Rangers say the animal's behavior was influenced by mating season and visitors feeding him. A viral video that shows the animal sniffing and head-butting a photographer garnered national attention.
"We've had elk in the park for 12 years now and this is the first time we've had an elk make aggressive contact with a human," Ranger Joe Yarkovich said. He said the park had been working with the animal since last September.
"We worked that animal 29 different occasions. . . using bean bag rounds, paint balls, catching him, tagging him and releasing him on site, Yarkovich said.
He said euthanizing him was the only option, and the park looked at zoos and refuges. He said a lesson can be learned from the elk: don't feed the wildlife at national parks and keep your distance.