Prior to the intruduction of Gray wolves into Yellowstone Park in 1995, the Northern Yellowstone Elk numbers were about 19,000. In just thirteen years with no other intrusive factors than the Gray wolf, those numbers have been reduced by two thirds to just over 6,000. The Gray wolf that was introduced may have been responsible for the extinction of the native timber wolf. While in the northwestern part of the state the whitetailed deer are decreasing at an alarming rapid rate as the wolf numbers are increasing exponentially. If this continues, the elk of Yellowstone could be exterminated by wolves and deer populations irreversibly reduced in the next few years.
http://www.saveelk.com/