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Post by Montezuma on Apr 11, 2023 2:35:20 GMT -5
Here discuss about basic facts about bears like their ecology, diet, daily pattern and other things.
Here is an email from a bear expert David meanwell.
Hello. I am fasinated in bears and in your work for them and want to have a question that, generally speaking, are North American Brown Bears collective more aggressive and much larger than Asiatic or European brown bears?
Yours sincerely,
Reply:
HI Syed,
Thanks for your email.
There is a great deal of variety in the size of individual brown bears. Kodiak bears are, on average, the largest subspecies but there will be some individuals smaller than some individual Kamchatka brown bears - the largest Eurasian subspecies. Generally the smallest subspecies is the Himalayan brown bear.
On aggressiveness, that varies very much from individual bear to individual bear with no one subspecies being generally more or less aggressive than another. When it comes to interaction with humans, aggressive bears tend not to survive for long and natural selection plays its part in limiting the spread of aggressive brown bear genes - the more passive bears tend to survive longer and have more offspring. That said any female bear with cubs will likely be very aggressive if they feel their young are under threat.
One of the smaller species, the sloth bear, is probably the most dangerous to humans. Brown bears tend to rely more on their size as a deterrent rather than actually attacking.
Kind regards, David
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Post by oldindigosilverback on Apr 12, 2023 9:07:30 GMT -5
/\ Actually it is the polar bear that is more dangerous to humans as it is hyper carnivorous and most likely to view humans as prey. Regarding aggression varying between individuals is correct but there is a source Brobear posted saying the barren ground grizzly is the most aggressive individual. The only brown bear to encounter a larger bear than itself is the barren ground grizzly. The Himalayan brown bear seems to be more passive than the Asiatic black bear. Most of the info is good otherwise .
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Post by arctozilla on Jul 23, 2023 3:49:58 GMT -5
"Scientists have studied this process and found that while bears will typically lose 20 to 40 percent of their fat during hibernation, they don’t lose any muscle mass." www.vitalground.org/fat-bear-week-science/So that means that the bears' fat will not affect his muscle mass. Strongest men are fat too, cat fanatics excuses don't hold up.
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Post by oldindigosilverback on Jul 24, 2023 8:46:07 GMT -5
I am curious to know how much white muscle fibre bears have. Although male polar bears do not hibernate, female bears polar bears hibernate without losing any bone mass.
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Post by Montezuma on Sept 21, 2023 15:30:38 GMT -5
Can someone please tell the average and max weight, shoulder height, and length in order of these bears? Actually, estimates alot so i cannot figure out the exact one. Males only.
1. Arctodus simus:
Average weight: ? Max weight: ? Height: ? Length: ?
2. Arctotherium anguestidens:
Average weight: ? Max weight: ? Height: ? Length: ?
3. Cave bear: Average weight: ? Max weight: ? Height: ? Length: ?
4. Indarctos atticus:
Average weight: ? Max weight: ? Height: ? Length: ?
5. Tyrant Polar bear:
Average weight: ? Max weight: ? Height: ? Length: ?
6. Agrotherium africanum:
Average weight: ? Max weight: ? Height: ? Length: ?
7. Steepe Brown bear:
Average weight: ? Max weight: ? Height: ? Length: ?
8. Ursus ingressus:
Average weight: ? Max weight: ? Height: ? Length: ?
9. Florida spectacled bear: Average weight: ? Max weight: ? Height: ? Length: ?
10. Ursus Deningeri:
Average weight: ? Max weight: ? Height: ? Length: ?
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Post by Gorilla king on Sept 21, 2023 16:20:04 GMT -5
As we already know, these are all estimations based on fossils. Nothing is for certain.Can someone please tell the average and max weight, shoulder height, and length in order of these bears? Actually, estimates alot so i cannot figure out the exact one. Males only.
1. Arctodus simus:
Average weight: ? Over 1500 lbs. Max weight: ? Over 2800 lbs.Height: ? 10 feet tall on hind legs.Length: ? 2. Arctotherium anguestidens:Average weight: ? Over 1500 lbs.Max weight: ? Over 2800 lbs.Height: ? 11 feet tall on hind legs.Length: ? 3. Cave bear: Average weight: ? 1100 to 1300 lbs.Max weight: ? 2200 lbs.Height: ? 145 cm at shoulder.Length: ? 2.8 meters.4. Indarctos atticus: no data on this species.Average weight: ? Max weight: ?Height: ?Length: ?5. Tyrant Polar bear:Average weight: ? 350 to 1000 kg (single fragmentary ulna).Max weight: ? Unknown.Height: ? 145 cm.Length: ? 3.5 meters. 6. Agrotherium africanum:Average weight: ? 700 to 1200 lbs. (Only known range).Max weight: ? 1200 lbs.Height: ? 165 cm.Length: ? 7 to 8 feet.7. Steepe Brown bear:Average weight: ? Unknown.Max weight: ? 2200 lbs.Height: ? 160 cmLength: ? 2.9 meters8. Ursus ingressus:Average weight: ? UnknownmMax weight: ? 2310 lbs. (Largest known specimen).Height: ? 1.7 meters at shoulder.Length: ? 2.3 meters.9. Florida spectacled bear: Average weight: ? 330 to 660 lbs.Max weight: ? 660 lbs.Height: ? 100 to 120 cm.Length: ? 2.2 meters.10. Ursus Deningeri:Average weight: ? 330 to 1300 lbs.Max weight: ? 1300 lbs.Height: ? 135 cm at shoulder.Length: ? 2.5 meters.
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Post by Montezuma on Sept 22, 2023 13:23:24 GMT -5
Well, thanks for that. Very nice information to be honest. So if you see the largest size of extinct bears in order, it appears out to be as:
1. Arctotherium anguestidens: 680 - 1270 kg, 11ft
2. Arctodus simus: 680 - 1270 kg, 10 ft
3. Ursus maritimus tyrannus: 350 - 1000 kg, 11'5 ft
4. Ursus arctos priscus: 1000 kg, 9'6 ft
5. Ursus spelaeus: 500 - 1000 kg, 9'2 ft
6. Agriotherium africanum: 320 - 545 kg, 7 - 8 ft
These bears appears the largest in orderwise. The problem is that the variations are alot. There are manifold sources acclaiming varied masses and lengths as some say anguestidens measured 11 to 14 ft and some claiming the arctodus being about 12 ft long. Its a challenging matter to enact exact or nearly precise weights and length as results differ alot.
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Post by Gorilla king on Sept 22, 2023 13:42:19 GMT -5
That's correct, different sources state different weights and measurements. I went thru the different threads and sources and gathered the most reliable info we have in those threads. As you cam see, for Simus and Angustidens i left out the length. I believe though, that a 14 foot tall bear is unreliable, more like 12 foot at max.
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Post by Montezuma on Sept 23, 2023 12:05:07 GMT -5
Yeah, i was just looking for different sources about the exact sizes of Arctodus and anguestidens and there are abound varying from time to time research to research. The only thing on which all agree is the the South American Gaint short-faced bear was larger and more robust than his North American cousin. How much bigger? Well, thats uncertain. Here are some details that i found of sizes:
According to these 2 official National Geographic videos, Arctodus simus was over 11ft tall and weight from 1200 to 2000 pounds.
Here are some weight estimates of both Arctodus and Anguestidens where the former is told to weight from 700 to 800kg whilst the latter is 1588 to 1749kg.
www.semanticscholar.org/paper/The-Largest-Known-Bear%2C-Arctotherium-angustidens%2C-a-Soibelzon-Schubert/ea0c390c1332be944af2678b2cbe074f6bdd975f
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Post by Gorilla king on Sept 23, 2023 12:09:35 GMT -5
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Post by Montezuma on Sept 23, 2023 12:24:32 GMT -5
Oh shit. I never thought of that. To be honest, i am searching for an expert contact to see the seek some answers and have emailed some of them. However, i still got my speculations too.
According to this research by experts, around 1000kg Arctodus simus are to be more commonly found than previously thought.
"Body mass estimates obtained from major limb bone measurements reveal that A. simus specimens of around 1000 kilograms were more common than previously suspected".
www.google.com/search?q=demythologizing+arctodus+simus&sca_esv=567639170&authuser=2&sxsrf=AM9HkKmbGHYqigdTuH6C43RP2Zwi1H-Qyw%3A1695459867776&ei=G6oOZcndLqu39u8PyP-
So i can unhesitantely speculation large arctodus specimens easily reaching above 1000 kg. Was anguestidens larger, similar or smaller than simus? We don't know but since its 'officially' proclaim the former being larger than the latter, so i tend to agree until we don't get a newer offical info. Here are though my estimates:
Arctodus simus:
Average weight: 600 to 1,000 kg Maximum weight: 1,300 kg Shoulder height: 4 to 5.10 ft Maximum height: 6 ft Average length: 8 to 11 ft Maximum length: 12 ft
Arctotherium anguestidens:
Average weight: 900 to 1500 kg Maximum weight: 1700 kg Average height: 5.2ft to 6.2 ft Maximum height: 6.6ft Average length: 10 to 12 ft Maximum length: 14 ft
Its just my guess. Errors are sure.
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Post by arctozilla on Sept 23, 2023 13:33:05 GMT -5
"The only thing on which all agree is the the South American Gaint short-faced bear was larger and more robust than his North American cousin"
Well that's what a lot sites say.
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Post by Gorilla king on Sept 23, 2023 14:26:22 GMT -5
That's what was thought at first, but the thing is this, up to date, the largest Arctotherium's humerus is slightly shorter than the largest Arctodus's humerus, so the largest specimens found of the 2 species should be around the same weight. The different methodologies used is what gave those different estimates. If the methodologies used were the same, we would have gotten a very similar weight for both.
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Post by oldindigosilverback on Nov 1, 2023 9:40:46 GMT -5
Muscle strength in overwintering bears.Unlike humans, bears retain their muscle tone when moribund for long periods.
Black bears (Ursus americanus) stay inside their winter den for five to seven months of the year, during which time their body temperature drops to about 4 °C below normal1 and they do not eat, drink, urinate, defecate or show any other perceptible activity2. Although inactivity in humans, for example as a result of confined bed rest, weightlessness or limb immobilization, leads to atrophy of skeletal muscle, loss of muscle tone and impaired strength, we show here that the black bear does not suffer a similar deterioration. We find that overwintering black bears lose less than 23% of their strength over 130 days — unlike humans, who are weakened by a predicted 90% strength loss over the same period. In rodents and humans experiencing muscle atrophy resulting from inactivity or starvation, there is a reduction in the number and size of muscle cells (fibres)3, in the ratio of slow-oxidative to fast-glycolytic fibres4, and in the myofibrillar protein content5. We have investigated how these parameters are affected in overwintering black bears by taking muscle biopsies from denned bears during early and late winter. Remarkably, we found no loss of skeletal-muscle cell number or size. In addition, some muscles retained their protein content and oxidative capacity completely, whereas others showed a slight reduction in the ratio of the two metabolic types of fibre and in their protein content. In view of these findings that bear muscle shows none of the typical signs of disuse atrophy and indicating that bears are likely to retain their locomotor prowess through the winter, we tested whether their muscle strength was affected by prolonged starvation and immobility. We monitored hind-leg flexion of bears in the field during late autumn, just after denning, and again in early spring before they emerged from their dens (Fig. 1). Muscle strength was measured using a modification of a non-invasive force-assessment technique that had been previously validated in a hospital setting on humans for diagnosing neuromuscular disorders, for assessing weakness due to disease progression, and for evaluating therapy7. We were able to quantify the strength of the dorsiflexor muscle (tibialis anterior) of wild bears in their natural setting by measuring muscle contraction in response to supramaximal stimulation of the common perineal nerve. Figure 1: Non-invasive system for measuring strength of muscles by force assessment in a sleeping bear. Components consist of a stabilizing metal brace that holds the bear's leg in a secure horizontal position; a foot plate with force transducer to detect the evoked torque produced by the electrically stimulated tibialis anterior; a hardware device for nerve stimulation, signal amplification and signal conditioning, plus a computer for stimulus delivery, equipped with data-acquisition software for recording, analysing and displaying all signals simultaneously, together with a battery power-source. Human strength tested on a similar apparatus registers typically as around 0.54 newton metres (Nm), which is comparable to the strength predicted for bears by extrapolation to their hibernation muscle temperature9. Muscle force measurements in lower-limb extensor and flexor muscles of humans under conditions of confined hospital-bed rest or simulated space flight show that there is a daily loss of strength of about 0.7% as a result of limb unloading10. If strength loss as a result of atrophy were to occur at this rate in bears, a decrease in peak torque force to about 0.0675 Nm (90% loss of strength) would be expected after 130 days of inactivity (Fig. 2). But surprisingly, even though we found a significant decrease in torque force, bear strength remained at around 0.35 Nm under these conditions, corresponding to a loss in strength of only 23% (Fig. 2). Figure 2: Muscle strength in hibernating black bears. Left, peak torque force (in newton metres, Nm) of the tibialis anterior in six bears tested in response to a multiple-pulse stimulus to the perineal nerve. Bears were tested at their den site in the autumn (blue bar) and again in the spring (pink bar); vertical lines are 1 s.e.m. Right, peak torque force (Nm) of ankle dorsiflexion in healthy humans determined using a similar apparatus and protocol. Green bar, predicted strength at a leg temperature similar to that of the bears; yellow bar, predicted strength after 130 days of atrophy at 0.7% strength loss per day. Skeletal muscle protein and strength can be conserved by using alternative sources of protein, by recycling urea nitrogen back into protein synthesis, or by rhythmically stimulating the muscles. Hibernating bears may therefore be able to retain their strength by synthesizing new amino acids and protein from urea nitrogen11, or by shivering and undergoing isometric muscle contraction through the winter, or by drawing on labile protein reserves such as visceral smooth muscle and extracellular matrix. Understanding these processes in hibernating bears may provide new insight into treating muscle disorders and into the effects of prolonged hospital-bed confinement, antigravity and long-distance space travel on humans. www.nature.com/articles/35059165/
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