Penguins are popular and instantly recognizable birds, but they can also be finicky eaters with a restricted diet that is threatened by irresponsible practices. A better understanding of what penguins eat can help promote the protection and conservation of their food-rich habitats and give penguin rehabilitators more resources for successfully meeting these unique birds' dietary needs.
Penguins are carnivores with piscivorous diets, getting all their food from the sea and relying on clean, healthy seas for rich sources of nutritious prey. The exact foods different penguin species take depends on their range, bill size and shape, foraging behavior, and other factors, but the most common foods include:
- Fish: Silverfish, lantern fish, sprats, pilchards, mullets, anchovies, sardines, cod, opal fish, and other small fish are the majority of most penguins' diets. Large populations of these types of fish are essential for penguins to thrive.
- Crustaceans: Smaller penguins may eat large quantities of krill, and other crustaceans such as shrimp and crabs make up small parts of some penguins' diets.
- Cephalopods: Occasional squid and cuttlefish make up a small part of some penguins' diets, particularly larger penguin species that are able to dive deeper while foraging.
Many penguins are opportunistic feeders and will sample a wide variety of different prey. They will adapt their feeding patterns to match what foods are most widely and easily available at different times of the year and in different parts of their range.
Penguins hunt all of their prey in the ocean, and their amazing swimming abilities and keen underwater eyesight give them predatory advantages. Hunting tactics vary by species and may include both deep and shallow dives to seek out prey. Those techniques may change depending on the habits of their preferred foods as oceanic currents and weather patterns change with El Niño years or other mitigating factors.
The distance penguins travel to hunt can also vary widely. For example, emperor penguins often travel 300-500 miles or further from their nesting sites to forage for several weeks at once, while Galapagos penguins rarely venture further than a mile from their nests to seek out prey. Many penguins hunt in small groups, but others, such as the yellow-eyed penguin, prefer solitary ventures.
Because penguins depend on their highly insulated plumage as protection and waterproofing, they undergo severe fasting periods during molting. It is not unusual for a penguin to lose 25-55 percent of its body weight while molting because it cannot enter the ocean to feed, and nesting penguins may also suffer severe weight fluctuations between foraging trips. Fast periods can last for several weeks and are typically preceded and followed by lengthy foraging trips when the bird will regain significant amounts of weight.
When penguins do catch a fish or other type of prey, they swallow it whole. These birds do not have a crop, but their two-chambered stomach stores food in the first chamber, the proventriculus, so it can be carried back to chicks. The majority of digestion takes place in the bird's gizzard, with the aid of grit to help crush tougher materials.
Captive Penguin Diets
Penguins in captivity do not undergo the long fasting periods or weight fluctuations that wild birds face. Instead, their diets are strictly controlled by rehabilitators, biologists, zookeepers, veterinarians, and other caretakers, and they are typically hand-fed whole or chopped fish similar to what their wild cousins would be able to catch. Occasional supplements may be added to captive penguins' diets as needed to ensure a solid nutritional balance essential to keep them healthy in their unique, artificial habitats.
Help Feed Penguins
While no penguin is a backyard species, and they will not visit fish ponds no matter how well-maintained they may be, birders can still help "feed" penguins. Because penguins' diets depend on healthy oceanic habitats, reducing water pollution and litter is essential to preserve penguins' food supplies. Birders who eat fish themselves should always be sure their own food is obtained through responsible, wildlife-friendly fishing practices or farming techniques. Support laws that protect the ocean can help protect penguins' food sources as well. Donations are always welcome at penguin rehabilitation facilities or conservation centers that specialize in seabirds and penguins, and those donations can help provide a healthy meal for resident penguins.
By understanding what penguins eat and how they hunt, birders can help ensure that these unique and charismatic birds have just as many rich, healthy food sources as any land-based bird, keeping penguin populations thriving for many generations of birders to enjoy.
Davis, Malcolm. The Molt Of The Emperor Penguin. The Auk, vol 62, no. 1, 1945, pp. 144-144. Oxford University Press (OUP), doi:10.2307/4079981