Humboldt penguins Spheniscus humboldti

The Italian naturalist Antonio Raymondi once visited the Islas Chincha in Central Peru, in the middle of the 1800s. He was amused to find "hundred of thousands" Humboldt penguins breeding in burrows dug by themselves in the guano deposits. By that time, the Peruvian Government allowed to some European countries to harvest the guano (bird drops used as a rich soil fertilizer) as a mean of external debt payment. Guano was mined from the islands with adverse effects not only on birds that produced it (cormorants, boobies and pelicans), but also on seabirds that depended upon it. Humboldt penguins were maybe one of the most affected as they use the guano for building their burrows and because they do not fly, becoming easy target for guano workers. If you visit the Islas Chincha now, you will only sight some scattered groups of penguins in small islets. Penguin numbers on these islands does not exceed 100 birds.

Human population in the coast increased in the nineteenth century and less natural habitats for penguins were available. A growing fishing industry developed in the 1960s which led to the collapse of anchovy stocks (the main prey of penguins) in 1973. Fishermen did not only overfished the Humboldt penguin food, but poached them for food and collected chicks as pets. They still do so. Likewise, at least 10,000 wild Humboldt penguins were exported to foreign zoos between 1939 and 1978, a number much larger than that found in the wild. In September 1977, the Peruvian Government classified the Humboldt Penguin as vulnerable species and in 1981 this bird was listed in Appendix I (endangered status) of the Conservation on International Trade in Endangered Species of Wild Fauna and Flora, which prohibits international trade.

In 1981 the population size of Humboldt penguins in Peru was estimated at 4500 - 6000 birds (Hays 1984). Twenty years later, after the occurrence of El Niño 1997-98, one of the strongest on record, approximately 5,000 birds were counted in Peru. The most important breeding colony was located at Punta San Juan (15^o22'S), which held between 36% and 41% of the total population in 1999 and 2000. Why the Humboldt penguin population in Peru is not increasing?

Humboldt penguins are affected by humans, but also by natural factors like El Niño events. Humboldt penguin numbers fluctuate under natural conditions because the marine environment where they live is highly unpredictable. To avoid natural extinction, Humboldt penguins are well-adapted to cope with changes in food supply. Thus, they have a high breeding frequency and in "good years" some pairs can have two clutches (they lay two eggs per clutch) in a year and successfully rear four chicks. They can also reach sexual maturity at early age (2 years) and replace clutches if they lost their eggs. Recruitment of young birds into the adult population is very important for Humboldt penguins. In good years, up to 30%-35% of chicks that leave their nests return to their colonies the following years. This is a high rate of recruitment for a penguin, but in poor years only a few number will come back. Nobody knows where chicks go after fledging. All we know is that they are not on land for at least six-eight months. The resources they depend upon at sea is crucial for their conservation and some data show that when anchovy biomass is high in the southern coast, more fledglings will be back the next year. Thus, the knowledge of the feeding areas of juveniles is an important concern for future research. All these traits make possible that the population increases sharply after El Niño years and that numbers can be large enough to face the next El Niño. The increase of El Niño occurrence in the last decades and the quick depletion of marine resources by humans even after El Niño years, challenge future Peruvian conservationists in the following years. 

Humboldt penguins are generalist predators, and this is also an advantage in an unpredictable environment. Although anchovies, silversides and squid are the preferred preys, Humboldt penguins can feed on more than 50 different species of fish when anchovies are not available. Even if anchovies are not available for other seabirds (anchovies migrate to deep cold waters in warm years), Humboldt penguins can dive deep (up to 150 m) to reach them. However, fishermen set gill nets to capture other fish species near their breeding grounds and hundreds of penguins accidentally die entangled in the nets.

The choice of a good nest is important for breeding pairs. If the nest is located far away from ocean swells and if it is covered with a roof, Humboldt penguins will have a breeding success better than those nesting in beaches or seacaves (Paredes and Zavalaga 2001). Burrow nests in the guano deposits of the cliff tops or slopes are the best, so avoid guano harvest in these nesting sites is decisive for its conservation. Artificial nests set on poor quality habitats may be another solution to increase breeding success of penguins (Paredes and Zavalaga 1998). In order to secure the long-term survival of Humboldt penguins in Peru, the solution is to leave the guano untouched and to reduce the levels of disturbance and poaching during guano harvesting. This has been successfully done at Punta San Juan in 2001 through a sign agreement between the Wildlife Conservation Society in Peru (directed by Dr. P. Majluf) and PROABONOS (the Government agency in charge of the Guano Reserve System). This agreement allowed WCS to keep observers during harvests and to fence off the penguin colonies so they were excluded from harvesting.