Groups of emperor penguins protect from the cold thanks to social huddling.

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Emperor penguins breed during the cold Antarctic winter, where temperatures can reach -30C and below. To conserve energy and protect themselves from the cold, they adopt a behavioral strategy of huddling close together in large groups. Huddling is considered key to their ability to live in such a cold place. They have different huddling patterns across different breeding stages, with the largest number of penguins huddling during the egg incubation period, when the males must survive fasting while also trying to keep their eggs warm.

Within a huddle, emperor penguins shift their position in a wavelike movement. Every 30-60 seconds a penguin will move, triggering neighboring penguins to also move. These actions/reactions result in a wave of movements across the huddle, which over time leads to large scale movement of the huddle. This can increase the size of the huddle, by allowing smaller huddles to eventually join together. These small movements also affect the organization of the huddle by increasing the density, from creating a more orderly arrangement as each penguin finds their ideal position.

Over time, huddles grow larger as individual penguins join or other huddles join together, causing the penguins to be more tightly packed together, which can sometimes cause the penguins to get too hot. When they need to get rid of the excess heat, the penguins leave the huddle in an abrupt breakup. This relatively slow increase in huddle size followed by rapid separation is a behavior that further allows them to regulate their exposure to unwanted temperature.

To learn more about social huddling in emperor penguins and the research exploring this phenomenon, watch this bioGraphic video entitled, “Lens of Time: Huddle Masters” by Spine Films.

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“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.” (Zitterbart et al. 2011:e20260)

Journal article
Coordinated movements prevent jamming in an emperor penguin huddlePLoS ONE 6(6): e20260June 1, 2011
Zitterbart DP, Wienecke B, Butler JP, Fabry B

“Social thermoregulation is a cooperative strategy in which animals actively aggregate to benefit from the warmth of conspecifics in response to low ambient temperatures. Emperor penguins, Aptenodytes forsteri, use this behaviour to ensure their survival and reproduction during the Antarctic winter. An emperor penguin colony consists of a dynamic mosaic of compact zones, the so-called huddles, included in a looser network of individuals. To maximize energy savings, birds should adjust their huddling behaviour according to environmental conditions. Here, we examined the dynamics of emperor penguin aggregations, based on photo and video records, in relation to climatic factors. Environmental temperature, wind and solar radiation were the main factors contributing to huddle formation. The analysis of individual movements showed that birds originating from loose aggregations continually joined huddles. Sometimes, a small number of birds induced a movement that propagated to the entire huddle, causing its breakup within 2 min and releasing birds, which then integrated into looser aggregations. Different parts of the colony therefore appeared to continually exchange individuals in response to environmental conditions. A likely explanation is that individuals in need of warmth join huddles, whereas individuals seeking to dissipate heat break huddles apart. The regular growth and decay of huddles operates as pulses through which birds gain, conserve or lose heat. Originally proposed to account for reducing energy expenditure, the concept of social thermoregulation appears to cover a highly dynamic phenomenon that fulfils a genuine regulatory function in emperor penguins.”  (Ancel et al. 2015: 91)

Journal article
New insights into the huddling dynamics of emperor penguinsAnimal BehaviourDecember 1, 2015
André Ancel, Caroline Gilbert, Nicolas Poulin, Michaël Beaulieu, Bernard Thierry

Journal article
Huddling behavior in emperor penguins: Dynamics of huddlingPhysiology & BehaviorJuly 30, 2006

Journal article
The origin of traveling waves in an emperor penguin huddleNew Journal of PhysicsDecember 16, 2013
R C Gerum, B Fabry, C Metzner, M Beaulieu, A Ancel, and D P Zitterbart

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Emperor PenguinAptenodytes forsteriSpecies

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