A healthy calf crop helped Yellowstone National Park鈥檚 bison rebound somewhat from one of the deadliest winters in the animals鈥 recent history, according to a .
An estimated 1,551 bison were killed in 2022-23, equal to about 27% of the of about 6,000 animals. This summer鈥檚 population was estimated in August at about 4,800 animals, according to Chris Geremia, bison program manager.
As a result, the Park Service is recommending no more than 1,100 animals be removed from the population this season to ensure the herd size remains above 3,500, a population target meant to maintain the animals鈥 genetic diversity.
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Meeting
The recommendations come as members of the Interagency Bison Management Plan (IBMP) attend their annual at Chico Hot Springs Resort on Tuesday, Oct. 31. The Montana Department of Livestock is the host of the meeting, which rotates among the partners.
The gathering starts at 8 a.m. and comes following of the Park Service鈥檚 proposed , released this summer.
Gov. Greg Gianforte and the leaders of Montana Fish, Wildlife & Parks and the Department of Livestock signed a letter, which in part said the National Park Service didn鈥檛 cooperate during the planning process. The leaders called the park鈥檚 staff 鈥渦ncollaborative and obstinate鈥 and referred to Yellowstone鈥檚 analysis as 鈥渄eficient and misstated.鈥
The state leaders also emphasized Montana 鈥渉as always managed and participated as an IBMP partner with a bison population of 3,000 as the goal,鈥 not the park鈥檚 stated minimum of 3,500.
In the end, the state executives asked the Park Service to reconsider its management proposals or litigation is inevitable.
Tolerance
The 17-page letter includes a not-so-veiled threat that should the Park Service proceed with its proposed bison management plan as written, the state might revisit the 2015 decision by then-Gov. Steve Bullock to expand the so-called tolerance zone for bison to the west and north of Yellowstone into Montana.
The state leaders called 鈥渦nreasonable鈥 the park鈥檚 assumption in writing the bison management plan that tolerance zones would persist. On Tuesday鈥檚 agenda is the topic of reviewing bison management roles in the tolerance zone. That will be followed by the consideration of the 2023-24 operations plan.
In the aftermath of the state鈥檚 letter, conservation groups supporting bison and the park are preparing for a fight.
In a Monday press release, the Greater Yellowstone Coalition鈥檚 executive director, Scott Christensen, wrote: 鈥淚t's clear the vast majority of Montanans and citizens of this country support a balanced, modern approach to conserving Yellowstone's iconic bison, and so do we. Over the past nearly quarter century, there have been significant changes in the Gardiner and Hebgen basins that have opened more critical winter habitat for bison, new management tools developed like the Bison Conservation Transfer program, and major advances in science. We commend Yellowstone National Park for recognizing the need to update its approach to bison management in ways that reflect current conditions.鈥
Recommendations
In its proposal to IBMP partners, the Park Service advised the number of bison killed or captured this coming winter should depend on the magnitude of the migration. The agency also called for restricting bison removals to the north of Yellowstone. In culling the herd, no more than 20% should be calves with more females taken (57% to 70%) than males.
If enough animals migrate out of the park, some could be trapped and tested, with brucellosis-exposed bison shipped to slaughter. Brucellosis exposure is endemic in Yellowstone. If spread to livestock, the disease can cause pregnant cattle to abort. Fear of bison infecting cattle with brucellosis is Montana鈥檚 main reason for restricting the animals鈥 movements outside the park.
Elk also carry brucellosis, but are not similarly confined. Instead, the state works to keep cattle and elk separated, especially in the spring when it is believed the disease is more likely to be transmitted by infected birthing material.
Record hunt
This past winter, extended cold and deep snow drove Yellowstone bison north into the Gardiner Basin, resulting in the on record聽鈥 at least 1,010 bison were shot. Another 282 were placed in the Bison Conservation Transfer Program, which moves live, disease-free bison to tribes once they finish a quarantine protocol.
Montana hunters killed 75 bison. Another 37 were shot by the Park Service or Fish, Wildlife & Parks wardens after being wounded. Fifty-three bison were considered 鈥渦nattributed harvests.鈥 Eighty-eight bison were captured and shipped to slaughter with the meat given to tribes. Six bison died in the Park Service鈥檚 holding facility.
Due to the deaths, by May the bison population had fallen to around 3,960 animals, but the calving rate this spring was around 45 calves per 100 2-year-old females. The proportion of females, about 57%, is a 10-year high, the Park Service said.
鈥淭he status of the bison population illustrates its resiliency to removal of up to 25% of the population,鈥 Geremia wrote.