Even well-meaning tourists can stress out penguins.
A new study published in the journal BMC Ecology contrasts with earlier research that concluded tourism had no immediate, negative effects on penguins.
"To some extent, all human activities appeared to affect penguins, as we always recorded a heart rate stress response to the various stressors we exposed the birds to," lead author Vincent Viblanc told Discovery News, adding that "our results do not mean that tourism should be prevented.
"Strict guidelines and rules for observing the animals from a distance, using binoculars for instance, with minimal noise should be implemented and abided by," said Viblanc, a researcher in the Department of Ecology and Evolution at the University of Lausanne.
He and colleagues Andrew Smith, Benoit Gineste and René Groscolas made the determinations after studying a king penguin colony on the protected Possession Island in the sub-Antarctic Crozet Archipelago. The penguin population there has experienced over 50 years of constant human disturbance.
For the study, the researchers compared 15 king penguins, breeding in areas disturbed daily by humans, with 18 penguins breeding in undisturbed areas. All selected penguins were brooding a chick aged from 2 days to 1 month.
The scientists mimicked the actions of tourists, by approaching the penguins up to about 33 feet (10 meters) and making noise. In addition to hearing sounds created directly by humans, many of the penguins are also regularly exposed to noise pollution from machines that operate on the outskirts of the colony.
Penguin heart rate, an indicator of stress, went up in each instance, although the birds reacted "differently to various stressors depending on whether they were in a colony area subjected to continuous human presence or not," Viblanc said.
The researchers next captured certain penguins and again measured their stress. In this case, the birds’ responses were not attenuated.
"This makes sense," Viblanc explained, "when considering that captures can be assimilated to predation events, and it would be costly for the birds not to respond adequately to them by mounting a stress response. On the other hand, mounting a stress response when observing tourists at a distance is not necessary, and birds then save energy and avoid deserting their egg or chick by habituating to those 'non-dangerous' stressors."
The penguins that often see and hear humans therefore somewhat get used to people, although the health effects over time of raised heart rate levels — even minor increases — remain unknown for penguins.
"What the research suggests is that penguins habituate to the presence of tourists, which are observing them from a distance," Viblanc explained. "Stress habituation in this species may be a way to deal with distant observers, which the penguins have learned to be non-dangerous."
He and his colleagues believe that their conclusions could apply not only to other penguin species, but also to many other animals. In this case, the animals refer to wild ones impacted by tourism, researchers themselves, and other forms of well-intended human interference.
Brian Walker of Gonzaga University and his team had previously studied Magellanic penguins and found no immediate negative effects due to tourism. Walker and his colleagues, however, noted that "long-term consequences are much harder to document, especially in long-lived animals such as Magellanic penguins. Our data shows that quantifying the consequences of human disturbances on wildlife is rarely simple and straightforward."
Viblanc said, in future, he might try to compare the levels of stress hormones in penguins breeding in areas of frequent human disturbance with those in penguins breeding in undisturbed regions. Such studies might also attempt to see if potential chronic stress impacts reproductive behavior and other aspects of penguin health.