Abstract
Identifying behavioral mechanisms that underlie observed movement patterns is difficult when animals employ sophisticated cognitive‐based strategies. Such strategies may arise when timing of return visits is important, for instance to allow for resource renewal or territorial patrolling. We fitted spatially explicit random‐walk models to GPS movement data of six wolves (Canis lupus; Linnaeus, 1758) from Alberta, Canada to investigate the importance of the following: (1) territorial surveillance likely related to renewal of scent marks along territorial edges, to reduce intraspecific risk among packs, and (2) delay in return to recently hunted areas, which may be related to anti‐predator responses of prey under varying prey densities. The movement models incorporated the spatiotemporal variable “time since last visit,” which acts as a wolf's memory index of its travel history and is integrated into the movement decision along with its position in relation to territory boundaries and information on local prey densities. We used a model selection framework to test hypotheses about the combined importance of these variables in wolf movement strategies. Time‐dependent movement for territory surveillance was supported by all wolf movement tracks. Wolves generally avoided territory edges, but this avoidance was reduced as time since last visit increased. Time‐dependent prey management was weak except in one wolf. This wolf selected locations with longer time since last visit and lower prey density, which led to a longer delay in revisiting high prey density sites. Our study shows that we can use spatially explicit random walks to identify behavioral strategies that merge environmental information and explicit spatiotemporal information on past movements (i.e., “when” and “where”) to make movement decisions. The approach allows us to better understand cognition‐based movement in relation to dynamic environments and resources.
Highlights
Recent empirical and theoretic work suggests that cognition and memory are important for animals’ daily movements (Fagan et al, 2013)
We address whether gray wolves (Canis lupus) integrate spatiotemporal aspects of their own travel history into their movement decisions
That memory of travel history is important in wolf movement decisions is reasonable because wolves exhibit little daily overlap in use of their territory, especially in winter, and it raises the questions as to the underlying mechanism (Jedrzejewski, Schmidt, Theuerkauf, Jedrzejewska, & Okarma, 2001)
Summary
Recent empirical and theoretic work suggests that cognition and memory are important for animals’ daily movements (Fagan et al, 2013). The probability of selecting a location is modeled as a logistic weighting function of the spatial attributes time since last visit (TSLV), distance from territory edge (edge), and prey density (prey) within a spatially explicit movement model. Contrary to predictions by the “risky places hypothesis,” which accounts only for varying antipredator behavior across sites with different long-term predation risk, observations of elk responses to wolves suggest that antipredator behavior adjusts dynamically to the presence of wolves in line with the “risky times hypothesis” and the “risk allocation hypothesis” (Creel, Winnie, Christianson, & Liley, 2008; Robinson & Merrill, 2013) These behavioral responses lower predation success, an effect called behavioral depression of prey (Charnov, Orians, & Hyatt, 1976). Each location of a wolf was attributed to the grid cell in which it fell
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