Posts Tagged ‘bird sex’

Wild Swans

February 20, 2009

swan_flying1

Writing adequately about swans and their place in mythology and literature would take a very long time indeed.  We started the process early in the history of this blog when we began our series about bird sex.  (Part I, Part II, Part III)

cygnus

Today, while waiting for the end of winter, that season during which the constellation Cygnus the Swan is not flying up the Milky Way high overhead, we turn to Edna St. Vincent Millay’s poem of a woman inspired by wild swans to open her heart to all the myriad joys of life.

Wild Swans

I looked in my heart while the wild swans went over.
And what did I see I had not seen before?
Only a question less or a question more:
Nothing to match the flight of wild birds flying.
Tiresome heart, forever living and dying,
House without air, I leave you and lock your door.
Wild swans, come over the town, come over
The town again, trailing your legs and crying!

Edna St. Vincent Millay

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Photo Credit: Ginger Holser, WDFW photos.

Turkeys

November 25, 2008
Wild Turkey

Wild Turkey

Benjamin Franklin famously believed that the national bird of the United States should be the wild turkey.  Of course, he also thought the rattlesnake would be a good symbol for the new country; because this is a bird blog, we’ll let that go.

In a letter to his daughter Franklin wrote about the bald eagle,

He is a Bird of bad moral Character. He does not get his Living honestly. You may have seen him perched on some dead Tree near the River, where, too lazy to fish for himself, he watches the Labour of the Fishing Hawk; and when that diligent Bird has at length taken a Fish, and is bearing it to his Nest for the Support of his Mate and young Ones, the Bald Eagle pursues him and takes it from him.

On the other hand, Franklin asserted,

For the Truth the Turkey is in Comparison a much more respectable Bird, and withal a true original Native of America . . . He is besides, though a little vain & silly, a Bird of Courage, and would not hesitate to attack a Grenadier of the British Guards who should presume to invade his Farm Yard with a red Coat on.

Franklin was right about the turkey being a native of North America.  It has been here a long time. Because of its large size and historical use as human food, the turkey has a good fossil record.  Fossils have been found as far back as the Miocene and the Pleistocene in North America. Archeology established long ago that many subsistence cultures ate them.

Female Wild Turkey with chicks

Female Wild Turkey with chicks

Hunting them must have been a challenge to those early hunters. Franklin aside, the birds are extremely wary; no wild turkey would have attacked a British Grenadier.  But it would have seen and heard that Red Coat coming from miles away and fled.  Wild turkeys possess keen eyesight and exquisite hearing which makes them hunting challenges even for their primary modern predator, humans.  Males prefer running away; females, flying.  Both can fly and at speeds up to 50mph.

That turkey in your kitchen for this Thanksgiving is a pale imitation of the real thing.  Because of the popularity of white meat — white because it is different muscle with less ability to store oxygen than dark muscle — your turkey was bred for a large breast.  In fact, domesticated turkeys raised for food have such large breasts they are incapable of mounting females for the cloacal kiss.  Instead the males are artificially manipulated and then milked for their semen which is then injected into the females to fertilize their eggs. Confined to quarters, these domesticated turkeys are tricked by artificial light into breeding year round so that the supply, especially now, is adequate.  Far too heavy for flight, it could never have escaped a British soldier.

But even though that Broad-breasted White Turkey you cut into this Thanksgiving is not the same as his wild, shrewd cousin, you partake of a North American tradition far older than Thanksgiving.

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If you need any help carving a turkey, here is a video of a pretty good way to do it.

Bird Sex, Part III

March 1, 2008

Dr. Olivia Judson, an evolutionary biologist who has a blog on the New York Times web site, recently asked one of the burning questions of modern science: Did Tyrannosaurus rex have a penis? Or two as some modern lizards do? Or, like most birds, none? (You can read her post here.) Modern birds may know the answer.

field_guide_trex.jpg

We know this question has been keeping you up nights and we’re happy to answer it.

Wait. Not so fast. First we need to set the stage. Five times in the known history of the planet mass extinctions wiped out most forms of life here. The biggest — the Permian-Triassic — happened about 251 million years ago, last Tuesday. (251 mya) The most well-known mass extinction was about 65 million years ago. (65 mya) This was the famous one, the Cretaceous Extinction, probably caused by an asteroid hitting the earth’s atmosphere somewhere above what is now the Gulf of Mexico. The resulting explosion vaporized everything nearby and sent up a cloud of dust so thick that it was decades before the sun shone through again. In the meantime almost all terrestrial life had starved or frozen to death, including the dinosaurs.

Not all life forms were wiped out. Obviously some survived; otherwise insufficient time would have passed for evolution to reach its pinnacle — the blogger.

A few bird ancestors lived through it. Specifically, two “superorders,” the Palaeognathae and the Neognathae. (There will be a test. ) Frankly, we know very little about how they came to exist before the extinction or how they survived it. About all we know for sure is that modern birds came from the two superorders, both of which came from dinosaurs. As Judson tells us, “Birds are more closely related to T. rex than they are to any living form.”

While we are fairly confident that birds evolved from dinosaurs we are not sure from which dinosaurs. One theory holds that birds evolved about 230 mya from Thecodonts. Another argues that birds developed from Theropods 150 mya. (Remember, there will be a test.) Still another asserts that birds arose from Dromaeosaurs about 110 mya. Which is correct depends on how dinosaurs learned to fly. Did they start by soaring or jumping or running after insects? More on that in a later post. Today we are concerned with sex, not flight.

As we discussed in our earlier posts about bird sex, which are here and here, most birds do not have penises. Procreation occurs when male and female birds touch their cloacae to one another. Only a few bird species possess penises. Some waterfowl and large flightless birds do. So do male crocodiles which, like birds, have cloacas; but also have a penis down which sperm passes on the outside, which is true for penis-owning birds as well. Crocodiles too descended from dinosaurs.

We’re close to the answer now. But first, we need to remind you that the fossil record does not answer the question about T-rex’s genitalia. The reason is simple: Except in a few mammals, penises consist of nothing but soft tissue which does not fossilize well. No fossil record of dinosaur penises exists. Which is why we look to birds for the answer.

Here is Dr. Judson’s answer:

The palaeos comprises the big flightless birds such as ostriches, emus, rheas, and cassowaries, as well as kiwis and an obscure (but flying) group of south American birds, the tinamous; the neos covers everything else. The palaeos have penises; like crocodiles, they keep them tucked into their cloacae. Again like crocodiles, the organ has an external groove for sperm. What’s more, the lineage leading to the other endowed birds, the ducks, geese, and swans, appears to have split off from that of the other neos relatively early.

This strongly suggests that the ancestor of all birds had a penis, and that at some point early in the evolution of the neognathous birds, the penis got lost.

Now you can get some sleep.

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Part I of this series.

Part II of this series

Bird Sex, Part II

August 20, 2007

A couple of weeks ago we began a series on avian reproduction with Yeat’s retelling of the myth of Leda and the Swan. We ended with the rhetorical question of why Zeus chose to become a Swan instead of some other bird before raping Leda. That post is here. Today, we supply the answer.

Male swans are among the few birds that have penises.

In fact, only male waterfowl and male flightless birds – ostriches, rheas, emus, cassowaries, and kiwis – have phalluses. All other birds evolved a different method of sexual reproduction that does not require a penis. We’ll start with them.

Because birds fly, they must be as light as possible. One of their many adaptations to that need are cloacas which both male and female possess. A cloaca combines the functions of a bladder, waste receptacle, excretory organ, anus and sex organ into one anatomical feature resulting in lighter weight. Another such adaptation is that most birds’ ovaries and testes shrink during the non-breeding season which further streamlines them for flight and reduces the sex drive in both, freeing up energy for flying, migration and staying warm.

When the breeding season is upon them, female birds’ ovaries enlarge as do male testes. The males produce sperm which travels from their internal testes (more streamlined arrangement than mammalian external male gonads) to the male cloaca which then is extruded from the bird’s body and swells with semen. After whatever breeding rituals particular to its species, the male mounts the female and pushes his cloaca against hers. In a matter of seconds the semen is transferred by this touch, known as a “cloaca kiss.” With the possible exception of some papillaries which may actually reach inside the outer edge of the female cloaca, no penetration takes place. In fact, birds really don’t copulate; they inseminate.

After receiving the semen, the females get to decide what to do with it. They can use it to fertilize eggs, save it for up to a month or get rid of it. Some females can lay numerous fertile eggs after only one sexual contact. Other species engage in much more copulatory contact, several times daily for as much as a month. Scientists suspect; however, that birds which copulate often do it for the same reason mammals do it: To maintain a pair bond. In other words, they use sex – as do humans – for more than reproduction. They do it to stay together. Lots of birds bond for life and it is no easier for birds than for us to stay together for an entire adult life. Plus, it probably feels good to them too.

But male waterfowls have a cloacal phallus. Sort of a corkscrew actually. Shaped like a ram’s horns. Technically it isn’t really a penis because it has no ureter inside it. No urine in birds. Urine requires too much water and, as any hiker of the Grand Canyon can tell you, water is heavy. No bird could fly with that much water on board. But that means there is no tube down which the waterfowl’s semen can pass. Rather, it is transported on the surface of the erect cloacal phallus. (Made erect, not by blood as in mammals, but by lymphatic pressure. More efficient, less weight.) The penis actually corkscrews into the female cloaca so waterfowls do “copulate” or, if you please, “screw.” Almost always on water and, for the female, frequently under water.

In many waterfowl species the males also engage in what scientists euphemistically call “Forced Extra Pair Copulations.” (FEPC) If a human male did it, we would call it “rape.” Not only did Zeus need a bird with a phallus to disguise himself, he needed an avian rapist in case Leda wasn’t interested in mating with a swan.

Imagine if Leda – a human female – could have rejected Zeus’s sperm. No Helen to burn Troy.

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Here is Part I of this series and here is part III.

Bird Sex, Part I

August 3, 2007

Birds form an integral part of the long history of humanity’s mythology. We’ll explore some of that mythology in the life of this blog. Today we’ll use one of those myths as an introduction to bird sex or “avian reproduction” as it should be called in polite society.

It is the myth of Leda and the Swan. ignacio_diaz_olano_leda.jpegLeda was the beautiful maiden whom Zeus desired. Zeus, knowing that his wife Hera violently disapproved of his sexual wanderings with beautiful mortals, tried to hide his sexual intentions toward Leda by disguising himself as a swan. The intercourse between Leda and Zeus – in most retelling of the myth – resulted in an egg from which Helen of Troy was born. Here is the most famous poetic versions of the myth.

Leda And The Swan
William Butler Yeats (1923)

A sudden blow: the great wings beating still
Above the staggering girl, her thighs caressed
By the dark webs, her nape caught in his bill,
He holds her helpless breast upon his breast.

How can those terrified vague fingers push
The feathered glory from her loosening thighs?
And how can body, laid in that white rush,
But feel the strange heart beating where it lies?

A shudder in the loins engenders there
The broken wall, the burning roof and tower
And Agamemnon dead.
Being so caught up,
So mastered by the brute blood of the air,
Did she put on his knowledge with his power
Before the indifferent beak could let her drop?

Have you ever wondered why Zeus chose to be a swan? Or why the first tellers of the myth told their audiences that Zeus became a swan instead of some other bird? Stay tuned. . . .

The painting, one of the more circumspect paintings of this famous myth, is by the Spanish artist Ignacio Diaz Olano (1860-1937)

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Here are other posts about bird sex:

Part II

Part III


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