Data from: How to find home backwards? Navigation during rearward homing of Cataglyphis fortis desert ants

Cataglyphis ants are renowned for their impressive navigation skills which have been already studied in numerous experiments during forward locomotion. The ants' navigational performance during backward homing when dragging large food loads has never been investigated until now.
During backward locomotion the odometer has to deal with unsteady motion and irregularities in interleg coordination. The legs' sensory feedback during backward walking is not only a simple reversal of the forward stepping movements. Further, it is challenging that compared to forward homing, ants are facing towards the opposite direction during backward dragging. Hence, the compass system has to cope with a flipped celestial view (in terms of the polarization pattern and the position of the sun) and an inverted retinotopic image of the visual panorama and landmark environment. The same is true for wind and olfactory cues.
In this account we analyse for the first time backward homing ants and evaluate their navigational performance in channel and open field experiments. Cataglyphis desert ants show remarkable similarities in the performance of homing compared to forward walking ants. Despite the numerous challenges emerging for the navigational system during backward walking we show that ants come off quite well in our experiments. Direction and distance gauging was comparable to the forward walking control groups. Interestingly, we find backward homing ants often to put down the food item and perform foodless search loops around the left food item. These search loops are mainly centred around the drop-off position (and not around the nest position) and increase in length the closer the ants come to their fictive nest site.