Peru’s Coastal Guano Birds Face Crisis as Population Drops over 75%, Scientists Say

Reuters

11:01 JST, August 14, 2025

LIMA (Reuters) — Scientists along Peru’s central Pacific coast are sounding the alarm that more action is needed to protect seabirds, sea lions, and penguins as climate change, disease and overfishing threaten their survival.

Research shows the number of guano birds has dropped by more than three-quarters in the past three years to around 500,000, according to local biologists, down from a population of 4 million in 2022.

These black-and-white coastal birds form an important part of Peruvian wildlife, producing large quantities of excrement used as a natural fertilizer.

“We are very alarmed by this sharp decline,” said Susana Cardenas, director of the Environmental Sustainability Center at Peru’s Cayetano Heredia University in an interview with Reuters. She monitors marine life at the Punta San Juan reserve roughly 530 kilometers south of Lima.

Breeding centers like the one Cardenas runs are helping to protect bird populations that she described as “golden egg-laying hens” because they were so fragile, yet valuable.

Peru’s state agency AgroRural counted 587,000 guano seabirds in June, spread across 22 islands and eight coastal points, that include cormorants, boobies and pelicans. That figure is down from an average of 4 million registered in recent decades by Peru’s Agriculture Ministry.

Scientists said that the sharp decline began with an outbreak of avian flu in 2022 that killed tens of thousands of birds, penguins and sea lions. The El Nino weather phenomenon disrupted marine ecosystems the following year, and forced birds to migrate. Then in 2024, overfishing of anchoveta — a primary food source from the anchovy fish family — further depleted populations.

At Punta San Juan, only 200,000 guano birds, 2,500 Humboldt penguins and 11,000 sea lions remain, the research center found.

The decline in bird numbers is hurting the guano fertilizer harvest, important for the local farming industry.

This nutrient-rich fertilizer is collected every five years under government supervision and exported in controlled quantities. The last collection was in 2024, but with fewer birds, the “sustainability of this activity will be at risk,” Cardenas added.

Peru’s Agriculture Ministry said in a response to a Reuters request for comment on the decline that it was developing a national plan for the repopulation of guano birds with various different conservation entities.

In April, authorities allowed the biggest catch quota in seven years of anchoveta, used in fishmeal, citing larger populations. But biologists said that the anchoveta populations were still not large enough to sustain both fishing and the bird populations that depend on them.

Sea lions and penguins that live in colonies along the Pacific coasts of Peru and Chile were also at risk from dwindling food supplies caused by changing weather patterns and overfishing.

Humboldt penguins could be extinct in 100 years, Cardenas said, if protections failed to increase. “Their population is trending downward, especially in protected areas where growth is most needed.”