Navigational knowledge of homebound Australian sugar ants, Camponotus consobrinus.
The Australian National University, Research School of Biology, Australia
Ants are known to employ different navigational information dependent on how familiar they are with the environment they are travelling in. Australian desert ants, Melophorus bagoti, for instance, when displaced a few metres from their normal foraging route switch between the directional information dictated by the path integrator, distant landmark cues and route cues (Narendra, JEB 2007). Depending on their familiarity with a particular path, ants appear to be relying more on skyline height comparison at unfamiliar locations and on a visual compass at familiar locations (Wystrach et al, JEB 2012). Thus, even within one species, individual ants make use of different sources of navigational information, depending on their knowledge-base and the conditions they find themselves in.
Inhabiting complex urban environments, the solitary foraging Australian sugar ant, Camponotus consobrinus, is confronted with landmark rich scenes as they travel to and from the nest. We are interested in the navigational strategies employed by C. consobrinus and how these relate to this species foraging ecology. We performed near and far displacement experiments on homebound foragers, to identify the navigational information involved in their successful return journeys. The near location was located within their local foraging range, whereas the far location was outside of their foraging range, an unfamiliar area without shared landmark information. Foragers that were displaced at the near location could either (1) be lost, as indicated by continuing search movements; (2) continue on in the direction where the nest would be had they not been displaced (indicating path integration, PI); (3) compensate for the displacement and return to the nest (indicating landmark guidance). Foragers displaced at the far location could either (1) be lost; (2) continue on in the direction of the nest (PI). Each of these displaced ants were then returned back to their original path and observed. We determined how directed each path was, and how correctly directed towards identified goals (PI vector to the fictive nest location, actual nest location, foraging tree location). We found that individuals displaced to the far location were poorly directed, circling the release point and generally remaining within one metre of the release, indicating that no visual information was sufficient to aid their return journey, but also that their paths were not influenced by the state of their path integrator. Individuals displaced to the near location however, were more directed and displayed an interaction between their path integration vector and landmark guidance, with some heading initially along their PI vector, only to adjust and compensate for the displacement heading towards the actual nest location. All individuals when released back to their original path were correctly directed to the actual nest location, suggesting that C. consobrinus are guided by route-specific landmark memories to successfully navigate home. It appears that C. consobrinus will use their path integration information in familiar, but not in unfamiliar locations, and is otherwise predominantly guided by landmarks. This raises the interesting question of how and how quickly displaced ants can detect whether the landmark panorama is familiar or not.
Tenth International Congress of Neuroethology, College Park. Maryland USA, USA, 5 Aug - 10 Aug, 2012.
Poster (but consider for student poster award)
Orientation and Navigation
(2012). Navigational knowledge of homebound Australian sugar ants, Camponotus consobrinus..
Front. Behav. Neurosci.
Tenth International Congress of Neuroethology.
30 Apr 2012;
07 Jul 2012.
Miss. Eliza J Middleton, The Australian National University, Research School of Biology, Canberra, ACT, 0200, Australia, email@example.com