I was originally going to make this post about cormorants in general, as the whole family is a pretty neat group of birds. But then I saw that there is a flightless cormorant, and couldn’t resist writing about this very unique species. Maybe one day I’ll go back and write about the entire family.
There are about 40 species of cormorants in the family Phalacrocoracidae, and the flightless cormorant is unique among them, as the rest are flighted birds. Flightless cormorants are found only on the galapagos islands, proving once again that that archipelago is one of the strangest places on earth where wildlife is concerned.
Flightless cormorants are the largest members of the cormorant family, growing to be 89-100 cm in length, and weighing up to five kilograms. Their wings have shrunk, and are currently only about a third of the size the flightless cormorant would need to fly. Flightless cormorants also have a very small keel bone, which is the bone flight muscles are attached to.
They have black feathering on their backs, and brown on their undersides. Flightless cormorants, like other species of cormorant, have webbing between all of their toes. They have hooked beaks and turquoise eyes, giving them a bit of a funny appearance. Males are about 35% heavier than females.
All cormorants are water birds, and flightless cormorants are no exception. Their webbed feet and strong legs mean flightless cormorants are excellent swimmers, and they use this skill to catch tasty meals. They normally feed on fish, eels, octopi and other sea animals, foraging on the ocean floor and staying near the coast. Although cormorants are water birds, they lack any kind of waterproofing in their feathers, and so must spend time drying their feathers after each dive. To do this, all cormorants adopt a characteristic wing-drying pose when they come out of the water: they spread their wings and hold them open so they can dry.
Breeding season in flightless cormorants takes place from July to October. During these months, the temperatures cool, which means food is more abundant, and the risk of the chicks getting heat stress is lower. Males court females by swimming around them in the water. The pair then move to land, where males bring females expensive presents, such as seaweed and objects that have drifted to the islands on the current.
The females uses theses gifts to build a nest, into which she lays three white eggs. Both parents incubate and care for the chicks, though usually only one of the nestlings survives. If things are going well and food supplies are still abundant, the female will leave when the chick is around 70 days old. She goes to find another mate, leaving the male to finish taking care of their chick.
Though flightless cormorants have a small population, and are limited to a very tiny area, they do breed quickly and so can recover from population crashes. As flightless birds, they are vulnerable to predation from introduced predators such as dogs and cats. They also rely on cold water for food and breeding, so these birds will be impacted by climate change. Still, for highly specialized birds living on two islands, they are doing pretty well for themselves.