Increased abundance of a common scavenger affects allocation of carrion but not efficiency of carcass removal in the Fukushima Exclusion Zone

Abstract

The 2011 nuclear accident in Fukushima, Japan caused the evacuation of > 100,000 people and prompted studies on environmental impacts of radiological contamination. However, few researchers have explored how the human evacuation has affected ecosystem processes. Despite contamination, one common scavenger (wild boar, Sus scrofa) is 2–3× more abundant inside the Fukushima Exclusion Zone (FEZ). Shifts in abundance of some scavenger species can have cascading effects on ecosystems, so our objective was to investigate impacts of the evacuation and the resulting increase in wild boar on vertebrate scavenger communities. We deployed cameras at 300 carcasses in the FEZ and a nearby inhabited area, and quantified carcass fate, scavenger species, and detection/persistence times. We also tested effects of carcass size and habitat on scavenger community composition and efficiency by balancing trials across two carcass sizes and habitats in each zone. Overall scavenger richness and carcass removal rates (73%) were similar in the FEZ and inhabited area, but species-specific carcass removal rates and occurrence differed between zones. Wild boar removed substantially more carcasses inside the FEZ, with implications for nutrient and contaminant distribution. Our results suggest carcass size affects scavenging dynamics more than human activity or habitat, and abundance changes of common scavengers can influence carrion resource allocation.

Scavenging on a Carcass of Sika Deer by Introduced Raccoon Dogs (Nyctereutes procyonoides) in Spring: A Case Report in the World Heritage Site of Yakushima Island, Japan

“…Japanese weasels were attracted to carrion but only fed on it for a short time after raccoon dogs opened it. Similarly, scavenging by weasels has been rarely observed in other regions of Japan (Sugiura et al 2013;Inagaki et al 2020;Enari and Enari 2021;Gerke et al 2022). On the three islands in Oki, where potential mammalian scavengers are only weasels, the contribution of invertebrates to the removal of experimentally-placed mouse carcasses was greater than that of weasels (Sugiura and Hayashi 2018).…”

“…In particular, the raccoon dog was the only species that could open the intact carcass in Yakushima and almost monopolized the carcass. Raccoon dogs have been known as the main facultative scavenger in other parts of Japan, including an introduced population on Chiburijima Island in Oki (Sugiura et al 2013; Sugiura and Hayashi 2018; Inagaki et al 2020; Enari and Enari 2021; Gerke et al 2022). Aggression over carrion among raccoon dogs, observed in the present study, implied that carrion was a preferred resource for them, even in the warm-temperate forest of Yakushima.…”

Functional compensation in a savanna scavenger community

“…(2018), (2) to mimic nutrients found in detrital resources and (3) because we are measuring the scavenging contributions of small‐ to medium‐sized scavengers, which readily eat small resources that would be ignored by larger animals. Moreover, few scavenging studies have used small food resources: most have employed vertebrate carcasses (Brown et al., 2015; Gerke et al., 2022; Hill et al., 2018; Huijbers et al., 2015; Inger, Cox, et al., 2016; Inger, Per, et al., 2016; Olson et al., 2012; Sugiura & Hayashi, 2018; Walker et al., 2021), which overlooks the role of scavengers that are attracted to smaller resources.…”

“…While some may disagree with our choice of bait size, we chose these baits and bait sizes for several reasons: (1) to enable direct comparison with the tropical rainforest experiment by Griffiths et al (2018), (2) to mimic nutrients found in detrital resources and (3) because we are measuring the scavenging contributions of small-to medium-sized scavengers, which readily eat small resources that would be ignored by larger animals. Moreover, few scavenging studies have used small food resources: most have employed vertebrate carcasses (Brown et al, 2015;Gerke et al, 2022;Hill et al, 2018;Huijbers et al, 2015;Olson et al, 2012;Sugiura & Hayashi, 2018;Walker et al, 2021), which overlooks the role of scavengers that are attracted to smaller resources. a different bait type.…”

“…Also, many previous studies have focussed on vertebrate scavengers (e.g. Gerke et al., 2022; Orihuela‐Torres et al., 2022; Walker et al., 2021; reviewed in Beasley et al., 2019), or invasive scavengers (Abernethy et al., 2016; Angulo et al., 2011; Brown et al., 2015; Turner et al., 2021). However, our knowledge of the role the role of native invertebrate scavengers is relatively incomplete, particularly for certain ecosystems.…”