Abstract
Animal populations are increasingly challenged by anthropogenic environmental changes. Species, populations and individuals vary in their ability to cope with exposure to human proximity. However, little is known about what drives habituation or sensitization in wild populations. Via behavioural observations and heart rate telemetry during experimental disturbance, we determined the habituation potential of yellow-eyed penguins, Megadyptes antipodes, a key species for nature-based tourism in southern New Zealand. Individual birds differed significantly in both their initial stress response and habituation potential. While some birds did not habituate, or even appeared to be sensitized by frequent disturbance, others habituated. Individual variation in habituation potential depended on previous experience with humans, sex and character (i.e. timid, calm or aggressive). Birds that were exposed to research that involved frequent interactions at the nest site, including blood sampling, several years prior to our experiments were less likely to habituate. Overall, females were more flexible than males in their stress response pattern, and calm individuals appeared to adapt more readily than aggressive birds. Character, classified during penguin-researcher interactions at the nest site, was independent of sex, age or previous experience, and was consistent over two seasons. Initial heart rate response to human approach, also similar between seasons, varied with sex and character of an individual. Yellow-eyed penguins may habituate to short and consistent approaches, but appear unsuitable for unregulated tourist visits at nest sites. Individual differences in habituation potential to human disturbance can have fitness consequences and may lead to contemporary evolutionary change in the composition of breeding populations. (C) 2008 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.