Behaviour 2019
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Twilight Navigation: an Austrian Bull Ant Uses its Vision to Find Home in the Pre-Dawn Darkness.
Vito Lionetti, Ken Cheng, Trevor Murray. Macquarie University, Sydney, NSW, Australia

Australian bull ants rely on panoramic views to navigate between their nest and foraging site. Myrmecia pyriformis is an exceptional nocturnal navigator, although there are open questions about the extent to which low light conditions affect their navigational abilities. We investigated navigational abilities of M. pyriformis by displacing them to three nearby and one distant location from their nest. We used different methodologies to identify the strengths and weaknesses of these practices. In the experiment, foragers were captured from the tree during their nocturnal foraging trip and displaced during the following astronomical twilight at four locations: West, North, South each 6.5m from the nest; and an Unfamiliar location 35m South of the nest. From ants walking on a trackball, and video tracking, along with GPS data we find that the majority of ants headed towards the nest location when displaced at the 6.5m locations. Ants at the unfamiliar location, however, showed a uniform distribution and exhibited search behavior. By contrast, releasing ants on a wooden Goniometer along with recording foragers’ initial headings, led to less clear results.