Home > Papers from 2011 > Searching for your nest

Searching for your nest

One of the cornerstone mechanisms for insect navigators is a systematic search strategy, for instance used when looking for their nest after their path integration system vector has “zeroed out”. The beauty of these searches is that they aren’t fixed motor patterns, rather, they reflect an individual’s confidence in its spatial knowledge. In this paper, Schulthiess and Cheng, study the statistical details of the nest search of the Australian desert ant.

Patrick Schultheiss writes ” When foragers of the Australian desert ant Melophorus bagoti navigate home, they use both visual navigation mechanisms and path integration. If they reach the nest area but fail to find the entrance, they engage in a systematic search. We looked at this search in displaced foragers, after they had completed the inbound journey in their familiar environment. It is made up of search loops, is centred on the (fictive) nest location and gradually increases in size. Similar to Tunisian Cataglyphis ants, a longer inbound journey leads to a larger search, most likely due to a decrease in accuracy of the homing vector. The interesting thing is that this effect is displayed after the ants navigated home in their familiar environment; so the (more accurate) process of visual navigation did not eliminate the (cumulative) errors of the path integrator.

We also investigated the search strategies used by Melophorus foragers. In optimal searching theory, animals are considered to move in straight lines (segments), separated by incidents of reorientation. In different search models, the segment lengths are drawn from different mathematical distributions (e.g. exponential, power law). We find that our searches are best described by a double exponential function. What this actually means is that, in the unfamiliar test-field, our ants show a mixture of two searches: one search with short segments, and one with long segments. Short segments may be useful for tight searches around the (fictive) nest, and long segments may be good to ‘loosen up’ this search and investigate new areas.”

Schultheiss, P. & Cheng, K. (2011): Finding the nest: Inbound searching behaviour in the Australian desert ant Melophorus bagoti. Animal Behaviour, doi: 10.1016/j.anbehav.2011.02.008

Categories: Papers from 2011
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