Panda Er Shun at the Toronto Zoo on April 29, 2014.
Colin McConnell—Toronto Star/Getty Images
September 30, 2015 7:01 PM EDT

Panda-monium is hitting North America again; after a summer that saw the delight of two baby pandas at Washington’s National Zoo followed by heartbreak when one of them died, panda-fans have two more panda cubs to look forward to in the near future, this time at the Toronto Zoo.

The zoo confirmed today in a press release that Er Shun, a female giant panda on loan from China, is expecting two panda cubs. The first fetal heartbeat was detected on Friday; a second one was picked up on Tuesday, “much to our surprise.”

“While this is a positive sign, the following three to four weeks are very critical,” the Zoo said in a statement. “Toronto Zoo staff are cautiously hopeful for healthy births within this time frame.”

Er Shun was inseminated using sperm collected from Da Mao, the male giant panda in residence at the Toronto Zoo, along with two other male giant pandas from China.

More Must-Read Stories From TIME

Write to Tanya Basu at

Read More From TIME
Related Stories