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Marcos Duran

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Geospiza Finch Expert

The Cormorant That Unlearned How to Fly

Saturday, April 1st of 2017. My fellow students and I walk down a trail on the island of Fernandina. It is the second day of our trip to the Galapagos Islands, and I try to ignore the sweltering, humid heat as I sit to rest on a hard, rocky surface. As I sip on some water, something catches my eye, off in a patch of rocks in the ocean. It is a trio of small-chested birds, squaring off and honking at each other over a piece of fish, or perhaps a mate. All of a sudden, in the middle of their epic duel, a sea wave splashes up and takes them for a swim. As they waddle, sopping wet back to their rocky patch, they take a small break from the action and form a temporary peace treaty to stretch out their wings in unison in order to dry them. I grin as they stand still, trying to hug the sun. Tiny, scrawny things, these wings are very much incapable of lifting the birds’ bodies, much less allowing them to fly for long distances. However, these seemingly pitiable wings are their trademark, for no other bird of the archipelago has them. These birds are none other than the Galapagos flightless cormorants.

Galapagos Cormorants.  Photo by Top Birding Tours Company.

The Galapagos cormorants are just like any other seabird. They dive for grub in the salty sea waters, they preen their feathers in an effort to appear better-looking, and they fight over women so much that even Popeye the Sailor Man would be proud. Yet, at a wing comparing competition, their short, stunted, and rather jokey looking wings earn them the “At Least You Tried” award. Why on earth would they have these useless wings that do not allow them to fly? In order to answer this question, scientists took to considering the other less funny looking flightless birds.

It was originally thought that all of the flightless birds, from ostriches to penguins to kiwis and cormorants, had descended from a single common ancestor who was also flightless. However, this is not the case, as it was discovered that these flightless birds all descended from different beings[1]. This head scratcher of a puzzle is turned into a full blown mess of a confusion when we consider that every other bird species in the Galapagos can fly, and that no other bird in the cormorants’ genus is flightless[2]. There must be a reason for this befuddling loss of flight. The fact that the cormorants look stupid with their wings doesn’t mean that they actually are stupid and one day just decided to not fly anymore.

Luckily for those of us who are curious about the matter, evolution might just prove to be the solution to this million-dollar question. It has been postulated that when the cormorants’ ancestor arrived in the Galapagos, it could still certainly fly[3] (this has also been considered a possible way that the cormorants came to find themselves on this archipelago). However, upon arrival, the ancestor encountered no natural predators, and was provided plenty of food year round in the form of fish[4]. With these luxuries, Grandpa Cormorant had no need for migration and couldn’t have gone anywhere even if he wanted to, considering that the islands that make up the Galapagos are all clumped together, separated from the rest of the world by oceans and seas, making a flight to anywhere very unlikely. Taking into account that flight is also used to evade predation, Grandpa Cormorant simply had no need for such great wings designed for flight. He had no need to expend his hard-earned energy on developing and maintaining them[5], and could instead focus this energy elsewhere, such as developing a larger body mass, or swimming for more grub.  

Yet, this is not enough reason to simply lose a pair of magnificent wings in exchange for a pair of scraggly ones[6]. These odd-looking birds would not appear to be hilarious if they had nothing to gain from it. Luckily for the cormorants however, the sacrifice of their dignity in order to adopt an awkward appearance has not gone unrewarded, as they had much to gain from losing flight.

As their wings became smaller, the cormorants’ body mass increased[7]. A large body mass is very disadvantageous for flying birds[8]. Imagine a plump little robin eating a seed off the ground. As it is happily munching away, old Granny Smith’s tabby cat spots it and decides it wants a snack. The robin sees it and flutters its wings as fast as it can, trying to fly back to the nest. A wild chase a la Indiana Jones style begins. Unfortunately for this plump robin, it can’t lift itself fast enough, and spends all of its energy quickly due to its heavy body and large mass[9]. Once this chase concludes, the robin will spend the rest of the day in the tabby’s litter box, at least until Granny decides to clean it.

While bearing a portlier figure may pose an unpleasant dilemma to flying birds, it is good for diving birds. It allows them to dive deeper and for longer periods of time[10]. Naturally, this larger body mass in the cormorants supplied them with better diving skills. In addition, their gawky wings do not get in their way while diving, thus making them quicker than a large-winged diving counterpart[11] such as the Galapagos Petrel.

Much of this evidence points towards these traits bringing a higher degree of fitness to the cormorants[12]. However, fitness here does not refer to having an athletic and strong appearance. The cormorants’ droll wings automatically disqualify them from such recognition. Fitness in this case refers to an organism’s ability to survive and reproduce in their home environment[13]. Thus these traits are passed on with a higher frequency, altering the populations’ gene pool, leading to these new traits. Who knew that these ludicrous wings actually help the cormorant pass on its genes? Not so ridiculous or stupid-looking now, are they?

When scientists first saw and studied these birds, they imagined how long it must have taken for the cormorants to evolve to their tiny wings. Now, after all this time, imagine their disbelief when they realized that these wings just popped up out of nowhere by chance! Based on current research, it is suspected that what led to the change is not an adaptation to the unique environment of the Galapagos, but rather, a mutation. A gene named Cux1 was found to be mutated in the flightless cormorant when compared to other species[14]. Now, some people, including the evolutionary biologists of old, would say that a single mutation might not amount to much. A change of one base-pair in the whole genome, which is millions of base-pairs long, affects the development of the organism? Really? Get out of here.

Unfortunately for the nay-sayers, it happens to be that the mutated Cux1 regulates the expression of cilia, tiny hair-like structures on the surface of cell membranes that serve to receive signals important for the development and function of cells[15]. This mutation led to particular cilia not being present, which in turn led to poor reception from an important protein related to limb growth, shrinking the wings of future generations of the ancestral cormorants[16].

Funny how one single mutation can alter so much of the organism’s development and growth. Take that, you non-believers.

This mutation could’ve resulted in disaster (Imagine if the mutation had targeted the legs! Now there is a funny picture). Luckily for the cormorants however, it actually ended up improving their survival and helped them pass on their DNA. Since the mutation was beneficial, it was selected for, and just like that, the cormorants’ wings shrank, bringing about the short, ludicrous wings we see today in the cormorants[17].  

It truly is amazing. These mutated chicken-like wings, that at first glance appear to be useless are actually beneficial to the Galapagos flightless cormorants, including the group I saw on Fernandina Island. As this group of cormorants finished their sunbathing break, they were quick to continue their squabble, waddling about all over the rocks and honking at each other. I sat there entertained by the performance happening before me, wondering if popcorn would be allowed on the island. I continued to witness this spectacle, only leaving when forcibly removed by our field guide, Fausto. That was not the last time we would see these peculiar fowl however. As our week on the Galapagos continued, we saw them multiple times, some of them exemplifying their flightless behaviors. From watching them dive spectacularly, to preening the feathers on their scrawny wings as they hug the sunlight, to honking at each other over some lucky bird gal. Everything these birds do can hook the average biologist’s attention, and our group was no exception. I will always remember these birds alongside every other thing we saw in the Galapagos. Because, after all, it’s not every day that you get to see a bird that has unlearned how to fly.

[1] Burga, Alejandro. “Loss of Flight in the Galapagos Cormorant Mirrors Human Skeletal Ciliopathies.” 2 Jul. 2016.

[2] Hayward, James L. et al.  “Temporal and Environmental Effects on the Behavior of Flightless Cormorants.” The Wilson Journal of Ornithology, vol. 125, no. 4, 2013, pp. 790–799.

[3] Wilson, Rory P. et al.  “What Grounds Some Birds for Life? Movement and Diving in the Sexually Dimorphic Galapagos Cormorant.” Ecological Monographs, vol. 78, no. 4, Nov. 2008, pp. 633–652.

[4] Burga, Alejandro. “Loss of Flight in the Galapagos Cormorant Mirrors Human Skeletal Ciliopathies.” 2 Jul. 2016.

[5] Elliott, Kyle H. “High Flight Costs, but Low Dive Costs, in Auks Support the Biomechanics Hypothesis for Flightlessness in Penguins.” Proceedings of the National Academy of Sciences of the United States of America, vol. 110, no. 23, 4 June 2013, pp. 9380–9384.

[6] McNab, Brian K. “Energy Conservation and the Evolution of Flightlessness in Birds.” The American Naturalist, vol. 144, no. 4, Oct. 1994, pp. 628–642.

[7] Wilson, Rory P. et al.  “What Grounds Some Birds for Life? Movement and Diving in the Sexually Dimorphic Galapagos Cormorant.” Ecological Monographs, vol. 78, no. 4, Nov. 2008, pp. 633–652.

[8] Elliott, Kyle H. “High Flight Costs, but Low Dive Costs, in Auks Support the Biomechanics Hypothesis for Flightlessness in Penguins.” Proceedings of the National Academy of Sciences of the United States of America, vol. 110, no. 23, 4 June 2013, pp. 9380–9384.

[9] Elliott, Kyle H. “High Flight Costs, but Low Dive Costs, in Auks Support the Biomechanics Hypothesis for Flightlessness in Penguins.” Proceedings of the National Academy of Sciences of the United States of America, vol. 110, no. 23, 4 June 2013, pp. 9380–9384.

[10] Elliott, Kyle H. “High Flight Costs, but Low Dive Costs, in Auks Support the Biomechanics Hypothesis for Flightlessness in Penguins.” Proceedings of the National Academy of Sciences of the United States of America, vol. 110, no. 23, 4 June 2013, pp. 9380–9384.

[11] Wilson, Rory P. et al.  “What Grounds Some Birds for Life? Movement and Diving in the Sexually Dimorphic Galapagos Cormorant.” Ecological Monographs, vol. 78, no. 4, Nov. 2008, pp. 633–652.

[12] Burga, Alejandro. “Loss of Flight in the Galapagos Cormorant Mirrors Human Skeletal Ciliopathies.” 2 Jul. 2016.

[13] Elliott, Kyle H. “High Flight Costs, but Low Dive Costs, in Auks Support the Biomechanics Hypothesis for Flightlessness in Penguins.” Proceedings of the National Academy of Sciences of the United States of America, vol. 110, no. 23, 4 June 2013, pp. 9380–9384.

[14] Burga, Alejandro. “Loss of Flight in the Galapagos Cormorant Mirrors Human Skeletal Ciliopathies.” 2 Jul. 2016.

[15] Burga, Alejandro. “Loss of Flight in the Galapagos Cormorant Mirrors Human Skeletal Ciliopathies.” 2 Jul. 2016.

[16] Burga, Alejandro. “Loss of Flight in the Galapagos Cormorant Mirrors Human Skeletal Ciliopathies.” 2 Jul. 2016.

[17] Burga, Alejandro. “Loss of Flight in the Galapagos Cormorant Mirrors Human Skeletal Ciliopathies.” 2 Jul. 2016.