why birds don't explode

Cecil's Columns/Staff Reports
1

Santa was uncharacteristically good this year, and presented his humble Beruang with not one, not two, but three of the sacred Cecil tomes. “Triumph of the Straight Dope” contains the (in)famous “exploding birds” column.
http://www.straightdope.com/columns/970502.html

It seems to me there is one fairly apparent counter-argument. Sure, dry rice will soak up liquid and expand, and we can assume this happens in the stomachs of birds. But what is the rice soaking up? Quite simply, it is soaking up the various intestinal juices that are already present in the bird’s stomach. No new matter is introduced; thus, no increase in bird mass, no expansion of bird guts, and no exploding birds. Alas, once again, science serves to make our world slightly less interesting… :wink:

2

I think you’re confusing mass and volume!
If what you siad were true, then vessels would never explode!

Ever mix vinegar and alka-seltzer? You’ll notice a great change in volume, but the mass is always conserved!

It’s the volume, not the mass, that could cause the bird’s stomach to rupture!

I’d rather have a bottle in front of me than a frontal lobotomy - Hawkeye 4077th

3

Ah, but alka-seltzer effervesces – a chemical reaction between the solid and the liquid creates a gas, which takes up more volume. In the article, I read no argument that rice reacts with stomach acid to create gas (and a literally killer case of heart-burn). Rather, the arguments ran along the lines of “rice outside a bird’s stomach can soak up liquid and expand; therefore, rice inside a bird’s stomach can also soak up liquid and expand.”

I agree, but counter by saying that while the volume in the bird’s stomach taken up by the expanding rice increases, the volume taken up by gastric juices decreases by the same amount. No matter changes state to take up more room. Thus, the total volume remains constant.

Unless the bird overeats, but that’s not what we’re talking about.

It is possible that I may have missed an “effervescence” argument somewhere in the article, in which case I apologize.

4

Your argument is strong and causes one to pause, but there must be other factors at work here.

I can only speculate that the starch of the rice is probably readily digested by the gastric juices. With the starch removed, the rice grain can now relax to an expanded shape.

I believe a cup of plain white rice yields 1.5x cups upon cooking (removing the starch).
The expanded rice then exerts excessive pressure on the stomach walls.

Note: It is more probable the bird internals may rupture rather than a total “explosion”.

I’d rather have a bottle in front of me than a frontal lobotomy - Hawkeye 4077th

5

Hmm, interesting… But does the cooked rice expand because the starch is disolved, or because it has absorbed water? I think I’ll conduct an experiment tonight. I’ll take a cup of rice, cook it, measure it, then let it dry, and measure it again. If the second measurement is the same, I would take it as evidence that rice doesn’t expand, but just soaks up juices that are already there. If, on the other hand, the second measurement is bigger, then we may take is as evidence that rice does undergo some structural change that increases it’s volume.

And science marches on…

6

It’s always a good idea to test these things, but I’m not convinced that your research plan is appropriate. For one thing, the test you describe does not parallel what happens in our birdie’s gut (unless I missed something and the bird somehow actually does let the rice dry out again in situ).
I think the only valid test to do would be to measure out a mixture of rice and a digestive juice analog (maybe dilute hydrochloric acid), make an accurate measurement of the volume of this mixture, let it sit till it’s all soaked up and see if it has the same volume. One could just cook it with water, but that would leave unanswered the possibility that digestion changes starch in such a way that it takes up more space than rice that has merely absorbed water

A couple of points:
“I believe a cup of plain white rice yields 1.5x cups upon cooking (removing the starch).” (Jinx)
Is this so? I have never noticed any large amount of starch being removed. Where does it go? I have always conceived of the rice cooking process as putting water into rice, rather than taking starch out of it. Also, is that .5 more cups than the cup of plain rice + water to cook in (e.g. 1 cup rice+1.5 cups water=3 cups compressed cooked rice)?
It is important that it be compressed (just smushed down with a hand would do), since fluffed rice or rice that is allowed to sit in an open container might reasonably be expected to take up more space than rice crammed into an elastic sack (stomach) without actually getting bigger by virtue of the fact that the grains at rest will have spaces between them but when compressed would deform and pretty much fill the whole space (I think).

Well, I guess I could obsess about this a bit longer but all this rice talk has made me hungry.

“Make me one with everything…” – the Dalai Lama, overheard at a hot-dog stand

7

I’ll admit…I may have my facts confused on the cooking of rice! Sorry!

I am interested to hear the results of Beruang’s experiment - even if does not simulate the birdie’s gut (per Woodja).

As I understand it, starch is just a chain of sugar molecules minus a H2O molecule. I guess the water could be taken in by the starch, but I don’t think it’s that simple.

Along these lines, with pasta, aren’t we boiling the starch out? Doesn’t float on top and/or leave a residue on the sides of the pot? Why not, then, with rice?

I’d rather have a bottle in front of me than a frontal lobotomy - Hawkeye 4077th

8

All of this neglects the fact that birds have gizzards, and eat rocks to help them break up grains so they can digest them.

I don’t think dead birds is really the concern for throwing rice at weddings. Rather, dead guests. Granny doesn’t walk too well even with her walker, why make the job harder by throwing roller bearings on the ground? But the eco-sensitive humans are more likely to respond to a plea on behalf of helpless birds who don’t know better than to be careful how much they eat rather than worry that the bride may be a widow too soon if the groom tumbles off that top step.

9

When I got married way back in 1983, bird seed was thrown at our wedding. How do I recall for sure? You don’t quickly forget how exquisitely romantic it is back at the hotel room to find that your underwear is full of bird seed.

But my point is that when I asked why bird seed instead of rice (fortunately the groom simply has to show up and not actually plan the weddings), I was told that it’s to reduce litter - that if you throw bird seed, the birds will eat it.

Could the exploding bird story have mutated from this? Exploding birds sounds to me exactly like what you would expect from people’s tendency to modify stories and propagate the ones that fit the “urban legend” style. We throw seed instead of rice for some reason having to do with birds, this mutates into someone thinking that rice is unhealthy for birds, then someone else adds his knowledge of how rice expands, and soon you have this factoid floating around which is almost believable, but somewhat shocking, making for great word-of-mouth value.

To me this sounds likely, so if we could get some dates on when seed-throwing actually started, and when the exploding-bird legend started, we might start putting the picture together.

10

Haven’t we heard? Rice or bird seed is passe!
Now, they have tiny bubbles we can blow at the lovely couple!

Until we find that tiny bubbles cause those picky birds preferring rice to bird seed to explode?

11

Along these lines, with pasta, aren’t we boiling the starch out? Doesn’t float on top and/or leave a residue on the
sides of the pot? Why not, then, with rice?

Well, some comes out in solution, but considering that pasta (and rice) is almost all starch, “boiling the starch out” would result in water with starch in it rather than starch with water in it (cooked rice/pasta). I guess It’s a technicality, or a cooking preference; God knows I’ve seen some pretty limp noodles and eaten some pretty mushy rice.

When I was a kid we threw pieces of alka selzer tablets to the seagulls. I never saw one explode, but they didn’t seem to like it very much. Come to think of it, I’m not a big fan myself. I see this as the next big wedding tradition: the happy couple driving away amidst a flock of birds, all spewing white foam. Very festive. They could even have multicolored tablets, for the avant guard wedding experience.

12

Ok wait a minute… Please tell me does alka-seltzer cause them to explode? I’ve been told it does but I haven’t tested the theory. Do they? Please save a bird and tell me before I have to perform experiments.

The ever insensitive, politically incorrect PitBullDawg.
Political correctness is a disease. Cure it with the truth.

13

OK, we have results for part one of the famous rice-cooking experiment.

I purchased a fresh box of Uncle Ben’s plain white rice. Cheapest of the national brands (at least at my Jewel), I deduced this would be the variety most likely to be thrown at a wedding. Unable to find any dilute solution of hydrochloric acid, I opted instead to simply follow the directions on the back of the box. One cup of rice plus 2.25 cups of water plus small amounts of butter and salt were boiled for 20 minutes. The results: all the water was absorbed, and I had 3.5 cups of cooked rice. This slight increase in volume is probably within an acceptable margin of error for my admittedly crude measuring instruments.

Of course, few bird stomachs ever reach the boiling point. To somewhat more accurately recreate those conditions, I took another cup of rice and let it soak in 2.25 cups of water at room temperature for an hour (longer than an grain would actually sit in a bird’s gut, unless said bird was profoundly constipated). I then drained the rice and discovered I had 1 7/8 cups of rice and 1 5/8 cups of water – exactly as much matter coming out of the experiment as I had going in.

I interpret this as evidence that rice alone cannot make a bird’s stomach rupture or explode by the method described in the article. The rice does absorb liquid and expand, but the total volume of rice plus liquid in the bird’s stomach remains constant. I welcome alternate hypotheses.

For part two of the experiment, I spread both rices out on cookie sheets to dry overnight. I wanted to measure their post-experiment volume to see if they permanently changed shape, or had simply swollen up and would shrink back. Sadly, this morning both were still damp to the touch. With luck, I will be able to conclude this phase of the experiment ove the weekend, and be able to report back to you on Monday.

As for Alka Seltzer and seagulls – I heard this too, as a kid, from my older brother. After reading Brunvand’s first book, I realized that everything my older brother told me as a kid was an urban legend.

14

Well, we did do it as kids (25 years ago), rather than just hearing about it, but we never had the spectacular results that were later reported and found to be legend. All that happened was that they eventually went away to find someone offering actual food. I can’t even confirm that they really ingested the stuff, it’s quite possible that they just spit it back out.
We were very disappointed.
My feeling is that a bird eating an alka selzer would expel the gas through the path of least resistance, i.e. mouth or anus, before
anything ruptured. The usual reason given for
the explosion is that birds don’t burp (a fact
I can’t confirm or deny), but I doubt that a
sturdy and elastic stomach would rupture before releasing gases through a couple of holes that are already there.
Reality takes a lot of the romance out of the world.
Cecil also did a brief followup on this in http://www.straightdope.com/columns/970613.html

15

Good grief, the danger to the poor birds just gets worse and worse! Imagine what happens when a hungry bird gobbles up one of these irresistably glistening, floating bubbles: the bird’s stomach fills with a combination of soap and buoyant bubble gasses.

Now, birds have pretty low mass as it is, and with the additional buoyancy a bird with average wing strength would be unable to land. (And note that even a strong bird would have to realize that it should use its wings to push itself *downward[/], rather than upward - not at all natural for a bird.

Although birds are, of course, comfortable in the air, most must land on the ground to eat - and these bubble-filled birds can’t do that. Even birds that normally eat insects out of the air will find themselves unable to digest their food, due to the soap film lining their stomachs. Eventually, we’re faced with the prospect of whole flocks of dead, starved birds floating through the atmosphere, creating a hazard to navigation, getting sucked into jet engines, and generally giving people the willies.

The ideal bird-safe thing to throw at weddings is, of course, small gravel. It may not be quite as bride-and-groom-safe, but it’s worth it for the sake of the birds.

16

I think that some of you are forgetting a very important part of digestion; namely that it is not a closed system. There are constantly fluxuating volumes of gastric juices (yes, that’s a technical term) and their respective concentrations. Even if the volume of the foodstuff ceases to increase, the volume of the digestion aids does continue to increase, due to the differing molecules in the food triggering their constant and continued release.

And, it’s also importand to note that HCl isn’t the only substance that’s secreted by the digestive system. There are other chemicals that serve to break down other substances, and even their countering agents that keep the digestive system from, in effect, eating itself.

So, being that we cannot actually put ourselves in that particular environment, it serves to be noted that it’s entirely possible for the volume of ‘stuff’ in our Avian frien’s tummy to reach critical levels. And, with out proper mechanisms to release any sort of pressure build up (save for deposits on shiny cars), the possibility exists for ‘exploding’ birds.

“He who does not read is no better off that he who does not read.” Mark Twain

17

Re: Alka-Seltzer and seagulls

When I was in junior high, it was quite the pasttime among a certain element to bring Alka-seltzer to school and feed it to the gulls. Gulls were pretty well able to recognize the tablets (or pieces thereof) alone as something they didn’t want to eat, so the trick was to disguise them by wrapping them in something they would eat. Sandwich bread seemed like the best medium for this, as it could easily be molded and squished around the tablet. It ws important not to make the bait so large that a gull would need to eat it in several bites, though, so a third to a half of a tablet was the recommended dose. In this size, the gulls’ natural competitveness (there were a lot of gulls at my junior high at lunchtime) would cause them to bolt down just about anything even remotely edible.

For the record, even when I was with associates who were performing this stunt, I never did see an affected gull foaming at either end. I think this is primarily due to my associates’ practice of baiting the gulls from a covered area that faced onto the quad, rather than out in the open. This was apparently done to protect one’s self from the “fallout.” I have, however, seen gulls eat Seltzer-laced bait, then immediately fly off, looking unsteady and uncomfortable, to some secret destination on the other side of a building. I have even seen one of these uncomfortable-looking gulls drop something from his tail end as he flew. Whether this was a normal defecation, or one resulting from the administration of the Seltzer, however, I have no way of knowing.

Purely in the interests of the Straight Dope, and scientific knowledge in general, I am proposing an experiment. All I need to perform this experiment is a box of Alka-Seltzer, a loaf of bread and/or other bait, and an assistant to aid in bird observation, bait-lacing, authority-figure spotting, and result-tabulating. If you can assist in these areas, and can meet me in the beachy vicinity of Oxnard, Ventura, Carpinteria, or Santa Barbara, California (or points between) on a weekend, please indicate your availablity in this forum, along with contact info (email address), and I will contact you. If we can get several teams, so much the better. Bring a hat.