Little penguins are more aggressive on islands that experience greater unregulated human disturbance

Abstract

Animals living near urban habitats face many pressures linked with human disturbance. While individuals vary in their ability to cope with disturbance, it is predicted that individuals in highly disturbed environments will be bolder and more aggressive than those in less disturbed environments. Using little penguins, Eudyptula minor , we investigated whether individual aggressiveness was consistent across trials and whether aggressiveness was greater in colonies that experience higher levels of unregulated human disturbance. We scored aggressiveness at the nest, based on the penguins’ response to a standardized nest intrusion experiment, across four penguin colonies in South Australia. Nest defence scores were significantly repeatable over two trials, suggesting that it was a good indicator of personality in little penguins. Island was a significant predictor of nest defence score, with little penguins on Granite Island (the island with the greatest amount of unregulated human disturbance) being more aggressive than those on Troubridge Island (the island with the lowest amount of human disturbance). Considering that humans increasingly interact with animals, whether directly or indirectly, understanding the mechanisms behind nonrandom distribution of behaviours may have important implications for population management and conservation. • Animals in highly disturbed environments should be bolder and more aggressive. • In little penguins, nest defence scores were repeatable. • Aggressiveness correlated with levels of unregulated human disturbance. • Behavioural variation in relation to disturbance may be important for conservation.