Predators have monitored nearly half of border since 2013
                                
                                
                                    (Newser) -
                                    Predator drones guard nearly half the US-Mexico border where camera towers, ground sensors, agents, and fences are absent. Able to patrol remote areas like mountains and canyons, the drones capture high-resolution footage of an area every three days, the  AP  reports in an exclusive. Analysts then check the videos using...