The Effect of Disturbance on the Heart Rate and Behaviour of Adélie Penguins (Pygoscelis adeliae) During the Breeding Season

Summary

The behaviour and heart rate of nine incubating Adélie penguins (Pygoscelis adeliae) and one chick at crèche age were recorded in a breeding colony at Esperanza Station, Antarctica, during natural activity and disturbance. Heart rates were obtained by safety-pin electrode ECG and implantable radio-transmitters. In adults, minimal heart rate at rest was 86 bpm (beats per minute), rising to a maximum of 127 bpm when the birds were standing. Heart rates reflecting the degree of disturbance rose from resting levels to 110, 118, 127 and 145 when the stimulus was sheathbill, congener, human and helicopter, respectively. In the chick, normal heart rates were higher by 140 bpm than in adults (2.2 kg as opposed to 4.5 kg). Heart rates during natural activity ranged from 220 (sleep) to 287 bpm (food run). Disturbance resulted in heart rate increasing from resting levels to 240 (congener), 260 (approaching helicopter), 273 (helicopter overhead) to 310 bpm (capture by a human). Helicopters even when 1500 m away caused scattering of the birds and other panic reactions. A hand-reared chick in an enclosure did not show any fearful reaction (behaviour, heart rate) to helicopter approach whilst the observer was standing close by which indicates habituation to human disturbance. We propose that wild Adélie penguins, although often seemingly unconcerned, react strongly to man-made stimuli during the breeding season, resulting in reduced fledging and hatching success. Disturbance should be kept to a minimum.