On March 2 I visited the Sandia Crest House when it was, unfortunately, closed due to extremely inclement weather. I was fortunate enough to find a crowd of rosy-finches collected on the hill below the deck with the feeder. Most were obviously black, a couple were definite brown-capped, and then there were one or two that might have been gray-crowned. Unfortunately the viewing conditions were such that colors were difficult to discern, and I have no prior experience with differentiating among the rosy-finch species.
On the other hand, I was fortunate that a friend had a camera with a telephoto lens, and took the below pictures. I am curious whether any of the lighter-colored birds are gray-crowned, particularly the leftmost and rightmost finches in the last shot - any opinions?
To my eye, all the identifiable photos are those of Black Rosy-finches. The third photo shows part of the head and crown of a rosy-finch in the lower left portion that is consistent with the Brown-capped species. We would expect the Gray-crowned to show a warmer cinnamon or orange-ish tint, not evident in any of the birds as I see them here. The Black Rosy-finches may have buffy or brownish edges to their contour feathers but generally you can see they are quite dark at their base.