Penguin Facts: Habitat, Behavior, Diet

Penguins (Aptenodytes, Eudyptes, Eudyptula Pygoscelis, Spheniscus, and Megadyptes species, all in the Spheniscidae family) are perennially popular birds: chubby, tuxedo-clad creatures that waddle charmingly across the rocks and ice floes and belly flop into the sea. They are native to oceans in the southern hemisphere and in the Galapagos Islands.

Description

Penguins are birds, and although they may not look like our other feathered friends, they are, indeed, feathered. Because they spend so much of their lives in the water, they keep their feathers slicked down and waterproofed. Penguins have a special oil gland, called a preen gland, that produces a steady supply of waterproofing oil. A penguin uses its beak to apply the substance to its feathers regularly. Their oiled feathers help keep them warm in the frigid waters, and also reduce drag when they're swimming. Although penguins have wings, they can't fly at all. Their wings are flattened and tapered and look and function more like dolphin fins than bird wings. Penguins are efficient divers and swimmers, built like torpedoes, with wings designed for propelling their bodies through the water instead of air.

Of all the recognized species of penguins, the largest is the Emperor penguin (Aptenodytes forsteri), which can grow to four feet in height and 50–100 pounds in weight. The smallest is the little penguin (Eudyptula minor) which grows to an average 17 inches in length and weighs about 3.3 pounds.

Habitat

Don't travel to Alaska if you're looking for penguins. There are 19 described species of penguins on the planet, and all but one of them lives below the equator. Despite the common misconception that all penguins live among the icebergs of the Antarctic, that's not true, either. Penguins live on every continent in the Southern Hemisphere, including Africa, South America, and Australia. Most inhabit islands where they aren't threatened by large predators. The only species that lives north of the equator is the Galapagos penguin (Spheniscus mendiculus), which, in line with its name, resides in the Galapagos Islands.

Diet

Most penguins feed on whatever they manage to catch while swimming and diving. They'll eat any marine creature they can catch and swallow: fish, crabs, shrimp, squid, octopus, or krill. Like other birds, penguins don't have teeth and can't chew their food. Instead, they have fleshy, backward-pointing spines inside their mouths, and they use these to guide their prey down their throats. An average-sized penguin eats two pounds of seafood per day during the summer months.

Krill, a small marine crustacean, is a particularly important part of the diet for young penguin chicks. One long-term study of the diet of gentoo penguins found that breeding success was directly related to how much krill they ate. Penguin parents forage for krill and fish at sea and then travel back to their chicks on land to regurgitate the food into their mouths. Macaroni penguins (Eudyptes chrysolphus) are specialist feeders; they depend on krill alone for their nutrition.

Behavior

Most penguins swim between 4–7 mph underwater, but the zippy gentoo penguin (Pygoscelis papua) can propel itself through the water at 22 mph. Penguins can dive hundreds of feet deep, and stay submerged for as long as 20 minutes. And they can launch themselves out of the water like porpoises to avoid predators below the surface or to return to the surface of the ice.

Birds have hollow bones so they're lighter in the air, but a penguin's bones are thicker and heavier. Just as a SCUBA divers use weights to control their buoyancy, a penguin relies on its beefier bones to counteract its tendency to float. When they need to make a quick escape from the water, penguins release air bubbles trapped between their feathers to instantly decrease drag and increase speed. Their bodies are streamlined for speed in the water.

Reproduction and Offspring

Nearly all penguin species practice monogamy, meaning a male and female mate exclusively with each other for the breeding season. Some even remain partners for life. The male penguin usually finds itself a nice nesting site before attempting to court a female.

Most species produce two eggs at a time, but emperor penguins (Aptenodytes forsteri, the largest of all the penguins) raise just one chick at a time. The emperor penguin male takes sole responsibility for keeping their egg warm by holding it on his feet and under his folds of fat, while the female journeys to the sea for food.

Penguin eggs are incubated between 65 and 75 days, and when they are ready to hatch, the chicks use their beaks to break the shell, a process which can take up to three days. Chicks weigh about 5–7 ounces at birth. When chicks are small, one adult remains with the nest while the other forages. The parent tends to the chicks, keeping them warm until their feathers develop in about 2 months, and feeding them regurgitated food, a period which varies between 55 and 120 days. Penguins reach sexual maturity between three and eight years of age.

Conservation Status

Five species of penguins are already classified as endangered (Yellow-eyed, Galapagos, Erect Crested, African, and Northern Rockhopper), and most of the remaining species are vulnerable or near threatened, according to the International Union for Conservation of Nature's Red List. The African penguin (Spheniscus demersus) is the most endangered species on the list. 

Threats

Scientists warn that penguins worldwide are threatened by climate change, and some species may soon disappear. Penguins rely on food sources that are sensitive to changes in ocean temperatures, and dependent on polar ice. As the planet warms, the sea ice melting season lasts longer, impacting krill populations and penguin habitat.

Sources

• Barbraud, Christophe, and Henri Weimerskirch. "Emperor Penguins and Climate Change." Nature 411.6834 (2001): 183–86. Print.
• BirdLife International. "Spheniscus demersus." The IUCN Red List of Threatened Species: e.T22697810A132604504, 2018.
• Bradford, Alina. "Penguin Facts: Species & Habitat." Live Science, September 22, 2014.
• Cole, Theresa L., et al. "Ancient DNA of Crested Penguins: Testing for Temporal Genetic Shifts in the World’s Most Diverse Penguin Clade." Molecular Phylogenetics and Evolution 131 (2019): 72–79. Print.
• Davis, Lloyd S. and John T. Darby (eds.). "Penguin Biology." London: Elsevier, 2012. 
• Elliott, Kyle H., et al. "High Flight Costs, but Low Dive Costs, in Auks Support the Biomechanical Hypothesis for Flightlessness in Penguins." Proceedings of the National Academy of Sciences 110.23 (2013): 9380–84. Print.
• Lynch, Heather J., William F. Fagan, and Ron Naveen. "Population Trends and Reproductive Success at a Frequently Visited Penguin Colony on the Western Antarctic Peninsula." Polar Biology 33.4 (2010): 493–503. Print.
• Lynch, H. J., and M. A. LaRue. "First Global Census of the Adélie Penguin." The Auk: Ornithological Advances 131.4 (2014): 457–66. Print.
• "Species Profile for African penguin (Spheniscus demersus)." ECOS Environmental Conservation Online System, 2010.
• "Threats to Penguins," Defenders of Wildlife.
• Waluda, Claire M., et al. "Long-Term Variability in the Diet and Reproductive Performance of Penguins at Bird Island, South Georgia." Marine Biology 164.3 (2017): 39. Print.
• Waters, Hannah. "14 Fun Facts About Penguins." Smithsonian, April 25, 2013.