The Humboldt penguin (Spheniscus humboldti) is a medium-sized penguin. It resides in South America, its range mainly contains most of coastal Peru. Its nearest relatives are the African penguin, the Magellanic penguin and the Galápagos penguin. The Humboldt penguin and the cold water current it swims in both are named after the explorer Alexander von Humboldt. The species is listed as vulnerable by the IUCN with no population recovery plan in place. The current population is composed of 32,000 mature individuals and is going down. It is a migrant species.
Humboldt penguins are medium-sized penguins, growing to 56–70 cm long and a weight of 2.9 to 6 kg. The sex of the Humboldt penguin cannot be recognised via differences in plumage, as they are monomorphic. The male is heavier and larger than the females. Their sex can be determined via head width and bill length; the male has a longer bill than the female.[ While all the Spheniscus penguins are close to each other in size, the Humboldt penguin is the heaviest species in the genus, with 123 females weighing 4.05 kg on average and 165 males averaging 4.7 kg. Humboldt penguins have a black head with a white border that runs from behind the eye, around the black ear-coverts and chin, and joins at the throat. They have blackish-grey upperparts and whitish underparts, with a black breast-band that extends down the flanks to the thigh. They have a fleshy-pink base to the bill. Juveniles have dark heads and no breast-band. They have spines on their tongue which they use to hold their prey.