Polar Bears: What Little We Know
Posted at 3:17 pm September 10, 2009 by Megan Owen
Chinook: Is she or isn't she?
Delayed implantation is just one of the adaptations polar bears have developed to cope with the challenges of life in the Arctic. This adaptation make predicting just when to expect newborn cubs quite a challenge.
Delayed implantation is a phenomenon common among all bears—at least we think! It serves its most obvious function in bear species that inhabit highly seasonal environments—that is to say, environments where food and good weather are not available year round. The more extreme the environment, the longer the delay: polar bears in the high Arctic are thought to delay implantation for about five months, whereas polar bears in more southerly latitudes may delay implantation by about three months. During this delay, regardless of how long it is, females go through an intensive feeding period during which they will gorge themselves on ringed and bearded seals for as long as possible before denning up in the fall. This summer feast allows them to deposit a thick layer of blubber that provides the essential nutritional support needed during the extended fast associated with pregnancy and denning.
True gestation takes about 60 days and typically begins in the fall, soon after pregnant females excavate and enter their subnivean (undersnow) dens. Females will remain in their dens until spring emergence, cubs in tow, ready to face the elements and begin the neverending search for food.
Fall will soon arrive in San Diego. Although it will be months before a chill wind is in the air, the change in day length (the first day of fall is that day when days begin to be shorter than nights) may cue hormonal and behavioral changes that prepare the polar bear for implantation, pregnancy, and impending motherhood. We are all watching Chinook with great anticipation: Is she or isn’t she? And when will she?
For a bear like Chinook, living at the San Diego Zoo where the weather is warm and food is always available, a layer of blubber is probably not necessary for successful reproduction. However, she has put on weight, and we are hoping that this is a sign that we will hear those hums and squawks from the den in the next couple of months. Stay tuned!
Megan Owen is a conservation program specialist at the San Diego Zoo. Read her previous post, Speaking of Polar Bears in Beijing.
Watch the bears daily on Polar Cam.
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September 10th, 2009 at 3:55 pm
I love the polar bears and the pandas. I am sitting on pins and needles waiting to hear if the beautiful Chinook is going to be a mommy!
Moderator’s note: So are we!
September 10th, 2009 at 3:59 pm
Have you tried offering her chocolate? It’s usually a pretty good sign that something hormonal is going on with a female!
September 10th, 2009 at 4:21 pm
Keeping my fingers cross !!! Megan don’t you guys have a polar cam in her den??? does she not use things to be comfortable in the den like how pandas use their boo’s to make it comfortable?? is she doing anything for us to think she really is? like eatting and eatting ?!! lol anyways I am excited !
Megan responds: Chinook is putting on weight, which is a great sign, and she tends to keep away from the other bears. We are hopeful!
September 10th, 2009 at 4:27 pm
I also love watching the polar bears and pandas, especially when there are wee ones too. I so hope that Chinook will have wee ones to enjoy soon. I’ve enjoyed reading all your blogs, especially the latest ones regarding that possibility, thank you very much for keeping us informed. We love San Diego and hope to make it there later this year (when it cools down!) LOL.
September 10th, 2009 at 4:34 pm
I always wonder if the conditions at a zoo’s location — even a wonderful one like SD! — prevent pregnancies that might otherwise occur. For example, I’ve wondered about birthing dens that are shaped more like they might be in nature (rounded, as SD has) versus ones that have square edges/right angles. Reading this entry added climate to the mix. It’s too bad, in a way, that we can’t communicate to the bears that it’s ok, safe, good to be pregnant/give birth even though their evolutionary sense tells them something’s odd.
September 10th, 2009 at 4:38 pm
Please, please, please, pretty please Chinook!
September 10th, 2009 at 7:17 pm
Thank you for the update. I love the polar bears. I hope Chinook as babes but can wait for next year if she does not have them this year. Love to wacth them.
September 10th, 2009 at 7:34 pm
Waiting patiently for Chinook to really give us the signs that she is really pregnant! Is she or isn’t she? I hope that she IS pregnant! Love watching baby polar bears! I have watched a couple of programs about baby polar bears on Animal Planet, and they are so cute when they are small! So, Chinook, let us know, ok? We’re waiting on you!
Chari Mercier
St. Pete, FL
September 10th, 2009 at 8:28 pm
C’mon Chinook!! Don’t disappoint!! You and Kalluk would make beautiful cubbies!!
September 10th, 2009 at 9:51 pm
Poor Chinook!! Such pressure to be under…It’s easy to forget that this is all new to her too…but her instincts will kick in and hopefully everyone will know soon if she is indeed “with bear”…Let’s try and remember that “all good things come to those who wait”….
September 11th, 2009 at 6:16 am
What is exciting is if Chinook is pregnant she will most likely have two offsprings. Siblings are adorable and so much fun. Scout and Montana are proof of that.
September 11th, 2009 at 7:40 am
Den cam?
Moderator’s note: A den cam has been installed in hopeful anticipation of a joyous event!
September 11th, 2009 at 7:44 am
I’m curious…have you started doing ultrasounds yet? Since baby polar bears are about 4 times larger than a panda cub when born, at what point might you see them on the ultrasound? Does Chinook participate in these ultrasounds willingly? Has she shown any signs of creating a den?
Remember, we are a greedy lot and want every little tidbit of info on the impending birth.
Moderator’s note: We have been doing ultrasounds on Chinook. Keeper JoAnne will be sending us a blog soon about this and other happenings at the Zoo’s Polar Bear Plunge.
September 11th, 2009 at 9:25 am
SDZ is awesome – a den cam – bravo. They are the best!
September 11th, 2009 at 9:35 am
The plunge looks very inviting today; but I don’t see any bears yet. Tell JoAnne that we will be as patient as possible in waiting for a blog entry from her about the ultrasounds and how Chinook is doing!! So happy to hear that there is a den cam already in position!
September 11th, 2009 at 9:37 am
Oops…spoke too soon. One of them is out there now. So glad to have them back in view.
September 11th, 2009 at 11:02 am
How exciting that ultrasounds are being done! I was wondering how the warmer San Diego weather would affect a polar bear pregnancy and confuse nature. I was also wondering about denning. If a female normally has snow and dirt to dig in to create her den and possibly promote the implantation of the eggs, would not being able to go through this natural procedure confuse Chinook’s hormonal instincts and possibly abort a pregnancy? When will she get access to a denning area in case she is pregnant and what sort of materials will she have at her pleasure to den with? For example the pandas have bamboo to shred. What do polar bears use or what will Chinook have to make a safe and hygenic den? Thanks! Say hi to the bears for me!
P.S.~The plunge looks super clean! The water is so clear and you can really see all the rock formations at the bottom, now!
September 11th, 2009 at 12:04 pm
Thanx every so much for the update, on Chinook and the plunge. I’m curious though what is the new barrier being constructed for, and if Chinook has access to her den, is she using it, and will we SDZ’s faithful cam viewers be be able to have daily access to her denning, any time soon ? I’m so hopeful she is with cub(s), but if not, there’s always next year. Since the 8th, I’ve been waiting for a blog on our other favorite bears. Thanz again for the update !
September 11th, 2009 at 12:20 pm
Thanks for the info Megan. My fingers have been crossed for so long now that they’ve gone numb! Little Polar Bears would really be the icing on the cake for 2009 at the SDZ.
September 11th, 2009 at 12:23 pm
I am keeping my fingers crossed for Chinook. But another den to watch, oh my I guess I’ll never get any work done if she has cubs.
September 11th, 2009 at 2:03 pm
Thanks for the update, Megan. We must all remember to be patient. Nature is in control here and all the animals instinctively do what their genes dictate. Human interferance is a very unwanted thing, and can jeopardize the successful outcome everyone is hoping to see. SDZ is as excited as we are, since it has been a very long time since there were pitter patter of small white furry paws. You are doing everything possible for the betterment of the Polar Bear Plunge for a pregnant female and her potential cubs. I marvel at how quickly you were able to alter the whole exhibit to provide for potential pregnancy and cubs which was not in the plans when it was built. Although we all mourn the loss of Shikari, her passing made a new world of possibilities, and I am certain she would have been very happy for her sister Chinook to have this opportunity for motherhood. So many research study options have come about from the change in plans.
Stay tuned loyal bear fans this is going to be one incredible year of raising many species of bear cubs in San Diego CA.
September 11th, 2009 at 3:46 pm
I CAN’T WAIT TO FIND OUT IF CHINOOKS GONNA BE A MOMMY!!!
I have waited soooooooooooooooo long to see if there were going to be any baby polar bears born at Sandiego!!
Now is there any traditon about naming polar bear cubs like you do with the pandas???
And how often do polar bears have twins??
I pray that she is pregnant with 1 or 2 healthy and strong little ones!!!! How fun would that be!!!!
September 11th, 2009 at 4:18 pm
just popped on– what a picture!! I think it’s chinook(dirty brown on it ) is sleeping on a crushed blue pool, with her head behind the wall!!!! Oh how cute!!!! Wish we could send postcard snaps of the bears like we do the panda’s!
September 11th, 2009 at 5:27 pm
The plunge ppol is so clear, it is amazing one can see the rocks on the bottom on the cam. I am happy to see the resident polars are out enjoying their “beach” again. Someone is snoozing on the beach beside the pond. Chinook? 5:30 PM What is the orange or red object next the the polar bear? Is it a toy or a pile of carrots, or their weekly animal?
September 11th, 2009 at 5:45 pm
Oh, I wish that Chinook will be a Mommy soon….how great and wonderful that will be:-). Chinook, all of us here are praying for your good health.
And Diane of Victoria, you made me smile…hmmm, do you think Chinook will have chocolate:-)? I LOVED chocolate, especially when that monthly period is coming.
Thank you, Megan for the update. SDZ, as always, YOU’RE THE BEST!!! And WOW for the den cam….I’ll be religiously watching it too just like Bai’s baby.
September 12th, 2009 at 4:42 pm
Oh, which bear is this? What a lovely closeup of one of the bears sleeping on the rock that juts out, next to but not on the palm branch, resting their head on their paw, getting ready for a nap? Looks too small and thin for Chinook or Kalluk. It is 4:40pm, Polar cam time (7:40 on east coast). Please let me know! Is this my beloved Tatqiq?
September 12th, 2009 at 8:53 pm
I’d like to think that even if I didn’t live in San Diego, I would be a member of the Zoo/Wild Animal Park! You all bring such joy to my life.
Thank you for the Live Cams, which I send to all my friends — maybe hoping they’ll donate to help keep up the Zoo, et al.
It would be wonderful to have a Polar den when little ones are born!! Maybe side-by-side videos with the Panda den.
Oh, heart be still!!
Gentle as you go…
September 13th, 2009 at 8:26 am
Thank you for the update, still keeping everything crossed, thanks for all you do for theese beautiful animals.
September 13th, 2009 at 2:22 pm
Hi! Just got on polarbearcam, and saw a polar bear laying down on a light blue plastic thing that could’ve been a wading pool mouthing on something. Don’t know which polar bear that was, but he/she was looking very relaxed! Good to see at least one polar bear back on the cam after the hard work you all did on the pool.
Hope we get an update soon about Chinook. Still patiently waiting for the word about whether she’s pregnant or not!
Enjoying a nice quiet day at home watching panda, elephant, and polar bear cams as well as a couple of football games on my birthday today! Not afraid to say my age–57 years old today, 9/13! There are a couple of birthdays coming up for the ellies, too!
Well, gonna go back to the cams! Thanks moderator for the confirmation about the 3 deers in the elephant yard! Will check back in later on.
Chari Mercier
St. Pete, FL
September 13th, 2009 at 2:35 pm
Well, I thot I was going to go check the cams, but went back to the polar bear cam again and watched the one polar bear that was laying down on that blue plastic thing get up and start playing with it, moving it around, repositioning the thing, then use a big rag to clean up a big spot on the plastic thing. Then, the bear laid right back down on his/her repositioned blue plastic thing that she now calls a bed. She just claimed it for herself (or himself)! Another polar bear came into view, looked around, saw 2 other pieces of rags laying down by the plastic thing, then promptly took both of them! Like I said, don’t know who these bears are, but they were pretty funny with their actions on the cam! Now, I’m guessing that the bear on the plastic bed maybe Chinook, because it looked like she was in her nesting practice mode. Hope someone can recognize these bears for me because all 3 of them are like identical triplets that no one can tell apart! They are still fun to watch anyway!
Now, going back to the other cams!
Chari Mercier
St. Pete, FL
September 14th, 2009 at 5:54 am
I hope Chinook is going to be a mom!
September 14th, 2009 at 7:18 am
Would like also to find out about the barrier ! no pressure Chinook, just take your time !
September 14th, 2009 at 12:42 pm
Looks like a sibling dining table moment. One on the left (Kalluk) appears to have spouted off something at the one on the right (Tatqiq)? I am happy to see them enjoying their sparkling clean pool. Last night even in the dark, with the pool lights on you could see all the details on the bottom. Kudos to the pool cleaners. You did an excellent job and fast too. Pros for sure.
Hopefully you are planning to tell us more details, that you feel safe in providing, about the changes to the exhibit including the barriers, as you have time. Preparing for the potential denning up and birth of cubs is of greatest urgency and importance right now. We all (including keepers) are staying tuned to find out what Chinook has in store for us in late 2009 and beyond.
September 14th, 2009 at 12:52 pm
love the new look of the pool!!! One bear is swimming circles right now and the other
is sunning on the rock ledge in the ‘blue’ water…
September 14th, 2009 at 3:31 pm
For deb #11, I think a first-time mother polar bear is more likely to have just a single cub. But that’s not a rule, just a tendency. And Chinook is not real young, if that has an impact.
I think the wading pool is a trophy of Kalluk’s. He likes to lie on it. I guess it’s been warm in San Diego, huh? I wondered if it felt cooler in hot weather than the rocks underneath. Without a doubt, he’s been upset recently and wanting his comforts.
I’m not sure warm weather would affect Chinook any more than it affects us. She’s not feeling the excitement we generate on these blogs. Hopefully she’s just doing what her body tells her.
September 14th, 2009 at 6:00 pm
“Momma” Chinook sure is lounging a lot when I check in lately. Glad she can sprawl her wide self out on the rocks, the beach, or the mulch pile and thorough indulge herself in blissful rest. If she is indeed pregnant, she will have her paws full over the coming two years. She deserves the rest now.
September 15th, 2009 at 7:47 am
I visited the Zoo last Thursday and was disappointed that Polar Bear Plunge was closed. Is that due to construction to prepare for the possibility of having cubs? When will Polar Bear Plunge re-open? Also, do you have any upcoming snow days for polar bears?
Thank you for the interesting blog.
Moderator’s note: We’ll soon have a new post about Polar Bear Plunge that may answer some of your questions.
September 15th, 2009 at 11:30 am
It’s no wonder I haven’t found a job! All I ever do now is watch the animal cams to make sure everyone is doing okay. While every one of us know these animals are in the best of care, it’s our maternal instinct to oversee that you’re not missing anything, and reassure us when we have any doubts, or answer any questions. It’s a great education tool, too. Thank you. sooo much for the updates.
Whether or not we have baby cubs, will we ever be able to send postcards from this site? I hope so. I watch these three as much as I watch the Pandas! I love watching them play w/their “enrichment”, and close-ups under the water-fall. I didn’t realize there was a little pond like area there but recently saw one of them rolling around as if they were scratching their back in the water, just thoroughly enjoying themselves.
Oh yeah, how does one perform an ultrasound on a polar bear?! Besides…. very carefully! Do you have to dart them?
Moderator’s note: We don’t have the budget to add the postcard feature to Polar Cam. And Chinook fully cooperates with the ultrasound procedure. We’ll have a post with photos soon regarding this and other happenings at Polar Bear Plunge.
September 16th, 2009 at 12:38 am
#38 Aunt Nancy, keep a camera next to your computer then whenever you want to ’send a postcard’ you can. Also, you don’t miss any of the action like you do when sending a postcard, and can click away to your heart’s content (and a pile of dead batteries!).
I too have been enjoying the beautiful clean pool. It’s lovely being able to see the bears’ leg and body movements under the water. Now I want to jump in more than ever!
September 16th, 2009 at 3:13 pm
One of the bears is having fun rolling in something (carrots?) in the sun! The pool is quiet right now but boy does it look nice and clean! Right to the very bottom. One of my favourite views is when the bears at night goes in the water, just before dawn and swims by the underwater lights. I bet it must be so clear to see now! Thank you camera operator for following one of the bears earlier during their swimming excursion all over the plunge! It was fun to see them swim up close!
September 17th, 2009 at 12:02 am
If you look very closely you can see two bears on the rocks fast asleep. They blend in very well.
September 21st, 2009 at 3:17 pm
looks like Chinook(I think I see brown) is just chillin in the pool on her haunches
and holding her toes! What a great view the camera has now!!
September 21st, 2009 at 4:49 pm
I’m thinking we’re having a baby! One of the bears has been it this corner (not one I’m familiar with) all afternoon, and appears very uncomfortable stretching & pushing off the walls, breathing heavily. Is this a sign? I do hope so!
October 5th, 2009 at 11:51 am
my name is logan and i love polar bear
October 27th, 2009 at 10:45 am
That would be so wonderful to see a baby for Chinook. Way to go Chinnook
. Would Chinook get weird eating habits like cravings for different foods, like humans do?
October 31st, 2009 at 7:57 am
I’m curious. I thought Polar Bears ate mostly fish. Why do I see what appears to be carrots and wood branches in the area where they live?
Moderator’s note: The carrots are snacks, and the palm fronds/wraps make great “toys.”