Time-mapping and future-oriented behavior in free-ranging wild fruit bats

Abstract

Episodic memory and mental time travel have been viewed as uniquely human traits.^1,2,3 This view began to shift with the development of behavioral criteria to assess what is referred to as "episodic-like memory" in animals.^4,5 Key findings have ranged from evidence of what-where-when memory in scrub-jays, rats, and bees; through decision-making that impacts future foraging in frugivorous primates; to evidence of planning based on future needs in scrub-jays and tool use planning in great apes.^{4,6,7,8,9,10,11,12,13} Field studies of these issues have been rare, though there is field-based evidence for future-oriented behaviors in primates.^8,10,14,15 We report evidence that free-ranging wild fruit bats rely on mental temporal maps and exhibit future-oriented behaviors when foraging. We tracked young bats as they navigated and foraged, documenting every tree they visited over many months. We prevented the bats from foraging outside for different time periods and monitored their foraging decisions, revealing that the bats map the spatiotemporal patterns of resources in their environment. Following a long period in captivity, the bats did not visit those trees that were no longer providing fruit. We show that this time-mapping ability requires experience and is lacking in inexperienced bats. Careful analysis of the bats' movement and foraging choices indicated that they plan which tree to visit while still in the colony, thus exhibiting future-oriented behavior and delayed gratification on a nightly basis. Our findings demonstrate how the need for spatiotemporal mental mapping can drive the evolution of high cognitive abilities that were previously considered exclusive to humans.

Keywords: Egyptian fruit bat; GPS tracking; captivity experiments; episodic-like memory; field experiments; foraging behavior; future planning; nutritional analysis.