Landmark learning, cue conflict, and outbound view sequence in navigating desert ants

Mobile animals need to reliably find goal locations and animal navigators acquire and use multiple cue sets within their environment designating direction and distance estimates of these locations. Foraging ants use multiple navigational tools including path integration and the learning of the landmark panorama. During landmark-based navigation, foragers first acquire the landmark cues around the nest through preforaging learning walks, and then learn non-nest site cues along their foraging routes. Here, we explore both foragers' ability to extrapolate views from around the nest to local displacement sites and landmark learning during the first foraging trips away from the nest area. During Experiment 1, foragers were given variable amounts of exposure to the nest area before being displaced 8 m away where their return trips were recorded. In Experiment 2, foragers' return trips from a site 8 m from the nest were recorded with the surrounding landmarks during either the outbound or inbound trip obstructed from view and with/without the aid of a homeward vector. Foragers were unable to correctly orient or return home efficiently regardless of the exposure level to the nest panorama, suggesting an inability to extrapolate views from learning walks and supporting recognition-based navigation. Foragers were able to use experience of either the outbound- or inbound-view sequence to initially orient home, yet were unable to quickly return to the nest when only exposed to the inbound route. Our results suggest that exposure to the outbound foraging path is critical for efficient homeward route formation.