30 May 2013

Penguin diving through the scales of time

Little penguin.
Photo credit: Phillip Island Nature Parks.
AUSTRALIA - An international research team has uncovered complex patterns in little penguin dives and revealed a sophisticated level of organised and adaptive behaviour.

The detailed patterns are like the repeated design on a head of broccoli, or the intricate geometry found in growing crystals, swirling galaxies and heart rates. The term “fractals” is used to describe these repeated patterns across varying spatial or temporal scales.

“If you look at a head of broccoli you can see a series of bumps and swirls. These patterns are repeated as you look closer and closer. We took fractal analysis one step further to study diving behaviour of penguins,” said Dr Andrew MacIntosh, leading study author from the Kyoto University, Japan.

To look at this behaviour, the researchers attached miniature computers to the backs of little penguins at Phillip Island near Melbourne, Australia.

“The computers recorded thousands of sequential dives and allowed the research team to examine diving patterns from very fine to very large time scales,” explained Dr Yan Ropert-Coudert from the Centre National de la Recherche Scientifique (CNRS) in France.

The research, published today in Nature’s open access journal Scientific Reports, reveals a remarkable similarity between the patterns in little penguin dives lasting around 2.5 minutes to diving that extended for up to 5.5 hours.

“This reflects the presence of some general organising principle underlying penguin behaviour,” said Dr MacIntosh.

Fractal patterns are thought to be well attuned to changing environments and the research team believes the complex patterns observed in diving may provide an optimal foraging solution for little penguins.

If dive sequence complexity is lost it may be an indication that little penguins are operating in a sub-optimal state.

“Think of the stereotypical repetitive and functionless swimming patterns displayed by penguins and seals confined to small tanks and in some zoo and aquaria,” said Dr MacIntosh.

For the wild penguins of Phillip Island, the new insight into the intricacies of their diving behaviour will contribute to their conservation.

“The complexity of diving behaviour can be related to the reproduction and survival resilience of animals in a changing environment,” said Dr AndrĂ© Chiaradia, a penguin biologist from Phillip Island Nature Parks where the penguin dives were recorded.

“Understanding the complexity of little penguin dives is a powerful tool for responding to observed changes in their behaviour that may indicate a negative change in their environment.”

Phillip Island Nature Parks has been conducting penguin research for over 43 years. The self-funded, not-for-profit organisation reinvests ecotourism revenue into conservation, research and education programs across the parks. The fractal research was also funded by grants from the Japan Society for the Promotion of Science and the Kyoto University Primate Research Institute, Centre National de la Recherche Scientifique (France), Region d’Alsace (France), the French National Research Agency and the Australian Academy of Science.

Source
Broccoli bumps linked to penguin dives [press release], 27 May 2013, Phillip Island Nature Parks

Scientific Reports citation
MacIntosh, A.J.J., Pelletier, L., Chiaradia, A.,  Kato, A., & Ropert-Coudert, Y. (2013). Temporal fractals in seabird foraging behaviour: diving through the scales of time. Scientific Reports, 3, 1884. doi:10.1038/srep01884

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