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Captive Sloth Bear Size
Mindy Babitz to the Bear Care Group Sloth bear keepers - I need your help! I need weights/weight ranges for female sloth bears. Thank you in advance ? Here's a cute bear picture for your time. . .  *This image is copyright of its original author Lauren Etkins Kayla is generally in the 82-92kg range. Is that Remy? Dallas LaDucer 19yo male is 132kg-145kg but he came to us much smaller at 119kg. 8yo female is 130kg-177kg(birth weight). And my little Furball is 17kg and growing. James Ford We have a 16 year old female, her weight is usually 75-77kg Mindy Babitz My female is big too. I'm battling nutrition because they want her down to 80kg from her recent high of 112kg (3yo). I know her mom in Little Rock is also big at 130kg right now. I suspect there's a wider range of body types for female sloth bears than is in the books which is why I'm asking around. I think our bear looks great - not fat - at her current weight. And on her diet she's hungry, anxious, and starting to pace. In the Bear Care Group we teach if your bear has good muscle and does not turn into a pear when they stand up, then they're in good condition. Nutritionists at many zoos however body score bears like they're cats. But bears aren't supposed to be thin like cats. Anyways I was also surprised at the lower weights. But then we used to have a Sri Lankan female who was about 90kg. Dallas LaDucer Yeah, I'd say my male is in great condition at like 140kg and ive read that males can get upwards to 180. My female (in the video) is a big girl, super furry and is nursing, but I don't feel that she's overweight either. ? Mindy Babitz The adult males we've had have gone between 130-160 and were in good condition. Our female is super furry as well as you can see in the photo. I really think that coat accounts for some of the weight. No one believes me about that though. Unfortunately I can't shave a bear and weigh it to see for sure. Lol! 
At the request of @peter, I have come up with a formula to describe the relationship between pad width and the weight of bears.
This was shared in the "Edge of extinction" thread:  *This image is copyright of its original author I ran a linear regression based on the 9 specimens (did not use the 600 kg specimen) and the results were as follows:  *This image is copyright of its original author In this dataset, the relationship was not significant (p = 0.235). For that reason, there is no point in elaborating on the formula on the top right as it is useless. Visually, it seems the two ~145 kg specimens with paw widths of 16 cm are outliers causing the issue, but I cannot remove the outliers unless I have some justification. However, the lack of significance above seems to have been a type II error due to a lack of power. Blanchard published a study on Yellowstone bears which detailed bear weights and paw sizes in different age groups. While this is not as optimal as having individual weights, the foundation for estimation will still work as there are a good amount of datapoints. Here are the results (n = 21):  *This image is copyright of its original author The association is very significant (p <<< 0.05). The relationship is also very significantly positively allometric as the 95% confidence interval for the scale factor of 3.9091 (95% CI 3.34-4.47) is significantly different from 3. This means a small change in pad width has great change in weight. In sum, the formula Mass = 3.9091log(Pad Width) - 6.1869 seems to be a powerful tool to estimate bear weight. There is a clear association between these two variables and bears get heavier quicker than their paws get wider.
Some Sloth Bear size information
 *This image is copyright of its original author  *This image is copyright of its original author
 *This image is copyright of its original author  *This image is copyright of its original author
  *This image is copyright of its original author  *This image is copyright of its original author
Age related growth patterns of male brown bears based on two grizzly bear populations (data taken from Blanchard, 1987 and Glenn, 1980)
Alaska Peninsula Average weight for the age class 5y-8y (sexually mature): 291kg (642lbs; n=16) Average weight for the age class 9y+ (fully grown): 389kg (858lbs; n=5) Absolute weight difference between the two age classes: 98kg (216lbs) Relative weight difference between the two age classes: ~34% Yellowstone NP Average weight for the age class 5y-8y (sexually mature): 173kg (381lbs; n=29) Average weight for the age class 9y+ (fully grown): 213kg (470lbs; n=32) Absolute weight difference between the two age classes: 40kg (88lbs) Relative weight difference between the two age classes: ~23%
Reply # 338 continued...
Kodiak Bear (data taken from Hensel and Troyer, 1969) Average weight for the age class 5y-8y (sexually mature): 267kg (589lbs; n=9) Average weight for the age class 9y+ (fully grown; spring specimens): 455kg (1002lbs; n=2) Average weight for the age class 9y+ (fully grown; fall specimens): 523kg (1153lbs; n=2) Absolute weight difference between the two age classes: 188kg (415lbs) Relative weight difference between the two age classes: ~70% (12-25-2020, 10:47 PM)Maritimus77 Wrote: Reply # 338 continued... These postings of yours are debatable. Firstly I think that brown bears are commonly considered as fully grown starting at the age of 8 years old. At that age skeleton is developed mostly to full size. Some marginal changes still happen, but not so much. I don´t know where you took the idea, that brown bears should be 9+ years old to be considered fully grown when scientific sources mostly mention 8 years as starting point. At that age it can be seen how tall bear is on hind legs and also shoulder height, even though it will be in more robust condition later. Then again trying to put there some averages when sample size is only two bears isn´t reliable at all. It´s just a possibility, which can be right or wrong. So claiming that 455 kg would be average weight of Kodiak bears in spring time doesn´t stand up critical scrutiny with that small sample size. Same of course when looking at Alaskan peninsula brown bears. Average from 5 only is quite questionable. It is just slightly better estimation/guess. So while it can be calculated, conclusions should be very careful and with great caution as result can be false information. Personally I think, that when sample size is approximately ten or more individuals it starts to approach some reliability although caution is still needed.
@Shadow
"Males reached mean adult size in 7 of the 11 dimensions by 6 years (body length, girth, height at the shoulder, neck circumference, head length, front pad length, and rear pad width) and in all 11 by 9 years." This is from Blanchard's study. The 4 dimensions that still kept growing until 9y of age were the contour length (body length over the curves), the width of the head, the width of the front pad and the length of the rear pad. So according to the measurements they listed, those male grizzly bears weren't fully grown in all dimensions until the age of 9 years. This note is from Glenn's work: "At least 95 percent of ultimate male dimensions of height at shoulder, total body length, body length, hind-foot length, skull length, chest girth and neck circumference were completed by 6 years; weight and total skull size by 8 years and zygomatic width by 10 years." Note that he is referring to 95% here in contrast to Blanchard's work; based on skull measurements it may last until 10y of age until we can speak of a fully grown brown bear in terms of certain cranial/morphological attributes. This next quote refers to Blanchard's study again: "In general, males appeared to steadily gain weight annually until at least 15 years of age (Fig. 2)." The annual weight growth of males may last until 15y of age; so a fully grown brown bear in terms of body measurements and body weight may be relatively old pushing the 15y mark (probably also relies on the specific population and their attributes, not every population of brown bears will experience identical growth I guess). "So claiming that 455 kg would be average weight of Kodiak bears in spring time doesn´t stand up critical scrutiny." I didn't claim anything so far; I just posted the results of three datasets without any personal evaluation of mine. I agree with you that the sample size is very low and respective changes with an increased sample size are unpredictable. My question therefore: You are a very experienced poster, are you aware of any additional data listing the weight of fully grown Kodiak bears? I am only aware of the 1969 study on them, maybe there is something you have at hand that I don't know about; we might be able to increase the sample size then. (12-26-2020, 12:08 AM)Maritimus77 Wrote: @Shadow I didn´t see there any real justification to use 9+ years old as fully grown. Trying to push it further and further is artificial thing to do. When looking at it how things are commonly considered, an 8 years old bear can be considered to be fully grown. They do get more robust still, but overall differences are marginal. Some discussion can be when talking about biggest of the big bears, but overall it´s better to use commonly agreed age ranges to avoid confusion. And what comes to sample size of two, it´s beyond low, frankly saying it´s useless. So stating some weight changes 70% based on useless information is just the same. It´s unreliable and useless statement. I´m sorry to be this frank, but here in wildfact idea is to avoid spreading misinformation and sometimes things are said frankly.
@Shadow
My intention wasn't to push anything further; you asked me where I get the idea from that 9y would be the usual age where brown bears completed their growth. The authors mentioned that certain measurements kept growing until 9y of age, some even until 10y of age in the case of peninsula grizzlies, that's where I got the idea from. I just responded to the question that you have asked me. You are not frank, you are accusing me of posting misinformation. I just posted the numbers of certain datasets and their relation to each other, no interpretation or personal statements attached to it by me. (12-26-2020, 12:27 AM)Maritimus77 Wrote: @Shadow I am frank, putting average weight from sample size of two is unreliable and using such result then to calculate weight differences is misinformation. So yes, I say it frankly that you are now posting misinformation because your posting includes it. And it´s something what we here try to avoid. And when seeing it to happen, it´s pointed out. I don´t accuse that you did it on purpose, but you used very questionable data to calculate size differences in between age groups. Here one example for scientific study concerning brown bears and quote: "Standardized body size measurements of body mass, body length, and skull size were collected, and mean spring litter size of cubs of the year was also reported for each population. We only included bears ≥ 8 years of age in our analyses as structural growth is largely completed by that age (Hilderbrand et al. 2018a) and allowed us to eliminate age from our analyses." https://link.springer.com/article/10.1007/s00300-019-02501-8
@Shadow
I posted three datasets, raw numbers and their relation to each other. You could have adressed that there is a high danger that this can be misinterpreted and could lack reliability. Instead you accused me of: 1. Pushing wrong things further and further 2. Posting useless information 3. Producing useless statements 4. Spreading misinformation The excerpt you shared referred to Hildebrand et al. (2018) as the original source for their exclusion of brown bears below 8y of age. This is part of Hildebrand's excerpt: "Full body‐frame size, as evidenced by asymptotic skull size and body length, was achieved by 8–14 years of age across populations and sexes. Lean body mass of both sexes continued to increase throughout their life." So for one point they are solely referring to two measurements (body length and skull size) whereas the excerpts I shared take much more aspects into account and for another point they give a general range of 8-14y for the completion of full body-frame size. Picking out the lowest number and disregarding the general range could also be questioned. |
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