Testing for change over time in key movement metrics
Across diverse data types, a key indicator of learning is a change in the response measured as a function of ‘time in the environment’ (Fig. 3). While not sufficient to say confidently that learning has occurred, a strong signal that an animal’s movement behavior has changed with experience suggests that it is learning. For example, the range occupied by a group of newly translocated animals would be expected stay very close to their point of release as they focus on learning attributes of their new environment, but wander more widely as time since release increases as they start to exploit their new environment more widely (e.g., total daily displacement, He et al. 2019).
Decreases in the rate of range expansion over time indicates that translocated individuals may have learned to favor certain parts of the landscape. In this case, exploration shifts to an exploitation phase (Berger-Tal et al . 2014) as translocated animals exhibit a greater probability of revisiting previously visited areas (Fig. 3a). Similarly, exposure to a hostile landscape element (e.g., human habitation) may condition wild animals to avoid such elements, altering their spatial distribution to favor locations far from habitation (Fig. 3b). This issue has been particularly well investigated with elephants (Hoare et al . 1999, Cheptou et al . 2017)
Animals that ‘sample’ different landscapes during exploratory movements may ultimately settle in landscapes featuring the kinds of elements they encountered and exploited during the exploration phase. This can occur during dispersal, during which animals effectively sample and make decisions in an environment about which they are completely naïve. Wolves have been shown to show less avoidance of human elements, in particular relatively little-used forest roads, in new territories after a greater level of exposure and use during a dispersal phase, suggesting that they might have learned that that benefits of using those human elements outweigh the risks (Barry et al. In Press). Translocation, which can be considered an artificial and more abrupt dispersal, also requires decision making in novel environments. Changes in movement behavior (and improved survival) were recorded following translocation of naïve elk from a savannah landscape in Alberta to a forested landscape in eastern Canada (Fryxell et al . 2008).
Migration is another scenario featuring time-dependence in characteristics of movement (Fig. 3b). For example, both Muelleret al. (2013) and Jesmer et al. (2018) report changes in migration performance as a function of animals’ time in a landscape (Table 2). On smaller scales, foraging journeys from a central place and other kinds of daily activity patterns can show the same kind of performance gains as a function of experience or age (de Grissacet al. 2017; Votier et al. 2017; Wakefield et al.2019) (Table 1).