The Toronto Zoo is welcoming two baby bison this month.

The wood bisoncalves — both females — were conceived using artificial insemination. They were born on July 2 and July 5.

The Zoo works with the University of Saskatchewan and Parks Canada to breed the bisoncalves as a part of a research project. This is the fourth year bisoncalves have been bred via artificial insemination.

Wood bison populations are currently threatened by diseases like tuberculosis and brucellosis and the breeding is an attempt to preserve and distribute disease-free sperm or embryos in herds.

"Reproductive technologies, such as artificial insemination, are important tools for improving the genetic management of small populations," says Dr. Gabriela Mastromonaco, curator of Reproductive Programs and Research at the zoo. "These techniques will help us overcome the challenges of managing the endemic disease that is threatening wood bison herds in the wild."

Bison facts:

  • The gestation period for a bison is about nine months. 
  • Bison cows leave the herd and give birth alone and rejoin the herd with the calf as soon as it is able to stand, which is about two to three hours after birth.
  • Calves nurse for up to one year and remain with their mother for three years or until they become sexually mature. 
  • A bison is not fully mature until it is eight years old.
  • The wood bison life span is about 20 years.

Toronto Zoo began efforts to protect wood bison populations in 1977, with captive breeding and the reintroduction of animals back into the wild.

More information about the bison is available at the Zoo’s Wood Bison Exhibit.