Novel location data reveal spatiotemporal strategies used by a central-place forager

Abstract

Central-place foragers in risky landscapes experience conflicting behavioral demands that they must balance by appropriately adjusting how they move throughout their home ranges. We used novel mini-GPS technology and time local convex hull analyses to determine how golden-mantled ground squirrels (Callospermophilus lateralis) use a spatiotemporal strategy to optimize foraging early in the year when individuals are in an energy deficit. By using serial correlation from GPS data, we could better understand how individuals use a time management strategy influenced by distance traveled from the burrow, location of food patches, location of refuge patches, and vegetative cover type. Individuals maximized time spent in food patches rather than in travel corridors or at the burrow, suggesting the need to forage was prioritized. Individuals spent more time at patches farther from the burrow relative to nearer patches, potentially as a function of intermittent antipredator vigilance activity and energy optimization. Individuals also had high rates of revisitation, but low visit duration, in risky canopy cover types, suggesting that individuals used areas of low vegetative understory cover to travel efficiently between high-value food patches. Increased predation risk incurred while traveling in these open areas was possibly offset by use of refuges. Understanding these spatiotemporal movement patterns and how they relate to dynamic intrinsic and extrinsic demands has the potential to redefine optimal foraging behavior and better inform management and conservation practices.