About 200 cowboys and cowgirls on Saturday herded Antelope Island's 600 bison to corrals on the north end as part of an annual roundup.
Later this week, veterinarians and state park wildlife biologists will weigh, vaccinate and conduct various health tests on each bison to determine the herd's health.
To keep the herd at numbers the island can sustain, about 200 head will be sold at a public auction in mid-November.
Auction proceeds will go into the wildlife program into the wildlife management program.
The Antelope Island herd dates back to 1893, when a dozen bison were taken to the island by boat.