While Zonotrichia sparrows do hybridize (see Pyle 1997),
the description given strongly suggests 1st winter
Golden-crowned Sparrow. I spent an afternoon sketching
Golden-crowns and White-crowns during the spring migration
of 1991. At one point there were about 250 Golden-crowns
Dan Fay's backyard.

Some of my sketch work can be found at:
http://home.pacifier.com/~mpatters/details/zono.GIF

You might also what to check Rising's Sparrows of the
US and Canada (1996). The 1st winter individual is,
unfortunately drawn looking out at the reader, but
is nevertheless representative.

--
Mike Patterson Alas, to wear the mantle of Galileo,
Astoria, OR it is not enough to be persecuted
celata at pacifier.com by an unkind establishment,
you must also be right.
---Robert Park
http://www.pacifier.com/~mpatters/bird/bird.html