Thanks, Namikaze. Grizzle, everyone here is correct - there's bits and pieces here and there. For my money, the one (unreleased?) EarthDawn sourcebook (Dragons of Barsaive is what's poking my brain) describes there being four basic stages of a dragon's life - hatchling, adolescent, adult, and great. As told to the in-game-world author, the issue with the second stage is that the dragon reverts to a primal level, dominance challenges and attacking other Namegivers, etc. etc. It is implied
strongly that these adolescent dragons are, in fact, wyverns and the like, but the Great Dragon being interviewed denies it almost to the point of physical violence, which seems to me a case of 'The dragon doth protest too much, methinks.' Guilty conscience, shame for descending to such a state, whatever.
For pure Shadowrun, however, adult dragons are still breeding, and (generally) turning their eggs over to Great Dragons to be cared for and, eventually, hatched. Great Dragons rarely actually breed (one of the first mentions of Masaru has him/her having an egg that gets stolen, etc. etc.) and if they were to do so, it would undoubtedly be have pretty serious impact. Clutches of eggs exist (check into
this thread for some notes on current groupings of eggs), and considering history, it is entirely possible - even likely - that some of those eggs are left over from the end of the 4th World and are getting ready to hatch soon.
In regards to dragons in the Barrens, Seattle
does now have a couple of hometown lizards, one of which is experimenting with anti-radiation magic ...