More on blackish stain on swan

In my effort to search out possible information about the blackish staining on the one Trumpeter Swan I posted about below, I searched the Trumpeter Swan Society website. I emailed that group and received a prompt email in return noting that the bare skin of the lores likely doesn't extend any further back on the crown than on the other Trumpeter Swan I posted about. The blackish staining on this bird's crown makes it difficult to see where the black lores end. SeEtta