QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Åkesson, S. Articles by Wehner, R. Search for Related Content PubMed PubMed Citation Articles by Åkesson, S. Articles by Wehner, R.

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

Susanne Åkesson^* and Rüdiger Wehner

Department of Zoology, Zürich University, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland

View larger version (8K): [in a new window]   Fig. 1. Experimental arrangement used for training (A) and recording (B) the search trajectories during homebound runs in individually marked Cataglyphis ants. The ants were all trained to visit a feeder (F) located 16 m southeast from the nest entrance. The search trajectories of individual ants were then recorded for ants released in four different compass directions (NW, NE, SW and SE in B) in a separate test field. The nest (N) was located diagonally 100 cm northwest of the landmark in the southeast corner of the four-cylinder landmark square arrays. The side of the landmark square corresponded to a distance of 282 cm between the centres of the landmarks. The diagonal distance between the landmarks was 400 cm.

View larger version (39K): [in a new window]   Fig. 7. Search density plots for experiments in which the ants were trained to locate the nest in the centre of a four-cylinder square array of landmarks (open circles in inset). Search densities recorded during 3-min periods are given for data from all release sites combined (All) as well as separately for different release sites (N, E, S, W). The density of search activity is given as a percentage for each 20 cmx20 cm square pixel (N=225 squares) within the four-landmark array. The inset shows the configuration of landmarks (open circles) and release sites (stars) used during training and testing. N, nest.

View larger version (44K): [in a new window]   Fig. 8. Same experimental paradigm as in Fig. 7 but with the landmark array used for testing rotated by 45° relative to the training situation (for the latter, see inset in Fig. 7). N=27 ants each released from all four points of the compass. For further explanation see Fig. 7. N, nest.

View larger version (46K): [in a new window]   Fig. 2. Search density distributions for a group of individually tracked desert ants searching for the fictive position of the nest located within a four-cylinder landmark array. Search density distributions are given for releases from directions identical with (SE) or different from (NW, NE, SW) the training direction. If it lived long enough to complete the experimental period, each ant had been released from all four directions. An open circle depicts the position of the hypothetical nest. The sides of the square are 282 cm between the centres of the landmarks. The four cylindrical landmarks are positioned in each of the four corners of the search density square. Colour scales indicating the relative search densities in each 20 cmx20 cm square pixel are given beneath the distribution for each group. N=16 (NW), N=18 (NE), N=20 (SW) and N=22 (SE) ants.

View larger version (27K): [in a new window]   Fig. 3. Three-dimensional search density distributions of individually tracked desert ants searching for the nest located within a four-cylinder landmark square array. The fictive positions of the nest are depicted by open arrows. Data are given separately for the first and the second 1.5-min recording periods in the upper and lower graphs, respectively. The ants were released in four different compass directions relative to the landmark square (NW, NE, SW, SE). The four cylindrical landmarks are positioned in each of the four corners of the search density square. N=16 (NW), N=18 (NE), N=20 (SW) and N=22 (SE) ants. The same data are presented in Fig. 2 for the entire 3-min recording periods.

View larger version (11K): [in a new window]   Fig. 4. The landmark panorama within the landmark square provided four alternative positions where the ants could search for the fictive nest. The box-plot representation depicts the median number of positions at which the ants were recorded searching for the nest. Median values (filled squares) are given for the four directions from which the ants had been released. Releases from southeast correspond to releases from the training direction. Limits for minimum and maximum values (lines above and below the boxes) and 25-75% percentile ranges (open boxes) are given. N=16 (NW), N=18 (NE), N=20 (SW) and N=22 (SE) ants (same data pool as that represented in Fig. 2). For further information, see the text.

View larger version (34K): [in a new window]   Fig. 5. Examples of searching trajectories for two ants recorded after releases from four different compass directions after a short training period (see text). Open black circles indicate the positions of the landmarks; stars represent the sites of release. The green lines indicate the search trajectories of ants released from southeast, i.e. from the direction from which they had approached the nest during training. According to the criteria used to define the number of search positions, ants 235 and 311 both exhibited four search positions.

View larger version (26K): [in a new window]   Fig. 6. Examples of the trajectories of eight ants (four in A and four in B) searching for the nest within a four-cylinder landmark array recorded after releases from four different compass directions. All ants were released from the direction of training after at least 3 days of training. Open circles indicate the positions of landmarks; stars denote the sites of release; the black arrowheads at the edge of the grid point to the fictive position of the nest. Each search trajectory selected by an individual ant is represented by a coloured line.