Cormorant, Galápagos

Phalacrocorax harrisi

phylum: Chordata

class: Aves

order: Pelecaniformes

family: Phalacrocoracidae

status: Endangered, IUCN

range: Ecuador (Galápagos Islands)

Description and biology

The Galápagos cormorant, also known as the flightless cormorant, is the only one of the world's 29 cormorant species that is flightless. It is a large bird, measuring about 35 to 40 inches (89 to 100 centimeters) long and weighing anywhere from 5 to 9 pounds (2.5 to 4 kilograms)—making it the heaviest bird in the cormorant family. Males are larger than females. Its feathers are dark brown or black and they are much thicker and softer—and more like hair—than the feathers of other cormorants. The eyes are a bright turquoise and the bill is long with a hook at the end. This cormorant's wings are mere stubs; the part of the breastbone that would normally support the flight muscles in a bird that can fly is very small in the flightless cormorant. On the other hand, the Galápagos cormorant's short black legs are heavier and

more powerful than those of other cormorants. With them, the large bird propels itself through the water with powerful kicks. It is an excellent diver and a fast, efficient swimmer.

The Galápagos cormorant feeds underwater. Its diet is made up of small fish, eels, squid, and octopus. When hunting, the cormorant swims with its body almost entirely submerged in the water. Only its head and neck remain above the surface. When it spots its prey, the bird dives in a jack-knife movement using powerful kicks to shoot through the water. The cormorant stays within 330 miles (100 meters) of the shore when it swims.

Galápagos cormorants have a very elaborate courtship routine. Starting in the water, the male and female swim around one another in a kind of dance with their heads held in a snakelike manner. They then go to shore, where they continue their routine. When the initial dance is over, the two birds build a nest of seaweed. Often the nest is situated within a colony of nests made by a dozen or more other Galápagos cormorant couples on hard-to-reach sheltered rocky beaches or in lagoons. The male then begins to bring little additions for the nest to the female—"gifts" of more seaweed, dead starfish, or bits of litter, such as plastic bags, bottle caps, or rope. The female will add these gifts to the nest. Two or three eggs are laid, usually in the spring, summer, and fall. The incubation period—in which both parents take turns sitting on the eggs to keep them warm—lasts about 35 days. Both parents initially take care of the young, but if there is enough food, the female will leave the male with the offspring (he will stay with the young for about nine months), and go off to find another mate. The female can breed as many as three times in one year.

Habitat and current distribution

The Galápagos cormorant lives in limited parts of the coastline of the Galápagos Islands off Ecuador, primarily in cold currents off the shores of the Fernandina Island and off the northwest shore of the Isabela Island. The total population is estimated at around 1,000 individual birds, but this population dips and recovers in years when the weather changes, such as in El Niño years.

History and conservation measures

Because there were originally no natural enemies of the Galápagos cormorant within its habitat, the bird had no need to fly and the species eventually lost the ability to do so. Instead, it developed its swimming skills. Humans eventually brought cats, dogs, and pigs onto the islands, and feral (domestic animals that have escaped into the wild) populations developed. Suddenly the cormorant had predators on the islands. The birds were particularly ill-equipped to protect themselves, since they had no fear of their enemies and they lacked the means to fly away from danger. Feral dogs in particular drastically reduced the population. In recent times, however, feral dogs have been eliminated from the cormorants' habitat.

DID YOU KNOW?

In 1835, a young naturalist (someone who observes nature to find its laws) named Charles Darwin visited the Galápagos Islands aboard the British ship HMS Beagle. There, as he collected specimens of the abundant plant and animal life, he began to get the idea for his theory of evolution when he noticed that similar species were found on separate islands. The islands, with their thousands of species, were a wonderful place for the study of plant and animal life. With no aboriginal inhabitants, they had been left undisturbed by humans until the seventeenth century. Even today, most animals on the islands lack the instinct of fear because there were no natural predators before humans arrived. Although the islands were used by pirates and hunters during the seventeenth and eighteenth centuries, and small colonies were established there by Ecuador in the nineteenth century, most of the islands' current human population of 18,000 came later in the twentieth century. Recognizing the extraordinary natural abundance of the Galápagos Islands, the Ecuador government established 97 percent of the islands' area as a national park in 1959. In 1986, the waters around the islands were placed under protection as well. Despite an active resource management campaign under the Charles Darwin Foundation, the islands have human-related conservation problems stemming from feral animals, introduced plants, and illegal fisheries.

Although the tourist populations that pour into the Galápagos Islands are not usually able to make their way into the remote habitats of the flightless cormorants, their presence has further reduced the population. Sea-cucumber fisheries (sea cucumbers are sea animals prized as food in many Asian markets) have been established in the waters off of the islands. Pollution of many kinds has reached the islands, including an oil slick from the oil tanker Jessica that ran aground off the island of San Cristobal in 2001, spilling hundreds of thousands of gallons of fuel into the waters. Net fishing around the islands has been responsible for the deaths of individual birds that get caught in the nets, as well as the depletion of their food from the waters.

The Galápagos cormorant population has always responded to changes in climate with a change in its numbers. A routine climate change, El Niño, occurs every two to seven years, with a change in winds that causes a rise in water temperatures. This causes the death of many South American fish. During El Niño of 1982-83, the worst ever recorded, Galápagos cormorants stopped breeding and the population was reduced by 49 percent. Within one year, however, the population had recovered. Although the population has the capacity to bounce back after a seasonal climate change, it may not be able to bounce back if more than one change in environment occurs. The oil slick on top of an El Niño, for example—or the more permanent climate changes due to global warming that may take place in the early twenty-first century—would threaten the already reduced population with extinction.

In 1977, the Charles Darwin Research Station began carefully observing the populations of Galápagos cormorants and continues to provide necessary data for the continued efforts to protect the birds and their habitat.