Supposedly, corvids are highly susceptible to west nile, and the population of crows, ravens, whiskeyjacks, and jays showed not the least bit of decline in the areas I hunt. The DNR in MN warned us, a few seasons past, that a pile of dead corvids that was discovered was not something to take lightly. I've never seen that, however. But, I wouldn't be surprised if that is or becomes a factor.
Pheasant roadside counts are down as well. I hold off on pheasants until the corn and beans start coming out of the fields, usually most of a month past the opener.
There aren't too many dumb birds left at that point.

Best,
Ted