Dragon watch

It has been kicking around my head in various iterations for a while.  Sparked when I saw a bunch of little birds attacking a bigger one.  I thought what if the other bird just ate them and I thought what if that occasionally happened, how would that have changed the behaviour of those birds evolutionarily?

Core idea: Dragons!

There are many people who see dragons of various sizes from the small ones to e very large.  The assumption has been that they are different species.  It is not true.  The smallest are those seen in the dead of night, those fire bugs, that shine a flame out to scorch night insects.  The very largest live in distant mountains and dwarf most towns with their bulk, and there is legend that there are bigger still.  Some are smaller than songbirds and a few are as big as people.  What is true to all the species is that they have similar characteristics that vary in size only.  They tend to prey on animals a third their size or smaller, but almost never a tenth their size unless they encounter prey in numbers.  They are canabalistic when smaller in size and the larger ones appear quite intelligent.  They are all quite territorial, especially when older, and have been known to leave off other activities to do battle with a rival.  No one has ever seen a hatchling or an egg.  

Until now, that is.  The Great lens maker of city of Gerok beside the Great River that drains the Plains of Caranus.  He joined a series of lens together to focus on a raindrop that had just fallen, and he discovered a perfect pearl like stone in the center of the drop.  He stated that the night before a great dragon had passed overhead and this was the first pearl within a drop that he had seen.  He stated that the pearl quickly unfolded into a minuscule little worm that swam around in the drop and seemed to grow before his eyes.  

** Dragon dust falls from dragons of a certain size, it drifts in the winds until the rain clears it away.  After soaking up the water for a while the dust hatches  into a microscopic dragon which feasts upon the micro organisms and the other dragons that it finds.  The observed growth spurt was more likely the canabalism of the first dragon by the second, although they do grow fast in this stage, it can take hours to grow significantly.  When the dragon leaves the water, it seems to have already developed the power of flame.  In this stage it scavenges off the leavings of bigger animals and preys on nearly microscopic insects.  They have to be carefully as the dragon can also be lunch.**

The ecological niche for the dragon is every level.  The smallest sizes need to eat constantly, the larger sizes subsist entirely on magic.  The in-between sizes cause the most damage to mankind; the house sized dragons feasting once a year on herds of cattle or devastating a town.  Smaller sizes picking off stray cattle or humans more often, goats a sheep.  After they reach man sized, they gain a certain amount of intelligence and control of magic.  This increases as they age and grow.  Although there are different names for different sizes of dragons they are the same creatures.  Sphinxes, manitcores, wyvrens, griffons and many others are just different ways people have used to describe different dragons.  There is great variation in dragon appearance and they have great personal control of their appearances with magic depending on experience and variety.