There wasn't a LOT of detail in the Ted X talk I saw about Nuclear power, but he was pretty plain about the fact birds, bees and many other types of insects were being badly affected by huge Wind and Solar installations.
I am unsure if they are related specifically to this latest report on birds, but I guess it's all contributing.
My guess would be that effects of solar and windmills etc on bird population would be pretty minimal overall - or at worst local, but the reduction in bird (and probably originally insect) population seems to be global. Possibly a combination of habitat loss (some of which could be caused by CC) and large scale monoculture farming using (very effective) insecticides.
Climate change will probably have devastating effects on some migratory birds, if they're stopping on their seasonal migration route to feed and the food isn't there any more because of a change in climate, then they're doomed.
I didn't get the impression they were insignificant but agreed that not the largest impact. I think it's a matter of trying to take as many factors into account as possible.