Interest in trophic interactions and ecosystem functions derived from carcass consumption by scavengers has been increasing. Here, we conducted the first evaluation of scavenging processes in an ecosystem with heavy snow, located in northern Japan, which is characterized by the limitations of visual and odor cues to detect carcasses. In this study, we verified the behavioral traits and assemblage compositions of avian and mammalian scavengers, which consumed six different carcass types buried in snow. We measured the visits of scavengers using camera traps between 2010 and 2020. The total scavenger richness observed was relatively low (only 12 species) compared to warmer biomes. We observed seven avian scavenger species, but their visit frequencies were extremely low compared with those of nocturnal mammalian scavengers, such as raccoon dogs (Nyctereutes procyonoides) and martens (Martes melampus), which were able to detect carcasses more rapidly and frequently. Our findings imply that large snow piles significantly prevent avian scavengers from detecting carcasses. In contrast, the snow piles could protect carcasses from the freezing air and ensure the occurrence of a basal level of microbial decomposition, possibly leading to carcass decomposition. This probably results in carcasses still providing odor cues for mammalian scavengers with heightened sense of smell. Moreover, considering the high carcass consumption rate (91.3% of full-body carcass; n = 23) and short carcass detection times (approximately 90 h) observed, it is possible that scavenging in heavy snowfall conditions has become systematically integrated into the foraging tactics of many mammalian scavengers.
Nationwide depopulation in modern Japan has led to contrasting changes over the last half‐century: shrinking human communities and recovering populations of Japanese macaques (Macaca fuscata). These changes have triggered macaque damage to public livelihoods, often resulting in decision‐making directed toward strictly regulating macaque populations. To optimize conservation interventions required today, we aimed to identify macaque habitats with conservation priorities to enhance population connectivity. To quantify the current population connectivity, we conducted a least‐cost path analysis by assigning an inverse of habitat suitability as resistance. For this, we collected geo‐information on home ranges of 2288 troops, accounting for >70% of the total number of troops in Japan. Moreover, we composed a minimum spanning tree using least‐cost paths to provide optimal population connectivity. Consequently, the modeled resistance showed that, although human‐induced barriers (i.e., flat areas where people frequently reside) and geographical barriers (i.e., alpine regions >1500 m above sea level) had the highest dispersal cost, macaques presented a high plasticity in the occupation of different forest types. The minimum spanning tree, composed of 77 modeled corridors, detected the vulnerability of population connectivity in western Japan and assigned conservation priorities to these isolated populations to preserve the stepping‐stone paths of macaque movement.
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