Thanks to some well-timed photos taken by Guy Monty, I've been able to
obtain a little more evidence to support the identification of the Iona
bunting as a female McKay's.

One photo, showing a spread tail from below, seems to show that Rectrix 3
has the amount of dark near its tip that several sources report as being
diagnostic for McKay's. I must admit, however, that I had some difficulty
ascertaining just how translucent the rects were and whether an additional
dark area in R3 was actually just the dark R2 showing through.

In another photo of a spread wing, Primary 1 appears immaculate. This
feather should have extensive dark in female Snow Bunting. Even immature
male Snow Bunting should show some dark in this feather. Furthermore the
Iona bunting's P2 shows only a small area of dark in the shaft tip.

Also the dark tips of the primaries are actually brownish gray. This is
further evidence that the bird is a female, though the sharply-pointed dark
centers of its scapulars--which I mentioned in an earlier message--reliably
sex it female.

In regards to a size difference between Snow and McKay's, all sources that
I've consulted indicate no size difference. McKay's, however, is a heavier
bird (up to 15 g heavier), though this difference appears to be based solely
on the weights of three male McKay's in July.

Regards,
Jason Rogers
Banff, AB
hawkowl at hotmail.com