I used my Canon I got off ebay for a bill over a year ago that has a 50x optical, but in that shot (first and any others took that zoomed in) was at the 50x but I took it to 60X with it and digital so it would not pixelate like a mofo.
And as mentioned, the sun was on the other side of the bird rather then behind me, and was SUPER bright out, so it was very hard to get any kind of a decent shot, and was the best I could do, even with the first one run through some filters, it was the best I could get out of it.