Search

There are many hypotheses explaining the diversity of colours and patterns found in nature, but they are often difficult to examine empirically. Recent studies show the dark upperside of the wings of gliding birds could reduce drag by decreasing the density of surrounding air. It may therefore be expected that species with darker wings have less efficient wing morphology than their paler counterparts. I conducted a phylogenetic comparative analysis of the Larinae (gulls) to test whether wing loading is a predictor of wing darkness. I found that, for each standard deviation increase in wing loading, wing darkness is predicted to increase by 1.2 shades on the Kodak grey scale. Wing darkness is also negatively correlated with the distance from the equator of species’ breeding and resident ranges. Furthermore, heavier species have lower aspect ratio wings, suggesting that dark wings have evolved to improve the trade-off between maneuverability and long distance flight.

Wild animals encounter humans on a regular basis, but humans vary widely in their behaviour: whereas many people ignore wild animals, some people present a threat, while others encourage animals' presence through feeding. Humans thus send mixed messages to which animals must respond appropriately to be successful. Some species appear to circumvent this problem by discriminating among and/or socially learning about humans, but it is not clear whether such learning strategies are actually beneficial in most cases. Using an individual-based model, we consider how learning rate, individual recognition (IR) of humans, and social learning (SL) affect wild animals' ability to reach an optimal avoidance strategy when foraging in areas frequented by humans. We show that ‘true’ IR of humans could be costly. We also find that a fast learning rate, while useful when human populations are homogeneous or highly dangerous, can cause unwarranted avoidance in other scenarios if animals generalize. SL reduces this problem by allowing conspecifics to observe benign interactions with humans. SL and a fast learning rate also improve the viability of IR. These results provide an insight into how wild animals may be affected by, and how they may cope with, contrasting human behaviour.

With an increasing human population and expansion of urban settlements, wild animals are often exposed to humans. As humans may be a threat, a neutral presence or a source of food, animals will benefit from continuously assessing the potential risk they pose in order to respond appropriately. Herring gulls, Larus argentatus, are increasingly breeding and foraging in urban areas, and thus have many opportunities to interact with humans. We recently found that herring gulls take longer to approach food when being watched by a human. However, it is not known whether aversion to human gaze arises from experience with humans, and whether individual differences in responsiveness are a result of differential exposure. Here, we tested whether herring gulls' responses to human gaze differ according to their age class and urbanization of their habitat. We measured the gulls' flight initiation distance when an experimenter approached with either a direct or an averted gaze. Neither gull age class nor urbanization significantly influenced the effect of human gaze on flight initiation distance. However, as recently fledged juveniles responded strongly to the experimenter's gaze, aversion to human gaze may not require extensive exposure to humans to develop. Gulls in urban areas could be approached more closely than those in rural areas, consistent with findings in other species. These results indicate that gaze aversion is present early in development and that exposure to humans may influence gulls' responses to perceived risk from humans. Investigating the processes generating individual differences in responses to humans will provide further insights into human–wildlife interactions and the effects of urbanization.

Humans have a profound effect on the planet’s ecosystems, and unprecedented rates of human population growth and urbanisation have brought wild animals into increasing contact with people. For many species, appropriate responses towards humans are likely to be critical to survival and reproductive success. Although numerous studies have investigated the impacts of human activity on biodiversity and species distributions, relatively few have examined the effects of humans on the behavioural responses of animals during human-wildlife encounters, and the cognitive processes underpinning those responses. Furthermore, while humans often present a significant threat to animals, the presence or behaviour of people may be also associated with benefits, such as food rewards. In scenarios where humans vary in their behaviour, wild animals would be expected to benefit from the ability to discriminate between dangerous, neutral and rewarding people. Additionally, individual differences in cognitive and behavioural phenotypes and past experiences with humans may affect animals’ ability to exploit human-dominated environments and respond appropriately to human cues. In this review, we examine the cues that wild animals use to modulate their behavioural responses towards humans, such as human facial features and gaze direction. We discuss when wild animals are expected to attend to certain cues, how information is used, and the cognitive mechanisms involved. We consider how the cognitive abilities of wild animals are likely to be under selection by humans and therefore influence population and community composition. We conclude by highlighting the need for long-term studies on free-living, wild animals to fully understand the causes and ecological consequences of variation in responses to human cues. The effects of humans on wildlife behaviour are likely to be substantial, and a detailed understanding of these effects is key to implementing effective conservation strategies and managing human-wildlife conflict.

While many animals are negatively affected by urbanization, some species appear to thrive in urban environments. Herring gulls ( Larus argentatus ) are commonly found in urban areas and often scavenge food discarded by humans. Despite increasing interactions between humans and gulls, little is known about the cognitive underpinnings of urban gull behaviour and to what extent they use human behavioural cues when making foraging decisions. We investigated whether gulls are more attracted to anthropogenic items when they have been handled by a human. We first presented free-living gulls with two identical food objects, one of which was handled, and found that gulls preferentially pecked at the handled food object. We then tested whether gulls' attraction to human-handled objects generalizes to non-food items by presenting a new sample of gulls with two non-food objects, where, again, only one was handled. While similar numbers of gulls approached food and non-food objects in both experiments, they did not peck at handled non-food objects above chance levels. These results suggest that urban gulls generally show low levels of neophobia, but that they use human handling as a cue specifically in the context of food. These behaviours may contribute to gulls’ successful exploitation of urban environments.