What's Happening to the Birds?

Recently, in Arkansas, there have been reports of blackbirds randomly falling from the sky.  They were discovered on New Year's Day, and so many people believe that all of the deaths are the result from either a miss fire of fireworks, or the trauma of them exploding into the sky and frightening them to death.  Although that is a possibility, I don't believe that is the cause.  Fireworks are let off all over the world for New Year's, and for other holidays, such as Independence Day, and there are never reports of birds falling from the sky.  I personally think that the cause of the deaths, may be either contaminents in the air, or a result of something they ate.  There is so much pollution nowadays in the world, that it leaks into the air, into the water; this causes many animals to die off because they are not used to such contaminents in their environments.  This may be my theory, but there are many others besides this, and no one seems to have a clear answer, yet.