| dc.description.abstract | Context: Anthropogenic change is affecting many species, with both positive and negative impacts. Human habitat modification and resource subsidies have helped opportunistic species, leading to demographic expansions. However, anthropogenic changes may also harm these opportunists or present future risks, for instance, dependence on subsidies or increased human wildlife interactions. Understanding human influences on these opportunistic species’ ecology is essential for their effective conservation and management in a changing world. Approaches: Using gulls (Laridae) as a model, this thesis first summarises global trends in their abundance and distribution, the drivers of these changes and the challenges for their conservation and management. The three subsequent chapters examine how human activities have influenced the ecology of lesser black-backed gulls (Larus fuscus) in northwest England, combining telemetry data, and field sampling and monitoring. First, I investigate changes to gulls’ foraging ecology and adult body condition after landfill closures. Second, I investigate population-level differences in movement and breeding ecology between neighbouring urban and coastal colonies. Finally, I examine the degree of individual foraging site fidelity both within and among colonies. Results: First, the review highlighted anthropogenic change as a key driver of demographic expansions in gull populations; however, there were geographic biases in the literature and evidence of recent declines suggest ecological processes linking humans and gulls are complex, necessitating care when making decisions about gull conservation and management. Second, telemetry data revealed strong behavioural responses to anthropogenic perturbations, with increased foraging effort and habitat-switching observed following landfill closures. Third, I found evidence for foraging habitat segregation between urban and rural lesser black-backed gulls. However, this did not results in major differences in diet or breeding performance between colonies. Finally, I found a high degree of individual variation in foraging site fidelity, with populations composed of a mixture of site faithful and varied individuals. Implications: The review highlights the urgent need to quantify the efficacy of management approaches in mitigating gull impacts and conservation measures in arresting gull declines. The observation of spatial segregation between breeding habitats demonstrates clear differences in foraging ecology between colonies, and highlights measures targeting urban foragers as a useful tool for mitigating human-gull interactions and the need for conservation action, such as the restoration of coastal ecosystems, to boost declining coastal colonies. Additionally, the finding of habitat-switching following landfill closures suggests anthropogenic perturbations will alter the distribution of foraging gulls and increase the incidence of human-gull interactions and possibly conflict. However, we found that site fidelity, use of urban habitats and responses to landfill closures varied among years, colonies, and individual gulls. This demonstrates the need for long-term monitoring of ecological and demographic responses to human activities across a range of colonies. This will provide the requisite ecological evidence to develop landscape-scale management plans for opportunistic species such as gulls, which balance mitigation of negative impacts with conservation. | en_GB |
