I like those shots - do you run them through any post-proc'ing? Picassa has a really sweet sharpening automation that I think its balls to the wall. . .
The birds we have here are pretty boring (looking). I took these while waiting for the train, and missed it twice because I wasnt paying attention. I like the last one the best. Shot with a D50 as well. . .
male house sparrow's... lots of those around here too. Ive just been waiting days to get the pic of the cedar wax wing, everytime i didnt have my camera there was a hugh flock around...so id get me camera, and theyd be gone
EDIT: Only a lil post processing on the first, blurred the background a bit to make the bird and berries stand out more