Some aggressive bears have led to trail closures at Shenandoah National Park. If you're camping or picnicking in the park, be sure to keep food out of a bear's reach/NPS file photo

Increasingly brazen bears have prompted Shenandoah National Park officials in Virginia to temporarily close some trails in the South District of the park.

Closures are in effect for the entire Big Run Loop Trail and the section of the Big Run Portal trail from the Big Run Loop to the Patterson Ridge Trail. Visitor access in this area of the park is prohibited.

A camping closure is in effect along a portion of the Appalachian Trail from Browns Gap (mile 83 Skyline Drive) through the Loft Mountain Campground area. This approximately 2.5-mile camping closure does not impact Loft Mountain Campground, designated campsites or huts along the AT where camping is permitted. This closure only affects backcountry camping off the AT.

This past weekend, an experienced backcountry hiker reported a bear that was unusually assertive in approaching him to obtain food, a park release said. The hiker reported the bear was not responsive to normal efforts to scare him away (waving his arms and making loud noises) and approached closely enough that the hiker hit and poked the bear with hiking poles before he went away.

“This is unusual and troubling behavior for a black bear," said park wildlife biologist Rolf Gubler, "and in an abundance of caution, we are closing the hiking trails in that area until this incident can be investigated further and the bear behavior further assessed.

“If this behavior is repeated, this bear may have to be removed from the population,” said Shenandoah Superintendent Jim Northup.

These closures will be in effect until further notice.

Black bears by nature tend to be wary of people. However, if you encounter a black bear while hiking or camping, park officials suggest you follow these safety tips:

* Never feed or approach a bear. Park regulations require you leave at least 50 yards to safely view a bear.

* Never store food or scented items (such as toothpaste) in your tent.

* Remain calm if you encounter a bear.

* Make the bear aware of your presence by speaking in an assertive voice, singing, clapping your hands, or making other noises.

* Make sure the bear has an escape route.

* Avoid direct eye contact and never run from a bear. Instead, slowly back away.

* To scare the bear away, make loud noises by yelling, banging pots and pans, or using an air horn. Make yourself look as big as possible by waving your arms. If you are with someone else, stand close together with your arms raised above your head.

* The bear may utter a series of huffs, make popping jaw sounds by snapping its jaws, and swat the ground. These are warning signs that you are too close. Slowly back away, avoid direct eye contact and do not run.

* If a black bear stands on its hind legs or moves closer, it may be curious and trying to get a better view or detect scents in the air. It is usually not a threatening behavior.

* Black bears will sometimes "bluff charge" when cornered, threatened, or attempting to defend a food source. Stand your ground, avoid direct eye contact, then slowly back away and do not run.

* If the bear does not leave, move to a secure area or at least 200 yards away.

Use bear spray only as a last resort and direct the spray at the bear’s sensitive nasal and eye areas. Black bear attacks are extremely rare. If a black bear does attack, always fight back! If you have to fight back, hit the bear’s eyes or nose.

If you become aware of a situation where a bear is "hanging out" in a campground or picnic area, where people are deliberately feeding a bear, or if you are involved in bluff charge situation or an actual contact incident, report it to park staff immediately. Emergency Line: 800-732-0911