Different types of anthropogenic disturbance affect tropical animals

Thomas, Mark (2024) Different types of anthropogenic disturbance affect tropical animals. Masters by Research thesis (MPhil), Manchester Metropolitan University.

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Abstract

These two distinct but interconnected studies aim to provide a comprehensive understanding of how anthropogenic disturbances, specifically noise pollution and human activities, affect both invertebrate and large carnivore behaviour. The integration of these studies allows for a holistic examination of how human-induced changes impact different taxonomic groups within tropical ecosystems, offering valuable insights for conservation strategies and ecosystem management. Anthropogenic disturbances, such as noise pollution and human activities, pose significant threats to the environment and wildlife. This thesis investigates the effects of anthropogenic noise on the behaviour of Acromyrmex octospinosus, a species of leaf-cutter ants, and explores the coexistence and behavioural adaptations of jaguars and pumas in human-dominated habitats. In Chapter 1, we examine the impact of noise disturbance on the foraging behaviour of Acromyrmex octospinosus in a laboratory setting. By subjecting ants to varying levels of noise -- Low (83 dB), Medium (97 dB), and High (101 dB) -- we observe a consistent decrease in ant movement speed across all noise treatments compared to the control group. Ant colony activity, measured by ant count, is not significantly affected by noise disturbance. Additionally, the size of leaf fragments varies across different noise levels. These findings provide robust evidence of how noise disturbance alters the foraging behaviour of leaf-cutter ants. In Chapter 2, we focus on the coexistence and behavioural adaptations of jaguars and pumas in human-dominated habitats. Tropical forests, which house a significant portion of the world's biodiversity, are increasingly threatened by human activities. By analysing camera trap data from Manu National Park in Southeastern Peru, we observe that jaguars and pumas employ strategies, such as spatiotemporal segregation and fine-scale changes in activity peaks, to coexist in areas with varying levels of human disturbance. We find a negative association between pumas and the human disturbance index (HII) and correlations between pumas and factors such as distance to water sources and prey composition. These findings shed light on the behaviour and coexistence mechanisms of these big cat species in human-dominated habitats and pristine rainforests.