Tagus Cove, Galapagos

This is a real treat, watching Galapagos penguins (Spheniscus mendiculus) playing and hunting in the cold surf of northern San Isabela. This area is perfect for these polar creatures, as the waters around the Galapagos are unusually cold thanks to the Cromwell and Humboldt currents, which carry frigid, nutrient-rich seawater from South America and along the equator.

Here in northern San Isabela, the penguins have the Cromwell current to thank for their ability to live here. The current runs east, along the equator, pulled by eastern blowing trade winds and flowing through the Galapagos until it hits the underwater slopes of San Isabela. This forces cold, nutrient-rich and oxygen-rich water up to the surface in a process called upwelling. The great masses of plankton that rise up increase the population of small fish, which increases the population of larger fish, which in turn increases the population of sea lions, flightless cormorants and penguins. 

Even with the cold water from the Cromwell current, the tropical Galapagos are far too warm for most penguin species. In response, these penguins have undergone the evolutionary process of insular dwarfism. This is when, due to limited food resources and less pressure from predation, animals on islands evolve to be smaller than their counterparts on the mainland.

Galapagos penguins are about half the size of their Antarctic ancestor, and, at a diminutive 20in (50cm) in height, are the second-smallest species of penguin in the world (after the little penguin of New Zealand). The penguin's small size has a threefold advantage. Firstly, it allows heat to dissipate more efficiently, keeping it cooler in the tropical heat. Secondly, the small size means the penguin needs less food, helpful for managing limited food supplies on a small island and fluctuations in fish density. Finally, a small size means less body fat, and therefore less insulation for the penguin, allowing even more heat to escape. Over time and through natural selection, these traits have come to define the Galapagos penguin, helping it survive as the only penguin species found north of the equator.

Even so, despite the cold water and the insular dwarfism, it’s still a bit warm for penguins, and so they’ve evolved a series of behaviours to keep themselves cool. These include panting like dogs and stretching out their wings to dissipate heat. They also exploit the volcanic environment of the islands by hiding in lava tubes to avoid the midday sun, an especially important chill-out zone for baby penguins who are more sensitive to the tropical heat.

Although the Galapagos penguin has evolved against all the odds to survive here, the reality of climate change and plastic pollution has devastated their populations, leading them to be declared an endangered species in 2000 by the IUCN. Galapagos penguins are uniquely vulnerable to a warming climate, and the truth is that if we do not stop burning fossil fuels and treating our natural world as a rubbish tip, these unique, fascinating creatures will vanish in the near future, along with thousands of other species, unadapted, as they are, to a changing climate.