Bird people of the Heartland

So thanks to the responses from my last post I've spent the day reading through the timeline of major events in Tamriel, and I'm curious if anybody has anymore knowledge about the "feathered bird men" that inhabited the Heartland of Cyrodiil, that is mentioned by Torval the Pilot? It is said when the Ayleid migrated there, these bird men disappeared and they were known to wear feathers...

Is there anymore mentioned? Are they the ancestors of the skyrim hagravens? Why/how did they disappear?

Edit:

These seem to be the main two theories so far:

1. They are actual bird-men who are (possibly) descendents of the Elhnofey, like mer and men. Their disappearance could be linked to the migration of the Ayleid to the mainland, whether by assimilation/interbreeding (thus giving future Ayleid generations bird like appearances), by being driven off (potentially being/becoming proto-argonians: lizards with wings and feathers), or by being killed off (by either invading Ayleid, or proto-khajiit).

2. They are Ayleid, and the misinterpretation of Topals journey is either a fantasy made up by him or a change made to his literature by someone further down the change to accomplish some agenda. There are connotations for the Ayleids having bird-like features and also for them just having bird-like apparel (perhaps to signify a belief in Auri-El). Their disappearance could be related to Topals work being false, to the breeding with other mer to become less bird-like, or to just the general destruction of the Ayleid race by men.