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Behavior

Frequent Fallers: Fat penguins have trouble staying on their feet

 

 

Article:

Willener, Astrid ST, et al. “Fat King Penguins Are Less Steady on Their Feet.” PloS one 11.2 (2016): e0147784.

Background:

Fig. 1: Penguins are highly skilled swimmers having adapted to a semi-aquatic life (http://www.emperor-penguin.com/empswim.html).

Fig. 1: Penguins are highly skilled swimmers having adapted to a semi-aquatic life (http://www.emperor-penguin.com/empswim.html).

Penguins are highly adapted and specialized creatures. They are fast and agile, inducing fear among their fish prey. At least that’s the case when they are swimming (Fig. 1). Arguably, the most endearing thing about penguins is just how awkward they are when they walk, or rather, when they waddle on the ice sheets (Fig. 2). Fortunately for penguins, most of their predators are seals and orcas, so their awkwardness is not lethal (Fig. 3).

Penguins can’t help but waddle. Their short legs are an adaptation for increased swimming efficiency and reduce heat loss. While slow, waddling is more energetically efficient for penguins than walking – it lets them use the momentum and energy from one step and put it directly towards the next step.

 

Fig. 2: Penguin awkwardness is hard not to smile at (

Fig. 2: Penguin awkwardness is hard not to smile at (giphy.com).

Fig. 3: It's a good thing these guys don't have to worry about predation on land!

Fig. 3: It’s a good thing these guys don’t have to worry about predation on land! (radiotimes.com)

 

 

 

 

 

 

 

King penguins (Aptenodytes patagonicus) are the second largest species of penguins, measuring up to 40 inches tall and weighing up to 35 pounds when stuffed with fish (Fig. 4). They fast for up to a month during the breeding season, when they waddle inland and care for their chicks. King penguins then make the long journey to the sea in order to feed, bring back food for their young, and build up fat stores to make it through their next fast. As a result of this feeding, king penguins can put on the pounds, all of which is put on around their abdomen and pectoral muscles. The combination of short legs and waddling already puts these penguins in a precarious position, but by adding a significant amount of weight on the front of their bodies may make their movement even tougher based on a shift in their center of mass (Fig. 5).

Fig. 4: King penguin colony in South Georgia (https://travelwild.com/resources/antarctica-wildlife/king-penguin/).

Fig. 4: King penguin colony in South Georgia (https://travelwild.com/resources/antarctica-wildlife/king-penguin/).

Fig. 5: There is a shift in the center of mass for fatter penguins which may contribute to them falling more often (Astrid Willener).

Fig. 5: There is a shift in the center of mass for fatter penguins which may contribute to them falling more often (Astrid Willener).

 

 

 

 

 

 

 

 

Recently, researchers set out to find whether added weight alters the locomotion of these penguins, behavior that has actually been observed in humans of different weights.

The Study:

Antarctic researchers captured male king penguins, shortly after a feeding event, and observed their locomotion. Penguins were fixed with a small device placed along the spine at the level of their hip that could record acceleration and movement in three directions. Penguins were then run on treadmills (yes, there are such things as penguin treadmills!) (Fig. 6) where their acceleration in three directions, leaning angle, leaning amplitude, waddling amplitude, and stride frequency were recorded.

Fig. 6: Penguin treadmill. This was used to observe and collect data on locomotion (Astrid Willener).

Fig. 6: Penguin treadmill. This was used to observe and collect data on locomotion (Astrid Willener).

Penguins were run on these treadmills shortly after capture and again after two weeks of fasting in order to compare locomotion between fatter penguins and slimmer penguins.

Surprisingly, researchers ultimately did not find any differences in the locomotion of fat penguins and skinny penguins. However, high variability was observed in the leaning angle, amplitude, and waddling amplitude in fat penguins, indicating that fatter penguins are more unstable on their feet. This finding was supported by observational data which showed fat king penguins fall over a lot more.

The Significance:

Fig. 7: Oof! Shake it off buddy (reddit.com).

Fig. 7: Oof! Shake it off buddy (reddit.com).

This study shows that fat penguins might be more enjoyable to watch (Fig. 7). Well, maybe not that, but it is interesting to note that these penguins don’t change their locomotion based on their body size. Although they may fall more often when fatter, they do not make an effort to prevent that. This study does also highlight the use of new technology in observing animal behavior and locomotion.

Gordon Ober
PhD. Student/Ecologist/Craft Beer Enthusiast

I am a doctoral student in the Thornber Lab at the University of Rhode Island. I am a climate scientist and marine community ecologist studying how climate change, specifically ocean acidification and eutrophication, alters coastal trophic interactions and species assemblages. Before starting at URI, I received a BS in Ecology and Evolutionary Biology from the University of Connecticut followed by 2 years as a research assistant in autism genetics at Yale University.

Discussion

One Response to “Frequent Fallers: Fat penguins have trouble staying on their feet”

  1. This article “Frequent Fallers” is about how penguins are gaining so much weight that they can’t walk or waddle well anymore. You see penguins have very small feet which is suppose to help them swim fast and agile, in which they do, but with small feet they can’t really walk and are stuck waddling.During breading season, male penguins tend to fast and after fasting they eat a lot to get ready for the next breading season, making them fatter. As these penguins started getting fatter, they started to fall over more frequently. This made the researchers, worried about the penguins survival. Researchers started to test a slim penguins locomotion wth a fat penguins locomotion on a treadmill.Although they did not find any differences on their locomotions, they did find out that the leaning angle on a fat penguin is greater so it is harder for it to walk. I believe that this a prolem for the penguin population. You see, male penguins are required to carry around thier egg until it hatches, to keep the egg safe. They even have the egg under thier stomach, so the egg is warm. It would be much harder to take of the egg wihout freezing it or let it break if you keep falling. Fathers will not be able to take care of these in this condition. Therefore fat penguins are a problem. One question I would like to ask is what would help stop penguins from getting fatter? Can we change their diet?

    Posted by Ehram | May 26, 2016, 8:11 pm

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