What to do if you don't have enough food? Little penguins will go home to "eat their parents"

Conservation biologist Dee Boersma first came into contact with the Galapagos Islands when she was a student in 1970. Over the past few decades, time has left its mark on her face, but traveling to the Galapagos Islands year after year is still Boersma's routine job.

Recent photo of Boersma | thewholeu.uw.edu

As an important place that inspired Darwin's thoughts on the origin of species, the Galapagos Islands is a holy place in the hearts of every biological researcher . However, the charm of the islands that has fascinated this "Jane Goodall in the field of penguin protection" for many years is far more than just a "pilgrimage": on the Galapagos Islands, which lie across the equator, live the penguins that she is always concerned about - the Galapagos penguins (Spheniscus mendiculus).

Galapagos penguin | Wikimedia Commons

Are there penguins in the tropics?

In most people’s common perception, penguins are always closely associated with the icy Antarctic. However, among the 18 existing penguin species[1], only the emperor penguin and the Adélie penguin can be considered pure “Antarctic natives”. Most other penguins do not breed in the Antarctic continent . They are only “passers-by” in the Antarctic, attracted by the abundant krill and fish during the polar day. Some temperate zone penguins will never set foot in the Antarctic in their entire lives. In fact, the earliest scientifically described penguins were discovered by sailors in the Age of Exploration on the coasts of South America, Africa and Australia. But after the Antarctic continent was explored, penguins were quickly and one-sidedly associated with the mysterious continent as the most common, densest and most beautiful life scene in the icy wilderness.

Approximate distribution range of existing penguins | wikipedia.org

In this way, the Galapagos penguins living on the equator are indeed a group of outliers. From the perspective of anatomical structure and geographical distribution, the Galapagos penguins seem to be the descendants of a group of wandering Humboldt penguins . The key to their drifting to the archipelago far away from the mainland and surviving to this day is the power of the Peruvian cold current. The surging ocean currents carry the cold waters of the Southern Ocean to the vicinity of the Galapagos, thus achieving the northern limit of the penguins' distribution. Since the northern end of Isabela Island, the main island of the Galapagos Islands, has crossed the equator, a small group of Galapagos penguins breeding here have even extended the distribution area of ​​this species to the northern hemisphere .

Galapagos penguins live near the equator | williamstephen56 / Wikimedia Commons

The cold current provides the Galapagos penguins with a basic survival guarantee, but it is far from enough to reproduce in the harsh tropical islands. In 1970, Boersma, who was attracted by the penguins, soon noticed this: she found that the survival pressure of the tropical environment has brought many changes to the body structure of the Galapagos penguins. Compared with the Humboldt penguins, the Galapagos penguins have shrunk in size by 25%, their fat has become thinner, and their feathers are more fluffy and sparse .

Galapagos penguins have even sparser feathers | Mike Weston/ Wikimedia Commons

Compared with other penguins, the molting mechanism of the Galapagos penguin is very unique. It is the only penguin that sheds its feathers twice a year , which is probably related to the higher intensity of feather damage. At the depth where the Galapagos penguins forage, the sea water temperature can drop to about 15°C, but when they go ashore to rest, they have to face temperatures of 40°C and the fierce scorching tropical sun . The changes in temperature and ultraviolet damage make feathers more susceptible to loss. Frequent replacement of feathers is an inevitable choice for Galapagos penguins.

But this choice is not easy for the Galapagos penguins. The waters around the Galapagos are not rich, and the presence of offshore fish schools depends largely on another ocean current running near the islands - the Pacific Equatorial Undercurrent . This ocean current running from west to east is hidden less than 100 meters below the ocean surface. The upwelling generated by its collision with the Galapagos seamounts brings nutrients from the bottom to the sea surface, nourishing the herring schools that provide food for most marine life on the island.

Galapagos penguin fishing underwater | annikaml / Wikimedia Commons

However, this undercurrent is very susceptible to the El Niño-Southern Oscillation (ENSO) phenomenon . When El Niño occurs, the undercurrent often weakens or shifts northward. Without the upwelling, the fish population around the Galapagos Islands will drop sharply. For Galapagos penguins, their smaller size cannot support them to follow the fish schools to more distant seas to find food. The smaller fat reserves evolved to fight the heat have also become a weak point in famine years.

Impact of extreme weather

In fact, many habits of Galapagos penguins have shown that this irregular food shortage has long existed. Even in the breeding season, penguins are always on guard against sudden changes in ocean currents. Unlike other penguins that hatch two eggs at a time, Galapagos penguins will deliberately stagger the time of laying and hatching two eggs. If there is a sudden change in food supply, the second egg will be abandoned without hesitation. Food shortage even affects the habit of sub-adult penguins to leave the nest. Boersma has found more than once that sub-adult penguins, who are supposed to hunt independently, have returned to their parents to beg for food after many futile attempts at sea.

Juvenile Galapagos penguin | aquaimages / Wikimedia Commons

Since 1970, Boersma has witnessed several catastrophes: the El Niño phenomenon in 1972/73 directly caused penguins to give up breeding, and the El Niños in 1982/83 and 1997/98 successively hit the Galapagos penguin population. According to her statistics, the Galapagos penguin population has declined by 70% since 1970.

A comparison of an emaciated penguin during an El Niño year (left, February 2016) and a healthy penguin during a normal year (right, February 2017) | Dee Boersma / galapagos.org

Frankly speaking, the special environment of the Galapagos is not friendly to penguins, but in Boersma's view, the lack of natural conditions is not the main cause of the catastrophe. Under normal circumstances, penguins will always gradually recover after the harsh environment. Otherwise, they would not have survived in the isolated archipelago until now. However, during the decades of her continuous research on penguins, the frequency and intensity of the El Niño phenomenon have become more and more intense , so that the penguins' resolute and cautious strategy cannot cope with it. And this local climate extreme is just a microcosm of global climate change dominated by human activities, and it is not only the Galapagos penguin that is tested by it.

Galapagos penguins breeding in a nest built by researchers in 2017 | Dee Boersma

To save the Galapagos penguins, or even to solve all the ecological crises today, the efforts of one old man alone are certainly not enough. Compared with the ocean current that determines the survival of penguins and the grand climate issue it involves, even a scholar as influential as Boersma can only make efforts as small and weak as a drop of water. However, the old man is still running around to appeal, because the efforts of drops of water are equally important , and countless drops of water can also gather into a surging tide.

Fortunately, we are at the forefront of this trend today. Facing the ecological crisis caused by climate change, the Chinese have taken the lead in making commitments. This commitment is not only for penguins across the ocean, polar bears on the Arctic ice sheet, and other species that work hard in other corners of the world, but also for you and me living on the blue planet.

This article comes from the Species Calendar, welcome to forward