Coordinated Movements Prevent Jamming in an Emperor Penguin Huddle

• Published in: PLoS ONE
• Main Authors: Zitterbart, Daniel P., Wienecke, Barbara, Butler, James P., Fabry, Ben
• Format: Text
• Language: English
• Published: Public Library of Science 2011
• Subjects: Research Article; Antarctic; The Antarctic; Huddle; Antarc*; Aptenodytes forsteri; Emperor penguins
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3106014; http://www.ncbi.nlm.nih.gov/pubmed/21673816; https://doi.org/10.1371/journal.pone.0020260

For Emperor penguins (Aptenodytes forsteri), huddling is the key to survival during the Antarctic winter. Penguins in a huddle are packed so tightly that individual movements become impossible, reminiscent of a jamming transition in compacted colloids. It is crucial, however, that the huddle structure is continuously reorganized to give each penguin a chance to spend sufficient time inside the huddle, compared with time spent on the periphery. Here we show that Emperor penguins move collectively in a highly coordinated manner to ensure mobility while at the same time keeping the huddle packed. Every 30–60 seconds, all penguins make small steps that travel as a wave through the entire huddle. Over time, these small movements lead to large-scale reorganization of the huddle. Our data show that the dynamics of penguin huddling is governed by intermittency and approach to kinetic arrest in striking analogy with inert non-equilibrium systems, including soft glasses and colloids.