Which of the following has NOT caused the Ogallala Aquifer to begin to dry up? Winds that cause evaporation Pumping water for irrigation Large numbers of migratory birds Years of drought

The correct answer is - Large numbers of migratory birds;

The number of the migratory birds has always been pretty high and it hadn't resulted in the drying up of the Ogallala Aquifer, not to mention that those birds can not even reach that water because it is underground. Also, the number of the migratory birds have been steadily lowering, so even if they were using that water for drinking, it wouldn't have caused the drying out.

The Ogallala Aquifer has started to dry out because of numerous reasons, with the usage of its water for irrigation being the prime reason. The droughts have become longer, and the temperatures little higher, while the rainfall slightly smaller, so all of that affected the reserves of water in the aquifer negatively.