Adelie penguins (Pygoscelis adeliae) live and breed in an physiologically demanding environment that requires individual birds to respond rapidly to fluctuating environmental conditions. The physiological and metabolic response of adelie penguins to stresses (helicopters, the presence of people and handling) were assessed and monitored using a visible/near infrared optical spectrometer attached to ... the back of individual birds. The instrument measures changes in heart rate, blood oxygenation, redox state of cytochrome oxidase and blood flow in the peripheral tissues. Only non incubating birds and those not going to sea were selected, 23 birds in total. Upon capture, the beak length and depth, flipper length and width and weight of the bird was measured to help determine the sex. The intrument was added to the back of the bird and they were released. Observations of the birds behaviour was recorded every minute. The main periods of stress were after the inital capture and during deliberately stressed periods when observers stressed the bird by standing 2-5 m from it for 2 minutes during the observation period.