You may also wish to post your question on the Siege forum. I do not have a tamer on any shard, but I know with the champ spawns and only ONE lost lands on Siege ie no trammel lost lands, the champ spawns do kinda seem to re locate everything on Siege, as opposed to TWO lost lands on other shards.
When I first went on Siege just walking around I remember seeing frenzied ostards up there near the lost lands where I was near the Marble Isle lost lands entry...to that island, that is in the mainlands.
But yeh post it on Siege cuz their tamers will be able to help direct you to where all those critters may be hanging out ...around thru the areas kinda messed up with Champ Spawns maybe relocating the normal hang outs of those creatures.
I remember llamas rideable and non rideables seem to be on Moonglow too, but yeh most we see are non rideables.
Anyhow post it again on Siege forum ..lots of tamers there probably tell ya where to find assorted ostards etc. and help ye out.
I am SOOO not the tamer so I personally can not help..but I am pretty sure those whom have tamers on Siege can...just repost it over there cuz unlike other shards we only have ONE lost lands with Champ Spawns ON them..kinda rearranges things.