|
|
Post by OldGreenGrolar on Nov 29, 2020 6:49:43 GMT -5
More on fat:
Thick layer of body fat / blubber (anatomical / physiological) - This can be up 10cm (4 inches) thick, it is used both for insulation and also for food storage to help survive when food supply may be intermittent especially in the summer months when bears often go hungry for long periods due to not being able to hunt their preferred food of seals. Up to 50% of a polar bears' weight can be fat! It also helps them to float naturally when swimming so avoiding having to use energy to keep their head out of the water. Processing body fat to gain metabolic water (physiological) - Polar bears store a lot of fat which they use for energy in the process combining it with oxygen to release carbon dioxide and metabolic water. They live in a polar desert with little access to fresh water especially in the colder months (which are in the majority) in this way they can get extra fresh water - camels do a similar thing with their stored fat. www.coolantarctica.com/Antarctica%20fact%20file/wildlife/Arctic_animals/polar-bear.phpPersonally, I believe it is pregnant female polar bears that can reach 50% of fat. Since the largest polar bear shot is estimated to produce 20% of fat. Polar bear's also have the highest metabolic rate of all bears.
|
|
|
|
Post by King Kodiak on Nov 29, 2020 11:01:59 GMT -5
Replies #36 and #37: great info there TheGreen.
|
|
|
|
Post by OldGreenGrolar on Nov 30, 2020 9:15:31 GMT -5
HOW THICK IS A GRIZZLY BEAR'S BODY FAT? Hibernation Grizzly bears hibernate inside dens they dig themselves, normally in remote mountain areas, where the snow will act as insulation. They usually hibernate for between five and seven months, going into their dens in October and November and emerging between March and May. During this time they don't eat or drink at all, which is why having a thick layer of body fat is extremely important. Pregnant females give birth to cubs while they're hibernating, around January time, and raise them in dens until April or May. When they awaken, they will have lost almost all of their layer of body fat and around 15 percent to 30 percent of their total body weight. animals.mom.com/grizzly-bears-awake-sleep-1603.htmlI think active polar bears have generally less fat percentage than that of brown bears.
|
|
|
|
Post by OldGreenGrolar on Nov 30, 2020 9:17:48 GMT -5
BROWN BEAR FATNESS INDEX
OCTOBER 27, 2016 / MIKE FITZ Brown bears get fat, often really fat. They also lose a lot of weight and sometimes become really skinny. They are often fat and skinny in the same year. When you watch brown bears, either in person or via bearcam, you can sometimes make a fairly accurate determination of a bear’s body fat and relative health by looking at its shape. Fatness can be used as an indicator of health in brown bears. Brown bears need to eat a year’s worth of food in six months or less to survive, and body fat is the key their survival. They can lose 30% or more of their body weight during hibernation and can continue to lose weight throughout the spring when few high calorie foods are available. In the Brooks River area, only after green plants begin to grow and salmon have arrived do most bears begin to regain lost weight and start to accumulate body fat. While fat is important to bears, a thin bear isn’t necessarily an unhealthy bear. Young subadult bears and yearling cubs, for example, often appear thin in spring and early summer before many high calorie food sources are available. These bears usually regain lost body mass in summer and early fall. Polar Bear International developed a handy scorecard to measure the relative fatness of polar bears. I’ve adapted it for brown bears. My brown bear fat index uses the same categories as the polar bear index, which ranges from skinny/emaciated to very fat/obese. I also included additional information for each category such as the age/sex class most likely to be in a category and the time of year bears are most likely to be in a category. Please note, my brown bear index is subjective and based on my observations at Brooks River, Katmai National Park, Alaska. The polar bear fatness index is also subjective, but less so than mine because researchers who handle immobilized bears can palpate the animal to estimate its body fat content. (Katmai’s Changing Tides project also tracks body fat content in female brown bears, but uses bioelectric impedence analysis.) fitznaturalist.com/2016/10/27/brown-bear-fatness-index/
|
|
|
|
Post by OldGreenGrolar on Nov 30, 2020 9:18:51 GMT -5
 In this photo from early July 2016, 503 Cubadult appears thin with slightly visible hip bones. His narrow body shape is not uncommon for young subadult bears (he was 3.5 years old in July 2016), and does not necessarily indicate poor health. Rather it reflects the time of year and his low rank in the bear hierarchy. From the same link as above. This means the fatter a bear, the more dominant it is generally. |
|
|
|
Post by OldGreenGrolar on Nov 30, 2020 9:22:32 GMT -5
Early-winter body mass and energy stores by nonreproductive and reproductive bears
.
Body-fat content of captive, nonreproductive black bears during the early winter has been reported to be between 31% (Farley and Robbins 1995) and 45% (Lundberg et al. 1976) of total body mass, which is comparable to the 28% reported here for free-ranging bears. Body mass of reproductive female black bears in the present study was about 50% greater than mass of nonreproductive females. This is similar to values reported in other field studies on black bears (Samson and Huot 1995) and polar bears (Atkinson and Ramsay 1995). But brown bears do not show this distinction (Hilderbrand et al. 2000). The additional body mass of reproductive females represents energy stores, which can assist in production of young. Here, we show that, of the 30 kg difference in early-winter body mass, 50% is due to larger fat reserves (15 kg) and 11% is from more protein (3.3 kg). Interestingly, the autumn hyperphagic period for bears coincides with the reproductive state of blastocyst arrest, when there is very little additional energy demand on pregnant females. Therefore, during this time, there must be alterations in hypothalamic control of appetite and body-fat set point (Mrosovsky and Powley 1977) of pregnant females, which are not energy driven to make them eat more and acquire additional reserves to accommodate later demands. academic.oup.com/jmammal/article/83/4/1020/2373111
|
|
|
|
Post by brobear on Dec 21, 2020 9:27:17 GMT -5
bearproject.info/wp-content/uploads/2015/11/2015-D1.19-PhD-Andrea-Friebe.pdf " A minimum amount of body mass and fat content (about 19% in brown bears) prior to hibernation is necessary for reproduction (Beecham, 1980, Elowe and Dodge, 1989, Rogers, 1976, Atkinson and Ramsay, 1995, López-Alfaro et al., 2013)" The period of fat accumulation (hyperphagia) starts in August, when the bears consume mainly berries rich in carbohydrates to gain adipose fat tissue before entering the winter den (Dahle et al., 1998). A low respiratory quotient has been documented for hibernating bears, which indicates a high fat combustion, whereas carbohydrates and proteins are conserved (Nelson et al., 1973, Nelson, 1980, Boyer and Barnes, 1999). Fat, with its high energy density, serves as an efficient caloric storage medium. Burning body fat produces water and carbon dioxide; the carbon dioxide is exhaled and the water stays in the blood (Nelson et al., 1973). Azotemia does not develop in hibernating bears, urea production is decreased, and urea is recycled and resynthesized into skeletal muscles and other body proteins, to preserve lean body mass (Nelson, 1989, Harlow et al., 2001, Nelson et al., 1983). Although bears exhibit little physical activity during hibernation, they do not develop osteoporosis (Donahue et al., 2006) and lose only little skeletal muscle mass, in contrast to humans, who would lose about 90% of their strength during the same period (Harlow et al., 2001, Shavlakadze and Grounds, 2006).
|
|
|
|
Post by King Kodiak on Dec 21, 2020 9:52:41 GMT -5
Reply #43: great find brobear. Its about the Winter ethology of free-ranging brown
bears (Ursus arctos) in central Sweden. The study is very long 100 pages.
|
|
|
|
Post by OldGreenGrolar on Dec 21, 2020 11:06:23 GMT -5
|
|
|
|
Post by OldGreenGrolar on Dec 21, 2020 17:59:03 GMT -5
|
|
|
|
Post by King Kodiak on Dec 21, 2020 18:44:29 GMT -5
Reply #46: that is a very good chart, the Yellowstone line basically coincides with the chart i posted here:
domainofthebears.proboards.com/post/42080/thread
In May which is spring, the Yellowstone grizzly is at a normal 23% body fat, June which is summer, the grizzly has only a 17% body fat, basically nothing. October is at 32% which is obvious. The most body fat percentage should be at late November before hibernation, should be close to 40%, but that is not in the chart.
|
|
|
|
Post by OldGreenGrolar on Dec 21, 2020 18:57:28 GMT -5
|
|
|
|
Post by OldGreenGrolar on Dec 21, 2020 19:01:11 GMT -5
bearproject.info/wp-content/uploads/2015/11/2015-D1.19-PhD-Andrea-Friebe.pdf" A minimum amount of body mass and fat content (about 19% in brown bears) prior to hibernation is necessary for reproduction (Beecham, 1980, Elowe and Dodge, 1989, Rogers, 1976, Atkinson and Ramsay, 1995, López-Alfaro et al., 2013)"The period of fat accumulation (hyperphagia) starts in August, when the bears consume mainly berries rich in carbohydrates to gain adipose fat tissue before entering the winter den (Dahle et al., 1998). A low respiratory quotient has been documented for hibernating bears, which indicates a high fat combustion, whereas carbohydrates and proteins are conserved (Nelson et al., 1973, Nelson, 1980, Boyer and Barnes, 1999). Fat, with its high energy density, serves as an efficient caloric storage medium. Burning body fat produces water and carbon dioxide; the carbon dioxide is exhaled and the water stays in the blood (Nelson et al., 1973). Azotemia does not develop in hibernating bears, urea production is decreased, and urea is recycled and resynthesized into skeletal muscles and other body proteins, to preserve lean body mass (Nelson, 1989, Harlow et al., 2001, Nelson et al., 1983). Although bears exhibit little physical activity during hibernation, they do not develop osteoporosis (Donahue et al., 2006) and lose only little skeletal muscle mass, in contrast to humans, who would lose about 90% of their strength during the same period (Harlow et al., 2001, Shavlakadze and Grounds, 2006). carnivora.net/siberian-tiger-v-ussuri-brown-bear-t8294-s2970.html#p148363Warsaw posted that on Carnivora.
|
|
|
|
Post by King Kodiak on Dec 21, 2020 19:51:55 GMT -5
|
|
|
|
Post by OldGreenGrolar on Dec 21, 2020 20:02:45 GMT -5
I should have listen to my senses. Somehow I felt that Brobear has posted at least one of the sources. A female brown bear needs at least 19% percent fat to be able to reproduce. Therefore, pregnant female brown and polar bears with 50% fat will give birth to healthy cubs.
|
|
|
|
Post by King Kodiak on Dec 21, 2020 20:06:48 GMT -5
Well if Warsaw posts something, you can bet your bottom dollar that Brobear has already posted it here, ha ha ha.
Yeah, that is great info, bears actually need all that fat.
|
|
|
|
Post by tom on Jan 10, 2021 18:14:47 GMT -5
Reply #46: that is a very good chart, the Yellowstone line basically coincides with the chart i posted here:
domainofthebears.proboards.com/post/42080/thread
In May which is spring, the Yellowstone grizzly is at a normal 23% body fat, June which is summer, the grizzly has only a 17% body fat, basically nothing. October is at 32% which is obvious. The most body fat percentage should be at late November before hibernation, should be close to 40%, but that is not in the chart.
OK so the south central Alaskan bears which I assume are coastal brown bears have their lowest body fat percentage in mid summer (july). This is prior to the Salmon runs. Right out of hibernation which I would guess could be late March to mid to late April depending on the location. By May the Bears have had a chance to forage and gorge themselves on plant matter etc.. Not exactly a high fat diet but non the less they are consuming lots of calories. So I'm not sure why the drop in body fat by mid summer? More activity, plant food sources are not as plentiful... ? or simply the Bears are not as hungry. I'm at somewhat of a loss on this. I'm sure there's a logical explanation though. |
|
|
|
Post by King Kodiak on Jan 10, 2021 18:25:33 GMT -5
|
|
|
|
Post by tom on Jan 10, 2021 18:26:05 GMT -5
Sorry, The orange line in the graph. this is from Greens chart
|
|
|
|
Post by King Kodiak on Jan 10, 2021 18:28:58 GMT -5
Sorry, The orange line in the graph. this is from Greens chart |
|
