Why are Humboldt Penguin endangered?

No, the Humboldt Penguin is not the only Penguin listed on the IUCN Red List. There are a total of 18 different penguin species listed on this list, ranging in status from "least concern" to "endangered" with the population trend decreasing. The Humboldt Penguin is listed as "vulnerable" with it's population trend decreasing, according to this list. For more details see sites listed below.