Biobullets Unlikely to Be Used on Yellowstone Bison

Park administrators recently put the kibosh on plans to shoot bison with “biobullets,” bullets laced with a vaccine to inhibit the spread of disease, saying the scheme was too ineffective to justify the expensive.
Bison in Yellowstone

Bison in Yellowstone

Looks like the periodic capture and slaughter of wild bison migrating outside of Yellowstone National Park will continue. Park administrators recently put the kibosh on plans to shoot bison with “biobullets,” bullets laced with a vaccine to inhibit the spread of disease, saying the scheme was too ineffective to justify the expense.

These biobullets would absorb into the bison’s body, vaccinating it against brucellosis, a disease that causes pregnant animals to abort their young prematurely. Researchers guess that roughly half of Yellowstone’s 4,600 bison have the disease. Vaccinating them would have been an effort to prevent further spread of the disease among bison and having it move into the bodies of livestock. Cattle ranchers supported the biobullet measure.

Unfortunately, Yellowstone chief scientist David Hallac says the biobullets just wouldn’t be effective. And if they’re not decreasing infection rates, he notes, they’re not worth the annual $300,000 cost. After a 30-day public review period, Yellowstone officials will announce the final decision for or against the biobullet measure.

Quick Bison Facts:

  • The NPS estimates that 4,600 bison live in Yellowstone.
  • Nearly all of the Yellowstone bison live in one of two breeding herds, the northern and central.
  • Baby bison are born in late April or May.
  • A full-grown male, or bull, can weigh up to 2,000 pounds, while the smaller full-grown female, or cow, weighs at most 1,000 pounds.
  • Bison typically live between 12 and 15 years, although a few have been known to live up to 20 years.
  • They can run up to 35 mph, no problem.
  • Bison primarily eat grasses and sedges, grass-like plants that live in wet soil or near water.
  • They can be aggressive and are surprisingly agile for their size.


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Bison in Yellowstone. Photo by Jeff Vanuga

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Bison in Yellowstone in spring

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