The word penguin carries a specific image: ice, huge colonies, frozen sea. Almost the whole family fits that image. There is one exception, and it does not live near ice: it lives on black volcanic rock, at temperatures around 26 degrees, in an archipelago crossed by the line of the equator.
It is the Galápagos penguin, and its oddity is not only the heat it endures. It lies in a detail of geography that makes it a unique case worldwide.
01 Where the border actually is
Every other penguin on the planet lives in the southern hemisphere. Without exception. This one does too, for the most part: close to 90 % of the population is on Fernandina and the west coast of Isabela, with smaller nuclei on Santiago, Bartolomé, northern Santa Cruz and Floreana.
The difference is made by Isabela's shape. The island is about a hundred kilometres long and its northern tip lies above the line of the equator. Since the penguins occupy that coast, there are individuals that live, swim and breed in the northern hemisphere. It is the only penguin of which that can be said.
The fact sounds like trivia, but it is not: it describes precisely how far a band of cold water reaches into the middle of the tropics. That is the real boundary, and the penguin merely marks it.
02 The current that makes it possible
The story begins far to the south. The cold Humboldt Current rises from the coasts of Chile and Peru, and it was that current that carried the species' ancestors from South America to the archipelago. Without it there would be no penguins here.
What keeps them here, though, is another current: the Cromwell, also called the Equatorial Undercurrent, which runs beneath the surface from west to east and strikes the archipelago's western flank. On striking it, the cold, nutrient-rich water rises.
That upwelling feeds swarms of small schooling fish, and those fish are the basis of the penguin's diet. That is why the species is not spread evenly across the islands: it is where the cold water rises, and where it does not rise, the penguin is not.
It is not the only one that depends on that mechanism. On the same coasts lives the flightless cormorant, another endemic of the archipelago, which lost the ability to fly because in a sea this productive it had no need to travel far for food.
03 How to bear the heat in a penguin's plumage
The water may be cold, but the air and the rock are not. A penguin on black lava at midday on the equator has a serious physical problem: it wears plumage designed to keep heat in and stands on a surface that stores it.
The response is a collection of small gestures. It holds its flippers away from the body to lose heat through them, leans forward so its own shadow covers its feet, the most exposed part, and pants with its beak open to cool by evaporation, just as a dog does.
To that add where it settles. It does not nest in the open: it seeks caves and deep crevices in the lava, which keep the temperature stable and stop the eggs overheating. The same rock that complicates its day solves its nest.
04 A calendar without seasons
Pairs are monogamous and stay together for life. They lay one or two eggs, incubation lasts 38 to 40 days and the chicks become independent at 60 or 65 days. So far, nothing extraordinary for a penguin.
What is extraordinary is the annual rhythm. Penguins of high latitudes moult once a year, in a fixed period. This one moults twice. Living where there is no summer or winter but a food supply that shifts with the currents demands a different upkeep of the plumage.
Breeding follows the same logic. There is no date marked on the calendar: there is a condition of the sea. When the upwelling works and there are fish, they breed; when it does not, they postpone.
05 Eighteen hundred, and falling when the water warms
The population is small and always has been. Between 1993 and 2003 it hovered around 1,500 individuals; in 2003, 1,351 were counted; in 2018 some 1,200 breeding adults were estimated, and recent figures speak of around 1,800. It is listed as endangered.
What makes it fragile is precisely what it depends on. When the water of the equatorial Pacific warms during an El Niño event, the upwelling weakens, the fish vanish and the colony is left without food. Declines of between 65 % and 77 % of the population have been recorded in such events.
It is a dependency with no safety net. An Antarctic penguin can travel hundreds of kilometres looking for another fishing ground; this one lives on a very specific strip of coast and has nowhere to go.
06 How to look at it
The first practical consequence is that you will not see it on just any island. If the itinerary does not take in Fernandina or the west coast of Isabela, the odds drop sharply. It is not a question of luck: it is a question of being where the cold water rises.
The second is that its size disconcerts. Barely half a metre and two or three kilos: if you expect the silhouette of polar documentaries, the first surprise is how small it is and how little it resembles a colony. There are no thousands of birds together here, there are scattered pairs among the rocks.
And the third is the one that gives the fact its meaning. A penguin on the equator is not a charming curiosity: it is the visible proof that beneath those waters runs a cold current that has no business being there. When you see it panting on the lava, what you are really looking at is the map of the ocean.
