Why bring the Vane Sisters in here? When VN wants to allude to them in later work, he does so in no uncertain terms.

J.A. Is in complete agreement here, that stiff vane thing is a pretty iffy connection. 

Northern mockingbirds do have a gauzy sheen to the plumage on their backs.

J.A. I had always wondered about that guazy description, because where I live in the southwest they don't look gauzy, but sort of dullish black topped with pale grayish undersides; their most striking quality here is the flickering strip of white running across their wings when they fly.

"Sybil as "tender mockingbird" calls out to Shade, between the ad and the preview of Marilyn Monroe), to come down to the TV...(is it accidental that the first phrase brings Monroe to my mind?) adds to the contrast with the awkward, taciturn Hazel these lines already evoke.

J.A.: That "tender mockingbird" is funny too, since I guess they're not known for their tenderness so much as their terror. I think I'd save that Marylin Monroe upward tail for later as well.