A Quite Fall?
Female polar bears require great quiet, security, and seclusion when they den. Interestingly, it was Kalluk whom Chinook first began to let know he was not welcome too close. For the next few weeks, Chinook will most likely be out in our large exhibit only in the mornings for a few hours, and then she will spend the rest of her day in the off-exhibit management yard we call Polar Bear Park and the adjoining bedrooms while Kalluk and Tatqiq take residence for the rest of the day in the exhibit.
Chinook’s change in behavior is normal for a female polar bear that is pregnant. Her den is installed, and the bedrooms that will act as outer chambers to her den are cozy and quiet. Yes, we have the cameras installed so when the time is right we will be able to share any greatly hoped-for additions to our polar bear family with anyone viewing Polar Cam. Is Chinook pregnant? When will she give birth? We don’t have the exact answers to these questions, but we sure are hoping for good news this fall!
Here’s what we do know: in March of this year, Kalluk and Chinook engaged in what appeared to be very successful breeding behavior. Polar bear gestation is 195 to 265 days. Counting it out, we would expect to see cubs born between October 9 and December 15. The majority of polar bears cubs in the U.S. have been born in late November, but the earliest was October 11. You can see Chinook’s timeline is well within normal timing!
We have also been participating in a fecal hormone study done by the Cincinnati Zoo’s CREW (Center for Conservation and Research of Endangered Wildlife). The study is working to develop a test to be able to confirm pregnancy in polar bears and also be able to differentiate between actual pregnancy and false pregnancy. If the current numbers and protocols are correct, then Chinook’s hormones indicate that yes indeed she is pregnant! But at this point this is not a perfect measurement, so again we have a level of uncertainty that only seeing cubs will remove.
Luckily, Chinook is the only polar bear in the world currently that is trained for ultrasound procedures! We have regularly been doing these exams every week. We have yet to find anything but all the normal abdominal parts. It is very much like the first years with our giant pandas. . .so much to learn! How do you find a fetus the size of a peanut in a 200-plus-pound panda? Well, you can imagine the challenge when the bear is a 600-plus-pound polar bear! Suffice it to say that even if we don’t confirm pregnancy with ultrasound, it doesn’t mean Chinook is not pregnant. But how exciting it will be if we can confirm and have the first-ever images of a polar bear cub before birth!
Soon we expect Chinook will want only to be in the park and bedroom/den area. Kalluk and Tatqiq will spend their time in the exhibit keeping up their wonderful work as ambassadors. And I suspect we’ll all be crossing our fingers just a little bit harder! Patience . . . patience . . . patience. . .shhhhhh, it will be a quiet fall!
JoAnne Simerson is a senior keeper at the San Diego Zoo. Read her previous post, Polar Bears: Oh, Miss Chinook!