Tracks for Egyptian fruit bats included in the field manipulation for testing the use of the communal roost as an information center hypothesis

According to the Information Centre Hypothesis (ICH), colonial species use
social information in roosts to locate ephemeral resources. Validating the
ICH necessitates showing that uninformed individuals follow informed ones
to the new resource. However, this following behavior may not be essential
when individuals memorize the resources’ locations. For instance, Egyptian
fruit bats forage on spatially predictable trees, but some bear fruit at
unpredictable times. These circumstances suggest an alternative ICH
pathway in which bats learn when fruits emerge from social cues in the
roost but then use spatial memory to locate them without following
conspecifics. Here, using a unique field manipulation and high-frequency
tracking data, we test for this alternative pathway: We introduced bats
smeared with the fruit odor of the unpredictably fruiting Ficus sycomorus
trees to the roost, when they bore no fruits, and then tracked the
movement of conspecifics exposed to the manipulated social cue. As
predicted, bats visited the F. sycomorus trees with significantly higher
probabilities than during routine foraging trips (of >200 bats).
Our results show how the integration of spatial memory and social cues
leads to efficient resource tracking and highlight the value of using
large movement datasets and field experiments in behavioral ecology.