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.

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 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 Visual navigation in insects: coupling of egocentric and geocentric information

1996 ◽  
Vol 199 (1) ◽  
pp. 129-140 ◽  
Author(s):  
R Wehner ◽  
B Michel ◽  
P Antonsen
Keyword(s):  
Path Integration ◽  
Dead Reckoning ◽  
Positional Information ◽  
Central Place ◽  
Visual Navigation ◽  
Topographic Map ◽  
Integration System ◽  
First Case ◽  
Starting Point ◽  
Vector Information

Social hymenopterans such as bees and ants are central-place foragers; they regularly depart from and return to fixed positions in their environment. In returning to the starting point of their foraging excursion or to any other point, they could resort to two fundamentally different ways of navigation by using either egocentric or geocentric systems of reference. In the first case, they would rely on information continuously collected en route (path integration, dead reckoning), i.e. integrate all angles steered and all distances covered into a mean home vector. In the second case, they are expected, at least by some authors, to use a map-based system of navigation, i.e. to obtain positional information by virtue of the spatial position they occupy within a larger environmental framework. In bees and ants, path integration employing a skylight compass is the predominant mechanism of navigation, but geocentred landmark-based information is used as well. This information is obtained while the animal is dead-reckoning and, hence, added to the vector course. For example, the image of the horizon skyline surrounding the nest entrance is retinotopically stored while the animal approaches the goal along its vector course. As shown in desert ants (genus Cataglyphis), there is neither interocular nor intraocular transfer of landmark information. Furthermore, this retinotopically fixed, and hence egocentred, neural snapshot is linked to an external (geocentred) system of reference. In this way, geocentred information might more and more complement and potentially even supersede the egocentred information provided by the path-integration system. In competition experiments, however, Cataglyphis never frees itself of its homeward-bound vector - its safety-line, so to speak - by which it is always linked to home. Vector information can also be transferred to a longer-lasting (higher-order) memory. There is no need to invoke the concept of the mental analogue of a topographic map - a metric map - assembled by the insect navigator. The flexible use of vectors, snapshots and landmark-based routes suffices to interpret the insect's behaviour. The cognitive-map approach in particular, and the representational paradigm in general, are discussed.

Population and Community Consequences of Spatial Subsidies Derived from Central-Place Foraging

2007 ◽  
Vol 170 (6) ◽  
pp. 902
Author(s):  
Fagan ◽  
Frithjof Lutscher ◽  
Katie Schneider
Keyword(s):  
Central Place ◽  
Central Place Foraging ◽  
Spatial Subsidies

Tree Swallow selection for wetlands in agricultural landscapes predicted by central-place foraging theory

The Condor ◽  
2020 ◽  
Author(s):  
Andrew S Elgin ◽  
Robert G Clark ◽  
Christy A Morrissey
Keyword(s):  
Habitat Selection ◽  
Central Place ◽  
Foraging Theory ◽  
Agricultural Landscapes ◽  
Tree Swallow ◽  
Field Margins ◽  
Central Place Foraging ◽  
Prairie Pothole ◽  
Prairie Wetlands ◽  
Selection For

Abstract Millions of wetland basins, embedded in croplands and grasslands, are biodiversity hotspots in North America’s Prairie Pothole Region, but prairie wetlands continue to be degraded and drained, primarily for agricultural activities. Aerial insectivorous swallows are known to forage over water, but it is unclear whether swallows exhibit greater selection for wetlands relative to other habitats in croplands and grasslands. Central-place foraging theory suggests that habitat selectivity should increase with traveling distance from a central place, such that foragers compensate for traveling costs by selecting more profitable foraging habitat. Using global positioning system (GPS) tags, we evaluated habitat selection by female Tree Swallows (Tachycineta bicolor) at 4 sites containing wetlands and where terrestrial land cover was dominated by grasslands (grass, herbaceous cover) and/or cultivated cropland. We also used sweep-net transects to assess the abundance and biomass of flying insects in different habitats available to swallows (wetland pond margins, grassy field margins, and representative uplands). As expected for a central-place forager, GPS-tagged swallows selected more for wetland ponds (disproportionate to availability), and appeared to increasingly select for wetlands with increasing distance from their nests. On cropland-dominated sites, insect abundance and biomass tended to be higher in pond margins or grassy field margins compared to cropped uplands, while abundance and biomass were more uniform among sampled habitats at sites dominated by grass and herbaceous cover. Swallow habitat selection was not clearly explained by the distribution of sampled insects among habitats; however, traditional terrestrial sampling methods may not adequately reflect prey distribution and availability to aerially foraging swallows. Overall, our results underscore the importance of protecting and enhancing prairie wetlands and other non-crop habitats in agricultural landscapes, given their disproportionate use and capacity to support breeding swallow and insect populations.

scholarly journals Path Integration Provides a Scaffold for Landmark Learning in Desert Ants

2010 ◽  
Vol 20 (15) ◽  
pp. 1368-1371 ◽  
Author(s):  
Martin Müller ◽  
Rüdiger Wehner
Keyword(s):  
Path Integration ◽  
Desert Ants ◽  
Landmark Learning
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