First published online October 17, 2008
Journal of Experimental Biology 211, 3370-3377 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.022715
Landmark guidance and vector navigation in outbound desert ants
Tobias Merkle1,* and
Rüdiger Wehner2
1 Centre for Visual Sciences, Research School of Biological Sciences, Australian
National University, Canberra ACT 2601, Australia
2 Institute of Zoology and Brain Research Institute, University of Zürich,
Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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Fig. 1. Experimental setups. (A) Experiment 1 (no landmarks). Ants trained to a
feeder located 10 m south of the nest entrance were captured immediately after
leaving the nest (0%-out ants) and transferred to the test field, where they
were released. (B) Experiment 2 (landmarks). As in experiment 1, ants were
trained to a feeder located 10 m south of the nest. A landmark corridor
consisting of six black cylinders was set up between the nest and the feeder.
The ants were captured immediately after leaving the nest (0%-out-LM ants) and
transferred to the test field, where they were confronted with no landmarks
(NL), a landmark corridor as during training (L0) or a landmark corridor
rotated by 90 deg. (L90). Grey squares indicate points of release.
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Fig. 2. Example of a 0%-out-LM ant in test condition L0 (A) and NL (B). Point of
release was at 0/0. Landmarks are shown as black circles.
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Fig. 3. Sample path showing the values that were determined for ants with
directional preferences: (A) direction the ant headed towards, (B) distance
reached by the ant in its preferred direction and (C) distance covered until
the ant exhibited its directional preference (for more explanations, see
text). Point of release was at 0/0.
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Fig. 4. Path layouts in different conditions. Density profiles of paths of (A)
0%-out ants (N=25) and 0%-out-LM ants in the three conditions (B) NL,
(C) L0 and (D) L90 (N=25 in each condition). Density was calculated
as the percentage of path length within each square divided by the total path
length of all ants in the respective condition. Release points and landmark
positions are indicated by large or small arrowheads, respectively. Side
length of squares, 1 m.
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Fig. 5. Sample paths. Paths of three 0%-out-LM ants in the three conditions NL
(green), L0 (red) and L90 (blue). Point of release was at 0/0. Landmarks in
conditions L0 and L90 are shown as red or blue circles, respectively.
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Fig. 6. Number (N) of ants that showed a directional preference (grey) and
ants that searched for the nest instead (black) for 0%-out ants (A) and
0%-out-LM ants in conditions L0 (B), NL (C) and L90 (D).
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Fig. 7. Comparison of ants that showed directional preferences in conditions L0 and
L90: (A) Directional deviations (deg.), (B) maximum distances covered (broken
line represents the distance between the release point and that of the fictive
feeder, m) and (C) distances covered until the ants showed their directional
preferences (m). Boxplots indicate medians (middle vertical lines), quartile
ranges (boxes), whiskers (error bars) and outliers (crosses).
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© The Company of Biologists Ltd 2008
