Although first seeing people is stressful for the penguins, habituation is rapid. The authors monitored the defensive head turns and the level of a hormone secreted in response to stress (plasma corticosterone) of penguins when encountering humans. "Head turns of penguins visited for 10 days were significantly lower than those of penguins visited for 5 days and were not significantly different than for penguins living in the [much frequented] tourist area," the authors explain. However, the authors stress that these results focus on the immediate. The consequences of the penguin's changing behavior may not become apparent until later in life.
When approached in their nest, Magellanic Penguins turn their heads back and forth, looking at the approacher with one eye and then both. When stressed, the increase in their hormones facilitates their ability to escape or outlast the situation. As stated, the results show no short-term negative impact of human visits, but long-term effects have not been reported. "These long-term consequences are much harder to document, especially in long-lived animals such as Magellanic Penguins," the authors conclude. "Our data shows that quantifying the consequences of human disturbances on wildlife is rarely simple and straightforward."
Magellanic Penguins nest in coastal colonies along the southern Atlantic and Pacific oceans of South America. The penguins in the study live in the largest and most visited colony of Magellanic Penguins at Punta Tombo, Argentina. More than 70,000 people now visit annually.