Looking and homing: how displaced ants decide where to go

Abstract

We caught solitary foragers of the Australian Jack Jumper ant, Myrmecia croslandi, and released them in three compass directions at distances of 10 and 15 m from the nest at locations they have never been before. We recorded the head orientation and the movements of ants within a radius of 20 cm from the release point and, in some cases, tracked their subsequent paths with a differential GPS. We find that upon surfacing from their transport vials onto a release platform, most ants move into the home direction after looking around briefly. The ants use a systematic scanning procedure, consisting of saccadic head and body rotations that sweep gaze across the scene with an average angular velocity of 908 s 21 and intermittent changes in turning direction. By mapping the ants' gaze directions onto the local panorama, we find that neither the ants' gaze nor their decisions to change turning direction are clearly associated with salient or significant features in the scene. Instead, the ants look most frequently in the home direction and start walking fast when doing so. Displaced ants can thus identify home direction with little translation, but exclusively through rotational scanning. We discuss the navigational information content of the ants' habitat and how the insects' behaviour informs us about how they may acquire and retrieve that information.

Head roll stabilisation in the nocturnal bull ant Myrmecia pyriformis: Implications for visual navigation

“…One testable prediction would be that ants keep their head more horizontally aligned when they perform scanning movements around the yaw axis and/or when they pause along their foraging path (Narendra et al, 2013c), compared with when they are walking (e.g. Wystrach et al, 2014;Zeil et al, 2014). It is also conceivable that there are ways of preprocessing, representing and comparing images that are robust against roll and pitch misalignments, a possibility that remains to be investigated.…”

“…However, it has only recently been considered in the context of the image (snapshot)-matching process (Ardin et al, 2015) that is thought to underlie the use of route and place memories for navigation (reviewed in Collett et al, 2013;Zeil, 2012). Recent studies on the Australian jack jumper ant, M. croslandi , and on the desert ant Melophorus bagoti (Wystrach et al, 2014) have investigated the way in which ants scan the panorama before deciding where to go, and have concluded that the ants do not look at particular features in the environment, but rather appear to perform a more global matching procedure between current and memorised views (Wystrach et al, 2014;Zeil et al, 2014). Confirming the results obtained by Ardin et al (2015) for pitch misalignment, we have shown here that misalignments around the roll axis of more than 10 deg between the memorised reference images and the current views are likely to pose serious problems for retrieving navigational information through such global image comparisons.…”

Three spectrally distinct photoreceptors in diurnal and nocturnal Australian ants

“…Ants in landmark-rich habitats however, including the two species studied here, are guided by the visual panorama, often in preference to path integration information (e.g. [23,25,51,52]). In such cases, spectral information may improve the reliability of navigational cues.…”

Ground-Nesting Insects Could Use Visual Tracking for Monitoring Nest Position during Learning Flights

“…The 3D flight path and the head yaw orientation were determined frame-by-frame using custom-made software (see [13,16] for details).…”