The Galapagos penguin (Spheniscus mendiculus) is the most northerly of all penguins, occurring on the Galapagos Islands, on the equator. It is the smallest of the South American penguins, with an average length of less than 50 centimeters.
This diminutive penguin has a black head and upperparts, with a narrow white line extending from the throat around the head to the corner of the eye. The underparts are white, with two black bands extending across the breast. The upper part of the bill and the tip of the lower part of the bill are black, but the rest of the bill and a bare patch around the eye and bill are pinkish yellow. The female Galapagos penguin is generally smaller than the male. Juveniles have a completely dark head, and lack the dark breast bands seen in adults. The Galapagos penguin has a longer and more slender bill than other penguins.
The Galapagos penguin displays a great number of unique behavioural adaptations that allow it to inhabit the Galapagos Islands and keep cool on land. These include standing with the flippers extended to aid heat loss, as well as panting and seeking shade. When standing on land, it tends to adopt a strange hunched posture, which shades the bare feet, a major site of heat loss.
The flexibility of breeding in the Galapagos penguin allows it to take advantage of times of high food abundance. When the surface temperature of the sea becomes high, the water becomes very poor in nutrients resulting in food shortages. During these periods, known as El Nino Southern Oscillations (ENSO), the Galapagos penguin will delay breeding completely until food resources improve.
Pair bonds are for life, enabling the Galapagos penguin to begin breeding quickly when conditions improve. The bond is reinforced by mutual preening and bill tapping. Two eggs are produced at an interval of around four days. Incubation takes up to 40 days and is shared by the male and female. After 30 days, the chicks develop plumage to protect them from the sun, and the chicks fledge after 65 days.
The Galapagos penguin is endemic to the Galapagos Islands, Ecuador. Approximately 95 percent of the population occurs on the western islands of Ferdinandina and Isabela, with the remaining 5 percent on Bartolome, Santiago and Floreana. This species has the smallest breeding range and lowest population size of any penguin. In 2007, the population numbered just 1,000 individuals.
The Galapagos penguin nests in cracks, caves and depressions in the island’s lava flows. It feeds near the shore in cool, nutrient-rich oceanic waters, where there is an abundance of prey year-round.