Four wood bison at Toronto Zoo are pregnant thanks to reproductive technology

The Toronto Zoo announced the pregnancy of four wood bison, a threatened species in Canada due to habitat loss and disease, through the use of reproductive technology.

The zoo issued a statement on Thursday, saying the pregnancies come after 13 years of research with the University of Saskatchewan on advancing assisted reproductive techniques for wood bison.

“We are so excited to do our part to help ensure a better future for wood bison. This research is critical to genetic diversity that is necessary to conservation efforts for wild bison populations across northwestern Canada” Dr. Gabriela Mastromonaco, the director of conservation science with the zoo, said.

“The loss of akeystone species such as bison would significantly change the landscape and alter the ecosystems that depend on them, which would ultimately threaten the community of species that they co-exist with.”

The Toronto Zoo currently cares for a herd of five male and 18 female wood bison. The zoo said that from mid-September into December, its reproductive sciences team spent days with the wildlife care team “moving bison through the handling system to undergo artificial inseminations or embryo transfers.”

“Every step in the process could have a large impact on the success of the bison’s pregnancies so each task is done with the utmost care for both the research and the wellbeing of our bison – from freezing and thawing the sperm and embryos, to transferring them to the females, to training and caring for the herd,” the zoo said in their statement on Thursday.

The zoo said it is “cautiously optimistic” that healthy bison calves will arrive in the spring, but will monitor the bison females very closely over the winter as the pregnancies progress.

Historically, wood bison were found across the boreal forests of northwestern Canada and Alaska. Due to changes in habitat, herds are now small and disconnected and remain only in northern British Columbia and Alberta as well as southern Northwest Territories and Yukon.

“Although wood bison have been downlisted from "endangered" to "threatened" since 1988, on-going diseases, such as tuberculosis and brucellosis, in wild wood bison populations continue to threaten this species,” the zoo stated. “Reproductive technologies, such as artificial insemination and in vitro fertilization, are important tools for improving the genetic management and connectivity of small populations.”

“These techniques will help us overcome the challenges of managing the endemic disease threatening free-ranging wood bison herds, and ultimately allow us to restore genetically diverse disease-free herds in the wild.”