I think I could add that most cell towers broadcast multiple frequencies too - they triangulate and beem content overlapping areas that just a few years ago didn't have these obstructions.
No... I don't think cell towers are the cause of CCD, at least not alone they are not. Can we easily discount them after seeing images of how honeybees form comb when electromagnets are placed near the hives - I don't know.
I think Earth is changing, trying to save "Her" self from the disease of humankind, our over-populating and over-polluting the planet. The creatures on Earth cannot keep up with both man's destructive nature and Earth's necessary climatic and cyclical events geared at preserving it.
Earth is a living and YES Breathing organism which is in crisis - not for the first time, nor the last, but we are witnessing how it takes measure to CLEANSE itself of deadly parasites and infection. I'm a firm believer that MAN can destroy MAN, but I don't think we can "Permanently" destroy Earth. For now, whether global warming, or some unknown LAST DITCH EFFORT that Earth will show us, Man will find out soon enough that supporting 6.5 billion people IS NOT PART OF EARTH'S PLAN.
Frogs are dying, bees are disappearing, migrating animals are changing paths, geological areas are growing or flooding or disappearing, Earth is changing to save herself - all we can do is standby and watch, because no matter where we are on the food chain, we are nothing more than passengers here on Planet Earth.