ISSN: 2639-216X
Authors: Deeti S*, Islam M, Lionetti VAG, Murray T and Cheng K
The nocturnal bull ants of the genus Myrmecia, Myrmecia midas travel in both bright and dim settings on the ground and also vertically up on trees navigating towards targets. It is known that foragers retain multiple panoramic memories of terrestrial landmarks as well as celestial cues along their foraging route. It is likely that they can compare these stored views with their current visual input to return to their nest. Here we examined whether nocturnal M. midas foragers’ navigational efficiency and success at view-based navigation suffer at low light levels (night time) compared with daylight levels of brightness. When exposed to panoramic cues in dim conditions, which had dimmer light levels than their peak foraging period, they were less well oriented and less likely to find the nest, with the catchment area smaller at night than during the day. At different displacement distances from the nest, initial navigational behaviours differed. Foragers displayed more scanning near the starting point at shorter distances, while with increasing distance they switched more to loops of systematic searching or heading off in some direction without scans. In the dim conditions, landmark guidance became less effective, perhaps explaining why foragers limit their navigational activities mostly to the twilight hours, when light levels are still adequate, and mostly forage in a tree through the night.
Keywords: Nocturnal Navigation; Systematic Search; Direct Navigation; Displacement Test; Orientation
