Fur Seal Meets Penguin: The Hunter vs. The Hunted

Seasonally abundant populations of some organisms are important to the ecosystem in which they are seasonally abundant. If the populations are over-hunted or over-bred, the ecosystem will be put out of balance and begin to degrade. Such an example is the Adélie penguin and Chinstrap penguin. They are relatively common in Antarctic waters, but recent work shows the importance to ecosystems common species. If the species were to decline even a little, the function, services, and structure of the ecosystem could collapse. The authors of this paper observed several encounters between the penguins (usually juvenile fledglings) and Antarctic fur seals.

The authors knew that the seals have hunted penguins before because it was done in an efficient, effective manner, and it did not look as though it was the seals first time at hunting penguins. They observed that after the catch, the seals would shake the penguin, ripping chunks of flesh, skin, and feathers off, swallowing the chunks. The authors observed a seal eating a carcass, but could not ascertain whether or not the seal killed or scavenged it. The authors also observed various sea birds taking advantage of the seals expertise in acquiring a penguin, and one bird (a Giant Petrel) actually “stole” a penguin carcass from a fur seal. The bird and the seal both had a carcass and were observed to be eating the flesh or stomach contents of the bird. It is possible that these hunting events occur wherever the penguins and fur seals ranges overlap.

Figure 1. A subadult male fur seal grasping a fledgling Adelie penguin (Photo by INV)

The two types of penguins and the fur seals are all common species in the Antarctic, and they overlap quite profusely. It is unknown how or why the fur seals hunt the penguins. It is possible that they learned their technique from Giant Petrels or other species of seals, such as the Leopard Seal which is known to regularly hunt penguins. The authors think it is possible that the seals supplement their typical diet with penguins in an opportunistic manner. They also think that penguin predation is a more regular occurrence than previously recognized due to the high amount of penguin feathers in seal scat.

 When examining the scat of many different seals from several different islands, it was found that the seals diet was predominately penguin with some krill (due to the pink coloration). Species of penguin was undetermined. The high amount of predation is thought to be near the end of the season when fledgling chick’s numbers are high and adults are returning from hunting, thus having a full stomach. This may suggest that penguins are actually an important part of the seals diet, and not just an opportunistic meal. If the fledglings are targeted only in an opportunistic manner, long term effects will be minimal. However, if they are targeting adult penguins, the effect will hit both the adults and the chicks, decreasing populations sizes overall. This could affect penguin ecology in general. 

Although this entire paper was based off of a few observations of fur seals preying on penguins thus making it partially biased, it may also indicate an increase in fur seal predation on penguins that are seasonally abundant, and this could cause a long-term decline in penguin numbers if the seals and their preying ways continue to increase. This paper was designed in the hopes of encouraging other naturalists to document observations such as these. It would be of great value for scientists to conduct systematic observations at different locations to determine the scope of this predation in its entirety.

References 

Orca Research Trust - Scientific Articles

The Plight of the Penguins

            Everyone loves penguins. From their distinctive waddle, to their tuxedo-like coloration, everyone can recognize these flightless birds. Mostly found on the frozen wastes of Antarctica, penguins are known for their swimming prowess as well as their ability to withstand the frigid conditions of their home. However, trouble looms on the horizon for these birds, as an international research team has discovered a strain of avian flu in the adélie penguin.

The adélie penguin

(Photo credit: George F. Mobley)

            The adélie penguin, Pygoscelis adeliea, is one of the more common species of penguin. Roughly 70 cm tall, these short penguins were discovered in 1840 by James Dumont d’Urville, a French explorer. The adélie penguin is typically found on small islands surrounding the coast of Antarctica, during the spring breeding season. Otherwise, they tend to spend most of their time out at sea, searching for food. Adélie penguins typically will eat krill and other small marine creatures, but will eat small fish and squid as well.

            While these penguins are incredibly good swimmers, reaching speeds of 72 km/hr. and diving to depths of 175 meters, they are also remarkably good walkers as well. Despite having the distinctive penguin waddle, these birds will walk 31 miles to go from their nests to the shoreline. The penguins’ main threat lies from predation by leopard seals and skuas, as well as the occasional orca.

            But there might be a new threat from these little penguins, one that could be much more dangerous, avian flu. This comes as a shock to Dr. Aeron Hurt, a senior researcher for the WHO Collaborating Centre for Reference and Research on Influenza, as no active strain of avian flu had ever been seen in Antarctic birds before. For this study, Hurt and his team collected swabs from the windpipes of 301 penguins and blood from 270 of those birds as well.

            Using real-time reverse transcription PCR, Hurt and his team found avian influenza genetic material in eight of the birds. Four of these viruses were able to be cultured, meaning that they were active and infectious. Not only that, but these strains of influenza all seemed to be H11N2 influenza viruses and were all very similar to each other. Worst of all, when comparing this genetic material to other known strains of influenza, Hurt and his team discovered that this strain was unlike anything they had ever seen before.

Dr. Aeron Hurt with an adélie penguin

(Photo credit: Aeron Hurt)

            Luckily, it seems that currently the virus isn’t doing any damage to the penguins and is not making the birds sick. It also appears to be exclusive to birds, as it couldn’t infect a species of weasel that the researchers used. However, it raises a lot of question for Hurt and his team. Namely, how often are avian influenza viruses being brought into Antarctica, whether animal ecosystems are allowing the virus to sustain itself, and whether or not the virus is being cryopreserved during the winter? For now, all we can try to do is keep trying to find where these virus strains are coming from and trying to find a cure before they mutate into something much more dangerous for the adélie penguin.

References:

http://animals.nationalgeographic.com/animals/birds/adelie-penguin/

https://www.asm.org/index.php/journal-press-releases/92941-distinct-avian-influenza-viruses-found-in-antarctic-penguins

Adélie Penguins: Winners of Climate Change?

http://static.dramastyle.com/images/3/10/7142/Happy-Feet-Two_7142_10.jpg

You may recognize the little guys above from the movie Happy Feet.  They were the feisty penguins with a Latin spice.  They are actually a specific type of penguin known as Pygoscelis adeliae or more commonly, the Adélie penguin.  These penguins inhabit the Antarctic coast, and in the movie, their home consists of nests made of rocks which is actually accurate.  In fact, in the video below, you can see what these nests look like.

Adorable, right?  All cuteness aside, from this video you can grasp the type of habitat that these penguins live in.  Adélie penguins need just the right amount of ice.  They use the ice for foraging, resting, molting, and migrating.  However, too much ice can result in energy-costing foraging trips and lower breeding success.  Their population success has been a recent topic of study with the rise in temperature in the Antarctic which can be seen in the graph below.

Average summer temperatures in degrees Celsius recorded at McMurdo Station, about 90 km south of Beaufort Island, Antarctic from 1958-2010 

Research suggests that the Adélie penguin population may actually be benefiting from this increased temperature.  A study conducted at Beaufort Island, Ross Sea, Antarctica (pictured below) showed just that.

Study area at Beaufort Island, Ross Sea, Antarctica. Left, the location of the Ross Sea; middle, the location of Beaufort Island, and right, the location of the main Adelie penguin colony

The results of this study showed that the habitat for the Adélie penguins in the Beaufort colony had actually increased by 71% since 1958.  This was attributed to the retreat of glaciers as well as the decrease in unsuitable snow patches.  It was these conditions that led to the expansion in the population as well as the increased immigration and decreased emigration in the area (which can be seen in the figures below).

Techniques in this study could be used to further survey the population distribution of these penguins in response to environmental factors.  In fact, in another study it was seen that plasticity of foraging response could be disrupted by extreme events such as sudden increases in sea ice concentrations.  

So are the Adélie penguins a winner in this temperature rise in the Antarctic?  I would say, from this data, it's quite possible.  However, the study only looked at the main colony of Adélie penguins, and have not done research on the other colonies present.  With further research, a more concrete answer could be given.

References:

1. Michelle A. LaRue, David G. Ainley, Matt Swanson, Katie M. Dugger, Phil O′B. Lyver, Kerry Barton, Grant Ballard. Climate Change Winners: Receding Ice Fields Facilitate Colony Expansion and Altered Dynamics in an Adélie Penguin Metapopulation. PLoS ONE, 2013; 8 (4): e60568 DOI:10.1371/journal.pone.0060568
2. Amélie Lescroël, Grant Ballard, David Grémillet, Matthieu Authier, David G. Ainley.Antarctic Climate Change: Extreme Events Disrupt Plastic Phenotypic Response in Adélie Penguins. PLoS ONE, 2014; 9 (1): e85291 DOI:10.1371/journal.pone.0085291