Coastal pastures leading to the decline of the horny toad is a load of crap IMO. The loss of rowcrop agriculture in a lot of the state had a lot more to do with it, not that they were converted to bermuda pastures.
I would believe that pesticides curtailed the reproductive rate before I believed the relatively small area of the state of Texas that is planted in improved bermuda pastures were the cause. I've been surrounded by red ants all my life and never seen one, so it is not lack of food around here. There are tons of klein pastures as well, and they are chock full of red ants.
I would imagine maybe disease, pesticide use (big maybe), or just cycles have contributed to their downfall. I've never seen one, and I'm surrounded by red ants. They are also up in the hills where no one can plant coastal, and there aren't any horny toads up there either.