**1. Introduction**

During the last two centuries, large carnivores have suffered drastic population declines, range contractions, and habitat fragmentation [1]. Although carnivores have adapted to almost every habitat, barely ~5% of the Earth's terrestrial land area contains five or more overlapping species of large carnivores [2]. Despite rarity and typically low population densities, large carnivores influence ecosystems in multiple ways through predator-prey interactions, i.e., carnivores are keystone species [3].

They affect prey and mesopredators in both demographic and behavioral terms, which can ultimately drive trophic cascades [4].

Although many large carnivore populations remain threatened [2], others are expanding nowadays in different continents [5,6], increasing the chances for different species to overlap. At the worldwide scale, northern Eurasia is the region with the greatest expansion range of a four-species guild (gray wolves *Canis lupus*, Eurasian lynx *Lynx lynx*, brown bear *Ursus arctos,* and wolverines *Gulo gulo*) [2,6]. Natural recolonization by large carnivores provides opportunities to study interspecific interactions among them, which is crucial to understanding how they can affect each other and lower trophic levels.

Several empirical studies on interspecific interactions among large carnivores have been conducted in northern Europe. Research has focused on habitat and resource use by different species in the large carnivore guild [7]; competition between species, such as wolf and lynx [8] and wolverine and lynx [9]; interference competition between trophic levels [10]; and on the demographic impact of coexisting predators on prey [11]. Interspecific interactions between the two largest carnivores (brown bears and wolves) that roam over large areas of the Northern Hemisphere have been studied in North-America (e.g., [12–14]) and in Scandinavia (Norway and Sweden) in recent years [15]. In Scandinavia, research has focused on wolf habitat selection at different spatial scales [16–19] and on the wolves' kill rates in areas sympatric and allopatric with bears [20]. In moose *Alces alces*—bear—wolf systems, predation is a major driver of moose population dynamics [21], so research has also informed management to optimize ungulate harvest yield where wolves and bears coexist [22].

The body of literature on large carnivores in northern Europe has highlighted the existence of individual variation in habitat selection and kill rates. For instance, wolverines display high individual variation when selecting home ranges [23] and lynx show individual variation in home-range size [8]. Large individual variation has also been shown in wolf home range size [24], bear habitat selection [25], and bear kill rates [26]. The latter implies different levels of specialization reflecting individual foraging behavior [27]; in turn, individual differences in predator behavior may help explain the large individual variation in bear habitat selection [17].

Intraspecific variation in habitat selection may be an adaptation for wolves and bears to reduce intra- and interspecific competition, i.e., individual variation may promote coexistence between these large predators [17]. The role of individual variation in habitat selection, activity patterns [28], and foraging behavior [27] at higher levels of biological organization is indeed gaining increasing recognition [29,30]. Individual variation can have consequences for population and community ecology [31], favoring coexistence of sympatric species [32].

Besides individual variation, seasonality is another important factor that may have implications for coexistence between large carnivores [33]. Seasonal and daily spatio-temporal patterns may influence the intensity of interspecific interactions and the resulting distribution of sympatric species [34]. In a Scandinavian context, wolves prey on moose all year round, bears often scavenge wolf kills, and both predators largely rely on neonate moose during spring [20]. Thus, individual and seasonal variation in predation and scavenging rates may help understand the patterns of wolf habitat selection and kill rates in relation to brown bear presence reported earlier. Namely, bear density has had a negative effect on the probability of wolf territory establishment in Scandinavia during the wolf recolonization process [16,18], and wolf kill rates are lower in areas sympatric with bears, despite wolves losing food to bears via scavenging [20].

In this study, we characterized the temporal use of a common prey resource by sympatric wolves and bears in Sweden, describing individual and seasonal variation in wolf–bear interactions. The latter can be direct, if individual wolves and bears meet at the same time, or indirect, if they use the same place or resource, but not simultaneously, which can provide evidence of exploitation competition, e.g., via scavenging. Describing individual variation and seasonal trends in kill and scavenger rates of competing carnivores can reveal underlying mechanisms behind the observed effects of bears on wolf habitat selection and kill rates at higher spatial and temporal scales. Ecological theory is improving the forecast of changes in species interactions and coexistence in a scenario of global change, but more

specific empirical data are needed to understand the mechanisms driving interactions and thus species coexistence (e.g., [29]). Our study contributes empirical data to document the role of individual variation and seasonality as drivers of interspecific interactions between apex predators via predation rates and scavenging, which in turn can also reflect on predator-prey interactions.
