Peru’s arid coastline holds a surprise for many visitors: a breeding population of Humboldt penguins, the country’s sole penguin species. These birds have endured repeated shocks in recent years, first from a severe outbreak of avian influenza and then from the disruptive effects of a strong El Niño event. Their numbers fell sharply as a result, leaving the population more vulnerable than before. Now scientists are tracking signs that another powerful El Niño is developing, raising fresh concerns about the species’ long-term prospects.
The Scale of the Recent Decline
Between 2022 and 2025 the Humboldt penguin population along Peru’s coast dropped by roughly two-thirds. The losses came in quick succession. An outbreak of H5N1 avian influenza struck breeding colonies in 2022, killing large numbers of adults and chicks. The following year, El Niño conditions altered ocean temperatures and reduced the availability of the small fish the penguins rely on for food. Recovery has been slow. Penguins require stable food supplies and safe nesting sites to rebuild numbers, yet both have remained limited. Researchers monitoring colonies near San Juan de Marcona report fewer breeding pairs returning each season. The sharp reduction has also narrowed the genetic diversity within remaining groups, which can make future recovery more difficult.
How Warmer Waters Disrupt Daily Life
Humboldt penguins feed primarily on Peruvian anchovy, a fish that thrives in the cold, nutrient-rich waters of the Humboldt Current. During El Niño years, warmer surface temperatures push this current deeper and farther offshore. Penguins must then swim longer distances to find enough food, which leaves less energy for breeding and chick-rearing. Observations from the current season already show adults spending more time at sea. Chicks left unattended for extended periods face higher risks from heat and predators. Similar patterns appeared during the 2023 event, when many nests failed. Scientists note that the intervals between strong El Niño episodes appear to be shortening, leaving less time for populations to rebound between disturbances.
The Added Pressure of Avian Influenza
The 2022 bird flu outbreak arrived at a moment when colonies were already stressed by changing ocean conditions. The virus spread rapidly among densely nesting birds, resulting in high mortality. Even after the initial wave subsided, lingering effects on breeding success continued into subsequent seasons. Health monitoring continues at key sites. Experts emphasize that another disease event coinciding with food shortages could compound the earlier losses. Vaccination or other interventions remain limited for wild seabirds, so prevention relies mainly on reducing additional stressors such as habitat disturbance.
What Researchers Are Watching Now
Climate scientists have stated that El Niño conditions are expected to develop with high probability in the coming months. United Nations Secretary-General António Guterres recently noted the 90 percent certainty of its arrival and warned that impacts will intensify an already warming world. For Humboldt penguins, that means continued shifts in prey distribution and potentially harsher breeding conditions. Andres Lescano of the Latin American Center for Climate Research has pointed out that climate change is increasing both the frequency and severity of these events. Field teams are therefore expanding monitoring efforts to track foraging ranges, chick survival rates, and any new signs of disease. Data collected this year will help refine predictions for how the species might respond if conditions worsen. The situation remains fluid. While some colonies show limited signs of adaptation, such as shifting nesting locations slightly, the overall trend points to ongoing pressure. Continued observation and protection of critical coastal habitats offer the clearest path to supporting the penguins through the next cycle of environmental stress.
