Polar Bears


Spring in Air for Polar Bears

Kalluk digs a pile of snow.

Kalluk digs a pile of snow.

For those of us who live in San Diego, it nearly always feels like spring. (Sorry to those who are experiencing the polar vortex that hit a majority of the country recently!) Despite our consistent temperatures in San Diego, our polar bears follow seasonal changes similar to their wild counterparts in the Arctic.

We recently completed denning season, which normally occurs in the fall months (see Is Chinook Pregnant?). Now we are expecting to start a new cycle: breeding season! Those of you watching our Polar Cam may have noticed three bears on exhibit again. Chinook was reintroduced to Kalluk and Tatqiq after her months of requested seclusion. Chinook was showing some interesting behaviors associated with den making, but we eventually determined that she would not have cubs this time around.

The reintroduction went smoothly, and all the bears acted calmly. At first, Kalluk followed Chinook very closely while she walked around the exhibit. Then they both jumped into the pool for over an hour of play. Eventually, Kalluk was able to separate himself from Chinook, and all the bears rested in their favorite spots in Polar Bear Plunge.

Kalluk has been showing signs that he is getting ready for breeding season, such as an increased interest in sniffing Chinook’s footsteps and urine. However, Chinook is mainly acting coy and disinterested in Kalluk other than play (which certainly could be interpreted as slightly flirtatious behavior). Stay tuned as the saga continues…

Polar Bear Team


Is Chinook Pregnant?

Chinook, left, and Kalluk frolicked in the snow a few months ago.

Chinook, left, and Kalluk frolicked in the snow a few months ago.

Around this time of year for the past few years, the number one question we are asked by those familiar with our polar bears is “Is Chinook pregnant?” We nearly always answer with “We sure hope so, but….” Some of you may wonder why we are so elusive with our answer year after year. There are a number of reasons, none of them clandestine. Mainly, the polar bear community is still searching for all the answers. Things are complex in the polar bear world!

Did you know that polar bears have a wide range for gestation, spanning from 164 to 294 days in the wild (195 to 265 days in managed care)? If we determined possible birth on this information alone, this year Chinook could have given birth from July through September, based on when she bred with our male, Kalluk. However, we are aware of research that has studied historic data of births of wild bears and with other observations in the wild. It is hypothesized that date of breeding may not solely determine date of possible birth. Instead, it is a little more complicated than counting days from breeding time. Births generally occur between November and December, with the occasional birth outside those months even when breeding occurs in January, for example (when Kalluk and Chinook bred). Lastly, female polar bears have both induced ovulation and delayed implantation, which makes determining timing and the triggers involved difficult.

We are trying! Through research, we are continuing to learn more and more. Every other day, we collect urine samples from Chinook and fecal samples three times per week, all for hormone analysis. With Chinook’s full cooperation, we perform ultrasound exams weekly once her den is in place. (The den was set up this year at the end of September.) Through research and collaboration, we hope to gain new insights into the complexities of polar bear reproduction and give you more definitive answers in the future to the question, “Is Chinook pregnant?”

The Polar Bear Team, San Diego  Zoo

Watch the bears daily on Polar Cam.


Polar Bears: Hormones

Kalluk enjoyed snow day earlier this month.

Kalluk enjoyed snow day earlier this month.

Many Polar Cam viewers have expressed concern about our male polar bear, Kalluk, and his repetitive or restless behaviors. It is hard to see him so driven by his hormones at breeding time if you don’t see his full day. He does eat and rest, but not for the long periods of time as he does when his hormones are not driving him. He is not suffering but just supremely distracted!

The reason we suspect his focus is at the one end of the exhibit is due to the stimulation he may receive there. There is certainly more visual activity with buses and guests stopping to look at him, and the breeze comes right through there, carrying great scent stimuli. Research has shown that there are chemical similarities between many industrial aromas and reproductive hormones. It may well be that Kalluk is constantly testing the breeze in case there is a receptive female polar bear about to come join him. No one really knows how far a polar bear can smell, but no one doubts that their sense of smell is more than anything we could compare.

We know from past testing of his testosterone levels that Kalluk experiences exceptionally high levels for a male polar bear. A recent study indicates that male polar bears’ highest testosterone levels occur from the age of 12 to 18. Kalluk just turned 12, so we may have a tough time for the next few years. We did witness one day of breeding last month on the day after Chinook rejoined Kalluk and Tatqiq; she had been by herself on a pregnancy watch for a few weeks. Their reunion seemed to be more about the excitement of getting together again instead of actual estrus. We fully expect to see another breeding period that lasts anywhere from a few days to a few weeks.

Once Chinook’s hormones indicate that she is ready for breeding, and her behavior indicates she is ready, Kalluk’s attention will turn to only her. Then, as the breeding season wanes, we will get our fun-loving boy back. Polar bear breeding season can last from January to June! Until then, we have increased the amount of fat in his diet, increasing the calories he has to use. We strategically give him enrichment, especially scents, and strategically make beds for him that are in his interest zone.

Rest assured that we are monitoring him closely and responding to whatever he shows might alleviate some of his frustration. Keep watching Chinook as well; she also gives indicators, although much more subtle, of her breeding season!

JoAnne Simerson is a senior keeper at the San Diego Zoo. Read her previous post, Polar Bears: Exam for Tatqiq.


Polar Bears: Well, Chinook?

Is she or isn’t she?

*Is she or isn’t she? We still don’t know for sure. Here’s what we do know: Chinook’s fecal hormone profile as of mid-November indicated that pregnancy was still a possibility but birth most likely would be no sooner than January. We have been doing weekly ultrasound exams since October, and the images neither confirm nor deny pregnancy. Polar bears are delayed implanters, so we don’t usually see the uterus unless there is something happening. As of the ultrasound exam this week, our veterinarians are still able to see her uterus. With both these indicators, we are definitely not throwing in the towel.

Chinook’s behavior, though, is picking up. She is playing every day on exhibit and in her back pool. Chinook is also soliciting lots of play time with her keepers. She does, however, go to sleep in her massive bed by noon, again both good and not-so-good signs for pregnancy. The good part: whatever the outcome, our girl is having a very comfortable time keeping us all on pins and needles!

*UPDATE: Chinook has very effectively communicated as of January 1, 2013 that she is NOT pregnant and please very much would like to go play with Tatqiq and that very handsome Kalluk. Today’s ultrasound session also convinced us that we are no longer on pins and needles. So tomorrow all three will be re-united. So uncross those fingers and toes and let them rest until next year!

JoAnne Simerson is a senior keeper at the San Diego Zoo. Read her previous post, Polar Bears: A Wild Study.


Polar Bears: A Wild Study

A polar bear mother with her yearling cubs strolls in the wilds of Manitoba, Canada.

It’s hard for me to believe that this year is my 12th in Churchill, in Manitoba, Canada, for polar bear season. Because of the unique water currents, geography, and ice formation, polar bears pass through this northern town every year on their way to hunting ringed seals after a few months of fasting when Hudson Bay is ice-free. The majority of time, visitors spend the days observing polar bears in the Churchill Wildlife Management Area beginning 15.5 miles (25 kilometers) from town. But today we are moving out to Wapusk National Park and Cape Churchill, another 15.5 miles away. Tundra Buggy Adventures is granted permits exclusively by Parks Canada to travel into this remote tundra habitat.

This travel requires hitching up all the Tundra Buggy lodge trailers to individual buggies and hauling them through tidal flats, snow drifts, and around large boulders. It’s a slow process, but along the way great views of the tundra and polar bear habitat can be seen. We are now just two hours into the drive and have already seen a fabulous gyrfalcon, fox prints, and polar bears: several subadult bears, one particularly large male, and a mom with two yearling cubs. I was extremely happy to see yearling cubs, as over the past three years I had not seen any older cubs, just cubs of the year, aka COY. Not seeing older cubs was unusual and perhaps indicates that cubs are not surviving past their first year.

Tundra buggies make their way to Wapusk National Park.

This year we are also seeing the ice forming a bit earlier than it has in the last few years. We have seen many bears already head out to begin hunting. Over the past decade, this would be a normal occurrence, but in the last few years the ice has not been formed enough for bears to get out and hunt for the winter until December. It is also good news, since most of the polar bears in Hudson Bay lost their hunting ice in July. Scientists studying this population estimate that the ice is disappearing a full three weeks earlier than normal for this region. The aerial survey from last year to evaluate the population of the Western Hudson Bay resulted in an estimated 1,000 polar bears, consistent with surveys from a few years ago. Unfortunately, average litter sizes were the lowest recorded, and yearlings and COY were proportionately fewer. This is possibly due to not only the earlier ice loss but also the later ice formation giving females less time to hunt and to provide for offspring.

Our destination tonight will be Cape Churchill, which has a great history of polar bear observation for both scientist and bear enthusiast. Typically this is where the biggest males stay, biding their time sparring while waiting for the ice. This area, too, is where, once the males have moved on, moms with cubs make their last walk to the coast and out to the ice. The opportunities to study polar bears and their behavior are hard to match anywhere else in the world.

We should reach the Cape in another eight hours. It will have been a very long day of travel. The reward will be tomorrow when we wake up in perhaps one of the most inspiring lands of ice and bears. I think how unbelievably blessed I have been for 12 seasons to be able to be a part of this. I can’t bear to think that this may all be disappearing quickly. The colleagues I travel with inspire me with knowledge that we can make a difference, the guests sharing this adventure inspire me with knowing there are some really great folks who are willing to make changes in their lives now to save this area by lowering their greenhouse gas emissions, and most importantly, I am inspired by the incredible polar bears that survive and thrive in this ice world.

I am so happy to see a mom and her two yearling cubs. It is their future that we hold in our hands, as well as the future of our own children, so that they, too, may be blessed to witness this amazing animal in this inspiring world of ice.

JoAnne Simerson is a senior keeper at the San Diego Zoo. Read her previous post, Polar Bears: Quiet Season.


Polar Bears and Climate Change

This is not a test!

Each day, the first thing I do when I sit down at my computer is to check with the National Snow and Ice Data Center (NSIDC) for the latest information on sea ice conditions and sea ice extent in the Arctic. At the beginning of August, it looked like the changes in sea ice extent over the summer were on pace to approach, or maybe even equal, the historic 2007 low. However, over the last couple of weeks, it has become clear that we were on a pace to overtake the 2007 record low and set a new minimum record for sea ice extent.

Several days ago, I checked the latest data; not only had we surpassed the 2007 low, we did it several weeks ahead of when the sea ice is typically at its lowest. This means we still have a few more weeks of sea ice melt to go, and the ultimate sea ice nadir for 2012 has not yet been reached. It is not hard to connect the dots and see that this is bad news for polar bears. However, what may not be obvious to most people is that this is bad news for wildlife all over the world and bad news for us.

Polar bears and the Arctic sea ice have long been noted as a “canary in a coal mine”; the changes in the Arctic environment provide a warning—a clear, loud, and un-ignorable warning—of how dramatically climate warming is changing our planet. We have to reduce our carbon footprint, and we have to do it NOW!

Even in light of this grim news, there are still signs that we are beginning to turn things around. Recent surveys have shown that an increasing majority of Americans understand that climate change is real and that the warming trends that have been documented over the past several decades are the result of human greenhouse gas emissions. The results of these surveys also suggest that most people understand that climate change will have catastrophic impacts on polar bears and other Arctic wildlife. For many of us, making the connection between our own everyday actions and the persistence of polar bears in the wild is enough to get us to make energy efficient choices.

However, we must also understand that, while the impacts of climate change are most vividly obvious in the remote Arctic, they are also impacting other habitats all over the world, including our own backyards, and that the resulting changes to our Earth will have far-reaching consequences for people everywhere. We have to do more. We have to move from “understanding” the impacts of climate change to “taking action” to reduce our carbon footprint.

Each and every one of us has the power to change our habitats in order to reduce our own personal greenhouse gas emissions. Future generations, and future generations of polar bears, are counting on you to reduce your carbon footprint.

Megan Owen is a conservation program manager for the San Diego Zoo Institute for Conservation Research. Read her previous post, Panda Cub: 704 Grams.

Calculate your own carbon footprint and get suggestions and easy household tips that help you reduce your carbon footprint (and energy bill), or visit Polar Bears International.


Polar Bears: Keeping Cool

Tatqiq knows how to stay cool!

The summer of 2012 will go down in history as one of the hottest on record. This brings lots of questions as to how polar bears at the San Diego Zoo can live in even the milder heat here. The first answer: our 130,000-gallon (490,000 liters) pool is chilled to under 55 degrees Fahrenheit (12 degrees Celsius). The shallow area allows the bears to lie down and even sleep if they choose. The mid-range allows for great soaking opportunities, and the 12-foot (3.6 meters) deep end allows for complete submersion and swimming. On most summer days, the breeze through the exhibit comes right off of San Diego Bay, so it is a cooling sea breeze. Throughout the exhibit there are numerous shaded areas with various bedding materials for the bears to sleep on. There is also a portable air conditioner we can direct up by the back area where they especially like to sleep. Inside the bedroom area, we also have air conditioning to take the heat out if absolutely necessary.

The real reason we can keep our polar bears comfortable, even on the hottest days, is by limiting the amount of fat they have on their body. For polar bears to survive the cold of the Arctic, they must build up at least 4.5 inches (11 centimeters) of fat over their body. They do this by eating seal blubber. A polar bear’s diet is 90 to 95 percent fat in the wild. They are so specialized for eating fat that they metabolize close to 90 percent of what they eat into body fat.

Here in San Diego, our nutrition staff has developed a diet that is 5- to 10-percent fat, so our polar bears get what they need for good health but not for bulking up for a cold winter. All of our bears would weigh much more than they do now if they had those fat layers. Kalluk, who is now over 1,100 pounds (500 kilograms), would probably be closer to 1,600 pounds (725 kilograms)! When polar bears put fat on, it goes first on their belly to protect their core. Do you know that the body temperature of a polar bear is the same as ours? 98.6 degrees Fahrenheit (37 degrees Celsius)! The fat then layers over their bum and spreads out over their body.

Here’s one way to tell our three apart: When you look at them in profile, Kalluk and Tatqiq have a rounding of their bellies, but from the top of the hip to the tail it’s flat. Since we keep a bit more weight on Chinook (just in case she might be pregnant), her belly is nice and round, and her bum matches! And let’s not forget the CARROTS! Polar bears get little to no nutrition or calorie from vegetation. Our three can eat as much as they like and not put on a pound. Currently, they get 100 pounds (45 kilograms) a day between them that gets chewed, swallowed, slightly steamed in their bellies, and then eliminated. As keepers, we call that job security!

One problem with warm weather we seem to be challenged with this summer is the algae growth. Our water quality team constantly monitors the pool’s water for safety and cleanliness, but algae is airborne until it finds moisture. With the warm temperatures and direct sun, we’re experiencing quite a bloom. We add rock salt to help, but, unfortunately, some of it has imbedded into Tatqiq and Kalluk’s hollow hair shafts. It sneaks in through the small breaks in the shaft formed by grooming. This won’t harm them in any way, but it’s pretty embarrassing to have polar bears with a greenish hue! Our polar bears were once famous for being green when they lived in the smaller grotto exhibit decades ago. Since moving to this exhibit in 1996, we’ve not had any “greening,” until this year. So in the next few days we’ll be hosting “spa days” for a purpose—mineral salt-water soaks for all! Chinook and Tatqiq have always been pros at the soak; Kalluk will be challenging, since he thinks it’s only about dive bombing his sister and then slurping the saltwater off his giant paws. He’s got 13 inches (33 centimeters) on each foot to slurp from!

Summer brings great fun but also great danger with the dry heat. It is sad to hear of fires burning across our nation, so many losing their homes. It’s heartbreaking to lose so much; thank goodness for insurance. In the past few decades, polar bears have lost their ice homes in an area the size of Texas and Alaska combined. We now see forest fires burning in the Canadian tundra, the place with one of the highest densities of polar bear denning, the place where our beloved Chinook was born. What insurance do they have? They have us. We must be the guardians of our planet. We must continue to reduce our greenhouse gas emissions, especially when it seems there is no hope. We still know it can be done. We must be the insurance to protect and insure that our children and grandchildren will still have the opportunity see the magnificent polar bear roaming our planet.

JoAnne Simerson is a senior keeper at the San Diego Zoo. Read her previous post, Polar Bears: Breeding Season.

Watch the polar bears daily on Polar Cam.


Polar Bears: Back to 3

Chinook enjoys some ice time in July.

Over the past week, Chinook has been more active and has been spending lots of time outside in our polar bear management yard instead of her bedrooms and den. On this past Sunday, we removed the den, and she seemed not to care. So this morning we reintroduced our fabulous threesome! After a brief greeting, all three settled on exhibit: Chinook in the mulch by the road, Kalluk on the point, and Tatqiq at the edge of the pool. All seem to be pleased with each other’s company. Chinook did go up to the doors after 30 minutes to see if we were around, but after sniffing and listening she went back out to her mulch bed.

The immediate future will be about continuing the ultrasound exams for a few weeks just to see any changes. Then as we approach the end of winter, we expect to see Kalluk’s behavior change, letting us know breeding season will be upon us shortly, and then. . .we all know the routine. So uncross you fingers and rest your hopes, at least until next fall!

JoAnne Simerson is a senior keeper at the San Diego Zoo. Read her previous post, Polar Bears: No Easy Answers.


Polar Bears: Getting Ready

Chinook enjoys snow day July 2011.

As you may already know, we are anxiously waiting to see if polar bear Chinook will have cubs this fall (see post Polar Bears: Dare to Hope). While we don’t have absolute confirmation yet that she is pregnant, her behavior and hormonal profiles look good, and we are hopeful. Of course, “hope” is just part of what we need right now: we also need to get ready!

For most of this year we have been monitoring and analyzing Chinook’s behavior and hormones, and these studies have provided great insight into her reproductive cycle. But our research effort really shifts into high gear during the postpartum period. If Chinook has cubs, we will be monitoring the behavior of mother and offspring and closely studying their acoustic communication. As part of a broader study of maternal-care patterns in polar bears (supported in part by Polar Bears International), every move that Chinook makes will be recorded on our den camera, and every squawk, moan, and hum emitted by her cubs will also be recorded, analyzed spectrographically, and correlated with both the cubs’ and Chinook’s behavior.

But what’s most important to the success of this research, and to the successful rearing and care of mother and cubs, is that all of our work is done without disturbing the bears. This requires thoughtful planning and making sure everything is in place BEFORE Chinook decides to go into her den to prepare for a birth. Every piece of equipment must be tested beforehand, because we can’t go back in and fix anything once Chinook has settled in. At this point, we are almost ready, and yes, we are very, very hopeful!

Megan Owen is a conservation program specialist at the San Diego Zoo Institute for Conservation Research. Read her previous post, Panda Su Lin: Cub.


Polar Bears: Dare to Hope

Chinook gives Kalluk's scruff a playful tug.

We’ve all experienced wanting something so bad that it hurts. People will tell you all kinds of things to make the waiting a bit less painful. You begin to fill your head with all the knowledge you can to know if it will really happen or not. And then comes the superstitions: don’t step on a crack, don’t talk about it, fingers and toes crossed. But no matter what, it just takes time to get the really special things that you want! What am I talking about? Wondering if polar bear Chinook is going to have cubs, of course! Is there anything else on our minds? Dare we hope?

As you know, Chinook and Kalluk marked Valentine’s Day 2011 by marking the start of the polar bear breeding season. If you were to ask Kalluk, he would tell you it was a successful season. The good news is that Chinook did not go back into season. This is very good, as we believe that when a female polar bear ovulates and there is fertilization, in most instances she will not cycle again that year. This is a good knowledge point.  Chinook, as many of you have observed, has also been putting on weight. This would not be due to carrying cubs, as they are barely over a pound at birth, but would make sense that her metabolism would compensate to hold as much as possible to nurse and provide for cubs—another good point of knowledge.

Polar bears experience delayed implantation, so we would expect to see Chinook changing behaviorally once the fertilized egg implants, around 60 days before birth. Yes, she is beginning to seclude herself away from Kalluk and Tatqiq. If gestation is 195 to 265 days for a polar bears, then from the 10 days of breeding, Chinook would be due between August 28 and November 16. Panic—it’s already September! Breathe, breathe. With such a long gestation, she could be implanting right now with a due date of early November.  Most polar bear births in North American zoos have occurred in the first week of November, the earliest was on October 13. Good things to know!

We have been collecting fecal samples for hormone analysis with the research branch of the Cincinnati Zoo and urine samples for hormone analysis with the Memphis Zoo. So far, nothing conclusive from the urine analyses, but the fecal analyses look positive for pregnancy. . .or pseudopregnancy. BUT—and yes, a big but—Chinook’s hormone profile is consistent with profiles of other polar bears that have given birth! Dare we hope?

So with knowledge in place, we’re avoiding walking under ladders, stepping on cracks, saying anything to jinx it, and above all, fingers and toes crossed. You better believe we are daring to hope that this time will be for sure!

JoAnne Simerson is a senior keeper at the San Diego Zoo. Read her previous post, Little Polar Bear: Lessons.