From the private notes of Lady Ilelahne SiDabolo:

Dragons are, as most anyone knows, beings of both legendary power and rarity. The latter is especially true since The Seminal War; many dragons were either slain in the fighting or perished in its wake. Other sections of this work will cover dragons of note, both past and present, while this section is intended as a general overview of the race as a whole.

Chromatic and Metallic dragons differ in more than just the color of their scales, and I do not refer simply to the element and shape of their breath attacks. both sub-races follow Bahamut, lay eggs, shed scales as they grow, and so forth. one of the differences (academic or irrelevant to the average Adventurer as it may be) is that Chromatic Dragons cast spells in the same manner as Dragon Blood Sorcerers while Metallic Dragons cast spells as Wizards. The critical difference is that Chromatic Dragons are innate spellcasters calling on their own natural abilities, while Metallic Dragons must learn and hone their talent through practice and study. This means that the abilities of Chromatic Dragons are relatively easy to predict, while Metallic Dragons have a much wider array of possible spells at their disposal. They still tend to specialize in a single school, the same as any Wizard of more mortal scale, but have thousands of years of experience. If one wishes to go looking for magical knowledge thought lost during The Seminal War, then a Metallic Dragon may be your best (or only) source.

Irrespective of sub-race, all Dragons are known to Hoard. This is speculated to be somewhere between an instinctive behavior and a cultural imperative, possibly even a divine command form Bahamut. I have spoken with several dragons on this matter in my years of research, and have never received a satisfactory, comprehensive answer. Accordingly, I will do my best to summarize this behavior.

Every dragon will Hoard. While the exact item of a Dragon's desire will change from dragon to dragon, the urge to collect and protect is universal. The older the dragon, the larger the Hoard. this is both because the number of things in a dragon's hoard tends to grow with time (and older dragons have had longer to collect things) and because older dragons tend to have stronger and / or more focused desires. More powerful / important / valuable items take up more 'space' in a Hoard. Accordingly, a Dragon may have many 'small' things in its Hoard, a few 'Large" things, or a mixture of the two. Not all Hoards are tangible. The most notable example of this is probably that of Gurvurm, who Hoards power over others. Such abstract hoards are rare, but not unheard of. they also tend to be more portable, and are often the province of dragons who have adapted a nomadic lifestyle in the wake of The Seminal War.

The desire / urge / need to Hoard emerges while a Dragon is still young, but can and often is, deferred until a dragon leaves the nest and strikes out on its own. if deferred for too long however, the Hoarding instinct will become harder and harder to resist. I could find no records of any dragon younger than a young adult without a hoard of some sort, even if it is only a few 'seed' items to sate the need. It is worth noting that a dragon will never change what it is Hoarding. They are reluctant to let items leave their hoard for any reason, and it is recorded that dragons will chase thieves to 'the ends of the world and beyond' both to recover what was taken and to punish the thief.

{A slip of parchment is tucked into the margins}

Addendum: dragon birth rates? no know new dragons since TSW. possibility of one in Trebor of all places, will need to check next I visit.