Amphibian populations have been declining sharply for years now, around the world. An item in today’s Science Daily suggests that the cause may be a enormously popular weed-killer, atrazine, which apparently “chemically castrates” most of the males that come into contact with it, and turns the rest into females.
You can learn more here. (I will also take this opportunity to pre-empt any waggish comments about how handy a jug of this stuff might be on a Friday night.)