Toronto Zoo welcomes three bison calves using 'innovative' reproductive method

Meet the Toronto Zoo's newest residents These wood bison calves were born using groundbreaking reproductive techniques that allowed the zoo to pre-determine their sex.

The Toronto Zoo has welcomed three wood bison calves, two females and one male, to their menagerie this summer.

The zoo said the three calves were born in late June using “innovative reproductive techniques” that allowed them to “deliberately” choose to breed females – a technique applied in an effort to keep wood bison populations stable and healthy.

“Although wood bison have been down-listed 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 said in a release issued Wednesday.

“Reproductive technologies, such as artificial insemination and in vitro fertilization, are important tools for improving the genetic management and connectivity of small populations.”

They say, ultimately, they hope the technique help restore “genetically diverse, disease-free herds” into the wild.

HOW DOES IT WORK?

The zoo is currently home to a herd of five male and 18 female wood bison.

The facility said they move the bison through a handling system from mid-September to December to undergo artificial inseminations or embryo transfers – both of which the zoo calls “extremely intricate processes.” It says the timing of each procedure is dependent on the animal’s ovulation cycle, which is synchronized using hormone injections.

“Every step in the process could have a large impact on pregnancy success, 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.