scholarly journals The guidance of desert ants by extended landmarks

2001 ◽  
Vol 204 (9) ◽  
pp. 1635-1639 ◽  
Author(s):  
T.S. Collett ◽  
M. Collett ◽  
R. Wehner
Keyword(s):  
Path Integration ◽  
The State ◽  
Visual Scene ◽  
Visual Features ◽  
Test Field ◽  
Experimental Conditions ◽  
Integration System ◽  
Compass Direction ◽  
Desert Ants ◽  
Cataglyphis Fortis

Desert ants (Cataglyphis fortis) were trained to follow a fixed route around a barrier to a feeder. Their homeward trajectories were recorded on a test field containing a similar barrier, oriented either as in training or rotated through 22 or 45. Under one set of experimental conditions, the homeward trajectories rotated with the orientation of the barrier, implying that the visual features of this extended landmark can determine the route independently of compass cues: the barrier provided a “visual scene” that controlled the trajectories of the ants. Under other conditions, the trajectories after rotation were a compromise between the habitual compass direction and the direction with respect to the rotated barrier. Trajectories were determined primarily by the visual scene when ants were allowed to return close to the nest before being caught and tested. The compromise trajectories were observed when ants were taken from the feeder. It seems that ants exhibit at least two separate learnt responses to the barrier: (i) a habitual compass direction triggered by the sight of the barrier and (ii) a visual scene direction that is compass-independent. We suggest that the weighting accorded to these different learnt responses changes with the state of the path integration system.

scholarly journals Visual navigation in desert ants Cataglyphis fortis: are snapshots coupled to a celestial system of reference?

2002 ◽  
Vol 205 (14) ◽  
pp. 1971-1978 ◽  
Author(s):  
Susanne Åkesson ◽  
Rüdiger Wehner
Keyword(s):  
Path Integration ◽  
Central Place ◽  
Visual Navigation ◽  
Central Place Foraging ◽  
Nest Location ◽  
Compass Direction ◽  
Desert Ants ◽  
Reference Information ◽  
Cataglyphis Fortis

SUMMARY Central-place foraging insects such as desert ants of the genus Cataglyphis use both path integration and landmarks to navigate during foraging excursions. The use of landmark information and a celestial system of reference for nest location was investigated by training desert ants returning from an artificial feeder to find the nest at one of four alternative positions located asymmetrically inside a four-cylinder landmark array. The cylindrical landmarks were all of the same size and arranged in a square, with the nest located in the southeast corner. When released from the compass direction experienced during training (southeast), the ants searched most intensely at the fictive nest position. When instead released from any of the three alternative directions of approach (southwest, northwest or northeast), the same individuals instead searched at two of the four alternative positions by initiating their search at the position closest to the direction of approach when entering the landmark square and then returning to the position at which snapshot, current landmark image and celestial reference information were in register. The results show that, in the ants'visual snapshot memory, a memorized landmark scene can temporarily be decoupled from a memorized celestial system of reference.

Pinpointing food sources: olfactory and anemotactic orientation in desert ants, Cataglyphis fortis

2000 ◽  
Vol 203 (5) ◽  
pp. 857-868 ◽  
Author(s):  
H. Wolf ◽  
R. Wehner
Keyword(s):  
Food Source ◽  
Video Tracking ◽  
Food Sources ◽  
Integration Scheme ◽  
Experimental Conditions ◽  
Feeding Site ◽  
Desert Ants ◽  
Feeding Station ◽  
Visually Based ◽  
Cataglyphis Fortis

Desert ants, Cataglyphis fortis, search for a repeatedly visited food source by employing a combined olfactory and anemotactic orientation strategy (in addition to their visually based path-integration scheme). This behaviour was investigated by video-tracking consecutive foraging trips of individually marked ants under a variety of experimental conditions, including manipulations of the olfactory and wind-detecting systems of the ants. If the wind blows from a constant direction, ants familiar with the feeding site follow outbound paths that lead them into an area 0.5-2.5 m downwind of the feeding station. Here, the ants apparently pick up odour plumes emanating from the food source and follow these by steering an upwind course until they reach the feeder. If the food is removed, foragers usually concentrate their search movements within the area downwind of the feeding site. Only when the wind happens to subside or when tail-wind conditions prevail do the ants steer direct courses towards the food. Elimination of olfactory input by clipping the antennal flagella, or of wind perception by immobilising the bases of the antennae, altered the foraging behaviour of the ants in ways that supported these interpretations. Ants with clipped flagella were never observed to collect food items.

scholarly journals Flexible weighing of olfactory and vector information in the desert ant Cataglyphis fortis

2013 ◽  
Vol 9 (3) ◽  
pp. 20130070 ◽  
Author(s):  
Cornelia Buehlmann ◽  
Bill S. Hansson ◽  
Markus Knaden
Keyword(s):  
Path Integration ◽  
Food Sources ◽  
Feeding Site ◽  
Desert Ants ◽  
Desert Ant ◽  
Vector Information ◽  
Pass Through ◽  
Path Integrator ◽  
Odour Plumes ◽  
Cataglyphis Fortis

Desert ants, Cataglyphis fortis , are equipped with remarkable skills that enable them to navigate efficiently. When travelling between the nest and a previously visited feeding site, they perform path integration (PI), but pinpoint the nest or feeder by following odour plumes. Homing ants respond to nest plumes only when the path integrator indicates that they are near home. This is crucial, as homing ants often pass through plumes emanating from foreign nests and do not discriminate between the plume of their own and that of a foreign nest, but should absolutely avoid entering a wrong nest. Their behaviour towards food odours differs greatly. Here, we show that in ants on the way to food, olfactory information outweighs PI information. Although PI guides ants back to a learned feeder, the ants respond to food odours independently of whether or not they are close to the learned feeding site. This ability is beneficial, as new food sources—unlike foreign nests—never pose a threat but enable ants to shorten distances travelled while foraging. While it has been shown that navigating C. fortis ants rely strongly on PI, we report here that the ants retained the necessary flexibility in the use of PI.

scholarly journals Do familiar landmarks reset the global path integration system of desert ants?

2003 ◽  
Author(s):  
M. Collett ◽  
T. S. Collett ◽  
S. Chameron ◽  
R. Wehner
Keyword(s):  
Path Integration ◽  
Integration System ◽  
Desert Ants

The Activation of Scene Gist: Global Versus Local Features

2017 ◽  
Author(s):  
Laura Shields
Keyword(s):  
Real World ◽  
Visual Information ◽  
Scene Understanding ◽  
Past Research ◽  
Local Features ◽  
Visual Scene ◽  
Visual Features ◽  
Global Features ◽  
Experimental Conditions ◽  
Scene Gist

The present study investigates how human observers understand real-world scenes. Past studies have shown that individuals infer the meaning or gist of a real-world scene within a single glance. The current study examined how much visual information is needed in order to elicit an understanding of a visual scene. Sixty participants were shown a brief presentation of a scene and the amount of scene information shown was manipulated across six experimental conditions, varying from only details at the centre (local features) to the full scene (global features). Local features are objects present in a scene, or can also be visual features such as textures, colours and other surface properties important for understanding a visual scene. Global features ecompass the actual space of the scene, including the geometry, spatial layout, and scene structure. Based on past research, we anticipate scene understanding will occur where global features are available, but not in conditions where only local features are available. However, preliminary results revealed that participants understood the gist of the scene even when minimal features were available to them. This study aims to further current research on scene understanding and the visual features required to comprehend complex visual information in our environment.  

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