In cooperation with the Arizona Game and Fish Department (AZGFD), NPS posted a webpage seeking individuals "skilled" in "bison removal."
Applications open to the public at 12 a.m. local time on May 3 through 11:59 p.m. on May 4, according to the site.
In an accompanying announcement detailing the work and qualifications of the September 2021 job, the NPS wrote that it was "concerned about increased impacts on park resources such as water, vegetation, soils, archaeological sites and values such as visitor experience and wilderness character" given the "current distribution, abundance, density and the expected growth of the bison herd on the North Rim."
"Reducing the herd size will protect the park ecosystem, resources and values," the agency said.
Twenty-five applicants will be selected from the pool, 12 of whom will be chosen using a random lottery system.
Those selected will be contacted by the NPS by May 17, 2021.
Volunteers must be U.S. citizens 18 years of age or older with valid identification; be able to purchase and pass a background investigation; have no criminal or wildlife violations; self-certify a high level of physical fitness ability; have a firearm safety certification and pass a marksmanship proficiency test; provide equipment; be available for the entirety of one of the assigned lethal removal operational periods; and meet additional requirements listed on the NPS FAQ page and application.
Park service employees are prohibited from volunteering.
The agency noted that the effort to reduce bison to a more manageable herd size is supported via consultation with traditionally associated tribes and the public in the 2017 Environmental Assessment conducted by NPS, the state of Arizona and the U.S. Forest Service.
"In addition to removal, Grand Canyon National Park biologists began piloting live capture and relocation in 2019. Since the program began, 88 animals have been captured and relocated to five American Indian Tribes through an agreement with the Inter-Tribal Buffalo Council," it explained. "These animals will augment existing herds managed by these Tribes."
Tribes would have equal opportunity to participate in lethal culling under separate pacts.
"In addition, NPS and USGS biologists have placed GPS collars on 25 animals to help with population estimates, migration patterns and temporal location," it continued. "Grand Canyon will continue live capture and relocation operations in the fall of 2021."
The Associated Press reported in October that the NPS looked to reduce the herd by about two-thirds, down from 600 to 200 bison.
NPS would select the age and sex of those targeted, and the number of bison allowed to be shot per team would depend on the number of skilled volunteers, each of whom would be able to keep one carcass, though not necessarily the one he or she shot.
However, while Grand Canyon and state officials have stressed that the lethal removal is not a hunt and the NPS cites "Finding of No Significant Impact," environmental and conservation groups have argued for nonlethal methods of removing the animals.
"Shooting animals accustomed to a non-threatening human presence — the park attracts nearly 6 million visitors a year — is a betrayal," the Humane Society of the U.S. wrote in a 2017 blog post. "The charges against the bison are trumped-up and best characterized as fake ecological news."
"I’m very nervous about there being a perpetual dependency on this use of people having to go into the park and shoot," the Sierra Club's Alicyn Gitlin told The Associated Press.
The Associated Press contributed to this report.