Hmm, I like the theory that the bird is an Aviar that can sense Investiture. Mraize is, after all, a worldhopper and a collector of useful things from other planets. It would be extremely unexpected and very effective, but I'm not quite sure how Mraize would use that to his advantage. Although just knowing if someone is using Investiture would be quite useful, especially if it means he can spot worldhoppers(and maybe even hordelings? I'm seriously reaching here, but does he have the ability to know if a cremling is actually part of an Aimian? Otherwise, how did he know to kill that cremling in WOR?)