Homesick dragons:
By now, after decades of my best efforts, I trust you have gathered that any animal has to mate with kin or face extinction in a few generations, and that this accounts for what we call “territoriality.”  In short if you are on a picnic, maybe not at this time of year in the northern hemisphere, and there are flies around your table, get out your swatter and clear the locals.  You will not be bothered further.  There will still be flies at all the other tables, but they will not come to you; you are outside their territory.  They’d rather starve than move far enough to risk complicating their gene pool.  Being as how they are flies, we can probably assume that they are not motivated by political theory. 

Well the same thing has been shown more dramatically, not to say expensively and dangerously, with dragons.  (Home sweet home for dragons, Nature, vol. 563 no. 7732 November 22, 2018 page 446.) Intrepid souls captured a number of grown members of the mighty Komodo dragon species, carried them to different valleys and different islands and then watched.  Pretty soon all the dragons had returned home except for the ones that would have needed to cross oceans, which apparently they cannot do, lacking an appropriate Columbus. 

So flies and dragons both need to marry kin, although they have no more clue about it than do humans with the exception of my dear readers.
Home page.