The Guanay cormorant was once extremely abundant, with millions of individuals across its range, particularly in Peru and northern Chile. While it is still considered common, their numbers have significantly declined from historical levels due to various pressures.

The Guanay cormorant is primarily found along the Pacific coast of South America, especially from northern Peru to central Chile. They also breed on coastal islands and rocky shores in these regions.

While not currently listed as endangered, the Guanay cormorant faces threats from overfishing, which depletes their primary food sources, and habitat disturbances from human activities. Conservation efforts are focused on protecting their breeding sites and ensuring sustainable fishing practices.

Guanay cormorants are indeed threatened by climate change, mainly because of its effects on their marine environment.

El Niño and La Niña Events are natural climatic phenomena becoming more intense and frequent due to climate change. El Niño, in particular, causes warmer sea temperatures, which can reduce the availability of cold-water fish like anchovies and sardines that the cormorants rely on for food. During El Niño events, there can be massive die-offs or reproductive failures in Guanay cormorant colonies due to starvation.

Guanay cormorants are colonial breeders, often nesting in large, dense colonies. They build their nests out of guano (bird droppings) mixed with feathers and other debris, which can form substantial mounds over time. Both males and females share responsibilities for incubating eggs and raising chicks.

Another bird that also uses the Guanay's guano for its nest is the Humboldt penguin.