Vol.:(0123456789) 1 3 Animal Cognition https://doi.org/10.1007/s10071-018-1218-7 ORIGINAL PAPER Odometry and backtracking: social and individual navigation in group foraging desert harvester ants (Veromessor pergandei) Nicola Plowes 1  · Yu Du 2  · Jenna V. Congdon 2  · Vadim Bulitko 3  · Everton S. Soares 3  · Marcia L. Spetch 2 Received: 6 July 2018 / Revised: 13 September 2018 / Accepted: 9 October 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Veromessor pergandei harvester ants are group foragers which use a combination of social cues (pheromone-marked columns) and individual cues (e.g., self-generated movement, visual cues) when exploring foraging areas for resources. Upon fnding food, individuals navigate back to the column, which guides their return to the nest. The direction and length of columns change between foraging bouts, and hence the end of the column (unlike the nest location) is non-stationary. We conducted displacement tests on returning foragers and present three novel fndings. First, returning individual ants accurately estimate their distance from the foraging area to the end of the column. Second, ants that reached the column but only traveled a small proportion of the distance to the nest either show homeward or random orientation; random orientation was seen when the column was long. Third, ants that have traveled most of the way back to the nest along the column show backtracking when they are displaced—orienting in the direction opposite to the nest—similar to Australian desert ants Melophorus bagoti. This commonality suggests that some navigation strategies are general across species, and are utilized by ants that navigate individually or socially. Keywords Ants · Veromessor pergandei · Navigation · Odometer · Column foraging · Backtracking Introduction Accurate navigation and efcient search behavior are impor- tant abilities for moving animals. These abilities are par- ticularly critical for central places foragers, such as colonies of ants, in which foragers must repeatedly and efciently search for resources to bring back to the nest. Navigational mechanisms and search strategies have been extensively studied in desert ants that forage individually, particularly Cataglyphis fortis from northern Africa and Melophorus bagoti from Australia; many studies have shown that these ants have well-honed navigation and searching abilities (e.g., Cheng et al. 2009; Legge et al. 2014; Narendra et al. 2008; Schultheiss and Cheng 2012; Wehner and Srinivasan 1981) that appear to be exquisitely adapted to the ecological con- straints of their individual desert environments (Cheng et al. 2005, 2014). When navigational mechanisms, such as path integration, route learning, and guidance by visual landmarks do not directly result in fnding a goal, ants engage in systematic search. Past research has suggested that individually forag- ing species of desert ants seem to engage in search behavior that is characterized by expanding loops, with the spread of Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10071-018-1218-7) contains supplementary material, which is available to authorized users. * Marcia L. Spetch mspetch@ualberta.ca Nicola Plowes nicolaplowes@gmail.com Yu Du du5@ualberta.ca Jenna V. Congdon jcongdon@ualberta.ca Vadim Bulitko bulitko@ualberta.ca Everton S. Soares schumack@ualberta.ca 1 Life Sciences Department, Mesa Community College, 1833 West Southern Avenue, Mesa 85202, USA 2 Department of Psychology, University of Alberta, BSP-217, T6G 2E9 Edmonton, Canada 3 Department of Computing Science, University of Alberta, T6G 2E8 Edmonton, Canada