... that in the mid-1600s S.T. many durulz started wearing wigs?
At least a couple of the various individuals denoted 'Argrath' spent some time to the east of Dragon Pass, in and around Pavis and the Wastelands of Prax. When they went west to fight in the Hero Wars and reclaim Sartar, they brought some of their Praxian friends and allies with them.
A quick recollection of the most famous birds of Prax will suggest one common characteristic: they're all bald. Condors, vultures, the ostriches rode by their pygmy masters--all distinctly lacking in hair on the head and neck. Even if they do possess some hair, it's at most a very faint layer of down, or a basal neck frill.
There are varying suggestions as to why this might be the case, ranging from mundane practicality to legends of vindictive spirits. Perhaps the latter has some truth to it, for there are tales that some of the wereducks that fled to Prax (in the aftermath of the fall of Boldhome in 1602 S.T., or Starbrow's Revolt in 1613 S.T.) started going bald, too.
This correspondence appears to have been transferred to Dragon Pass in the later 1620s S.T. Many ducks serving alongside ostrich-rider mercenaries started to moult. No-one's entirely sure why, but moult they did. The effect was largely limited to the head and neck feathers, though in some wereducks spread to the shoulder feathers (scapulars), too.
Now, durulz are quite proud of their plumage--especially your average mallard--and this came as a horrible shock. As the moulting spread, many sought ways to hide this displumagement. The answer? The feathered periwig.
Created from moulted feathers and down, these quite elaborate constructions soon became articles de rigueur for any self-respecting durulz, balding or not. Most tended to reach down to the scapulars, but some went even further. A few 'stylish' individuals sought feathers other than their own, from wondrous birds in far-off lands. The aesthetics of such are open to interpretation.
The moulting eventually stopped, but for a few decades this strange little people became a little stranger.