Wow, some pretty sharp criticism here! Thanks for providing the 100% view Paula 
I agree with the comments about the noise. The noise and artifacts are definitely the reason this was rejected. Looks like you applied sharpening along with saturation boost. It's just too much.
Personally, I think it is a very attractive photo of a peacock. If you have a RAW and can reprocess very minimally, without boosting the sharpness or saturation, and maybe do a bit of noise reduction in the green background areas, I think you might have a shot at approval.
Problem is, though, that would be an awful lot of trouble for a shot that ultimately isn't going to sell much even if approved. As has been mentioned, it's a low demand area. I even have a shot of a peacock from early in my micro days available in the free section of a couple of sites and it isn't even downloaded much for free.
Yeah, *some* ppl just weren't quite nice / delicate...

But what I like about this forum here, is that even if you get sometimes unpleasant reply most of ppl are so helpful and very patient, I really appreciate it here.

Still I'm kind of confused here. Just about few responses earlier someone said that very saturated photos sell awfully (surprisingly) good on stocks. And from this file I must say I do agree - on dreamstime it had 4 sells in a row, then one other photo and then again two more. Quite similar on shutterstock. So this is the very reason for my frustration when it was rejected.

I have no idea what to do to have nice saturated colours and not overprocessed photos but I think I'll need to work on this.
Btw do you have a good way to reduce noise? Like someone said 50D is not the lowest noise making camera (even though I believe that saying it's unacceptable over ISO 200 is way overstated

) I'm using mostly nik software Dfine in photoshop, or trying to force lightroom 3 to do something with noise (not with best results I must say, it's getting too smooth effects on the details...).
Maybe there's some good tutorial, or just good software to use?