I have read that, too. I don’t think we’ve experienced a reversal in modern times, however. I believe that will really mess with electronics, communications, etc. Sort of a natural, mega-EMP.
But there’ve been a lot of fairly recent (within the last few years) major die offs of birds and fish and ... The first link is about birds that mistook a Walmart parking lot for water...
http://www.geekosystem.com/dead-birds-louisiana/
http://abcnews.go.com/International/page?id=12565986
http://www.naturalnews.com/030985_mysterious_deaths_birds.html