The influence of hunger and sex on the foraging decisions of frugivorous bats

Abstract An animal's internal state can shift its behavior. Animals that would typically avoid dangerous foraging conditions may choose to forego safety when food is restricted. Furthermore, physiological demands such as gravidness can drive sex differences in foraging behavior among individuals of the same species. In bats, moonlight can impose risk: some bat species decrease or completely avoid foraging on full moon nights when visually oriented predators are most active. In this study, we tested the hypothesis that hunger increases risky foraging behavior. Previous work with the Jamaican fruit bat, Artibeus jamaicensis, demonstrated that this species shifts its foraging behavior in moonlight by increasing latency to land. In this experiment, bats trained to feed from a food platform were then observed landing in conditions of satiation and food-restriction, with and without the presence of artificial full moonlight. As predicted, we found that bats forage significantly more quickly when food-restricted than when satiated. We found that bats showed a nonsignificant trend to avoid moonlight via increased latencies to land on the food platform. Males—but not females—were significantly slower to land in the presence of moonlight when satiated but not when food-restricted. Our results demonstrate that internal state influences foraging decisions, with individuals landing faster when hungry than when satiated, but that the increased foraging risks associated with moonlight affect male bats more than females.