Northern Arizona'sFLAGSTAFF The bison herd in the northern part of Grand Canyon National Park will not be targeted for removal this fall.

The park used skilled volunteers selected through a highly competitive and controversial lottery last year to kill bison, part of a toolset to downsize the herd that's been trampling meadow and archaeological sites.

Introducing the sound of gunfire and having people near the bison was meant to make them return to the forest where they could be hunted. Efforts had no effect.

Sometimes they would come back the next day after moving a bit from where the activity occurred.

When the park approved a plan to quickly cut the herd's size, it was estimated that 500 to 800 animals were in the herd. The bison was declared America's national mammal in 2016 and is depicted on the National Park Service logo.

Tens of millions of bison were almost wiped out in the US due to hunting and a genetic problem.

A new management plan for the roughly 5,500 bison is being developed by the park. There are ways to reduce the number of bison sent to slaughter.

In Theodore Roosevelt National Park, bison are rounded up using helicopters and corrals, and then transferred to other states and national parks. bison herds can grow quickly if there is no natural predator to protect them.

The herd can be seen along the highway that leads to the North Rim entrance. Descendants of those brought to Arizona in the 1900s are bison.

The animals sought refuge in the national park when they realized they could be hunted on the nearby national forest. National parks don't allow hunting, but the agency has the power to kill animals that harm resources.

Most of the bison at Grand Canyon have been removed by corralling them and transferring them to Native American tribes. Volunteers were sought to shoot up to 12 animals.

People applied for the chance. They were able to kill four bison. The animals are large and can hide in dense stands of trees.

The program won't be repeated this fall but will be used in the future. There will be another corralling effort in the near future.

According to the Grand Canyon National Park, there are over 200 bison on the expansive Kaibab Plateau. Agencies that manage the land and wildlife in far northern Arizona will meet in July to begin discussing a long-term plan.

Larry Phoenix, an Arizona Game and Fish Department regional supervisor, said that creating more gaps in the state's bison hunting seasons outside Grand Canyon National Park will be part of the discussion.

The Game and Fish Department wants to expand the range for another herd of bison in far northern Arizona. The state imported 15 bison yearlings from a nature reserve in Montana in late 2017.

The bison won't follow the others into the canyon because they don't know about the other herd.

The bison population in the region has been difficult and costly to keep in check, and environmental groups are skeptical that fences can keep them from straying.

The forest service is being asked to do an in-depth review of the proposal that considers climate change and impacts to plants and animals.