Spatial learning overshadows learning novel odors and sounds in both a predatory and a frugivorous bat

Abstract

AO_SCPLOWBSTRACTC_SCPLOWTo be efficient while foraging, animals should be selective about attending to and remembering the cues of food that best predict future meals. One hypothesis is that animals with different foraging strategies should vary in their reliance on spatial and feature cues. Animals that store food or feed on spatially stable food, like fruit or flowers, should be predisposed to learning a meals location, whereas predators that hunt mobile prey should instead be biased towards learning feature cues such as color or sound. Previous studies suggest that nectar- and fruit-feeding bats should rely relatively more on spatial cues, whereas predatory bats should rely more on feature cues, yet no experiment has compared these two foraging strategies under the same conditions. To test this hypothesis, we compared learning in the frugivorous bat, Artibeus jamaicensis, and the predatory bat, Lophostoma silvicolum, which hunts katydids using acoustic cues. We trained bats to find food paired with a unique odor, sound, and location. We then dissociated these cues to assess which cue each bat had learned. Rather than finding that the frugivore and predator are on opposite ends of a continuum in their relative reliance on spatial and feature cues, we found that both species learned spatial cues with no evidence that either learned the sounds or odors. We discuss interpretations of these results in the context of past work on use of spatial cues versus feature cues. Compared to feature cues, spatial cues may be fundamentally more rich, salient, or memorable. LO_SCPLOWAYC_SCPLOW SO_SCPLOWUMMARYC_SCPLOWWhen animals learn how to obtain food, they could attend to many possible cues--such as the associated smells, sights, sounds, or locations of the food. It has been hypothesized that natural selection has shaped animals to pay particular attention to the types of cues that are most useful for finding their typical food. In bats, this would predict that predatory species that hunt mobile, noisy insects by sound should be biased towards learning a food-associated sound, whereas bats that eat stationary and silent fruit should be biased towards learning a foods location. We gave predatory and fruit-eating bats the opportunity to simultaneously learn food-rewarded odors, sounds, or locations. Regardless of their diets, both species of bats learned locations rather than the odors or sounds associated with food. Spatial cues may be particularly rich or salient, and when they are reliable, animals may use them for learning over other cues regardless of their typical food.