A yearling male wolf that Yellowstone National Park officials said had become habituated to people was killed by staff Tuesday along Fountain Flat Drive, north of Old Faithful in the Lower Geyser Basin.

"This wolf was clearly not behaving naturally, reducing our management options," Doug Smith, Wolf Project Leader, said in a statement. "Human safety is important so the difficult decision to remove the animal was made."

This is the first time such a management action has occurred since wolves were reintroduced in Yellow-stone in 1995-1996.

The wolf from the Gibbon Meadow Pack was first seen in the vicinity of Midway Geyser Basin in March. In recent weeks, it was frequently observed in Biscuit Basin and in the Old Faithful areas close to park visitors.

On at least three occasions, the wolf chased bicyclists and one motorcyclist reported an encounter with the wolf. Park staff also received reports of the wolf approaching people and cars - behavior consistent with a food-conditioned animal.

The wolf's repeat offenses demonstrated a habituation to humans and human food, escalating the concern for human safety, park officials said.

"Approaching wildlife, such as wolves, too closely can have detrimental results," Smith said. "We encourage visitors to keep their distance from wildlife and to not feed them."

Yellowstone staff attempted to haze the wolf, only to have it return and repeat its behavior.

The decision to remove the wolf was made in consultation with the U.S. Fish and Wildlife Service.

Park officials defended the killing, saying Yellowstone is committed to maintaining a wild population of wolves and must also manage them to prevent negative human-wolf interactions. The conditioning of wildlife - in particular bears and wolves - to groceries, garbage or intentional feeding, usually results in habituation, making them a potential danger to people and consequently may result in their destruction. That's also why park visitors are told to stay 100 yards away from bears and wolves, and 25 yards away from other wildlife.

The wolf population in Yellowstone National Park is estimated at 124 animals in 12 packs. Pups that were born this year have not been counted and are not part of the estimate.