Land managers have closed five drainages north of the river in the Hoback Canyon as the Bull Fire has grown to cover 860 acres on the Bridger-Teton National Forest.

Located east of Hoback Junction, the fire is burning in beetle-killed trees and subalpine fir. Observers flying over the area after a thunderstorm first spotted the fire July 23 and believe lightning started it.

The area around Bull Creek, Rough Hollow, Cow Creek, Bear Creek and Little Granite Creek are now closed because of fire danger. All the drainages are north of the Hoback River in the canyon between Hoback Junction and Bondurant.

The Hoback Shield climbing area remains open. The closures extend to include Pinnacle Peak and Cream Puff Peak.

“We’re into a drying trend this weekend,” Bridger-Teton fuels specialist Andy Norman said. “With warmer, dryer conditions we’ll probably see some increased fire behavior and fire managers will be planning their actions around that. People should not be surprised to see smoke from the fire this weekend.”

There are no structures or developed areas that are immediately threatened, officials said in a report, and the blaze is being allowed to burn to improve decedent wildlife habitat.

The fire’s growth, which managers said is not alarming, comes as Yellowstone National Park said it was winding down work on the Beach Fire. Located southeast of Bridge Bay, it was first reported July 18 and grew to cover 520 acres. Firefighters called it 95 percent contained but are still investigating its cause.

Yellowstone crews fought the Beach Fire “due to several factors including location, fuel and weather conditions,” officials said in a statement. It was burning in the backcountry adjacent to the 2009 Arnica Fire and several miles from any trails or roads.

Vice President Joe Biden visited the park Monday. A Yellowstone spokeswoman said Friday his presence had no influence on the decision to fight the fire.

Fire managers cautioned that the danger in the region is listed as high and used the incidents to remind campers to use normal precautions.

In the Bull Fire south of Jackson, heavy dead and downed fuels are dry and are the primary force driving behavior of the blaze, firefighters said in a daily report. One objective is to “allow fire to play its natural role in the ecosystem as a process of ecological change.” Another is to manage the fire in a cost-effective manner.

Smouldering and creeping characterize the fire’s “moderate” behavior in the morning while in the afternoon single trees and some stands may torch, or flame up to their tops.

One crew is camped out and patrolling the fire edge to supply information and data to managers and advisers.

Fire releases nutrients and minerals for plant growth and wildlife food, according to a summary of benefits provided by Steve Kilpatrick, a wildlife habitat biologist for Wyoming Game and Fish. Nitrogen, phosphorus, potassium, calcium magnesium and sodium become available and enhance plant growth and quality.

Plant nutrition increases for up to seven years after a fire, Kilpatrick wrote. The crude protein level of fire weed, a flower eaten by moose, elk and mule deer, has been documented to increase 4 percent to 6 percent for the first two years after a fire.