Abstract
Temporal and spatio-temporal niche partitioning is an important strategy for carnivore coexistence. Camera-trap data has been analyzed through several methods to assess the temporal and ...spatio-temporal niche partitioning. However, different analytical approaches used to may evaluate niche partitioning detect different results. In this study, we evaluated the temporal or spatio-temporal partitioning among sympatric medium-sized carnivores, red foxes, raccoon dogs, and Japanese martens, based on three analytical methods—the temporal overlap, temporal co-occurrence, and time-to-encounter analysis—to evaluate. From May to October 2019 and 2020, we obtained the activity of the target species using camera-traps in northeastern Japan. We analyzed the data with the coefficient of temporal overlap, probabilistic co-occurrence analysis, checkerboard score, and multi-response permutation procedures. The results of the assessment of the niche partitioning differed depending on the analytical methods based on temporal and spatio-temporal partitioning. Therefore, we conclude that the choice of analytical approach is important for evaluating the temporal and spatio-temporal niche partitioning.
Temporal niche partitioning may be influenced not only by interspecific competition, but also by weather conditions. Decreased food availability and dietary overlap between species can increase the ...degree of interspecific competition during winter, thereby promoting temporal niche partitioning. However, multiple species can be simultaneously active under similar weather conditions (high temperature and little snowfall) in winter to reduce energy costs and increase temporal niche overlap. In this study, we aimed to determine the degree of temporal niche partitioning among red foxes (
Vulpes vulpes
), raccoon dogs (
Nyctereutes procyonoides
), and Japanese martens (
Martes melampus
), and its variation with seasonal climate change in terms of interspecific competition and weather conditions. We obtained data on the target species through a camera-trap survey conducted in a heavy snowfall area in northeastern Japan. We analyzed the degree of temporal niche partitioning based on diel activity overlap, co-occurrence rates per night, and behavioral avoidance within 1 or 2 h. We also evaluated the relationship between the presence or absence of activity per night and nightly weather conditions (temperature, precipitation (snowfall), moonlight). We observed a high degree of temporal niche overlap among the three species. In particular, the degree of temporal niche overlap was higher in winter than that in other seasons because the activity of the three species was greatly affected by low temperatures and snowfall in winter. As a winter survival strategy, coping with the weather may be more important than avoiding competition. Our results conflict with the hypothesis predicting temporal niche partitioning in winter, suggesting that weather effects can be an important factor in varying temporal niche partitioning among carnivores.
Significance statement
This study revealed that the temporal niche overlap of three carnivores in northeastern Japan was higher in winter than that in other seasons because they were simultaneously active under similar weather conditions (high temperature and little snowfall) in winter to reduce energy costs. This indicates that coping with the weather may be more important than avoiding interspecific competition as a winter survival strategy. Our results conflict with the hypothesis predicting temporal niche partitioning among carnivores in winter due to restricted food resources and dietary overlap. This suggests that the different degrees of weather effects can be an important factor in varying temporal niche partitioning among carnivores. Because extreme changes in weather conditions such as extremely high temperatures, blizzards, and heavy rains, have occurred worldwide in recent years, weather conditions may significantly affect the niche partitioning among carnivores distributed in different environments worldwide.
Even in human-dominated regions such as urban and agricultural areas, there are organisms involved in the decomposition of animal carcasses. Therefore, it is possible that these complementary ...decomposition functions occur in different habitats. Here, we clarified the disappearance patterns of small mammal carcasses in forest and human-dominated (urban and agricultural) habitats in northeastern Japan, based on field experiments. All small mammal carcasses in both summer and autumn were removed by different scavengers within 6 days; therefore, there was little difference in the disappearance rate of carcasses between habitats. The scavenger groups that contributed to carcass removal of remains in the summer survey differed between sites, suggesting that the disappearance process varies with landscape and canopy openness conditions. Although many carcasses were removed by vertebrates during the autumn survey, the vertebrate species involved differed among the survey sites. This study suggests that ecological functions related to the decomposition of small mammal carcasses in anthropogenically modified habitats may be maintained by the complementary activities of vertebrates and invertebrates.
This study aimed to determine the effects of landscape differences associated with intensive agricultural activities on farmland use by medium and large mammals in Japan. We compared the species ...diversity of mammals that used farmland within three regions with different agricultural activity levels, and analyzed the relationship between the occurrences and escape responses of mammals in the farmland and surrounding landscape. We used spotlight count in intensive (high agricultural activity), intermediate (moderate agricultural activity), and non-intensive (low agricultural activity) areas. We observed 271 and 199 occurrences of mammals in spring and autumn 2021, respectively. Seasonal changes in mammals occurrence were due to a decrease in the number of raccoon dogs observed. Species richness tended to be lower in intensive agricultural areas than in other areas, suggesting that intensive agricultural landscapes negatively affect the community structure of medium and large mammals. Generalized additive models showed that the effects of the surrounding landscape on the occurrences and escape responses of raccoon dogs, red foxes, and cats differed among species. Only raccoon dogs were negatively affected by the surrounding farmland, suggesting high sensitivity to agricultural activities. Our results have important implications for the management of ecosystems in Japanese agricultural areas. Cette étude visait à déterminer comment les différences dans le paysage associées aux activités d'agriculture intensive affectent l'utilisation de terres agricoles par des mammifères de moyennes et grandes tailles au Japon. Nous avons comparé la diversité spécifique de mammifères utilisant des terres agricoles dans trois régions affectées par différents niveaux d'activité agricole. Nous avons ensuite analysé la relation entre les occurrences et la réaction de fuite des mammifères dans les terres agricoles et les paysages environnants. Nous avons réalisé des comptages nocturnes dans des zones sous activité agricole intensive, intermédiaire et faible. Nous avons observé 271 et 199 occurrences de mammifères au printemps et à l'automne 2021, respectivement. Les changements saisonniers d'occurrence de mammifères étaient dus à une diminution du nombre de chiens viverrins observés. La richesse spécifique avait tendance à être plus faible dans les zones d'agriculture intensive, suggérant un effet négatif sur la structure des communautés de mammifères de moyennes et grandes tailles. Des modèles additifs généralisés ont montré que les effets des paysages environnants sur les occurrences et la réaction de fuite des chiens viverrins, des renards roux et des chats différaient entre les espèces. Seuls les chiens viverrins étaient affectés négativement par les terres agricoles environnantes, suggérant une sensibilité élevée aux activités agricoles. Nos résultats ont des implications importantes pour l'aménagement des écosystèmes dans les zones agricoles au Japon.
In a heavy snowfall area in northeastern Japan, we clarified the diel activity patterns of and seasonal differences in three sympatric carnivores (red foxes, raccoon dogs, and Japanese martens) ...during winter and spring, and the interspecific differences among the activity patterns in each season. The activity time of the target species was obtained by camera-trap surveys at seven sites around the Experimental Forest of Yamagata University from January to June 2019. The diel activity patterns of each species, and seasonal and interspecific differences in the activity patterns were evaluated using the kernel density method. Red foxes showed a unimodal nocturnal pattern in spring, whereas they were also observed during the daytime in winter. Raccoon dogs showed a unimodal nocturnal pattern, and peak activity after sunset in both seasons. Japanese martens were clearly nocturnal during both seasons. Because there were a few interspecific differences in diel activity patterns among three species, species interactions had little effect on diel activity patterns. Our findings indicate that the diel activity of medium-sized carnivores responding to winter conditions may vary depending on species.
In this study, we evaluated the effect and extent of linear human disturbance caused by vehicle traffic on forest roads on animal activity time. Our research focused on four sympatric carnivores (red ...fox,
Vulpes vulpes
; raccoon dog,
Nyctereutes procyonoides
; Japanese marten,
Martes melampus
; and Asiatic black bear,
Ursus thibetanus
) living in the forest region of northeastern Japan. From August to November 2019, we obtained data on the activity time for each species from nine infrared-triggered cameras installed along two types of unpaved forest roads with different vehicle frequencies (high or low) and subsequently assessed the effect of vehicle-passing frequencies on activity using kernel density estimation and chi-square test. Red foxes and raccoon dogs were nocturnal on all forest roads; however, their nighttime activities were significantly greater on the forest road with a high vehicle-passing frequency than on the road with a low vehicle-passing frequency. Japanese martens showed a nocturnal pattern on all forest roads, and there was no significant difference in the proportion of nighttime activities between the forest roads. Asiatic black bears were highly active during the daytime on forest roads with a low vehicle-passing frequency, but were highly nocturnal on forest roads with a high vehicle-passing frequency. Our results suggest that human disturbance influences the ratio of daytime to nighttime activity in carnivores; however, the extent and magnitude of this effect are limited. This finding indicates that the spatial scale of effects of human disturbance on the activity of each animal species should be assessed before habitat management programs are implemented.
We evaluated forest road use by mammals in forest areas in northeastern Japan using a camera-trapping survey, considering road surface conditions. From August to December 2021, camera-trapping ...surveys were conducted on paved forest roads, forest roads without understory vegetation, forest roads with low-height understory vegetation, forest roads with high understory vegetation (herbs and shrubs), and forest interiors. We analyzed the differences in forest road use by mammalian species using non-metric multidimensional scaling and a generalized linear mixed model. We also assessed whether each species actively used forest roads using the road-use index, which indicates that individual animals walked along forest roads based on consecutive photographs. The paved forest roads and unpaved forest roads with no or low-height understory vegetation had a similar composition of species using the roads. The unpaved forest road with high-height understory vegetation showed a species composition similar to that in the forest interior; however, the results were different from those of the other three groups. Except for Japanese squirrels, mammals had little tendency to avoid forest roads and also indicated the existence of species (i.e., medium-sized carnivores) selectively using forest roads in the study area. Our results suggest that understory vegetation height on the forest road surface influences species composition through its effect on medium-sized carnivores and Japanese squirrels. This study provides useful knowledge on the relationship between human activities and wildlife, particularly in forest and wildlife management.
Animals that succeed as non-native species may have highly plastic characteristics. We conducted a radio telemetry survey for introduced masked palm civets (Paguma larvata), which inhabit rural ...landscapes in almost all of Japan, to clarify their habitat selection and intraspecific variation. We compared two generalized linear mixed models, one that did not consider individual differences and another that did, which indicated the importance of incorporating individual differences for evaluating habitat selection by this species. We obtained results of habitat selectivity for all individuals (i.e., common effect on the species) and for each individual using coefficients of fixed effects or fixed effects with random effects. Masked palm civets significantly selected deciduous broadleaved forests, artificial structures, rice fields, and orchards as a common effect for all individuals. However, these habitats were not necessarily selected as a significant effect for each individual. Deciduous broad-leaved forests and artificial structures were more important than other habitats. The wide range of possible environments and the plasticity of habitat selection shown in this study may partly explain the success of this species in expanding its distribution in Japan.
To understand and sustain carnivore communities and ecosystems, it is important to determine the mechanisms of coexistence and potential competitive interactions among carnivores. This study examined ...how carnivores coexist and how climatic environmental shifts affect the potential competitive interactions among medium-sized carnivores. The seasonal trophic niche overlap of red foxes, Japanese martens, and raccoon dogs in the cool-temperate zone in Japan was evaluated, where there are distinct seasonal changes, especially from heavy snowfall. Faecal analysis of red foxes (n = 107), Japanese martens (n = 125), and raccoon dogs (n = 100) from 2019 to 2021 showed that carnivores share the main food items and their annual dietary overlap is relatively high despite the co-occurrence of carnivores. These results have indicated that the carnivores have potentially strong competitive interactions, and various competition avoidance mechanisms besides niche partitioning may facilitate the coexistence of carnivores in Japan. The study also found that the degree of trophic niche overlap varied by season, indicating that shifts in environmental conditions, particularly food abundance and snowfall, may affect potential competitive interactions among carnivore guilds.
