Yes I have noticed it too CD, we usually have a lot of bluetits and finches around and are not seeing many at all this year, there does seem to be a glutt  pigeons and  magpies, perhaps these are frightening off the little ones.

I have also noticed it with other little creatures aswell, butterflies and bees don't seem to be around so much now either.

Such a shame, we need these little creatures they all play a part in the great stream of things.