Efficient wildlife management requires precise monitoring methods, e.g., to estimate population density, reproductive success, and survival. Here, we compared the efficiency of drone and ground approaches to detect and monitor GPS-collared female moose (Alces alces) and their calves. Moreover, we quantified how drone (n = 42) and ground (n = 41) approaches affected moose behavior and space use (n = 24 individuals). The average time used for drone approaches was 17 minutes compared to 97 minutes for ground approaches, with drone detection rate being higher (95% of adult female moose and 88% of moose calves) compared to ground approaches (78% of adult females and 82% of calves). Drone detection success increased at lower drone altitudes (50-70 m). Adult female moose left the site in 35% of drone approaches (with > 40% of those moose becoming disturbed once the drone hovered < 50 m above ground) compared to 56% of ground approaches. We failed to find short-term effects (3-h after approaches) of drone approaches on moose space use, but moose moved > 4-fold greater distances and used larger areas after ground approaches. Similarly, longer-term (24-h before and after approaches) space use did not differ between drone approaches compared to days without known disturbance, but moose moved comparatively greater distances during days of ground approaches. In conclusion, we could show that drone approaches were highly efficient to detect adult moose and their calves in the boreal forest, being faster and less disturbing than ground approaches, potentially making them a useful tool to monitor and study wildlife.

Survival among juvenile ungulates is an important demographic trait affecting population dynamics. In many systems, juvenile ungulates experience mortality from large carnivores, hunter harvest and climate-related factors. These mortality sources often shift in importance both in space and time. While wolves (Canis lupus) predate on moose (Alces alces) throughout all seasons, brown bear (Ursus arctos) predation and human harvest happen primarily during early summer and fall, respectively. Hence, understanding how the mortality of juvenile moose is affected by predation, harvest and climate is crucial to adaptively managing populations and deciding sustainable harvest rates. We used data from 39 female moose in south-central Scandinavia to investigate the mortality of 77 calves in summer/fall and winter/spring, in relation to carnivore presence (defined as wolf presence and bear density), summer productivity, secondary road density, winter severity and migratory strategy (migratory versus resident) using logistic regressions. Summer mortality varied significantly between years but was not correlated to any of our covariates. In winter, calf mortality was higher with deeper snow in areas with wolves compared to areas without and increased more strongly with an increasing proportion of clearcuts/young forests in the presence of wolves compared to when wolves were absent. Lastly, increasing hunting risk was associated with higher calf mortality, and migratory females had higher calf mortality compared to stationary ones. Our study provides useful insight into mortality rates of moose calves coexisting with two large carnivores and with an intensive harvest pressure. Increasing our understanding of the mechanisms driving calf mortality both in summer and winter will become increasingly important if the populations of wolves and bears continue to expand and the moose population declines, and both summers and winters become warmer.

Spatial patterns of human hunting and predation risk are mediated by the physical landscape, with human hunting risk often associated with habitat features contrasting those linked to risk from large carnivores. Risk patterns from hunters and large carnivores can also vary in time, which may allow prey species to adjust anti-predator strategies not only in risky places but also during risky times. We examined whether moose (Alces alces) in south-central Scandinavia adjusted diel habitat selection during and after the hunting season in response to contrasting human hunting and wolf (Canis lupus) predation risks. We found evidence for a diel and seasonal shift in habitat selection of moose consistent with a behavioural adaptation to no human hunting risk at night and after the hunting season. We found no evidence that moose responded to the spatiotemporal variation in wolf predation risk since moose selected habitats of high wolf predation risk both day and night during and after the hunting season. Human hunting risk was therefore the main driver of moose habitat selection during the hunting season while decreasing in importance during times when hunting did not occur. However, since we did not find evidence for a diel or seasonal shift in habitat selection consistent with an increase in the importance of wolf predation risk during the night and after the hunting season, our study is in line with the notion that moose in Scandinavia are currently naïve to wolves. Our findings show the importance of including the effects of humans in studies of predator-prey dynamics within anthropogenic landscapes. An increased understanding of the risk effects arising from humans and large carnivores and the responses of prey might be important for managing ungulate populations, since behaviours aimed at reducing exposure to risk may also affect crucial demographic traits like growth and reproduction.