Phase transitions in huddling emperor penguins

Richter S, Gerum R, Winterl A, Houstin A, Seifert M, Peschel J, Fabry B, Le Bohec C, Paranhos Zitterbart D (2018)

Publication Type: Journal article

Publication year: 2018

Journal

Book Volume: 51

Article Number: 214002

Journal Issue: 21

DOI: 10.1088/1361-6463/aabb8e

Abstract

Emperor penguins (Aptenodytes forsteri) are highly adapted to the harsh conditions of the Antarctic winter: they are able to fast for up to 134 days during breeding. To conserve energy, emperor penguins form tight groups (huddles), which is key for their reproductive success. The effect of different meteorological factors on the huddling behaviour, however, is not well understood. Using time-lapse image recordings of an emperor penguin colony, we show that huddling can be described as a phase transition from a fluid to a solid state. We use the colony density as order parameter, and an apparent temperature that is perceived by the penguins as the thermodynamic variable. We approximate the apparent temperature as a linear combination of four meteorological parameters: ambient temperature, wind speed, global radiation and relative humidity. We find a wind chill factor of -2.9 °C (ms^-1)^-1, a humidity chill factor of -0.5 °C/%rel. humidity, and a solar radiation heating factor of 0.3 °C (Wm^-2)^-1. In the absence of wind, humidity and solar radiation, the phase transition temperature (50% huddling probability) is -48.2 °C for the investigated time period (May 2014). We propose that higher phase transition temperatures indicate a shrinking thermal insulation and thus can serve as a proxy for lower energy reserves of the colony, integrating pre-breeding foraging success at sea and energy expenditure at land due to environmental conditions. As current global change is predicted to have strong detrimental effects on emperor penguins within the next decades, our approach may thus contribute towards an urgently needed long-term monitoring system for assessing colony health.

Authors with CRIS profile

Involved external institutions

Centre Scientifique de Monaco (CSM) Monaco (MC)

How to cite

APA:

Richter, S., Gerum, R., Winterl, A., Houstin, A., Seifert, M., Peschel, J.,... Paranhos Zitterbart, D. (2018). Phase transitions in huddling emperor penguins. Journal of Physics D: Applied Physics, 51(21). https://doi.org/10.1088/1361-6463/aabb8e

MLA:

Richter, Sebastian, et al. "Phase transitions in huddling emperor penguins." Journal of Physics D: Applied Physics 51.21 (2018).

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