You might think that banging together two metal bars in close proximity to a penguin would be cruel. But it turns out that they actually don’t seem to mind too much, at least not if they’ve lived alongside similar noises for the last 50 years or so.

A new article published today in BMC Ecology outlines the efforts of a group of researchers to find out exactly what effect long term chronic disturbance from humans can have on wild populations of king penguins.

It’s well known that disturbance from humans can have detrimental effects  on some wild animal populations, and that this is a particularly troublesome issue in an age of increasing ecotourism and encroachment into wild spaces. Previous research has shown that other species of penguins can experience reduced breeding success in areas of high tourism, as well as reduced levels of offspring provisioning from parents. In other birds such as the unusual-looking hoatzin, juveniles may even be exposed to reduced survival in areas disturbed by large numbers of binocular-wielding visitors.

What is less well recorded is what effect scientists can have on these wild populations when they study them. But this is exactly what Vincent Viblanc and colleagues from University of Strasbourg, the Centre National de la Recherche Scientifique (CNRS) and the University of Lausanne set out to do when they devised the “sound stress” experiment involving metal bars and penguins. 

The research subjects – a large colony of king penguins residing in the subantarctic Possession islands – were well used to the presence of humans, with some penguins residing just meters away from a scientific research station that was established on the island in the early 1960s.

In order to replicate the typical disturbance experienced by these penguins from the research station, the team performed a number of chronic and acute stress tests on two groups of penguins living in contrasting areas of high and low disturbance. By strapping heart-rate monitors onto the experimental penguins, the researchers were able to gauge exactly how stressed their subjects were.

Intriguingly, they found that those penguins living in close proximity to the research station appeared to have become habituated to low-levels of human disturbance (including the metal bar test), although both groups were equally stressed by direct handling by the researchers.

Such a result suggests that long-term, low-level habituation to chronic stress may actually be beneficial to wild populations in helping them adjust to the presence of humans, and minimize their physiological investment in eliciting a stress response. This has profound implications for  researchers studying wild populations if they are to minimize the impacts of their work on their study subjects, and maximize the accuracy of their findings in the absence of unintended bias.

The next question posed by this research is to what extent this disturbance may be selective. For instance, it is not clear whether the penguins living in undisturbed areas are simply less used to human disturbance, or whether they actively seek out quieter areas to escape this stress.

As the number of tourists travelling to ever more remote locations continues to rise, we should probably try to find out.

You can read comments from the authors in an interview with our Press team here.

Images of penguins, hoatzins, or any other creature would also be welcome in the BMC
Ecology Image Competition.