by Nataly H. Aranzamendi
Penguins feed on fish, plankton and all kinds of jellyfish standing at the top of the food chain. Most top predators do not worry much about being eaten, since they are generally the hunters. But penguins are not quite at the top of the food web, more in the middle, a position called a mesopredator. Penguins have some natural enemies threatening them both in the ocean and on land. Let’s meet their most famous aquatic foes.
Leopard seals are vicious hunters with a bad reputation. Their big size (almost 3.5 m on average and up to 320 kg)1, solitary nature and aggressive behavior give most people the chills, especially when seeing them hunt underwater. Although leopard seals prey on large proportions of fish, Emperor penguins comprise their main penguin prey. There are also records of leopard seals attacking King, Adelie, Rockhopper, Chinstrap and Gentoo penguins1,2. Their favorite hunting technique is the ambush. Leopard seals hover under ice edges, almost completely underwater waiting for the birds to jump in the ocean1.
One of the leopard seal’s favorite tactics is to wait for juvenile penguins to jump in the water for the first time. Seals know that young penguins are still not experienced in the water, and in particular have difficulty at swimming and hunting simultaneously, thus these young penguins become a relatively easy prey to catch.
Seals also wait for those moments when penguin abundance is at its greatest, for example, during the breeding season2. Leopard seals attack adult penguins during foraging trips. Penguins have no choice, as they need to venture into the ocean regularly, because they need to feed their partners and offspring. The leopard seal’s successful hunting technique makes them one of the most feared predators in the Antarctic ecosystem.
Photo source: gailhampshire from Cradley, Malvern, U.K [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)]
Killer whales have a diverse diet, but it has been observed that different populations specialize in specific types of prey3 . Although penguins are not their main prey items, the orca’s distribution range overlaps with that of several penguins in Antarctica, therefore, it is not surprising that orcas occasionally feed on penguins.
Orcas have been recorded preying on Emperor, Gentoo and Chinstrap penguins3,4. The magnitude of the predation impact by killer whales on penguin populations has not yet been quantified4. Two types of orcas have been identified chasing penguins: type B, seal specialists and type A, whale specialists, although with no records of predation for the latter3.
Unlike leopard seals, orcas are highly organized social animals that live in family groups. Killer whales have shown fascinating hunting techniques and an extremely advanced communication system between members. One thing that is absolutely fascinating about killer whales is that such behaviors are passed from generation to generation and now scientists believe that this is a clear evidence of animal culture3.
One technique used by orcas to catch penguins and seals is to perform “wave hunting.” In this technique, swimming groups create waves that are aimed to flip pieces of floating ice where penguins are resting. Once the ice is flipped, there is (almost) no escape for the prey3 .
The evidence for sea lions and fur-seals preying on penguins is more extensive. Although most sea lions are largely dependent on fish and smaller marine vertebrates, many of them have been recorded preying on penguins.
For example, Antarctic fur seals have been documented preying on King penguins ashore5. Similarly, South American sea lions have been observed attacking and killing Rockhopper and Gentoo penguins in Argentina, Chile and the Falkland Islands6,7. Sea lion predation on penguins has been observed both during swimming at sea and while resting on land.
Finally, there are records of New Zealand sea lions feeding on yellow-eyed penguins. In this case, the sea lions are from a recovering population with numbers steadily increasing. This increase may cause a major threat to these endangered penguins if predation rates intensify8 .
So far, we have discovered a variety of penguin enemies living and hunting in the same waters as penguins. Nonetheless, penguins are also at risk on land, where more enemies await for adults and their offspring. Stay tuned to discover our next story.
To be continued….
What do you think about where penguins sit on the food chain? Let us know! Also, please help us continue to learn more about penguins by donating to Penguins International. We more than appreciate your support!
You can also read more about penguins in the following blogs:
Penney, R. L., & Lowry, G. (1967). Leopard seal predation of adelie penguins. Ecology, 48(5), 878-882.
Pitman, R. L., & Durban, J. W. (2010). Killer whale predation on penguins in Antarctica. Polar Biology, 33(11), 1589-1594.
Hofmeyr, G. J. G., & Bester, M. N. (1971). Predation on king penguins by Antarctic fur seals. Vol 4.
Rey, A. R., Samaniego, R. S., & Petracci, P. F. (2012). New records of South American sea lion Otaria flavescens predation on southern rockhopper penguins Eudyptes chrysocome at Staten Island, Argentina. Polar biology, 35(2), 319-322.
Cursach, J. A., Suazo, C. G., & Rau, J. R. (2014). Depredación del lobo marino común Otaria flavescens sobre el pingüino de penacho amarillo Eudyptes c. chrysocome en isla Gonzalo, Diego Ramírez, sur de Chile. Revista de biología marina y oceanografía, 49(2), 373-377.
Lalas, C., Ratz, H., McEwan, K., & McConkey, S. D. (2007). Predation by New Zealand sea lions (Phocarctos hookeri) as a threat to the viability of yellow-eyed penguins (Megadyptes antipodes) at Otago Peninsula, New Zealand. Biological Conservation, 135(2), 235-246.