The Desert Ant's Navigational Toolkit: Procedural Rather than Positional Knowledge

Self Cite

123

Cataglyphis desert ants are famous navigators. Like all central place foragers, they are confronted with the challenge to return home, i.e. relocate an inconspicuous nest entrance in the ground, after their extensive foraging trips. When leaving the underground nest for the first time, desert ants perform a striking behavior, so-called learning walks that are well structured. However, it is still unclear how the ants initially acquire the information needed for sky-and landmark-based navigation, in particular how they calibrate their compass system at the beginning of their foraging careers. Using high-speed video analyses, we show that different Cataglyphis species include different types of characteristic turns in their learning walks. Pirouettes are full or partial rotations (tight turns about the vertical body axis) during which the ants frequently stop and gaze back in the direction of the nest entrance during the longest stopping phases. In contrast, voltes are small walked circles without directed stopping phases. Interestingly, only Cataglyphis ant species living in a cluttered, and therefore visually rich, environment (i.e. C. noda and C. aenescens in southern Greece) perform both voltes and pirouettes. They look back to the nest entrance during pirouettes, most probably to take snapshots of the surroundings. In contrast, C. fortis inhabiting featureless saltpans in Tunisia perform only voltes and do not stop during these turns to gaze back at the nest -even if a set of artificial landmarks surrounds the nest entrance.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Fleischmann

Grob

Wehner

et al. 2017

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123

“…This is the central question we have addressed in the present study. We already know that landmark guidance (LGmediated behaviour) can take precedence over fully paying out the home vector (HV-mediated behaviour) (Wehner, 2008;Cheng et al, 2009;Wehner, 2009), and that even when this is the case, the path integrator keeps running in the background (Sassi and Wehner, 1997;Andel and Wehner, 2004;Knaden and Wehner, 2005). It is neither switched off nor reset whenever the ant is foraging.…”

Section: Discussionmentioning

confidence: 99%

Vector-based and landmark-guided navigation in desert ants inhabiting landmark-free and landmark-rich environments

Bühlmann

Chen

Wehner

2011

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SUMMARY Two species of desert ants – the North African Cataglyphis fortis and the central Australian Melophorus bagoti – differ markedly in the visual complexity of their natural habitats: featureless salt pans and cluttered, steppe-like terrain, respectively. Here we ask whether the two species differ in their navigational repertoires, in particular, whether in homing they place different emphasis on their vector-based and landmark-based routines. In trying to answer this question, we applied the same experimental paradigms to individual foragers of either species on either continent: training and/or testing with and/or without artificial landmark arrays. We found that the open-terrain species C. fortis runs off its (path integration) home vector much more readily even in unfamiliar landmark settings than the cluttered-terrain species M. bagoti. These data support the hypothesis that C. fortis has a higher propensity to rely on vector-mediated navigation, whereas in the same experimental situations M. bagoti more easily switches to landmark-guided behaviour. In the actual navigational performances, such species-specific propensities are most likely shaped by environment-dependent individual experiences.

“…It is this feat of navigation that made C. fortis, a prime example of a solitary central place forager, a model organism for navigation (for a review, see Wehner, 2008). The key to the ants' navigational success is path integration (Müller and Wehner, 1988;Wehner, 1982; for a review, see Collett and Collett, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Even though they are confronted with only a few obvious visual landmarks in their natural environment, and therefore rely predominantly on vector navigation (for a review, see Cheng et al, 2014), many studies have shown their ability to learn and use artificial landmarks successfully (for a review, see Wehner, 2008). It is important to note that landmarks may serve different navigational purposes.…”

Section: Introductionmentioning

confidence: 99%

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

Fleischmann

Christian

Müller

et al. 2016

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131

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.