How House-Hunting Ants Choose The Best Home

Dr Elva Robinson and colleagues in the University of Bristol's School of Biological Sciences fitted rock ants with tiny radio-frequency identification tags, each measuring 1 / 2,000 (one two-thousandth) the size of a postage stamp, then observed as they chose between a poor nest nearby and a good nest further away.

The ant colonies showed sophisticated nest-site choice, selecting the superior site even though it was nine times further away than the alternative. The best nest was chosen, despite the fact that very few individual ants made direct comparisons between the nest-sites.

When a colony of rock ants needs to emigrate to a new nest, scouting ants first discover new nests and assess them then the scouts recruit nest-mates to the new nest using tandem-running, where an informed ant leads a second ant to her destination. When the number of ants in the new nest reaches a quorum, scouts begin rapid transport of the rest of the colony by carrying nest-mates and brood.

In the Bristol tests, very few ants appeared to make direct comparisons between the two nests by making multiple visits to each before choosing one or the other. However, approximately half (forty-one percent) of the ants that first visited the near nest later switched to the far nest, whereas only a tiny minority (three per cent) of the ants that first visited the far nest switched to the near nest. This ultimately resulted in the entire colony ending up in the better nest.

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Source: Science Daily