Passerines suspending molt prior to migration then resuming it at a later
date is relatively rare though not unknown. A close encounter with a
predator is more likely. Songbirds lose their tail feathers very easily.

If you were a raptor chasing a small flock of birds and one was much whiter
than the rest - which one would you go after ?

Stuart

----- Original Message -----
> A
> couple of theories have been put forth to explain this. It is thought
that
> the birds might have left the breeding grounds prior to having completed
> their molt. If so, the molt might have been suspended until the birds
> reached their destination. Stressed by her journey, the female may have
> been unable to supply her developing rects with a normal amount of
pigment.
> The other theory suggests that the birds lost rects during encounters with
> predators. I think this is the more likely one, since rects are molted in
a
> sequence that, at least in the male, was not being followed. Certainly
the
> birds were much whiter and, thus, more conspicuous than the Snow Buntings
> they were with. This may be why there have been no recent sightings of
the
> male.
>
> I don't know if Bethel, AK has a Christmas Bird Count, but if it does, it
> would be interesting to see if the folks there picked up any McKay's last
> Christmas.
>
> Regards,
> Jason Rogers
> Banff, AB
> hawkowl at hotmail.com