*2.2. GPS and Predation Data from Bears and Wolves*

Studies of predation by wolves and bears on moose in the study area were conducted during two time periods; late winter and early spring (hereafter, "late winter"; from mid-February to the end of April) and early summer (hereafter, "early summer"; from the beginning of May to early July). For this study, we conducted predation studies of wolves in 2010–2015, and of bears overlapping with wolf territories in 2014 and 2015. Both wolves and bears were darted and immobilized from helicopters, according to accepted veterinary and ethical procedures [42], as determined by an ethical committee (Djurförsöksetisk nämnd) and the wildlife management authorities (Naturvårdsverket). The breeding pair in each wolf pack (6 wolves in total) was equipped with a GPS collar (Vectronic Aerospace, Berlin, Germany) and was monitored during each study period. In 2014, we monitored the predatory behavior of two wolf packs and 11 radio-collared bears with overlapping territories, and in 2015 we monitored one of the packs and nine collared bears (Tables 1 and 2; see also Figure 2 in [17]). There are more bears in the study area, but up to 80% of the adult female bears and 50% of the adult males have been radio-collared [43].

We searched for carcasses of killed prey at clusters of GPS locations [20,26] and recorded cause of death and age of the dead animal. We built clusters independently for bears and wolves, and we used the time of first bear or wolf location within each cluster of GPS locations as the time of death of each killed prey. We downloaded and plotted the GPS locations in ArcView GIS (Environmental Systems Research Institute, Inc., Redlands, CA, USA). We created a buffer around each location with a radius of 100 m and overlapping buffers generated clusters of ≥2 locations [44]. We uploaded them into handheld GPS receivers (Garmin, Olathe, KS, USA) and we visited all the generated clusters of GPS locations of wolves and bears within the study periods in the field. As in previous studies [20,26,45], we generally visited the clusters of locations after 3 days, trading off carcass detection and avoidance of disturbance of study animals. Kills were relatively easy to find; even the predation of a neonate moose

removed the understory vegetation, as previously reported [26] and typically the jaws and other small pieces of bones and skin were present. As additional sign, within each cluster of GPS locations we also recorded if there were tracks, scats, and hair of wolves or bears in the ground and lying vegetation, at the sites where prey were consumed and/or at surrounding daybeds within the clusters.

**Table 1.** Individual variation in the number of neonate moose calves killed by brown bears in central Sweden in early summer, during the moose calving season, according to bear sex and age categories, including the specific period in which each bear killed moose calves.


**Table 2.** Wolf territories for which GPS clusters were visited in 2010-2015. Start date and end date columns denote the time during which clusters were checked. Fieldwork in 2014 and 2015 was extended during the moose calving season, thus two fieldwork seasons are differentiated (a and b) for the wolf territories tracked during those years. Number and age class of killed moose per wolf territory and study period is also reported.

