Creatures Great and Small
Posted at 2:37 pm March 17, 2008 by Suzanne Hall
I have recently begun watching Chinook (pictured) and Kalluk as a part of a team of researchers conducting a breeding study on polar bears at Polar Bear Plunge at the San Diego Zoo. One day each week I observe this male-female pair as they come out on exhibit in the morning, recording their behavior and looking for signs of estrus-related behavior from them. It has been a while since I had the pleasure of routinely watching polar bears. The last time I participated in research on this species it was when our polar bear family included individuals with names like Buzz, Neil, Bonnie, and Castor; if those names are familiar to you, then you know how long ago that study effort was!
My first day observing Chinook and Kalluk came chock-full with several moments of awe. The first was upon getting a good look at Kalluk. He’s a young male, less than half of giant panda Gao Gao’s age, and yet the size difference between them is astonishing. Kalluk, as a representative of the largest bear species on the planet, is a towering hulk. Despite his lean frame, I am told he weighs in excess of 850 pounds, or 380 kilograms (compare that to Gao Gao’s mere 160-pound, or 70-kilogram, weight). Resting on his backside in an erect seated posture, he is taller than I am. And when he stands on his rear legs to get a look at something placed up high, well, even NBA stars would have a run for their money looking big next to Kalluk.
I have spent most of my time over the last few years working with the (not so?) giant panda and the sun bear, the two smallest living bears. What factors might account for the great difference in size that we see in the spectrum from these smallish bears to the massive polar and brown bear species? One major contributing factor is the different environmental niches that these species inhabit.
The largest bears are cold weather animals, living in harsh, extreme climates much of the year. Coping mechanisms to deal with cold and its resultant food shortages include hibernation periods, insulating fat deposits to keep the heat in, and (in the case of the polar bear) translucent hairs which aid in conducting sunlight down to the skin to increase heat absorption. But increased size is also a fundamental way of coping with coldness, as the basic principle of surface-to-volume ratios indicates: the larger the body, the smaller the surface area relative to body volume. This reduced surface area ratio allows for a lower rate of heat loss.
Compared to the harsh, cold climates polar bears inhabit, sun bears enjoy warm, tropical habitats. The steamy rain forests from Borneo to Thailand and India were the birthing grounds of this species, and the bear benefited from a smaller size to aid in rapid dissipation of heat to avoid thermostress. But what about pandas? Don’t they typically inhabit snowy, cold mountain passes more closely resembling the habitat of a larger brown bear? Why aren’t they so large?
One answer to this question lies in the evolutionary history of the panda. Long before man came to be so populous in China, pandas could readily be found in the lowlands of southeastern China, at about 1,600 feet (500 meters) above sea level. The panda populations probably expanded and contracted in range many times as the temperature alternately warmed and cooled, with warm weather allowing expansion due to the increasingly favorable conditions for bamboo growth in warm seasons. Thus, at some points in the panda’s evolutionary history, this ancient bear species enjoyed warmer climates and survived well with a smaller size.
Of course, the question of size differences among bears is more complicated than the surface-to-volume picture I have sketched here, but it does provide a partial answer to the wide variety of sizes achieved across the eight living bear species. It even explains some of the differences seen between subspecies, such as the discrepancy between the warm summering grizzly populations relative to their colder cousins, the big Kodiak brown bear. Next time you have a chance to visit your local zoo and observe the bears housed there, maybe you will see their body sizes in a whole new light!
Suzanne Hall is a senior research technician with the San Diego Zoo’s Giant Panda Unit.
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March 17th, 2008 at 9:46 pm
Suzanne,
Thanks again for your ever so informative blog on bears, and not just the giant pandas that you work so closely with!!!
I have always wondered why Kalluk is so much bigger than his sibling sister, Taqiq. I thought perhaps it was due to him being the male bear, hence being larger in frame; however, your blog opens up a whole new perspective on how these bears cope with extreme climate changes. I am glad that you now have something else to occupy your interests by conducting research on these wonderful polar bears.
BTW, does SDZ collaborate with the zoos in Germany, given the fact that they have been hand-rearing two polar bear cubs in the recent years? It would definitely be interesting to see whether Chinook and Kalluk mate and produce cubs next winter, and how Chinook would care for her cubs!
March 18th, 2008 at 12:38 pm
Suzanne, I just read a article in our local paper about nutrition in zoo animals mainly polar bears, gorillas, lions and tigers. Jennifer Watts from Brookfield zoo in Chicago is hatching a Weight Watchers style plan for the animals. the idea is to assign points to food that is used for training or enrichment and they are given a extra amount for the week.Indianapolis zoo is giving polar bears sugar free jello hidden in their habitat. Toledo zoo is feeding wolves deer road kill and the lions and tigers whole calf carcasses. they want to provide a additive free method. They say that this is better because livestock and pet foods resulted in weak bones and in some cases fractures or malnutrition.Watts said too much of the GOOD stuff can cause a few love handles in bears and the big cats.So hooray for all the nutritionist who are watching out for all our critters. Suzanne you always give so much interesting information and I always learn so much from your Blogs .Thank You so much. I know that I for one could use a few less calories and weight watchers sounds pretty good
March 18th, 2008 at 12:43 pm
Thanks, Suzanne, for another very educational piece. It never ceases to amaze me the differences between species and sub-species. Animals that live in the same habitat can vary so greatly as well. The education one can gain from these blogs is price-less. Thanks for keeping us up to speed on all the bears.
March 18th, 2008 at 2:09 pm
Barbara #2, NZP is one of the few zoos in the US, don’t know if SDZ has one too, that has a zoo animal nutritionist on staff, and they are very tuned into the needs of the animals in their care. I am sure that they are consulting with many of the zoos who don’t have a nutritionist on staff. Thanks for sharing the article. It is very informative. It is amazing how far both animal nutrition and veterinary care, both essential for long term survival of captive and wild animals, have come in the past decade. The world’s animals will be better for knowing all of this critical information, as long as humans get out of their way and stop destroying their natural habitat and therefore their innate feeding and migration patterns.
Moderator’s note: The San Diego Zoo has a Nutritional Services Department with two nutritionists as part of its staff. Here is a blog about them that you might find interesting: http://www.sandiegozoo.org/wordpress/default/nutritionists-to-serve-and-protect/
March 18th, 2008 at 5:54 pm
Suzanne – thanks for another valuable update on all the studies the SDZ does. It’s still hard for me to comphrend that giant pandas are part of the bear species. So many varities in size & habitat. They all have one thing in common – they are all endarged. But at least the other bear species know how to mate – unlike the giant pandas who seem to have no clue on how ” to do it” . From what I read on the last blog at least Tian was determined this year – poor guy – 3 years of pacing (after Tai’s birth) with nothing to show for it.
March 19th, 2008 at 5:54 am
Early here on the west coast (5:53) and I just checked the NZ Pandacam — Mei Xiang and Tian Tian are already going at it hot and heavy this morning. Tian Tian is surely a persistent suitot — no way was he going to let Mei run away from him! Amazing — and lots of vocalizations!
March 19th, 2008 at 6:17 am
Margaret #4 thanks for the info, the article i mentioned also spoke how nutrition and care has advanced of the the last decade. I like you believe that we are our own worst enemies when it comes to destroying habitat, I have noticed a increase of critters around my area that are being displaced by new strip malls and housing complexes. We have a need for both but a gentle balance needs to exsist. The article that the moderator mentioned was fantastic and informative, I never realized all the aspects of a nutritionist job. My hat goes off to all of you who work so hard to make sure all our animals are healthy. I need to get motivate to get away from the tv and that bagel every day, but the one thing I won’t ever stop is feeding all the critters who come looking for food,it’s just another bag of food and we just happen to have the best animal control officer you could ask for.
March 19th, 2008 at 7:06 am
Thanks Moderator, for the clarification. I thought that SDZ had two nutritionists, and that you had written about the benefits to your diverse animal population of the expertise they provide. They even plan healthful birthday and special events treats.
Animals at both zoos are blessed to have dedicated professionals examining every aspect of their nutritional needs and providing daily guidance as to what they should be fed to help them maintain optimal health and stamina.
Kudos to all!
March 19th, 2008 at 7:15 pm
After watching the video of ” Mei had a date” on youtube was not suprised that the NZ reports that while Tian & Mei Xiang tried their best natural mating did not happen so they perfomed AI on Mei Xiang. Poor Tain sure did try but seems like while Mei was ready she did not help by being in ” the right position” From a video of Yang Yang & Lun Lun she backed right up to him but even then he didn’t get it -good thing we have Gao & Bai .
I have a question as to why it’s taking so long to get an official statement from Wolong about Mei Sheng. Someone metioned the unrest in Tibet & possible commuciation problems but it’s been months now & ZA has their PhD, Ben Charlton in Woong doing a study & have had 2 updates from him this week.
March 19th, 2008 at 10:33 pm
Hello panda lovers. I have now joined the ranks of those fortunate enough to have seen our darling SDZ pandas in person!! Oh, what a thrill it was!! I went to SDZ on March 17 and 18 and remembered all the tips that many of you gave me. Special thanks to the moderator and to Bobbie Wood for such detailed hints.
On March 17, we got to the zoo right at 9 a.m. and asked the gentleman at the information booth what the quickest way was to get to the pandas. His instructions were to take the path that went through the Fern Canyon and follow the signs to Panda Canyon. Sure enough, in no time we were there. I recommend this route to anyone planning on visiting. The path through the ferns is quieter and very relaxing. A warning though: this route includes some steps and inclines. (Gao Gao was not on exhibit, unfortunately.) The first panda we saw was Su Lin. What a gorgeous bear she is! She was munching up a storm when we got there and so was Bai Yun. Miss ZZ was zonked in one of the hammocks – not much action there, much to our disappointment. But it was still awesome to finally see them for real. There must have been some rain the day before because all of them displayed some evidence of ” rain play.” We came back later in the afternoon around 4 p.m. – well, this time, ZZ was active, but still up in the tree, moving around the branches that held her hammock. This time, we got some good pictures of her. When I read the postings on the blog that evening, it appears we would have seen more action if we had come earlier. Sigh. We resolved that the next day we would try to improve our timing. (I also noticed that when the crowds are sparser in the morning, there isn’t much reminding from the zoo attendants to keep the line moving.)
March 18, we were back early in the morning – again, Bai and Su Lin were hard at work on their piles of bamboo and, you guessed it, the Zoomer was sound asleep in the same hammock she was in the day before! So, we went to see the other exhibits before returning in the afternoon – this time, we just kept going back in the lineup as soon as we got through – they don’t mind you doing this. We saw much more action this time. Su Lin was asleep – she looks so beautiful when she sleeps with her head resting on her paws; however, we did get to see her walking around and even getting into her pool for a few minutes. I kept wishing she would climb one of the trees but she only went part way. In the meantime, ZZ was playing shy. After she woke up, she came down to see Momma Bai, but then proceeded to make her way inside. We watched as Bai tried to coax her back outside – even trying to grab a hold of her neck to pull her out. Well, we all know she has a mind of her own – she was playing so hard to get we were beginning to think we would not ever get to see her in action. But, Bai must have worked her magic and ZZ finally came out. This time, there was no holding her back. One of the keepers had come in to do a bit of clean up. ZZ noticed the rake leaning against the outdoor platform. She grabbed the handle with her mouth and started making her way up the tree with it. She lost it a couple of times, of course, but that little trooper would not give up. She was bound and determined that this new ” toy” was going up the tree with her!! Finally, the keeper finished and took the rake away. And for ZZ, that was the end of that adventure. She went back to her hammock and lay down for another snooze. What a wonderful visit we had, although we are sorry we missed seeing the great Gao Gao.
I have to say how impressed we were with all the zoo staff that we encountered. And we did enjoy the rest of the zoo very much, as well. The gorillas were a hoot! So were the orangutans, the gibbons, the macaques, the flamingoes, the sea otters, the polar bears, and many more! We saw creatures that we had never heard of before – such an eye opener on how much beauty and wonder we can still learn about our world, and how much we have to do to ensure that it will be here for the next generation. We took so many pictures – will post them as soon as we get back to Canada. We loved San Diego and its friendly people, and the wonderful weather!! We will be back for sure!
Moderator’s note: Thanks for sharing, pandafan. Sounds like you had a great time!
March 20th, 2008 at 1:07 pm
Pandafan, thanks for sharing your experience at SDZ. I hope you also got to go to the WAP, as there is more to be seen there as well, and it is unlike any ” zoo” facility I know anywhere in the world. It is the most naturistic environment for all the animals that live there because there is much more room for larger exhibits. If you didn’t get there too, plan on going to both places on your next trip. It is well worth it!
March 21st, 2008 at 2:07 pm
Looks like one of the kiddie pools (purple) is back on the rocks for enrichment. Since it is sitting beside the pool it is hoped that it will be used in the water??? I look foward to checking in later to see if it is providing great fun and entertainment.