The Antelope Island State Park bison roundup, which took place on Saturday, October 24, 2026, utilized horseback riders to move nearly 800 bison into holding corrals to facilitate essential health screenings and population management. The event, a long-standing tradition, marks the first phase of a multi-step process to ensure the long-term health of one of the nation's oldest public bison herds.
Managing Herd Health and Stress
The first phase of the roundup involved riders starting at 9:00 a.m. from Fielding Garr Ranch to push smaller bison groups into one large herd. According to Utah State Parks, this movement into holding corrals allows the animals to rest, which helps reduce stress levels and makes them more cooperative during the subsequent health assessment phase.
While the roundup typically concludes between noon and 3:00 p.m., the park notes that the unpredictable nature of these wild animals can cause variations in timing. During the event, the Roundup Rendezvous area hosted a festival featuring food trucks, retail booths, and educational activities for local spectators and international visitors.
Health Screenings and Identification
Following the initial roundup, the second phase of management is scheduled to take place from October 27 through October 29, 2026. During this period, known as the working of the bison, staff will sort and separate animals one at a time to conduct individual health screenings.
These screenings include checks for pregnancies, parasites, and other health issues. During this process, each bison receives a small RFID tag that serves as a permanent identification linked to digital records containing their health information. Once checked, the animals are either returned to the island or kept in corrals for upcoming sales.
Balancing Ecosystem Resources
The necessity of these management efforts stems from the island's unique ecosystem, which lacks natural predators capable of reducing the bison population. To prevent the herd from exceeding the island's habitat capacity, park officials must artificially manage the population size.
State Parks officials stated that the manageable herd size for the island is between approximately 500 and 550 bison. With an annual birth rate of between 100 and 200 calves, the excess animals are sold at a public auction to balance the food supply for other island residents, including pronghorn, bighorn sheep, and mule deer.
Auction and Revenue Impact
The revenue generated from these sales supports the Wildlife and Habitat Management Program, which funds habitat work and improvements to bison infrastructure. The upcoming bison auction is scheduled for November 3, 2026, and will be available online and streamed in the Larry H. and Gail Family Theater.
Historical data from 2025 shows the scale of these sales, with 257 animals sold for a total of $626,950. The highest bid recorded during that sale was $5,200 for a 2-4 year bull.
Historical Reproductive Data
Research into the reproductive ecology of the Antelope Island herd has historically highlighted the complexities of managing the population. A study published in the Great Basin Naturalist noted that pregnancy rates in the herd have historically been lower than those found in other free-ranging, noncommercial bison herds in North America.
The study observed that pregnancy rates showed a significant linear decline of 2.5% per annum and noted that cows in specific age classes exhibited lower-than-expected pregnancy rates.
