The Flightless Cormorant

A Tale of Island Colonisation

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A Tour of Flightless Birds

Contents

Endemic to the Galápagos Islands, the flightless cormorant is the only cormorant in the world that cannot fly. Instead, it is adapted to hunting in water — with larger, more powerful webbed feet, and insulating fur-like feathers. It still spends much time drying after a dive, spreading its tiny wings in the sun.

*Sources for information and photos are at the bottom of the page.

The Birth and Colonisation of the Galápagos

The Galápagos is a young archipelago, geologically speaking. The eldest of the islands is likely no more than five million years old, some only a few hundred thousand, while others are being formed to this day. The forces behind their creation are powerful and primordial. The Nazca tectonic plate births volcanoes in the Earth's crust as it moves eastward towards the South American plate. As volcano after volcano erupts, their molten ejecta cools and settles, building up in layers until, in the middle of the ocean, there is land where there was none before. Today, the Galápagos' volcanic origins are obvious, as most of the major islands are dominated by one central volcano — apart from the largest, Isabela, which was forged by six volcanoes rising from the sea.

Galápagos giant tortoise (Chelonoidis niger)

Galápagos centipede (Scolopendra galapagoensis)

As they formed, these young islands offered new lands full of opportunity. First came the plants, carried by wind or water currents. They took seed in the volcanic soil and grew to cover the dry islands in scrubby, desert-like vegetation. Then came the first animals. Most arrived from mainland South or Central America, but in what order is difficult to determine. Iguanas were likely carried off on an uprooted tree during a storm, and by some fortunate chance washed ashore on this new land — over time, evolving to feast underwater on offshore algae, becoming marine iguanas. Tortoises too, were probably stolen by the sea, their hardy natures and buoyant shells allowing them to survive the harrowing journey. They arrived on islands with no predators and little competition and grew to become the largest tortoises on Earth. Marine animals, such as fur seals and sea lions — and adventurous penguins, that travelled to live farther north than any of their kind — came riding the waves and populated the archipelagos' shores.

Flighted animals surely made an easier journey, undertaking the 965 kilometres (600 miles) from mainland South America to the Galápagos on the wing. To the butterflies, grasshoppers, and dragonflies (among various other arthropods) the vast journey must have been akin to hopping planets — but even non-flying insects made it over, with the island now home to its own endemic variant of black widow spider and a nearly foot-long (30-cm) centipede. Two species of bats are a few of the only non-marine mammals native to the islands (the others being a couple species of rice rats). Hawks, herons, and doves arrived on feathered wings — the latter of which belongs to a family of intrepid island settlers. The ancestor of the famous Darwin's finches might have, like the reptiles, been taken by a storm, whipped by winds out to sea, or perhaps arrived by some navigational fluke. On the Galápagos, a single finch species diversified into the 18 or so species that live there today. Sea birds such as gulls, frigatebirds, albatrosses, and boobies are pelagic; spending most of their lives soaring above the sea, travelling far and wide. For them, finding the newly formed islands was likely no challenge. And, at some point in the past, probably around two million years ago, before the largest island (Isabela) even rose from the ocean, arrived an ancestral cormorant. All odds indicate that it made its journey flying, utilising the powerful wings and strong flight that are typical of cormorants. Then it settled on these isolated islands, and never flew again.

Marine iguana (Amblyrhynchus cristatus)

Galápagos penguin (Spheniscus mendiculus)

Darwin’s finches (Thraupidae spp.)

The Galápagos Flightless Cormorant

Silhouettes of cormorants line the volcanic island shores of Isabela and Fernandina. The birds' colours are basalt and ash, as if sculpted from the dark lava rock on which they stand. Slaty grey and remarkably large webbed feet grip onto the uneven surface. Short fans of dark feathers protrude from their rumps. Their bodily plumage is more akin to fur than feathers; thick and insulating against the elements. Long, serpentine necks flex and fold as they preen, or stretch up towards the sky as if to nip at the sun with their long beaks, hooked at the ends. Their eyes are ultramarine gemstones, set in dark metamorphic rock.

These are large birds — measuring up to a metre (3.3 ft) tall — and they stand proudly in the archetypical cormorant fashion; with upright posture and wings proudly spread to the world. But their wings are stubby, sparsely feathered little things, each only measuring some 25 cm (9.8 in), about one-third of the size of other cormorant species. Needless to say, the soaring days of the Galápagos cormorants — now known as flightless cormorants — are far behind them. As they adapted to their flightless existence, their bodies grew bulkier and heavier, unconstrained by the needs of flight. Today, the flightless cormorant is the heaviest of any living species at up to 5 kilogrammes (11 lbs), which may not sound like much, but for the typically light frame of a bird, it's significant.

“The wings of a flightless cormorant measure some 25 cm (9.8 in) — about one-third of the size of other cormorant species”

Cormorants are skilled hunters beneath the water's surface. Maybe you've seen one swimming along a river or lake, dipping beneath the water for a minute or more, before popping up in a different spot, and then swiftly diving again. But, of the 40-something cormorant species, the flightless is likely the most skilled beneath the waves. It hunts in shallow offshore waters. As it dives, it tucks its dwarfish wings to its sides and extends its neck forward, becoming a sleek torpedo propelled by the powerful kicking of its webbed feet. It pursues fish, octopuses, and squid, spearing them with its sharp-tipped beak; eating small prey underwater but bringing its larger catches to the surface to more easily scoff them down. It usually dives to depths of around 10 to 15 metres (30 - 50 ft), but it can supposedly descend to 70 or 80 metres (230 - 260 ft), where the ocean floor allows it. And this cormorant only became flightless in the last two million years — compare that to the other flightless divers, the penguins, who lost their flight over 60 million years ago and had that much more time to fine-tune their diving skills. So, this relatively young cormorant species is on the first few stepping stones of its evolutionary path and, given the opportunity, it could become as aquatically adapted as the tuxedo birds down south, or possibly even more so.

A trait the flightless cormorant shares with all of its relatives is its feathers; they are wettable. After every foray in the water, it must stand itself in the sun, wings akimbo, to dry off. Most other birds, such as waterfowl like ducks and seabirds like gulls, have waterproof outer feathers — that's why you don't see them perching with their wings spread by the waterside. It seems strange that a cormorant, a bird which spends so much time diving — essentially every time it wants to eat — does not have waterproof feathers. But while this seems like an oversight, the cormorant's waterlogged feathers actually let it sink more easily and dive deeper than most other birds. So it's a kind of trade-off: better diving which necessitates time spent drying.

“As of a 2022 count, there is an approximate total population of 2,085 flightless cormorants. It is considered a ‘vulnerable’ species by the IUCN.”

With feathers dry, the cormorant makes its way over the rugged black shore, hopping from one rock to another and using its tiny wings for balance. No matter how aquatic a bird is, none have found a way to breed at sea — even fishlike penguins and pelagic albatrosses must nest on solid ground (or ice). The flightless cormorant’s nest is found not far from the shore, built from materials given by the tide; from seaweed, flotsam and jetsam. A cormorant couple construct it together. The male scavenges from the sea, presenting his mate with aquatic plants, shells, bits of rope, or plastic debris — the two grunt coarsely at each other as these “gifts” are presented, proclaiming their contentment and strengthening their bond. As he brings the material, she arranges them to her liking, until a satisfactory nest is created; large and safe enough for their 2 to 3 white eggs and the naked little chicks they will hatch after 35 days of incubation. The parents take turns bringing back food to their young, who, very soon after hatching, grow fleecy coats of dark-brown feathers. The small chicks have even smaller wings, free of shining feathers, looking like some strange, soft raptorial appendages. At two months they fledge, but they enjoy their parent's attention — and free food — for four months more. Caring as the parents are, by the time the chicks fledge at 6 months, usually only one has survived. The father is the one to say goodbye to the chick. Typically, he alone cares for it during its last period of dependence, while the mother has already gone to find another mate. A pair bond rarely lasts for more than one or two seasons.

At two years old, the young cormorant finally matures and must court a mate of its own. Many flighted birds begin their courtship in the air: bald eagles grasp each other in a twirling spiral, arctic terns fly high while presenting gifts of fish, and house swallows zoom from one nest site to another, showing each spot off like enthusiastic real-estate agents. The flightless cormorant begins its impassioned dance in the water. A male and female swim around one another in spiralling circles, their long necks bent into a serpentine posture, occasionally rising above the waves in a fluttering of tiny wings. The male then leads the female onto shore, both keeping their necks bent in a snake-like manner with bills pointed down. Upon the shore, the two perform a version of a “penguin walk”; waddling side by side, at times intertwining necks, until they reach a suitable nesting site where they will build their seaweed nest. Each flightless cormorant will likely perform this display many more times, for while the average lifespan seems to only be around 13 years, some are said to have lived up to 50.

The ancestor of the Galápagos cormorant is believed to have arrived some 2 million years ago, before its current home islands — Isabela and Fernandina — were even formed.
It usually dives to between 10 and 15 metres (30 - 50 ft), but has been recorded at depths up to 80 metres (260 ft).
It can remain underwater for up to 3 minutes.
- Invasive predators including cats, rats, and feral dogs.
- A lack of marine prey due to human overfishing.
- Getting tangled in fishing nets.
- Pollution and climate change causing habitat degradation.
- Natural disasters such as El Niño.

“Typically, it is the male cormorant alone who cares for the couple’s chick during its last period of dependence, while the mother has already gone to find another mate. A pair bond rarely lasts for more than one or two seasons”

Today, there are estimated to be around 1,000 breeding pairs of flightless cormorants on the islands of Isabela and Fernandina — the latest count by the Galápagos National Park Directorate, taken in 2022 suggests that there is an approximate total population of 2,085 individuals. It is considered a ‘vulnerable’ species by the IUCN, with its most serious threats including invasive predators such as rats, feral dogs, and cats; lack of marine prey due to overfishing; getting tangled and trapped in fishing nets; the effects of pollution and climate change on its coastal habitat; and natural disasters such as El Niño, which can ravage the cormorant’s coastal home, resulting in many deaths. Fortunately, the species seems quick to recover — taking only about 18 months for populations to rebound after a disaster such as El Niño — and the species population trend is considered to be stable. It’s important to remember that, while a total species population in the thousands may seem very low, and there are certainly species with such numbers which are considered endangered or even critically so, the flightless cormorant's unique range, only being found on a few isolated islands, likely means that its population was never very large. So a tally such as 2,000 individuals shouldn’t necessarily set off panicked alarm bells, but it does warrant extra conservation attention, since smaller populations are much more vulnerable to freak events like natural disasters or deadly diseases.

When the ancestors of these fishing birds first arrived on the Galápagos Islands, they found waters rich with fish and land unpopulated by dangerous predators. Their ability to fly was no longer worth the costs and so their wings atrophied, their bodies grew heavier, and their webbed feet larger. They became the only flightless birds of their kind — a unique species crafted by the conditions of its isolation. The only way they "fly" today is by gliding beneath the waves.

Why Fly?

Isolated islands lay scattered throughout the world’s oceans. If you were to study their fauna, you’d begin to notice a few patterns. One such pattern pertains particularly to birds. These feathered fliers are perhaps the most adept dispersers of all animals, and as such, are typically some of the first to arrive on a new island or archipelago, say, one formed by volcanic activity. The first avian arrivals may be a few small songbirds caught in the tumult of a storm and blown out to sea or a flock of pelagic travellers who discover new land where they can perch and nest amidst the waves. Either way, it is flight that enables their colonisation of new lands.

Being able to fly is a supremely useful ability; you can search for food and resources from high in the sky, you can travel quickly to more plentiful areas, and perhaps most importantly, you can very effectively escape terrestrial dangers. At the same time, flight is extremely energetically expensive. The breast or pectoral muscles of birds are typically very large, as they are the primary muscles that power flight, and these muscles take a lot of energy to develop and maintain. And flight itself is a very costly activity. This is evidenced by the countless adaptations which birds have evolved to make their flight more energetically effective (or possible at all). Their bones are hollow to lighten their weight. They have a series of air sacs throughout their bodies, which both lighten their bodies further, and allow for air to flow continuously through their lungs, both on inhale and exhale. Some migrating birds, like godwits, can increase their number of red blood cells, meaning that they extract more oxygen with every breath. Other migratory birds, who must sometimes fly continuously for thousands of miles, are able to put on muscle and fat at an unprecedented rate — to the point where a human would be considered obese, likely have diabetes, and die from a heart attack — and they can burn fat for energy 10 times more effectively than humans. All to enable and optimise flight.

And because everything is a trade-off in evolution, the ability to fly can actually be a limitation. Hollow bones are fragile and easily broken — wings themselves, with their light frame and large surface areas, are easily injured. Flight limits the body type, size, and weight of a bird, and thus the niches it can fill. A bird can only become so heavy before flight becomes impractical, as dictated by the laws of aerodynamics. So, it's no surprise that the largest and fiercest birds to ever exist were flightless. And maybe most importantly, evolutionarily speaking, the large amount of energy invested into flight adaptations could be used instead for increased fecundity — more abundant offspring and thus a reproductive advantage.

And so the pattern has emerged, that as birds arrived on their new, isolated island homes — finding rich bounties (often on the ground, as many such islands have few or no trees) and no land predators — they lost their ability to fly. On these relatively safe and plentiful islands, where there is much less pressure or incentive to fly, the birds that wasted less of their energy and resources on unnecessary flight adaptations could invest them in other more useful endeavours, such as laying more eggs. These birds became more successful in their population, outbreeding their flight-adapted variants, and passing on their fly-less traits to their offspring. Eventually, over many many generations, the breast muscles and wings of these island birds atrophied, and they became fully flightless.

Flightless Birds of Today

Such has been the story with many bird species in New Zealand, where no mammalian predators lived (apart from marine mammals and tiny bats) before the arrival of humans some 700 years ago, and so the birds who colonised the North and South Islands occupied the typical mammalian niches — many of which are ground-based. Some examples include the famous flightless parrot, the kākāpō, and the iconic kiwis, but also lesser known species such as the takahes, large waterhens with broad red bills and face shields and rotund purple-green bodies, the weka, also known as the wood- or Māori hen, an inquisitive brown rail that's often very curious about humans, and even two flightless ducks, with the Auckland Island teal, endemic to the Auckland Islands 725 km (450 miles) south of mainland New Zealand, and the Campbell teal, endemic to the Campbell Islands even further south — once believed extinct.

A Series of Skeletons

A spectrum of wing atrophy; from a fully-flighted swan on the left, to the flightless parrot (kākāpō) of New Zealand, the giant, land-dwelling cassowary, and the kiwi, with tiny vestigial stumps for wings.

Further north, isolated amidst the Pacific Ocean, lives the critically endangered Guam rail, locally known as the ko'ko'. Before the 1960s, a population of over 10,000 is estimated to have existed. By the late 1980s, this rail was considered extinct in the wild. Evolving on an island free of rats and snakes, the introduction of these voracious predators — the brown tree snake arrived sometime after WWII, likely as a stowaway on a military cargo ship — dealt a deadly blow to this flightless bird (not even flying, arboreal-nesting birds could escape the invader, as the brown tree snake eventually eliminated 9 of the 11 native land bird species on Guam). Beginning in the 1990s, a captive breeding and release effort has reintroduced the Guam rail to nearby islands and in 2019 it became the second-ever bird (after the California condor) to be reclassified from ‘extinct in the wild’ to ‘critically endangered’ by the IUCN . Today, around 70 individuals live on Cocos Island (Islan Dåno') and about 150 live on Rota.

But perhaps the most isolated flightless rail, or bird of any kind, is the Inaccessible Island rail. This small — the smallest of any living flightless bird — dark-brown rail is endemic to the fittingly named Inaccessible Island, of the Tristan da Cunha archipelago. Situated in the South Atlantic, this is the most remote inhabited group of islands in the world; lying some 2,800 kilometres (1,750 miles) from the nearest landfall to its east in South Africa and some 3,200 kilometres (2,000 miles) from South America to its west. As of a count in 2016, this tiny rail has a population of around 5,600 but is considered vulnerable to dangers from invasive predators. Currently, there are none on Inaccessible Island, and there have never been, but one careless fishing vessel from the nearby Tristan da Cunha Island — which harbours house mice, brown rats, and feral cats — could break the rail's fragile ecosystem.

Between New Zealand and Australia, isolated in the middle of the Tasman Sea, is Lord Howe Island. Here lives the Lord Howe woodhen; a small, olive-brown flightless rail with blood-red eyes, currently considered endangered. Its population dropped to less than 30 individuals in 1980, but a survey in March of 2022 found 778 individuals — the highest count ever.

The islands of New Caledonia in the South Pacific, about 1,500 km (900 miles) east of Australia, are home to a species of large, drab, flightless rail unimaginatively known as the New Caledonian rail (which is either critically endangered or possibly extinct), and the kagu; not a rail, but an utterly unique flightless bird with long orange legs upon which it struts, blue-tinged greyish-white feathers, and an extendable, pompous-looking crest of head feathers — it is the country's national animal.

Going from isolated islands to a more cosmopolitan viewpoint, let’s consider some of the most astonishing of the flightless birds; the ratites. This far-flung group include the ostriches of Africa, rheas of South America, the emu and cassowaries of Australia and New Guinea, and, somewhat unexpectedly, joining these giants are the tiny kiwis of New Zealand. The traditional view was that these birds all initially descended from a single flightless ancestor, which became split into separate populations as the supercontinent of Gondwana broke up and drifted apart. But more recent evidence, in the form of DNA recovered from Malagasy elephant bird bones (more on these giants later), suggests that this isn't the case; the elephant bird's closest relative is not the geographically closest ostriches, as would be expected from the orthodox theory, but kiwis, from the other side of Gondwana. This, and the fact that kiwi fossils suggest a more recent evolution from flighted ancestors, advocates for the view that the ratites may have followed a path of island (or continent) hopping, via flight, each time settling down and becoming large (most of them) and flightless.

Nowhere to Run, No Way to Fly

The stories of most flightless island birds are struggles for survival. A few — such as the Lord Howe woodhen and Guam rail — are hopeful. Unfortunately, most aren’t. The variety of flightless island birds alive today pales in comparison to those that have gone extinct. "Gone" may be too soft of a word, for most were hunted, beaten, and eaten by the first mammalian land predators to arrive on their islands: humans. Others suffered from the passengers we brought with us, whether intentionally or not; our rats and mice, cats, mongooses, and snakes. Most didn’t survive to bounce back.

Islands were once home to feathered giants; the largest birds to ever live.

New Zealand had some ten, perhaps more, species of moa. Part of the ratite group, they resembled their emu and ostrich relatives, but ranged from around turkey-sized to the tallest bird known to ever live; the North Island giant moa, standing up to 3.6 metres (11.8 ft) tall. These beastly birds were so adapted to life on the ground, that they lacked any vestigial wing bones at all. They thrived until shortly after the arrival of the Māori people around 1250 AD. The elephant bird of Madagascar, another ratite, was not as tall as the giant moa but quite a bit heavier — weighing well over 500 kg (1,100 lbs) — making it the heaviest known bird ever to live. Its eggs reached sizes of 33 cm (13 in) long and 1 metre (3.3 ft) in circumference, holding the contents of around 200 chicken eggs. This creature thundered across the African island until around 1000 AD, when it was driven to extinction, likely as a result of human activity.

We've already met many flightless rails — the takahe and weta from New Zealand, the New Caledonia rail, and several that cling to isolated islands the world over. It's clear that this family (Rallidae) of plump, wading birds have an affinity for hopping islands, settling down, and becoming flightless. There is even evidence that the white-throated rails which settled the Aldabra Atoll did so twice; the first population arrived and became flightless but was wiped out by a flood, followed by a second population who also independently lost the ability to fly — these are the Aldabra rail (Dryolimnas [cuvieri] aldabranus), a flightless subspecies of the white-throated rail, that live there to this day.

The great auk was the penguin of the north. It lived in the waters of the North Atlantic, where it expertly dove beneath the choppy waves to catch fish, and waddled onto isolated rocky islands to nest and breed. Standing around 70 cm (2.3 ft) tall, with a white belly and black back, it looked very much like a penguin — and sailors who saw it called it such. But it was unrelated to the flightless birds of the south. The undersized, folded wings at its sides and its thick razor-bill betray its real relations: it is an auk, a member of the Alcidae family, which includes auks, murres, guillemots, and puffins. The 24 living species inhabit the rocky shores of the northern hemisphere and, although not particularly graceful, all can fly. The unique outlier that was the great auk went extinct in the 19th century due to overhunting by humans — the last confirmed pair was killed by fishermen on an island off of Iceland in 1844.

“There is evidence that rails settled the Adabra Atoll twice, becoming independently flightless both times.”

An elephant bird egg, an ostrich egg, and a hummingbird egg.

The razorbill and little auk — close living relatives.

But, once upon a time, it seems that whichever island one sailed to would present a unique species of flightless rail marooned thereupon. New Zealand used to have several more species than those alive today. Six of them lived on the Chatham Islands group, off the eastern coast of New Zealand's South Island. The Chatham Island rail, or Mātirakahu, was first discovered in 1872, but by 1894, soon after cats settled on the island, the rail was proclaimed extinct (22 years from discovery to extinction). The other Chatham rail species followed in the same fashion — all perishing in the 19th century.

On the other side of the world, on an isolated volcanic island in the South Atlantic, lived the Ascension crake. It serves as a grim warning of what may befall the tiny Inaccessible Island rail if its isolation is ever violated. Little was known about this endemic crake — some fossils, a sketch, and a short description — before it likely perished in the 18th century following the introduction of rats, and if not then, it surely didn’t survive long after 1815, when cats were introduced to the island.

Like on the Chatham Islands, six species of rails once inhabited the Mascarene Islands, east of Madagascar. The red rail shared its island home of Mauritius with the famous dodo and around the year 1700 met the same fate. To the west, the island of Réunion also had its own rail, which likely went extinct earlier in the 17th century, while, to the east, the endemic flightless rail on the small island of Rodrigues lasted into the 18th century before it too vanished. All likely met their end to the combined forces of rats, cats, and overhunting.

Laysan, a northwestern island of Hawaii, harboured a small endemic rail whose home was devastated by, among all things, domestic rabbits. The rabbits feasted on the island’s vegetation, multiplied, and feasted more; eventually stripping Laysan, turning it into a barren dust bowl. With insufficient nesting sites, the Laysan rail went extinct on its home island in 1923 — while a few individuals were evacuated to the Midway Atoll, the last Laysan rail died there in June of 1944. The endemic flightless rake of Wake, in the middle of the Pacific, was the only native land bird on the coral atoll. It met its end between the years of 1942 and 1945, because of our Second World War. Occupied by the Japanese, a U.S. blockade trapped thousands of soldiers on the atoll. Starving, they relieved their hunger by way of these inquisitive, helpless birds.

Barely anything was known about the Ascension crake before it went extinct in the 18th century.

Six species of rail sequentially disappeared from the Mascarene Islands in the 17th and 18th centuries.

The Wake Island rail — the atoll’s only native land bird — was eaten to extinction during WWII by trapped and starving soldiers.

More than any other bird family, rails have fallen victim to extinction at the hands of humans.

The Future of Flightless Birds

“The last dodo bird was seen on it’s Mauritius Island home in 1662.”

These far-flung islands — the New Zealands, Mascarenes, Hawaiis, and Galápagos’ — are the birthplaces of the world's most eccentric and interesting species — the colossal Galápagos tortoises and behemoth lizards from Komodo, wild arrays of finches and honeycreepers with bills like hooked needles or thick nutcrackers, leaping lemurs with dog-like faces, and the menagerie of plump flightless birds like the Galápagos cormorant or the sprinting rails — but they are also some of the most fragile ecosystems in the world. They’re like millenia-old glass sculptures; beautiful but brittle. If we want them to survive into the future, for their beauty and novelty, for the unique life they host and the natural history they hold, we must be protectors and preservers, not invaders and butchers.

The Rails of Yesterday

In the past 400 years, humans are known to have caused the extinction of 26 rail species. These are just the documented cases -— there were likely more.

In the 19th century, six species of rail went extinct on the Chatham Islands of New Zealand.

The Chatham Island rail was only known for 22 years before it died out.

The Laysan rail went extinct on its home island in 1923 — while a few individuals were evacuated to the Midway Atoll, the last Laysan rail died there in June of 1944.

It’s no great mystery why flightless birds, especially, have suffered the brunt — the blunt club — of human violence. It’s much easier to catch and bash a portly runner than a swift flier. But, even if they could take to the skies to escape such a fate, they probably wouldn’t have even tried. These island residents had no fear of humans when we arrived on our boats and came marching to slaughter their entire kind. Isolated for millions of years with no predators on the ground, they lost their fear of anything moving over land. A story about the marine iguanas of the Galápagos and none other than Charles Darwin presents this case in point. Darwin was dumbstruck by how "tame", or unwary, the animals of the Galápagos were. They were so lax that he was able to walk right up to an iguana and it would not flee to shelter in the sea, even though it was a skilled swimmer. He then picked it up and threw it in the water. It almost immediately returned to the land, back at his feet. He tossed it in again and again, and every time it returned to land. This led to his realisation that it had a pre-programmed response to danger: get to land. This is because the only threats the Galápagos marine iguana evolved alongside were those from the sea (e.g. sharks) and none on land. So naturally, when it felt like it was threatened, its instinct was to take shelter on land.

This refusal to flee, or general unconcernedness about potential threats, is referred to as ‘island tameness’ and you can still see it to this day on isolated islands around the world — even where invasive predators such as feral dogs and cats, mongooses, and rats now do pose a serious danger. And so, this combination of flightlessness (lack of escape options) and tameness (unwillingness to escape) made these island birds the prime targets for hungry, or sometimes just cruel, human sailors. With no conception of extinction, people believed that the slaughter could last forever, that a species was ever plentiful. That belief was shattered on Mauritius, one of the Mascarene Islands off of eastern Madagascar. The last dodo bird was seen by human eyes in 1662. Not long after, the entire species, with all of its millions of years of evolutionary history was gone — wiped from existence by us. It was a grim realisation of the power our species holds, and, although many did not see it for some time yet, a charge to use that power with responsibility.