Exploration correlates with settlement: red squirrel dispersal in contrasting habitats

1. Dispersers in heterogeneous habitat theoretically should target the habitat(s) where reproduction and survival (i.e. fitness) will be highest. However, the cues that dispersing animals respond to are not well understood: differences in habitat quality ultimately may be important, but whether animals respond to these differences may be influenced by their own familiarity with different habitats. 2. To determine if dispersers reacted to differences in habitat, we documented the exploratory movements, dispersal, and settlement patterns of juvenile North American red squirrels (Tamiasciurus hudsonicus) originating in adjacent patches of different habitats. 3. Dispersers originating in mature, closed-canopy forest (linked to higher female reproductive success and smaller territories) did not explore contrasting open forest with lower tree densities, and the magnitude of the dispersers' explorations was relatively similar. In contrast, dispersers from the open forest habitat made explorations that carried them into contrasting, mature forest habitat, and their explorations were more variable across individuals. 4. When settlement occurred, it was strongly philopatric in all groups of dispersers, although the distances and directions favoured during the exploratory phase of dispersal remained strong predictors of where settlement occurred. Overall, processes favouring philopatry (i.e. maternal influences, competitive advantages, etc.) appeared to dominate the dispersal of our study animals, even those that were exposed to higher quality habitat during their explorations. 5. Secondarily, annual stochasticity (or some correlate) affected the scale of exploration and timing of settlement more than the relative quality of habitat in which dispersers were born. 6. Studies such as this that seek to understand the relative importance of individual experience, habitat familiarity, and habitat quality are important to ultimately understanding how individual animals and populations react to habitat heterogeneity.