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Solitary foraging ant species can employ an array of navigational tools to successfully return to the nest from foraging trips, including path integration and vision-based navigation. Species inhabiting cluttered environments that are visually rich, like Melophorus bagoti and multiple Myrmecia species, rely heavily on cues from these visual landmarks and the surrounding panorama. Additionally, these ant species can utilise the sky compass to orient by detecting both the sun’s position and the sky’s UV and polarised light gradients. Multiple characteristics of landmarks, the surrounding panorama and the sky compass cannot be realistically manipulated in the natural environment but can be readily manipulated by using a virtual reality (VR) environment under laboratory conditions. Here we present a novel virtual reality system that projects a visual panorama using commercially available projectors. This system provides a 300° visual panorama and includes a spherical treadmill system to record the individual’s movement and orientation. We present a thorough description of the virtual reality system and demonstrate the system’s performance by comparing the orientation in the virtual reality system and the natural environment. Individuals in virtual reality conditions did not orient towards the nest, suggesting the VR system is missing some crucial component for navigation.

A critical reoccurring challenge facing mobile animals is the need to reliably find goal locations (e.g. food or nest). To solve this problem, animal navigators acquire and use multiple cue sets within their environment, which designate direction and distance estimates of these locations. Navigational cues can conflict, which adds a further challenge, requiring the navigator to integrate these cues before moving. Foraging ants are expert visual navigators known to use both learned panorama cues and path integration to navigate. This thesis examines navigational memory, learning and cue choice in two Australian ant species, the diurnal ant Melophorus bagoti and the nocturnal bull ant Myrmecia midas. M. bagoti is a solitary foraging desert ant endemic to Central Australia. Foragers are shown to retain robust memories of both the nest skyline and multiple non-nest site skylines. Forager orientation performance shows evidence of retroactive interference after changes are made to the skyline at the same site. When presented with cue conflicts between the terrestrial and celestial cue sets, foragers appear to choose dynamically based on experience and cue reliability in accordance with the Temporal Weighting Rule. Foragers with directional conflicts in their inbound and outbound routes show evidence of rapid vector calibration to the inbound route.This calibration appears to have a directional limit of around 45˚. When foragers are restricted to the nest site, they are unable to extrapolate panorama cues from the nest to local sites but only require one experience of the homeward route to learn the correct nest direction. Furthermore, exposure to the outbound foraging path appears critical for efficient homeward route formation in this species. M. midas is a previously unstudied solitary foraging bull ant that forages nocturnally. Foragers show a strong reliance on terrestrial panorama cues in cue choice tests and only weak use of accumulated vectors. Foragers that are subjected to polarised light manipulations during route navigation dynamically weight the terrestrial and celestial cues during the foraging trip. M. midas foragers also navigate using the panorama while on the tree face, exhibiting similar solutions to navigational challenges on the ground and when navigating in three dimensions. Both species show heavy use of panorama learning and memory along with flexible use of navigation strategies.

Ants are a globally distributed insect family whose members have adapted to live in a wide range of different environments and ecological niches. Foraging ants everywhere face the recurring challenge of navigating to find food and to bring it back to the nest. More than a century of research has led to the identification of some key navigational strategies, such as compass navigation, path integration, and route following. Ants have been shown to rely on visual, olfactory, and idiothetic cues for navigational guidance. Here, we summarize recent behavioral work, focusing on how these cues are learned and stored as well as how different navigational cues are integrated, often between strategies and even across sensory modalities. Information can also be communicated between different navigational routines. In this way, a shared toolkit of fundamental navigational strategies can lead to substantial flexibility in behavioral outcomes. This allows individual ants to tune their behavioral repertoire to different tasks (e.g., foraging and homing), lifestyles (e.g., diurnal and nocturnal), or environments, depending on the availability and reliability of different guidance cues. We also review recent anatomical and physiological studies in ants and other insects that have started to reveal neural correlates for specific navigational strategies, and which may provide the beginnings of a truly mechanistic understanding of navigation behavior.

Solitary foraging ants commonly use visual cues from their environment for navigation. Foragers are known to store visual scenes from the surrounding panorama for later guidance to known resources and to return successfully back to the nest. Several ant species travel not only on the ground, but also climb trees to locate resources. The navigational information that guides animals back home during their descent, while their body is perpendicular to the ground, is largely unknown. Here, we investigate in a nocturnal ant, Myrmecia midas, whether foragers travelling down a tree use visual information to return home. These ants establish nests at the base of a tree on which they forage and in addition, they also forage on nearby trees. We collected foragers and placed them on the trunk of the nest tree or a foraging tree in multiple compass directions. Regardless of the displacement location, upon release ants immediately moved to the side of the trunk facing the nest during their descent. When ants were released on non-foraging trees near the nest, displaced foragers again travelled around the tree to the side facing the nest. All the displaced foragers reached the correct side of the tree well before reaching the ground. However, when the terrestrial cues around the tree were blocked, foragers were unable to orient correctly, suggesting that the surrounding panorama is critical to successful orientation on the tree. Through analysis of panoramic pictures, we show that views acquired at the base of the foraging tree nest can provide reliable nest-ward orientation up to 1.75 m above the ground. We discuss, how animals descending from trees compare their current scene to a memorised scene and report on the similarities in visually guided behaviour while navigating on the ground and descending from trees.