The use of human behavioural cues by urban herring gulls

Populations of herring gulls (Larus argentatus) have declined rapidly in Britain and Ireland, but this species is increasingly breeding and foraging in urban areas and has become a source of human-wildlife conflict. Although there is a large body of literature on the behaviour of herring gulls in traditional rural colonies, urban-dwelling gulls and the behavioural drivers of their apparent success in urban areas have been less studied. Gaining a better understanding of the factors that lead to negative interactions between humans and gulls would provide an insight into how human-gull conflict can be mitigated. As gulls in urban areas often forage on anthropogenic food, they are likely to interact with humans regularly and may therefore make foraging decisions based on human cues. In this thesis, I investigate whether herring gulls use behavioural cues from humans when foraging in urban areas. I first tested whether herring gulls use the direction of human gaze when approaching an anthropogenic food source. I found that herring gulls do respond to this cue: gulls took longer to approach and peck at food when they were subjected to direct gaze. I then tested whether gulls respond specifically to human eyes rather than head direction, and whether this response is influenced by gull age or location. I found that both adult and juvenile gulls responded aversively to direct gaze, and that gulls in urban areas could be approached more closely than their counterparts in rural areas. Next, I considered whether herring gulls are attracted to objects with which humans have associated. To do this, I tested whether herring gulls peck at objects more frequently after observing a human handling the object. I found that the type of object was important: gulls pecked at handled objects comprised of packaged food, but were less likely to approach and peck at handled objects when they were not food-related. Taken together, these results strongly suggest that herring gulls foraging in urban areas use human cues. Finally, I developed an individual-based model to investigate how free-living, wild animals respond to humans in a landscape where some humans provide food or behave neutrally, while others present a threat. I showed that (a) a fast learning rate is adaptive when it would be better to avoid humans but not when it would be less energetically costly to remain close to humans, (b) an ability to recognise individual humans can help animals overcome this problem, but may only be useful if animals repeatedly encounter humans who differ inter-individually in their behaviour, and (c) socially learning about humans is likely to help animals approximate an optimal avoidance strategy. These findings provide an insight into how herring gulls, and potentially other animals, are able to forage successfully in human-dominated environments. Furthermore, by understanding the cues that gulls use, people have the opportunity to modify their behaviour to reduce the frequency of negative interactions with gulls