The Humboldt penguin, Spheniscus humboldti, is a medium-sized species endemic to the Pacific coast of South America. Its geographic range extends along the highly productive, cold-water current that flows from southern Chile north to Peru, a current from which the species takes its name. The penguins breed on rocky coasts and offshore islands, utilizing burrows or sea caves for nesting. The unique oceanographic conditions of this region create the foundation for the entire marine ecosystem, directly influencing the life and distribution of this flightless seabird.
Primary Dietary Components
The Humboldt penguin functions primarily as a piscivore, meaning its diet is overwhelmingly dominated by fish. The majority of its intake comes from small, schooling fish species found in the pelagic zone of the ocean. This focus on dense aggregations of prey allows the penguins to maximize their energy return during foraging trips.
While fish constitute the bulk of their meals, cephalopods, such as squid, also form a regular and important part of the diet. The consumption of cephalopods and other secondary prey items, like small crustaceans, often increases when primary fish stocks become scarce or unavailable. Overall diet composition can vary significantly between northern and southern colonies, reflecting the local availability of schooling fish species.
Specific Prey Species
The core of the Humboldt penguin’s diet relies on two highly abundant forage fish species: the Peruvian Anchovy (Engraulis ringens) and the South American pilchard (Sardinops sagax). These are the foundational energy sources, particularly for colonies in central Chile. These species thrive due to the exceptional productivity of the Humboldt Current, which brings cold, upwelled water rich in plankton to the surface. The penguins’ food supply is directly dependent on the health and stability of this current ecosystem.
Other fish species are consumed regularly when anchovy and pilchard stocks are less available. Secondary prey items include the Araucanian herring (Strangomera bentincki) and various silversides (Odontesthes regia). In northern parts of the range, colonies may consume significant amounts of garfish (Scomberesox saurus). The ability to switch between these schooling species demonstrates necessary adaptability in an environment known for natural variability in prey distribution.
Foraging Strategy and Technique
Humboldt penguins are visual, diurnal hunters, generally leaving their colonies after sunrise to forage. They employ an active pursuit diving strategy, using their powerful, paddle-like wings to “fly” through the water and chase down fast-moving prey. Although they have been recorded diving up to 150 meters, the majority of foraging occurs within the upper 30 meters of the water column, targeting shallow schools of pelagic fish.
When feeding chicks, adults typically undertake short trips lasting around 10 hours, but they may make overnight trips exceeding 25 hours to meet their own energy needs. A key physiological adaptation that supports their marine lifestyle is the supraorbital gland, a specialized salt gland located above the eyes. This gland efficiently filters excess sodium chloride ingested from seawater and marine prey, excreting a concentrated brine that often appears to drip from the bill.
Environmental Impacts on Food Availability
The availability of the Humboldt penguin’s primary food source is highly susceptible to large-scale oceanographic changes. The El Niño Southern Oscillation (ENSO) events are the greatest natural threat to their food security. During an El Niño, the cold, nutrient-rich upwelling of the Humboldt Current is disrupted by an influx of warm surface water. This warming causes preferred prey, like anchovies, to disperse, move deeper, or migrate south out of the foraging range.
The resulting scarcity forces penguins to significantly increase foraging efforts. During strong El Niño events, penguins may travel up to 895 kilometers from their colonies and spend substantially more time diving. This food stress leads to widespread breeding failure and mass starvation, causing population declines as high as 65% in some years. Compounding this natural variability is intense commercial fishing pressure, which directly targets the same anchovy and sardine stocks the penguins depend on, reducing the overall prey base.