Scaling up movements: from individual space use to population patterns

Studying multiple individuals from multiple populations would add knowledge about the proportion of different movement strategies (migratory vs. resident) and how space use patterns vary within and across populations. This allows for effective conservation or management of partially migratory animal populations by identifying the appropriate size of management units and temporal interventions. However, this knowledge is often lacking as only a few individuals from a single population are tracked in space and time. To understand the drivers of intraspecific variation in movement patterns across a broad scale, we analyzed the multiannual space use of 307 moose (Alces alces), containing 544 single-year trajectories, from 10 study areas that are spread over a 1500-km latitudinal gradient. Using a novel approach, we quantified within-and among-population variation in movement and space use patterns. We identified the movement strategy (migratory, sedentary, nomadic, or dispersal) of moose and computed annual and seasonal home ranges. Individuals demonstrated variable movement strategies from migration to year-round residence. Summer home ranges were larger in northern study areas, whereas no geographical trends were detected among populations in winter home ranges. Individual-level traits, such as sex and age, along with factors related to the landscape, such as land use and habitat, explained variation within populations, whereas climatic factors such as temperature and vegetative productivity explained variation among populations. Importantly, the variables that explained individual-level variation in space use within populations were different for all our populations. We demonstrate the intricate interplay between individual life history and landscape scale variables and how they may determine the observed movement patterns and influence the scale of management.