individual fitness and populations of species ultimately depend on the carcass regime, e.g. carcass size, count, and areal extent, frequency and the scavenger guild. We discuss conservation implications and how carcass provisioning and landscapes of fear could be potentially used to manage populations and ecosystems, but that there is a gap in understanding that must first be bridged.

Temporal patterns of wildlife roadkill in the UK

“…Although scavengers may provide an important ecosystem service by removing carcasses from the environment [ 13 , 90 ], there may also be negative impacts, such as increased predation on eggs or chicks of native birds when the relative abundance of roadkill versus live prey shifts [ 10 ]. The presence of roadkill in an environment may also create a ‘landscape of fear’, in which predators attracted by the carcasses lead to avoidance of the area by smaller prey species, such as rodents [ 91 ].…”

Directed endozoochorous dispersal by scavengers facilitate sexual reproduction in otherwise clonal plants at cadaver sites

“…We took advantage of a large mass die‐off event in a relatively undisturbed mountain area to demonstrate that directed dispersal toward CDIs facilitates seedling establishment. Cadavers at the study site persisted over several years and continued to attract scavenging omnivores during the ericaceous berry season (Frank et al, 2020)—a crucial point for this mechanism to work. Although mass die‐off events have been consistently reported over the past decades (Fey et al, 2015), large numbers of terrestrial herbivores also die from natural causes (e.g., predation, starvation, or disease) leaving single cadavers in the landscape (Barton et al, 2019; Moleón et al, 2019).…”

“…Shortly after the mass die-off event (October 2016), a permanent, semi-regular 10 × 10 m grid of 75 0.5 × 0.5 m survey plots was established, covering a 179 × 66 m area incorporating the mass die-off and immediate surroundings (Appendix 1). The grid was established to monitor different aspects such as changes in vegetation, microbiota and animal interactions (e.g., by Steyaert et al, 2018 andFrank et al, 2020, though they used 1 × 1 m survey plots). Since it was difficult to predict the spatial scale of changes caused by the mass die-off, the main grid was supplemented by a 10 × 10 m grid of 25 survey plots superimposed over the area of highest cadaver density (Appendix 1).…”

Patchy indirect effects: how predators drive landscape heterogeneity and influence ecosystem dynamics via localized pathways

“…Carcasses may become sites of 'fatal attraction' (Sivy et al 2017) where smaller scavengers are killed by larger animals while competing for the same carcass. Ephemeral landscapes of fear and disgust may establish around carcasses as well (Moleón & Sánchez-Zapata 2021): smaller animals may be at risk for predation and thus avoid carcasses to reduce fatal encounters with larger scavengers ("landscape of fear"; Cunningham et al 2018;Frank et al 2020), while other species may avoid carcasses to prevent parasitism and infection risk ("landscape of disgust"; Buck et al 2018;Muñoz-Lozano et al 2019). Opportunistic scavengers attracted to carcasses may even kill other prey in the carcass vicinity (Cortés-Avizanda et al 2009a;Cortés-Avizanda et al 2009b;Spencer et al 2021).…”