Ya know, we had a great dove hunt this year in colorado. We shot 24 one afternoon, of whick 22 were eurasians so really we had alot of mourning dove left to shoot. Got 2 banded pidgeons as well. I digress,,, We hunt for a few hours and then clean the birds after they have been sitting around a little while. 2-4 hours. The instant you kill something, it starts to decay. The question is how much decay is acceptable? I can tell you that 4 hours isnt harmful at all.
hope this helps.