Impacts on the short-term physiology and behaviour of individual animals Short-term impacts are defined here as those that are reflected in the immediate responses of animals.
The responses of wildlife to external stimuli, such as approaches by tourists, areoften first expressed in the physiological state of the animal. Even if a disturbedanimal does not flee, or show other behavioural signs of disturbance, it mayexperience increased heart rate, body temperature or other endocrine responses tohuman presence (Ball and Amlaner 1980, Giese 1998). Elevated heart rate is regardedas indicating that an animal has perceived a threat associated with disturbance (Balland Amlaner 1980), and in some species increases in heart rate are consideredsynonymous with a stress response (Culik et al. 1990, Kosiorek and van den Hoff1994).Relationships have been identified between prolonged stress responses andsubsequent weight loss, reduced breeding success and increased vulnerability todisease (Siegel 1980). Direct relationships between elevated stress levels andreproductive effects have been made for sea lions (Harris and Leiper 1995), double-crested cormorants (Ellison and Cleary 1978), black skimmers (Safina and Burger1983) and auklets (Piatt et al. 1990)