In real nature, poisonous snakes attempt to save poison for later - because they have only limited amount of it. And instead of it they try to hide as soon as possible or to terrify enemy (if hiding is impossible) before accidental poisonous attack.

But fire-breathing dragons (Draco nobilis, not Draco vulgaris) are very big. And thus they cannot hide themselves easily. So, they have to choose between two options - to terrify enemy (that would be very easy), or kill it (unless they would have else plan what to do). And for killing they use mostly fire, because it is very efficient (I dare to say that the most efficient).

Dragons, if they are fire-breathing, they are fire-breathing because it is expected that they are fire-breathing, not for special anatomy that allow them to breathe fire (to paraphrase book Three Hearts And Three Lions by Poul Anderson).

So, they would breathe fire as often as possible, without any limitations. But still, why would fire-breathing dragons save fire for later, for more serious whiles?

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    $\begingroup$ They're your dragons. You can make them have limited fire. And what if they need it for bigger threats like another dragon than for a tiny human in a crunchy suit. $\endgroup$ – mVitus Nov 26 '17 at 0:00
  • $\begingroup$ Another thing to add is risks associated with biological combustion. In Terry Pratchet's Discworld for example, swamp dragons risk exploding if they flame too much. $\endgroup$ – mVitus Nov 26 '17 at 1:56
  • $\begingroup$ Forest fires are difficult to put out🚒 $\endgroup$ – user6760 Nov 26 '17 at 2:19

It turns out that "waste not, want not" is not reserved for small things. In fact, generally speaking, you will find the larger creatures are even more thrifty.

Consider this famous fireball. It consumed a 55 gallon container of non-dairy creamer. That's roughly 4,000 MJ of energy. If a dragon produced that fireball, it would have to consume at least that much in food, and realistically substantially more, because fireball making is not 100% efficient. It requires consuming at least 1 million Calories, which is on par with the amount of energy in one whole cow.

So as a hunter, how efficient are you with your food. Do you waste the cow, or do you save its energy for when it matters most?

Eat More Chicken!

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    $\begingroup$ +1 for using the mascot for one of my favorite restaurants $\endgroup$ – pojo-guy Nov 26 '17 at 2:05

Depending on time of day/location/etc., breathing fire could attract unwanted attention to the dragons. A couple of scrawny knights could be more hassle to kill than they’re worth, so the dragons might try to avoid breathing fire if it’s dark (and will therefore be a hugely obvious beacon to any dragon-killing people out there).

There’s also a risk to the environment - if they have a particular favourite hunting ground (I’m imagining deer in a forest), they might want to limit the risk of setting the whole forest ablaze, and ruining their easy food source.

Fire breathing could also have a sociocultural weight to it. It could be seen as a bit of a cop-out way to fight something small (you wouldn’t waste your fire on deer/humans, but would save it for another impressive dragon or gryphon or something), and you wouldn’t want to lose credibility by having other dragons think you needed to use your fire to hunt down a tiny sheep.

Or perhaps fire could be part of a mating display? As part of a ceremonial hunt (gathering food for your mate), fire is appropriate. Making cool patterns in the air while you do some fancy aerobatics - definitely sexy to another dragon. But just using it needlessly on other occasions? Kind of takes the excitement out of it a bit.


EDIT - I thought of another thing, so I hope it’s OK to add to my post:

I’m going to make one assumption: that your dragons are intelligent beings, not mindless beasts. If so, they would be able to exert choice over their use of fire, and it could easily be construed as a marker of civilisation in dragon communities.

To make a (perhaps odd) example, humans swear. For many reasons, at many times, which are generally judged to be more or less appropriate. If you aren’t able to ‘moderate your language’ in certain social contexts (you’re serving at a restaurant/in a big corporate meeting/etc.), you risk being seen as ‘uncivilised’. And yet, used in particular contexts, swearing can add impact to humour, force to arguments, emphasis to exclamations, and so on.

If you treat fire breathing in a parallel context, it might explain why dragons would or wouldn’t choose to breathe fire. If you’ve got a rebellious teenage dragon, they might breathe fire all the time. If you’ve got a dragon who’s lived for millennia, they might choose to breathe fire only against a particularly worthy opponent, or in a particularly significant moment of display. Overuse might seem to be a sign that you’re lacking in culture, and intelligent dragons might care a lot about social prestige.

If a dragon is hunting/fighting a creature, they know that they can use fire, but the thrill of the chase, the battle of wits, the physical challenge of the event may be considerably more intoxicating an experience than just resorting to fire.

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    $\begingroup$ I like the sociocultural spin. Dragons conserve fire for aesthetic reasons. It's so gauche to go around spewing and spewing. People will call you "Spewy". For centuries. $\endgroup$ – Willk Nov 28 '17 at 18:55

If I understand the question, you're presuming that there is no fuel or biological limitation on the dragon's ability to breathe fire; i.e. it is limitless magic.

That being the case, it would still make sense for them to avoid it in order to avoid destroying the environment they prefer to hunt in. Dragons, like most large predators, presumably would like to eat large herbivorous animals, and large animals go where there are plants to eat. Stray fire could set a forest or a field ablaze, which means the dragon will have to travel farther to find food in the future.


Dragons are apex predators, they are pretty much the definition of apex predators. Large, can fly, can breathe fire and are almost impossible to kill.

Therefore there isn't likely to be anything else hunting them and their defensive measures would be meant for fighting off other dragons.

Also as apex predators everything and everyone else is food, including humans. Dragon fire doesn't just cook things and leave a tasty morsel for the dragon to eat, it completely incinerates anything it touches and leaves only ashes.

Which isn't good for hunting.

If dragons work on the basis that everything up to another dragon is potentially dinner they will not use their fire because they want there to be something left to eat.

They will only use their fire if they feel sufficiently threatened, perhaps if they are wounded or attacked by multiple enemies at once (like a whole army rather then an individual human).


If we accept the premise that dragons have infinite fire capability, then "saving" has no meaning at all. We can hold our breaht for a time, which is useful for diving, for example, but we don't go around trying to save oxygen for later use. We simply assume there will always be breathable air around, and inhale every time we need.

The dragon would do the same if its fire it's always available, so you must put a restriction there. A possibility is @CortAmmon response, where the energy from producing fire must come from somewhere, and so it must not be wasted. Another possibility is that dragons may be hunt by dragon-slayers or even other dragons, so they always try to keep most of its fire capability to respond to an attack.

Other posibility is that fire is necessary for flying. The dragon would be sort of a hot balloon of gas, and without a reserve of fire capability its wings aren't strong enough to provide lift for such a massive body, leaving it grounded and vulnerable.


Fire requires fuel. If the fuel is rendered biologically, then it takes time to regenerate fuel after flaming, and there is a limit to how much fuel the dragon can store in its fuel pouches/bladders.


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