Image copyright AFP Image caption Officials say the bison are causing environmental damage in the Grand Canyon National Park

Physically fit and a crack shot? Then the US National Park Service has a job for you... in the Grand Canyon.

It is seeking volunteers to help cull a herd of bison in the famous gorge, which it says are damaging park resources.

About 600 bison live in the area, but experts say that could hit 1,500 in a decade if their numbers are not controlled.

A lottery system will be used to choose the shooters.

The bison are owned by the state of Arizona, and are descended from animals brought there in the 1900s.

Environmentalists say they are stampeding over vegetation, causing soil erosion, and contaminating water sources - damaging the habitats of other species.

Some of the luckier animals will be moved away from the Canyon, and others legally shot in the surrounding forests.

Officials want no more than 200 in the park's northern environs within three to five years.

Image copyright AFP Image caption Tourists enjoy the North Rim of the Grand Canyon

Most of the hunting is expected to be done between October and May, when the road to the Grand Canyon's North Rim is closed.

Snowmobiles and sleds will be used to transport the bison meat - or if necessary, helicopters. Volunteers may get the right to take one bison's worth of meat away with them, with the rest being given to food banks and local tribes.

Carl Lutch, the terrestrial wildlife manager for Game and Fish in Flagstaff, Arizona, told the Associated Press news agency the hunters would need specific skills. These could include the ability to hike 12km (eight miles) a day, carry a 27kg (4.3 stone) pack, and hit a paper plate 180m (200 yards) away five times.

National parks in Colorado, North and South Dakota and Wyoming have previously deployed shooters to reduce elk populations there.

The plan has had a mixed reception online, however. While one Facebook user praised it as a "win/win", another branded it a "slaughter".

Image copyright Facebook/Vyto Starinskas