Traveling through light clutter: Path integration and panorama guided navigation in the Sonoran Desert ant, Novomessor cockerelli

Abstract

Foraging ants use multiple navigational strategies, including path integration and visual panorama cues, which are used simultaneously and weighted based upon context, the environment and the species' sensory ecology. In particular, the amount of visual clutter in the habitat predicts the weighting given to the forager's path integrator and surrounding panorama cues. Here, we characterize the individual cue use and cue weighting of the Sonoran Desert ant, Novomessor cockerelli, by testing foragers after local and distant displacement. Foragers attend to both a path-integration-based vector and the surrounding panorama to navigate, on and off foraging routes. When both cues were present, foragers initially oriented to their path integrator alone, yet weighting was dynamic, with foragers abandoning the vector and switching to panorama-based navigation after a few meters. If displaced to unfamiliar locations, experienced foragers travelled almost their full homeward vector (~85%) before the onset of search. Through panorama analysis, we show views acquired on-route provide sufficient information for orientation over only short distances, with rapid parallel decreases in panorama similarity and navigational performance after even small local displacements. These findings are consistent with heavy path integrator weighting over the panorama when the local habitat contains few prominent terrestrial cues.

Varieties of visual navigation in insects

“…Across a number of well-studied ant species, learning the visual cues of the full terrestrial panorama (Fig. 3 ) around goal locations and along the foraging route is relied upon heavily for successful navigation (Freas and Cheng 2018 , 2019 ; Freas et al 2021 ; Graham and Cheng 2009 ; Mangan and Webb 2012 ; Narendra et al 2013 ; Wehner 2020 ; Zeil and Fleischmann 2019 ). Ant navigators are thought to rely on this panoramic scene rather than any individual landmarks as their vision is characterised by a wide visual field (~ 300°) coupled with low visual acuity, making discerning the characteristics of individual landmarks difficult (Schwarz et al 2011 ).…”

“…Small view memory catchment areas are also observed in open desert environments. The individually foraging Sonoran Desert ant Novomessor cockerelli typically inhabits cluttered environments, yet these deserts contain few prominent terrestrial cues with even distant mountain ranges being inconspicuous to the ant’s view (Freas et al 2021 ). The lack of prominent terrestrial cues that remain stable in the Sonoran Desert results in small catchment areas and subsequently N. cockerelli foragers are unable to successfully orient when displaced only a handful of meters away from known locations (Freas et al 2021 ).…”

“…The individually foraging Sonoran Desert ant Novomessor cockerelli typically inhabits cluttered environments, yet these deserts contain few prominent terrestrial cues with even distant mountain ranges being inconspicuous to the ant’s view (Freas et al 2021 ). The lack of prominent terrestrial cues that remain stable in the Sonoran Desert results in small catchment areas and subsequently N. cockerelli foragers are unable to successfully orient when displaced only a handful of meters away from known locations (Freas et al 2021 ). When environments do contain prominent landmarks that remain unobstructed by local clutter and are visible over larger distances, as has been characterised in M. bagoti , C. noda and M. croslandi , the panorama maintains a high degree of similarity as the ant moves away from a known location, facilitating correct orientation over longer distances (Fleischmann et al 2018b ; Murray and Zeil 2017 ; Narendra et al 2013 ; Wystrach et al 2012 ).…”

Directed retreat and navigational mechanisms in trail following Formica obscuripes

“…Within ants, many well-studied species forage solitarily and must navigate alone, yet trail following ants rely upon many of the same navigational mechanisms with the additional complexity of the pheromone trail also helping to direct movement. Much of what we know regarding the strategies of navigating ants is based on solitarily foraging species that rely heavily on the visual cues of the celestial compass and the surrounding panorama (the 360º scene given ants see in a ~300º field of view) to navigate (Cheng et al, 2009 ; Freas et al, 2021 ; Narendra et al, 2017 ; Warrant & Dacke, 2016 ; Wehner, 2020 ; Wystrach et al, 2013 ). However, there has been parallel interest focused on how trail following ants integrate both individual and communal types of information to navigate (Almeida et al, 2018 ; Aron et al, 1993 ; Czaczkes et al, 2019 , 2022 ; Freas & Spetch, 2021 ; Grüter et al, 2011 ; Jones et al, 2019 ; Minoura et al, 2016 ; Middleton et al, 2018 ).…”

“…Local vectors represents but one of multiple mechanistic differences underlying similar path integration-linked behaviours, including maintaining orientation, backtracking and partial vector suppression, all of which are mediated in V. pergandei by the presence of the pheromone rather than panorama views as is the case for solitary foraging ants (Collett et al, 1998 ; Freas et al, 2019a , b , c , 2020 ; Freas & Spetch, 2021 ; Plowes et al, 2019 ; Wystrach et al, 2013 ). In fact, with regard to view-based navigation, V. pergandei shows no evidence of using view alignment of the panorama to orient, despite living in a visually cluttered environment where sympatric solitarily foraging ant species actively rely on these same views to home (Freas et al, 2019a , b , c , 2021 ).…”