Galapagos Islands penguins have many unique traits which make it stand out from all other penguin species. The most unusual is where it lives, and when we cruise Galapagos we make the effort to see them during Zodiacs tours along the rocky shorelines. The Galapagos penguin, Spheniscus mendiculus, resides in the Galapagos Archipelago, a group of related islands which straddle the equator around 1000 km or 600 miles off the western coast of mainland South America. What makes it possible for them to survive on the equator is the presence of two cold ocean currents which affect the Galapagos Islands. From the southeast comes the Peruvian Coastal Current (also known as the Humboldt Current) that moves in a northwesterly direction as the Southeast Trade winds push the surface waters up the western coast of South America and then west along the equator. The movement of surface water results in up-welling along the length of the continental shelf off the western coastline. This brings enormous amounts of nutrients and cool, oxygen-rich water to the surface. As this prime water approaches the equatorial regions, the force of the tropical sunlight provides the final element needed to create one of the richest, overall marine environments in the world as the Peruvian anchovy industry evidenced for decades. The ancestor of the Galapagos Islands penguin is the Humboldt penguin which lives along the coast of Peru and northern Chile. It is likely that small flocks were occasionally washed offshore, however, molecular evidence indicates that around 4 million years ago a small population of Humboldt penguins successfully arrived in the islands and established a colony.
Penguins in the Galapagos Islands have their strongest numbers in the western regions of the archipelago due to the year-round up-welling of the Equatorial countercurrent, previously known as the Cromwell countercurrent. This keeps the water temperatures overall cooler throughout the year, even during a few months at the beginning of the year when the warm waters from the Panama region encroach on the archipelago. The Galapagos Islands penguins have adapted to survival in a marine environment with highly variable temperatures and a warm terrestrial environment. They have become considerably smaller than their ancestors, and are now the second-smallest species of penguin in the world after the fairy penguin/little blue because a smaller body mass is more efficient at radiating off heat than a larger body mass (law of thermodynamics). Galapagos water temperatures can range from 16º to 28ºC (60-82ºF), and the hot lava can get very hot at certain times of the year. Penguins in the islands maintain nesting and roosting sites inside the cool tubes and fissures to avoid as much heat as possible. Behaviorally, to cool off penguins hold their wings out at 45º angle allowing air to flow over less heavily-feathered areas; they can also increase blood flow to their feet and shade them, allowing for the convection of heat out into the air. It is thought heat loss can occur also through the facial skin around the bill, which on the Galapagos penguin covers a larger area than on any other species of penguin.
In years of a plentiful food supply, Galapagos Islands penguins can raise up to three broods of chicks in fifteen months, one or two eggs the norm. 90% of the Galapagos penguin population lives in the western region of the archipelago. In the early 1970’s, the first penguin census found around 6,000 to 15,000 individuals in Galapagos. After the El Nino of 1983, a census recorded the Galapagos penguin population down 77% to less than 500 individuals. Today, due to conservation measures and overall healthier years for the marine environment, we believe their numbers to range around 1,539 individuals (2008 census), although this number is down from 2,100 individuals from 2006. As can be seen, the changes in the population of the Galapagos penguin are indicative of an extreme sensitivity to changes in the environment and vulnerability to external factors. A recent study conducted in collaboration with the CDF and the GNPS indicated that the Galapagos penguin faces a 30% probability of extinction in the next 100 years due to the effect of increasing El Niño events. The Galapagos Islands penguin presently maintains a fragile hold in the islands but is receiving much attention from the science and conservation sectors.
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