Ontogeny of learning walks and the acquisition of landmark information in desert ants,Cataglyphis fortis

Abstract

At the beginning of their foraging lives, desert ants (Cataglyphis fortis) are for the first time exposed to the visual world within which they henceforth must accomplish their navigational tasks. Their habitat, North African salt pans, is barren, and the nest entrance, a tiny hole in the ground, is almost invisible. Although natural landmarks are scarce and the ants mainly depend on path integration for returning to the starting point, they can also learn and use landmarks successfully to navigate through their largely featureless habitat. Here, we studied how the ants acquire this information at the beginning of their outdoor lives within a nest-surrounding array of three artificial black cylinders. Individually marked 'newcomers' exhibit a characteristic sequence of learning walks. The meandering learning walks covering all directions of the compass first occur only within a few centimeters of the nest entrance, but then increasingly widen, until after three to seven learning walks, foraging starts. When displaced to a distant test field in which an identical array of landmarks has been installed, the ants shift their search density peaks more closely to the fictive goal position, the more learning walks they have performed. These results suggest that learning of a visual landmark panorama around a goal is a gradual rather than an instantaneous process.

Species-specific differences in the fine structure of learning walk elements inCataglyphisants

“…Therefore, we usually could not decide whether a learning walk was the first or a subsequent one. However, as the walks were only included in the data if the ants stayed within the recording area, and the ants move further away with more experience (Fleischmann et al, 2016), these walks were most probably early learning walks. In one colony of C. noda, we marked some of the naive ants with an individual color code in order to record subsequent learning walks of individual ants.…”

“…Since the first descriptions over a century ago (Peckham and Peckham, 1898;Wagner, 1907), learning flights have been investigated in great detail in wasps (Tinbergen, 1932;Zeil, 1993a,b;Zeil et al, 1996), honeybees (Becker, 1958;Capaldi and Dyer, 1999;Lehrer, 1991Lehrer, , 1993Opfinger, 1931;Vollbehr, 1975) and bumblebees Hempel de Ibarra et al, 2009;Philippides et al, 2013;Robert et al, 2017) using increasingly sophisticated techniques like harmonic radar (Capaldi et al, 2000;Degen et al, 2015Degen et al, , 2016Osborne et al, 2013) or high-speed cameras (Riabinina et al, 2014;Stürzl et al, 2016). Much less is known about learning walks of ants (Fleischmann et al, 2016;Jayatilaka, 2014;Müller and Wehner, 2010;Muser et al, 2005;Nicholson et al, 1999;Stieb et al, 2012;Wehner et al, 2004). However, these few studies document thatlike flying insects -some ant species exhibit a striking behavioral sequence at the beginning of their foraging life.…”

“…However, these few studies document thatlike flying insects -some ant species exhibit a striking behavioral sequence at the beginning of their foraging life. Desert ants in particular, which are well known for their navigational performance (Ronacher, 2008;Wehner, 2008;Wehner and Rössler, 2013;Wehner et al, 1996), use a considerable amount (up to 3 days; Fleischmann et al, 2016;Stieb et al, 2012) of their short lives (often less than a week; Schmid-Hempel and Schmid-Hempel, 1984) outside the nest to perform learning walks. Cataglyphis ants are thermophilic scavengers searching for dead arthropods during their extensive foraging excursions.…”

“…Before the successful completion of these extensive foraging trips, Cataglyphis ants perform learning walks characterized by several typical features: naive ants (called 'novices' below) move slowly around the nest entrance and explore all directions around it in subsequent learning walks (Fleischmann et al, 2016;Wehner et al, 2004). These ants include repeated body turns in their small excursions and they do not bring back any food items (Fleischmann et al, 2016;Stieb et al, 2012;Wehner et al, 2004). However, in novices, the characteristics of the learning walks, including circular movements as well as saccadic rotations with distinct stopping phases, have not yet been analyzed in detail.…”

Compass cues used by a nocturnal bull ant, Myrmecia midas

“…Wehner, 2003;Collett et al, 2006;Collett, 2012;Schultheiss et al, 2016). To obtain compass information from landmarks, ants first acquire visual information around the goal (Nicholson et al, 1999;Narendra et al, 2007;Baddeley et al, 2011;Zeil et al, 2014a;Fleischmann et al, 2016) through a carefully orchestrated series of learning walks that occur in different compass directions around the goal. When returning to the goal, ants move to match their current view to the memorized nest-oriented image to head toward the goal (Wehner et al, 1996;Collett et al, 2001;Graham and Cheng, 2009;Wystrach et al, 2011a,b;Zeil, 2012;Narendra et al, 2013a).…”