Narendra, AjayReid, Samuel F.Raderschall, Chloé A.2015-11-252015-11-251932-6203http://hdl.handle.net/1885/16710Insects face the challenge of navigating to specific goals in both bright sun-lit and dim-lit environments. Both diurnal and nocturnal insects use quite similar navigation strategies. This is despite the signal-to-noise ratio of the navigational cues being poor at low light conditions. To better understand the evolution of nocturnal life, we investigated the navigational efficiency of a nocturnal ant, Myrmecia pyriformis, at different light levels. Workers of M. pyriformis leave the nest individually in a narrow light-window in the evening twilight to forage on nest-specific Eucalyptus trees. The majority of foragers return to the nest in the morning twilight, while few attempt to return to the nest throughout the night. We found that as light levels dropped, ants paused for longer, walked more slowly, the success in finding the nest reduced and their paths became less straight. We found that in both bright and dark conditions ants relied predominantly on visual landmark information for navigation and that landmark guidance became less reliable at low light conditions. It is perhaps due to the poor navigational efficiency at low light levels that the majority of foragers restrict navigational tasks to the twilight periods, where sufficient navigational information is still available.AN acknowledges funding support from the Australian Research Council’s (ARC) Centres of Excellence Scheme, ARC Discovery Project and Australian Postdoctoral Fellowship (DP0986606), ARC Discovery Early Career Award (DE120100019), Hermon Slade Foundation and The Defence Science and Technology Organization. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.© 2013 Narendra et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.adaptation, biologicalanimalsantsaustralian capital territorygeographic information systemshoming behaviorlocomotionorientationcueslight2013-03-0610.1371/journal.pone.00588012015-12-11