Grey Wolf by waterfall, Montana Undoubtedly, one of the more popular species now found in Yellowstone Park is the gray wolf (Canis lupus). The adult male gray wolf stands 26 to 38 inches high at the shoulder and is usually 40 to 58 inches in length (excluding the tail). Males are 15 to 20 percent larger than females. The weight of gray wolves varies from 40 to 175 pounds. Coyotes are often mistaken for wolves; however, the coyote is actually much smaller at only 20 to 30 pounds in weight. The wolf was exterminated from Yellowstone National Park in the early 1900's ( Last one in Yellowstone was shot and killed 1926 by government bounty hunters who wiped out the park's last native wolves as part of a national wolf extermination program designed to protect ranchers' livestock ). At that time the train of thought was that the wolves would kill all of the elk and other animals and therefore tourist would not come to Yellowstone as their would be hardly any animals to view..(Such short sighted people). Also the wolf was basically thought of as a pest and vermin . Ranchers did not like them because they would sometimes kill their Livestock.. SO the general thought/mindset was kill it... Through a hard fought battle through the courts. The wolf (actually Canadian wolves as all of the U.S grey wolves were exterminated)was reintroduced back into Yellowstone in 1995 (I believe they started with about 31 wolves. It has been a major success,as they have adapted very well. Now the complete group of animals that roughly were in Yellowstone around the 1800's is now back in Yellowstone. The Food Chain balance has been restored. There are still some groups of distracters that would love to see the demise of this project/program.. Recently a entire pack of wolves were put to death in Idaho as they had wandered outside of the chosen/controlled area and the local ranchers complained of livestock being killed by the wolves and had the government dispatch of them.. The sad part of this is there is a fund set up by the government and Defenders of the Wild and other groups that will reinburst people for livestock etc that can be proven that they were indeed killed by wolves..