Phalacrocorax harrisi

| 15 Comments

Photograph by Dan Moore.

Photography contest, Second Place.

Moore.Galapagos_Flightless_Cormorant.jpg

Phalacrocorax harrisi – flightless Galápagos cormorant. Mr. Moore writes, “Having made its way to a small set of islands we now call the Galápagos and given sufficient food and no predators, the cormorant had no need to fly, so over the years lost its full-feathered wings. Its bright-orange companion is Grapsus grapsus – the Sally Lightfoot crab.”

15 Comments

Dang – if that thing lost the feathers and quadrupled in size, you’d have a Wyvern.

It’s a great picture; color, action, exotic creatures. Both obviously intent on watching something; this could’ve gone viral during the world cup.

This species is fine, but cormorants are serious pests in Texas. Sometimes they move move into small lakes and large ponds, and they won’t leave until they have killed off every single fish and large amphibian!

Forgive me if this belongs more on the bw, but has anyone ever considered a speculative evolutionary pathway to Wyverns? Or, for that matter, classic “4 limbs + 2 wings” dragons?

Leaving aside the fantasy details like breathing fire, there ought to be some possible path. I don’t know much about the phylogeny of pteradons, but perhaps there was a slightly more serpentine protopteradon species that could have branched off. As far as the sexapod variety, surely a gliding lizard could have started things off if it had ever come up with a way to produce upward thrust with those detached-rib wings.

Though the questions of ecological niche, food sources, and selection pressure remain. Could a combined aquatic-arboreal pathway be the key to getting gliding lizards into the skies?

david.starling.macmillan said:

Forgive me if this belongs more on the bw, but has anyone ever considered a speculative evolutionary pathway to Wyverns? Or, for that matter, classic “4 limbs + 2 wings” dragons?

Oh people have considered it alright. A while back there was a book called The Flight of Dragons (later made into an animated movie by Rankin/Bass, in the same visual style as The Hobbit). Then in 2004 there was a fictional documentary about finding the remains of dragons and tracing their fictional evolutionary history (though the program didn’t actually make it clear that it was fictional; lots of people to this day think it was real). Both of them give some pseudoscientific trappings to elements of dragon myths, like eating catalytic minerals to generate hydrogen for lift and fire-breathing. The documentary went into much more detail and had the original dragon line branching out into Western and Asian dragons of different types.

ksplawn said:

david.starling.macmillan said:

Forgive me if this belongs more on the bw, but has anyone ever considered a speculative evolutionary pathway to Wyverns? Or, for that matter, classic “4 limbs + 2 wings” dragons?

Oh people have considered it alright. A while back there was a book called The Flight of Dragons (later made into an animated movie by Rankin/Bass, in the same visual style as The Hobbit). Then in 2004 there was a fictional documentary about finding the remains of dragons and tracing their fictional evolutionary history (though the program didn’t actually make it clear that it was fictional; lots of people to this day think it was real). Both of them give some pseudoscientific trappings to elements of dragon myths, like eating catalytic minerals to generate hydrogen for lift and fire-breathing. The documentary went into much more detail and had the original dragon line branching out into Western and Asian dragons of different types.

Hard science for me, at least regarding this question. The morphological/anatomical challenges are interesting to me. If you want a sexapod design, the extant Draco volans lizards are headed in the right direction, but the extinct Kuehneosaurus had a second set of ribs that formed actual wings. But what selection pressure and environment could allow the wing set to migrate up on top of the spine and scapulae, gradually adding entire muscle groups first to allow for finer glide control and ultimately to provide thrust? What about the aeronautics? You need a certain minimum size to start with if your flight design is going to be able to support anything larger than an iguana.

The phylogeny of pteranodons seems promising for the Wyvern side of things, but I don’t know enough about it.

KlausH said:

This species is fine, but cormorants are serious pests in Texas. Sometimes they move move into small lakes and large ponds, and they won’t leave until they have killed off every single fish and large amphibian!

One man’s pest is another man’s ecological component. Cormorants are predators - feeding mostly on fish. They compete with man for fish and man ain’t happy about sharing. Keep in mind that many of those fish targeted by cormorants and man are non-natives and most of those Texas lakes and ponds are not natural. Cormorants are native to Texas. They have existed for a very long time in dynamic harmony with native species and natural habitats. If there’s a ‘pest’ in the scenario it’s man.

“Having made its way to a small set of islands we now call the Galápagos and given sufficient food and no predators, the cormorant had no need to fly, so over the years lost its full-feathered wings. Its bright-orange companion is Grapsus grapsus – the Sally Lightfoot crab.”

Great picture.

There may be more to the picture than the “cave fish eye” model of flight loss implied here.

Penguins, emus and ostriches deal with predator-rich environments, yet are flightless.

The stereotype of the Dodo notwithstanding, birds don’t seem to evolve to being flightless in low predator environments like new islands all that often.

Remember, many, many environments are accessible to birds. If bird populations on islands without many predators tended toward becoming flightless, we might expect to see quite a few examples of that.

Instead, it seems to be positive selection for some other trait, like swimming or running, that usually moves bird populations to being flightless.

The Dodo was subjected to a sudden invasion by the most ruthless and wasteful predator to ever exist in the biosphere. They were probably highly adapted to their environment. We killed them all and then stereotyped them as “stupid” for being killed.

harold said:

“Having made its way to a small set of islands we now call the Galápagos and given sufficient food and no predators, the cormorant had no need to fly, so over the years lost its full-feathered wings. Its bright-orange companion is Grapsus grapsus – the Sally Lightfoot crab.”

Great picture.

There may be more to the picture than the “cave fish eye” model of flight loss implied here.

Penguins, emus and ostriches deal with predator-rich environments, yet are flightless.

The stereotype of the Dodo notwithstanding, birds don’t seem to evolve to being flightless in low predator environments like new islands all that often.

In fact it has been very common. Not only are flight-capable wings not (much) needed where predators pose little threat, they require significant energy to produce and to maintain, and some birds are better off not being prone to being blown away from an island into an endless ocean.

Humans and/or animals that arrived with them killed off flightless birds on a host of islands, and many were not known until people began to dig in cooking pits and the like, and finding extinct flightless bird bones. Here’s a Wikipedia list of extinct flightless birds Many are from New Zealand, but there are a good many from other, previously low-predator zones as well.

Emus, rheas, and ostriches may have evolved to be flightless before their environments were predator-rich. A possibility, although something not easy to determine. Penguins do not often land upon predator-rich lands, and are fairly adept at avoiding predators in the water.

Remember, many, many environments are accessible to birds. If bird populations on islands without many predators tended toward becoming flightless, we might expect to see quite a few examples of that.

Bones of examples are fairly common.

Instead, it seems to be positive selection for some other trait, like swimming or running, that usually moves bird populations to being flightless.

The Dodo was subjected to a sudden invasion by the most ruthless and wasteful predator to ever exist in the biosphere.

You mean rats?

They were probably highly adapted to their environment. We killed them all and then stereotyped them as “stupid” for being killed.

No we didn’t. They tasted rather bad, and there are few dodo bones in the human-invaders’ dumps and fire pits. Rats are thought the likely culprit, eating the eggs laid on the ground.

Glen Davidson

Rats are thought the likely culprit, eating the eggs laid on the ground.

Well, eggs laid in nests made on the ground.

Glen Davidson

The common cormorant or shag

Lays eggs inside a paper bag.

The reason you will see, no doubt,

It is to keep the lightning out.

But what these unobservant birds

Have never noticed is that herds

Of wandering bears may come with buns

And steal the bags to hold the crumbs.

Flightlessness has evolved among Pacific island rails more than 700 times. See Steadman, D. W. 2006. Extinction and Biogeography of Tropical Pacific Birds. University of Chicago Press, Chicago, Illinois.

https://me.yahoo.com/a/JxVN0eQFqtmg[…]X_Zhn8#57cad said:

harold said:

“Having made its way to a small set of islands we now call the Galápagos and given sufficient food and no predators, the cormorant had no need to fly, so over the years lost its full-feathered wings. Its bright-orange companion is Grapsus grapsus – the Sally Lightfoot crab.”

Great picture.

There may be more to the picture than the “cave fish eye” model of flight loss implied here.

Penguins, emus and ostriches deal with predator-rich environments, yet are flightless.

The stereotype of the Dodo notwithstanding, birds don’t seem to evolve to being flightless in low predator environments like new islands all that often.

In fact it has been very common. Not only are flight-capable wings not (much) needed where predators pose little threat, they require significant energy to produce and to maintain, and some birds are better off not being prone to being blown away from an island into an endless ocean.

Humans and/or animals that arrived with them killed off flightless birds on a host of islands, and many were not known until people began to dig in cooking pits and the like, and finding extinct flightless bird bones. Here’s a Wikipedia list of extinct flightless birds Many are from New Zealand, but there are a good many from other, previously low-predator zones as well.

Emus, rheas, and ostriches may have evolved to be flightless before their environments were predator-rich. A possibility, although something not easy to determine. Penguins do not often land upon predator-rich lands, and are fairly adept at avoiding predators in the water.

Remember, many, many environments are accessible to birds. If bird populations on islands without many predators tended toward becoming flightless, we might expect to see quite a few examples of that.

Bones of examples are fairly common.

Instead, it seems to be positive selection for some other trait, like swimming or running, that usually moves bird populations to being flightless.

The Dodo was subjected to a sudden invasion by the most ruthless and wasteful predator to ever exist in the biosphere.

You mean rats?

They were probably highly adapted to their environment. We killed them all and then stereotyped them as “stupid” for being killed.

No we didn’t. They tasted rather bad, and there are few dodo bones in the human-invaders’ dumps and fire pits. Rats are thought the likely culprit, eating the eggs laid on the ground.

Glen Davidson

John Harshman said:

Flightlessness has evolved among Pacific island rails more than 700 times. See Steadman, D. W. 2006. Extinction and Biogeography of Tropical Pacific Birds. University of Chicago Press, Chicago, Illinois.

Interesting stuff, and I stand corrected. A mild example of the Dunning Kruger effect; I underestimated the number of extinct flightless birds that I had never heard of. I was also guilty of believing the stereotype that humans hunted down the Dodo.

(However, I should note that fresh meat protects against scurvy - it doesn’t contain much vitamin C but it does contain trace amounts, that seems to help. People on a vitamin C deficient diet do develop a craving for food sources of vitamin C, even though they don’t know why. Seventeenth and eighteenth century seafarers were voracious eaters of much of what they could catch when they landed on uninhabited islands. I’m sure there’s also some example of people dying of scurvy because they wouldn’t eat something that would have saved them, but there are also plenty of examples of the opposite.)

Still, I do find the success of some flightless bird species interesting.

The wikipedia page is unclear on the extent of hunting by humans http://en.wikipedia.org/wiki/Dodo It sounds as if not everyone liked the meat, but dodos were definitely hunted. I also remember reading (as Glen Davidson said) that their extinction may have been caused by rats eating their eggs (and this was in the 70s in a kids’ illustrated encyclopedia, so nothing cutting edge). Is there anything more definitive now?

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This page contains a single entry by Matt Young published on July 28, 2014 12:00 PM.

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