What food do penguins eat?
When readily caught, nutritious fish are in short supply, as is the case around South Africa due to overfishing and climate change, penguins are forced to turn to alternative fish species.
Most penguin species are piscivorous, meaning their diet consists entirely of fish. For some, such as African penguins, an abundance of small, nutritious fish such as anchovies or sardines is important to help them get through their fasting period - when they go hungry for weeks while new feathers grow - and to provide a healthy diet for their young.
Examples include Atlantic mackerel (Trachurus trachurus) and pelagic goby (Sufflogobius bibarbatus), which are often available but do not contain all the nutrients penguins need. Eating these fish means penguins have to spend more time hunting and use up even more than before.
In Antarctic and subantarctic waters, where small migratory fish are scarce, penguins have adapted to eating crustaceans such as krill, which are the main source of food for smaller penguins such as Adélie and chinstrap penguins. African penguins are generalists and will also eat shrimp if necessary, but this is not a sustainable diet for them, and they are not as adapted to hunt this type of prey as northern rockhoppers (the species of rockhopper present here in the aquarium).
Although jellies are very low in calories, at least four species (Magellanic, Adélie, yellow-eyed, and little penguins) are known to actively hunt jellyfish, even when nutritious prey is available. Scientists speculate that perhaps the jellies provide penguins with a nutrient that their other prey lacks, such as collagen, or that penguins selectively prey on carnivorous jellies—thus consuming all the microscopic animals that the jellies have collected.
Squid are quite low in calories compared to oily fish like anchovies, but when they migrate in large numbers, the energy saved by eating nearby squid is enough to keep hungry penguins going.
Humans want to eat the same high-calorie foods that penguins eat. When we overfish the species that penguins depend on, they have to swim to eat less nutritious food. For African penguins and other species with semi-fixed colonies, this means that adults are not eating enough to provide enough energy to feed themselves and their young. The result – an ecological trap that leads to chick abandonment and the decline of the endangered penguin population.
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