I am designing a cold-blooded dragon about the size of a house cat with a wingspan of 3 metres from tip to tip. It will climb on top of rocks at noon when there is ample sunlight overhead. I need it to take off vertically and remain several meters high in the air for at least ten minutes to escape from predators. What biological mechanism does the cold-blooded dragon need in order to perform such a feat?

  • $\begingroup$ It's much more energy-efficient to fly forwards rather than to hover, at least for all known flying creatures. $\endgroup$
    – Peter Shor
    Feb 9, 2020 at 19:05

2 Answers 2



All flying animals are warm blooded to some degree. Pterosaurs, birds, and bats are all warm-blooded. Insects are even warm-blooded compared to other arthropods, they are technically cold-blooded on the ground but use their massive wing muscles (which occupy most of their thorax) and to rev up their metabolism before they fly, and are temporarily warm-blooded while in flight. Other insects that spend long periods of time in flight (looking at you, bees and wasps) have additional adaptations to keep the body at the proper temperature.

Taking off vertically is also really energy-demanding because you are going straight up at a high angle of attack rather than at an angle or letting gravity, thermals, or a running start help you. Even among birds, only a few species can even take off vertically and in general it is taxing.

  • $\begingroup$ and to rev up their metabolism... are temporarily warm-blooded while in flight Is this the only way to accomplish flight? Does the fact that known flying animals are warm-blooded necessitate that they all must be because of metabolism factors? Would a passive "gliding" be compatible with cold blood? $\endgroup$
    – Zxyrra
    Jan 31, 2020 at 5:47
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    $\begingroup$ Yes. Basically without a high warm-blooded metabolism you couldn't flap your arms fast enough to achieve flight (this is why human-powered ornithopters never work). Flying animals usually have metabolisms even higher than most warm-blooded animals. There are cold-blooded gliders (Draco, flying frogs, etc.) but by definition they cannot take off vertically. $\endgroup$ Jan 31, 2020 at 6:44
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    $\begingroup$ This is probably why in most fantasy worlds, dragons are described as 'using magic to fly' and generally very reliant on magic. Because only magic can explain why a cold-blooded creature can breathe fire. $\endgroup$
    – TimSparrow
    Jan 31, 2020 at 12:53
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    $\begingroup$ Or they're just warm-blooded. You could make a wyvern-style dragon pretty easily evolutionarily (though fire would probably need a magical explanation). Pterosaurs are warm blooded. Dinosaurs are warm blooded. Crocodiles may have been ancestrally warm-blooded and lost it, and some of the Triassic archosaurs may have had high metabolic rates. $\endgroup$ Jan 31, 2020 at 16:03

By definition, dragons are reptiles, all of which are normally cold-blooded. Laying eggs is also a basic trait of reptiles world-wide.

For your cat-dragons, to avoid predators by taking off vertically, they would need highly adapted reflexes tuned to detecting that predator, and strong legs that would launch them high enough into the air to allow them to deploy their wings and begin flying without dropping back into the claws of their predators.

You may want to reconsider your wing engineering for your beastie as well as the larger wings will take more muscles and time to create lift for your creature to fly. Smaller wings that burst into action as the creature leaps would be more effective in achieving flight.

I'm not sure they would be limited to 10-minutes of fly time, you would need to define why they could only fly for short periods of time based on further refinement of your physiology. You are encouraged to read Anne McCaffrey's Pern series.

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    $\begingroup$ Because prolong flying could raise temperature in the dragon which is problematic since it cannot regulate its own temperature. $\endgroup$
    – user6760
    Jan 31, 2020 at 4:25
  • $\begingroup$ Prolonged flying does raise temperatures. Birds offset this heat with a number of methods... dangling their legs, bare skin on their faces and bodies radiates heat, increased blood-flow to their beaks also helps dissipate heat, efficient panting, etc. Your dragon creature is basically all bare skin and would dissipate heat more efficiently than most birds. $\endgroup$
    – user72081
    Jan 31, 2020 at 4:44
  • $\begingroup$ About egg-laying: mammals were layng eggs more time (120 My) than given birth (180-100 My). It's not only reptilian feature - in old times that was universal amoung large animals. $\endgroup$
    – ksbes
    Jan 31, 2020 at 8:01

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