Not Focused On Objects

Moebius Strip I I
MC Escher

Humans commonly use landmarks for navigation. We routinely focus on nearby objects such as buildings to guide our navigation. Don’t all animals navigate using nearby landmarks?

Apparently not. A group of scientists* tested desert ants, Melophorus bagoti, to determine if placing a large landmark next to their nest would alter their navigation. They erected a prominent landmark near to a nest and allowed ants to forage between a feeder and the nest with the landmark in place. Then they moved the landmark and observed the effect on returning foragers. In a similar experiment with sand wasps, Nobel Prize Winner, Niko Tinbergen placed pine cones next to a nest and moved them when the wasp was hunting out of sight. In this case, the wasp returned to the pine cones several meters from the nest and could not locate the nest.

In the ant experiment, the ants were disoriented and failed to locate their nest. However, unlike the sand wasp, they did not orient straight to the landmark that was moved. They clearly were not focused on the single most prominent nearby object.  Scientists concluded that ants navigate based on a fuller spectrum of visual patterns including the skyline panorama. A prominent local landmark is one part of the visual panorama but is not sufficient for navigation. Placing a large landmark near the nest obscures a portion of the skyline and alters it. Moving the landmark also changes the panoramic view and disorients the ants.

For ants navigating home, nearby objects may blow in and blow away, thus are not good cues over the medium to long term. Panoramic cues are more permanent and thus have been selected for a role in ant navigation.

*Antoine Wystrach Guy Beugnon and Ken Cheng. 2011. Landmarks or panoramas: what do navigating ants attend to for guidance? Frontiers in Zoology 2011, 8:21
http://www.frontiersinzoology.com/content/8/1/21