I'd have been tempted to join my colleagues in the press and the people we cover in mere opinion-mongering. But I've been powerfully shaped by a question I conceived earlier in my career: If a shark and a tiger were to fight, how many inches of water would it take for the shark to win?

The item I produced on the subject would've been impossible without shark expert Ralph S. Collier, who graciously answered the question put to him by email. The experience taught me a valuable journalistic lesson: If you send animal researchers outlandish hypothetical questions that touch on their area of expertise, they'll respond generously, especially if inter-species combat is involved*.

John M. Eadie chairs the Department of Wildlife, Fish, and Conservation Biology at the University of California, Davis, where his areas of expertise include avian ecology and waterfowl.

What does he think about Nick Kristof's soaring rhetoric and White House worries about being attacked on air, land, and sea?

"It could not fly," he insists, illustrating his argument by assuming a horse-sized duck weighing 1,000 pounds.

"At 1,000 pounds, the wing-loading (ratio of body weight to wing area) would be immense. The wing-loading of a mallard duck is less than 0.02 lbs/square inch (2.5 pounds over a wing area around 150 square inches). So, scaling up 400 fold (and it is not necessarily linear, but I will assume so for simplicity here), would require a wing area of 60,000 square inches = 416 square feet = 10 ft wide by 40 feet long," he explains. "The wings would have to be immense. Not likely (and indeed this is what limits the size of flying birds, in the absence of jet engines!). So, we don't have to worry about the terror duck attacking from the air. It would be a land lubber." **

The Obama Administration eventually started to ask better questions. "It's just one opponent—you can focus all your energy, attention, and strength on outsmarting it," the unnamed official told BuzzFeed. "Maybe it tires easily. Hard to know." In fact, it would tire easily:

With such a huge body, the problem of surface area to body volume comes into play. The terror-ducktyl would have a problem losing heat. Hence, a possible tactic would be to get it running around chasing me and it might overheat, stroke out, and die. Birds have higher body temperatures than mammals in any case (often very close to the 40 degrees Celsius upper lethal limit) so it might not take too much to push the duck over the metabolic cliff. Merits consideration.

And it would be easy to outsmart. "Ducks are dumb. There is a record of some research in which half of a duck's brain was removed surgically ... with no discernible change in its behavior," Eadie explained, though he didn't see that aspect of its biology as an unalloyed advantage. "The flip side, is that in battle, I could literally destroy half the terror-duck's brain and it would have no impact on the battle. Nothing worse than a dumb opponent who doesn't know how to quit."

So did he expect the fight against the oversized duck to be easier?

After all, as nature writer Sy Montgomery, author of Birdology, pithily pointed out in a separate email, "There once WERE horse-sized ducks: They were known as Mihirungs, giant flightless birds who stood up to three meters high and weighed up to half a metric ton. They lived in Australia during the late Tertiary and early Pleistocene. But where are they now? They must have a weakness.”

Perhaps so.

But despite its weaknesses, "I fear the duck," Eadie confessed.

Lest you worry that he's just a thoughtlessly embracing the conventional wisdom, as shaped by Alfred Hitchcock's 1963 horror movie The Birds and the chilling scholarly article "Aggressive Behavior and Interspecific Killing by Flying Steamer-Ducks in Argentina," with its talk of "aggression toward a wide variety of species not closely related taxonomically, or similar in appearance or food habits," don't fret: His arguments for the horse-sized duck's strengths are compelling.

As he put it:

(1) Birds (ducks) have a far more efficient respiratory system than mammals (one way flow through the lungs and they capture almost all of the oxygen passing through the lungs compared to half that in the lungs of mammals). The duck could easily outlast me.



(2) The wings of a 1,000-pound duck would be threatening armaments. Bird bones are hollow, but incredibly strong, especially the humerus (main wing bone). I have been beaten (literally) when banding Canada Geese and their wings can deliver a wallop that leaves bruises on even the most hardened of field biologists. The Giant Canada Goose (Branta canadensis maxima) is the largest goose in the world and can get up to 20 pounds—our terror duck would be 50 times the size! One wing thump would be a deathblow.



(3) Birds, when flying, bear their entire body weight on their wings. And, when migrating, they do this for 24-36 hours at a time. So, they are suspending their entire body weight by their "arms" held straight-out from their side. It is equivalent to a human gymnast holding the iron cross position for 24 hours. And lifting their body up and down repeatedly. You want to fight something that can do that?



(4) Even our ex-governor in California would envy the chest muscles of a bird. Their wings are powered by huge breast muscles (the pectorals major and pectorals minor) that lift and lower the wing and the bird's weight. These muscles comprise up to 30 percent of the birds body weight. So, our terror duck has 300 pound 'pecs. Nope, not wanting to face that.



(5) Waterfowl are omnivores, horses are herbivores. The duck could eat me, the horses would not.



(6) Birds have gizzards, known for their crushing ability. A shrike can digest a mouse in a few hours. Turkeys can crunch 24 walnuts in the shell in less than 4 hours and grind surgical lancets to grit in less than 16 hours. Aside from what the terror-duck's gizzard would do to me if it ate me, it could easily chomp down and grind to dust any weapon I might have.



(7) The bill of a duck is adapted for picking and sieving. It has ridges called lamella - regular teeth like edges on its mandibles. Nothing to really worry about for a regular-sized duck. But scaled up 400 fold (2.5 pounds to 1000), those 0.02 inch long lamella would be 8 inch long crusher blades with 50-70 of these arranged along the edge. Hmmm. Not wanting to faces that, thanks.



(8) Waterfowl are among the oldest existing group of birds. And we know quite well, now, that birds are actually dinosaurs (I kid you not). Their ancestry—theropod (maniraptoran) dinosaurs. They are relatives, and most closely aligned, with the group that includes tyrannosaurs and velociraptors. They have serious attitude and it comes with the family history.

Eadie is almost dismissive of the duck-sized horses.

Granting that they'd be fast and capable of fighting in a herd, he points out that "horses are edgy and easily spooked. Move toward one, especially quickly and unexpectedly, and they run away (if you have never tried to saddle even a tame horse, try it). And if they were scaled down to the size of a duck, even their most potent weapon (kicking with their hooves or biting) would not be lethal and would likely deliver little more than bruised or nibbled shins." Of courses, the horses could more easily run away, but it turns out they'd also be easier to best in a war of attrition:

At their high metabolic rate, and the increased surface area to volume ratio, the dorses would be challenged to keep up a fast or active lifestyle and find enough food, especially if they remained herbivorous. Horses spend a large part of their time eating even at their current size, given the long processing time required for digesting vegetation. At the size of a duck (with much more surface area to volume, such that they would rapidly lose metabolic heat), they would need much more food relative to their body mass. They would eat all day. So it would be easy to sneak up on them. Or starve them to death. Or woo them over with apples and sugar cubes. And if it got down and dirty, given the relatively frail ribs and femurs of modern horses (work horses excepted), I suspect that many of the dorses cold be dispatched with a swift kick.

Finally, just as there were giant birds that went extinct, Eadie points out, "there were indeed small horses (Eohippus, about the size of a small dog). They went extinct. That says something."

***

So wait just a minute, you might be thinking. If Eadie and a majority of people who've pondered this question say that the 100 duck-sized horses would be the easier biological opponent, why am I so sure that President Obama would fight the horse-sized duck?

Come now.

Prudence and biological consequences are low on the list of factors that dictate which wars of choice get waged, as so many maimed veterans of the Iraq War can attest. Political reality matters more.

Eadie understands as much. After engaging his graduate students in conversation, he came to realize that it would be politically disastrous for Obama to fight the duck-sized horses. Think about it. In America, the duck lobby is composed of duck hunters. The horse lobby is made up of horse lovers who succeeded in stopping Californians from buying horse meat. The young women voters essential to the Democratic coalition are far more sympathetic to veritable ponies than a giant, rape-obsessed mallard. Shooting the duck would be perfectly legal under existing law, or would at worst result in a citation for hunting without a license.

But killing the duck-sized horses?

"If Obama killed just one of the hundred 'dorses', he would be subject to legal action and huge fines under existing federal law (e.g. The Wild Free-Roaming Horses and Burros Act of 1971, the animal welfare act and, based on a recent case, even the National Environmental Policy Act)," Eadie points out. "There is no sport horsery! The legal implications would have him tied up in court, bankrupt or in prison faster than you can say Secretariat."

It's easy to anticipate the coalition that would form against him. Still upset about being dinged for putting Seamus on the roof and urged by his Rafalca-loving wife to intercede, Mitt Romney would lead the charge to draw up impeachment papers. Congressional Republicans would surely be amenable to cooperating.

Even barring that scenario, the politics are clear: You fight the giant duck. So what about the execution?

That's actually the clincher.

A moment's reflection is enough to understand that Obama would "fight" his inter-species foe the same way he "fights" militants. It would probably be hard to pummel a horse-sized duck to death or to slay it with a sword, but the commander-in-chief's weapon of choice is a Predator drone equipped with a Hellfire missile, operated under secret legal authority. Behind their computer screens in the Nevada desert, would it be easier for the drone pilots to kill the horse-sized duck, or the whole herd of duck-sized horses? The little equines would scatter, despite the preparatory steps even now being taken to prepare them for the duress of war:



In fact, it isn't clear that the American people would buy the notion of little horses being legitimate targets in the War on Terror. But the giant duck? Sure, its presence on American soil might complicate things. Even neoconservatives are made uneasy by the prospect of drones in American airspace. But that's where the real genius of choosing the horse-sized duck is revealed.

You've heard of avian flu? Yeah: bioweapon. Obama could plausibly claim that there are more WMDs in that monster duck than were ever found in Iraq, and he's surrounded himself with people who voted for that war in 2002. The whole Washington establishment and much of the nation would rally behind Obama against the duck. Go back to the beginning of this story and you'll see that even an unprompted Eadie, a dispassionate man of science, reflexively started referring to the foe as "a terror-duck." Given America's post-9/11 deference to POTUS in matters of terrorism, Obama would obviously choose "the terror duck" as his enemy. Its ducklings would be lucky to survive.

*I've had less luck getting answers from experts about ethics in centaur medicine, though I don't know whether that is because no blood sport is involved or because centaurs are mythical.

**Note to James Fallows: "Blind into Duckdad" for the April cover? Think about it.