The Impacts of environmental visual noise on individual and collective behaviour

<p>Ecological noise is an inherent part of all natural environments, with this noise often making it more difficult for animals to detect information. In this thesis I investigated the impact of two forms of dynamic visual noise on the behaviour of individuals and groups in two animal taxa. In Chapter 2 I found that a natural form of dynamic visual noise impairs the perception of three-spined sticklebacks (<em>Gasterosteus aculeatus</em>) and fish responded to this by selectively searching over more localised areas of their visual field. In Chapter 3 I found that fish had behavioural adaptations to mitigate the negative impacts of this noise by avoiding more visually noisy areas, and they achieved this by increasing their activity as a function of the locally perceived noise level. In Chapter 4 I asked whether pairs of fish compensated for some of the reduction in perception shown by individuals by adapting their social behaviour. I found no evidence to suggest that having access to social information improved the fish’s collective ability to detect information in their environment and while there was some evidence that fish relied more strongly on social information in noisy conditions, my results suggested that the benefits of socially derived information in this system were limited. Finally in Chapter 5 I explored how a different form of dynamic visual noise affected pheromone laying behaviour, a source of social information, in weaver ants (<em>Oecophylla smaragdina</em>). I found that ants laid pheromone more consistently overtime and showed greater preference for following a pheromone trail in higher levels of noise. Therefore ants could be increasing their reliance on social information in times of increased noise, allowing them to forage more effectively. My thesis demonstrates that animals have behavioural adaptations they can use to mitigate the impacts noise has on their perceptual abilities.</p>