A Galápagos Penguin
The Galápagos penguin (Spheniscus mendiculus) is a penguin endemic to the Galápagos Islands of Ecuador. It is the only penguin found north of the equator. Most inhabit Fernandina Island and the west coast of Isabela Island. The cool waters of the Humboldt and Cromwell Currents allow it to survive despite the tropical latitude. The Galápagos penguin is one of the banded penguins, the other species of which live mostly on the coasts of Africa and mainland South America. Due to their warm environment, Galápagos penguins have developed techniques to stay cool. The feathers on their back, flippers, and head are black, and they have a white belly and a stripe looping from their eyes down to their neck and chin. Each penguin keeps only one mate, and breeds year-round. Because there is no soft areas to nest, their nests are typically in caves and crevices which also provide protection against predators and the harsh environment. The Galápagos penguin has a lifespan of 20 years, but due to predation, life expectancy in the wild could be significantly reduced. They have been critically impacted to the point of endangerment by climate change and pollution caused by plastic waste due to tourism and urbanization.
The average Galápagos penguin is 48–50 centimetres (19–20 in) tall and weighs around 2–4 kilograms (4.4–8.8 lb). It is the second-smallest species of penguin, after the little penguin. Females are usually smaller than males. Galápagos penguins have a black head with a white border running from behind the eye, around the black ear coverts and chin, to join on the throat. The top of the beaks are black and fade into pink on the bottom. They have two black bands across the breast that connect to the back, the lower band extending down the flanks to the thigh. Juveniles differ in having a wholly dark head, grayer on side and chin, and no breast band.
Many years ago, the Humboldt Current is believed to have brought the penguins from mainland South America to the Galápagos Islands, where they have evolved in isolation into a separate species. Islands such as Isabela Island contained cold and nutrient-rich waters that provided abundant food, ensuring the survival and reproduction of penguins. Over millions of years, the penguins underwent adaptations, developing unique features that enabled their existence and allowed them to thrive under such an ecological niche. Today, the Galápagos penguins are among the smallest penguin species.
Ninety percent of Galápagos penguins live on Fernandina Island and the west coast of Isabela Island, in the western part of the archipelago, but small populations also occur on Santiago, Bartolomé, northern Santa Cruz, and Floreana. The northern tip of Isabela crosses the equator, meaning that some Galápagos penguins live in the Northern Hemisphere, the only penguins to do so.
Galápagos penguins are confined to the Galápagos Islands, foraging in the cool Cromwell Current during the day and returning to the land at night. They eat small schooling fish, mainly mullet, sardines, pilchards and anchovies, and sometimes crustaceans.They play a role in regulating the populations of the marine species they consume. At the same time, the adult Galápagos penguins are a food source for other predators such as sharks and whales. They normally range only a few kilometers from their breeding sites, depending on the cold, nutrient-rich currents to bring them food.
Air temperatures in the Galápagos remain in the range 15–28 °C (59–82 °F). During El Niño seasons, the penguins defer breeding because their food becomes less abundant; this makes the chances of raising offspring successfully unfavorable compared to the chances of dying in the attempt. This was especially detrimental during the 1982-83 El Niño, where a decline in population of 77% was observed. The penguins usually breed when the sea surface temperature is below 25 °C (77 °F). The strong tropical sun is problematic for this species. Their primary means of cooling off is going in the water, but other behavioral adaptations for thermoregulation come into play when they must remain on land. One method involves stretching out their flippers and hunching forward to keep the sun from shining on their feet, which exchange heat rapidly because they have high blood flow and lack insulation. Another method is to pant, using evaporation to cool the throat and airways. Galápagos penguins protect their eggs and chicks from the hot sun by keeping them in deep crevices in the rocks.
The Galápagos penguins' flipper-like wings and streamlined bodies enhance their easy movements in water. Their white and black colors also aid in thermal regulation and camouflaging. All these features promote and ensure survival in the harsh conditions present in their coastal habitat, hence the symbiotic relationship between the Galápagos penguins and their natural environment. The penguins' breeding patterns depend on finding suitable nesting places within the volcanic landscape. The Galápagos penguins find refuge in the cool and dark lava caves, which provide the appropriate conditions for raising their offspring since they offer protection from the sun, ensuring survival. This indicates specific behavioral patterns and features that enhance their adaptability in this particular environment.
Galápagos penguins are a monogamous species, each pair mating for life. There are around 1,000 breeding pairs of Galápagos penguins in the world, and breeding depends on certain climate events. During El Niño, birds may not breed due to these climate conditions. After completing courtship, with rituals including bill dueling, flipper patting, and mutual preening, the pair will build and maintain a nest. Most nests are seen between May and July because both quantity of food and climate conditions are typically most optimal. The nests are made within 50 metres (160 ft) of the water on the shore. Adults stay near the breeding area during the year with their mate. It lays one or two eggs in places such as caves and crevices, protected from direct sunlight, which can cause the eggs to overheat. Temperature of surface water also influences reproduction as they prefer temperatures between 17 and 22 °C (63 and 72 °F) to incubate, above 25 °C (77 °F) causes their nests to fail. Incubation takes 38–40 days, with both parents incubating.
One parent will always stay with the eggs or young chicks while the other may be absent for several days to feed. A pair usually rears only one chick. Galápagos penguins will molt before they breed, and are the only penguins to do this twice a year. Molting takes up to 15 days to complete. They do this for their own safety, as food availability in the Galápagos is typically unpredictable. If there is not enough food available, they may abandon the nest.
It takes about 60–65 days for the chicks to become independent. Newly hatched chicks have downy feathers that do not become waterproof until the chicks grow into juveniles. The juvenile plumage, attained by thirty days after a chick hatches, is dark brown or gray above and white below. These feathers are mainly needed to protect the chicks from the strong sun rather than keep them warm.
Bermudian naturalist Louis L. Mowbray was the first to successfully breed the Galápagos penguins in captivity.