The "King" of the bears - comparison between the Polar bear and the Brown bear

[Shadow]

(12-14-2018, 12:41 AM)Panther Wrote:

Shadow Wrote:I noticed something now, when I looked your posting again, which I didn´t notice before.  But here is what I noticed and it was quite interesting and also proving how easy it is to make charts giving possible a very wrong picture about situation.
Here is attached chart, which panther posted and where is given information like Alaskan peninsula bears would be clearly heavier, than Kodiak island bears. But when comparing these charts I noticed, that information in chart posted by panther is actually based to chart posted here by you and earlier by brotherbear.... And now we get to interesting part.
In "panther" chart there are mentioned 10 Kodiak bears to get average weight to bears 6+ years. Then representing Alaskan peninsula there are only 5 specimens 9+ years!!! So all bears at least 9 years old, which is not a meaningless detail, when from this other chart we can see, that comparison group of Kodiaks are at maximum 9 years old, 2 are 6 years old, 3 are 7 years old and then 5 are 8 years old. That is how I understand that chart. Or oldest max 9 years old. 
This is very strange comparison to make it like that, when there are 5 Alaskan peninsula bears 9+ years old. If we calculate Kodiak bear 8-9 years old where we have as big (small) comparison group, what happens. Suddenly we have figures, where Kodiaks have average weight 379 kg and Alaskan peninsula bears 389 kg. So difference is 10 kg and here we have to remember again, that Alaskan peninsula bears in this group can be assumed to be older. So actually when we make this comparison in most fair possible way considering information what we can use, there is practically same average weights between these bears. We have to remember, that these bears gain weight a year by year also after age of 9 years even though skeleton is practically as big as it can be. It could be, that if there would have been 2 older Kodiaks, that their average weight had been bigger after all. 
My conclusion is, that with this information it is not possible to say which subspecies has bigger average weight. But when looking at all information, what I have seen I assume, that it is after all Kodiak bear most probably. I think like that because local officials even today say, that Kodiaks are biggest bears there and vast majority of known "monster sized" bears are Kodiaks. And there has to be reason why trophy hunters are so eager to get license to hunt especially at Kodiak islands.
I can be wrong, but with known facts about bears and looking at these charts I dare to say, that not all statistics, even when printed at books are necessary accurate. There was time, when Guinness book of records claimed, that great white shark can be 12 meters long... I have read that specific book myself. Today we know better.

Well actually, the chart you attached, which I posted here earlier isn't my source or back up. I fairly disagreed with it in the discussion with @"brotherbear". Due to it giving info starting from 6+(roughly 7 year old) individuals and the number "300kgs" average being unlikely for a full sized bear of summer and fall.

As for the weight of 389kgs claimed for Alaska peninsula brown bears is based on Just 5 post-prime specimens. 
And the other study I provided where they gave 700lbs average, they showed average of 357kgs(787lbs) for Alaska peninsula brown bears based on 21 specimens. Which is more reliable and meaningful than the previous chart claiming '389kgs' figure.
The same problem with the chart posted by brotherbear. It was just based on 5 prime specimens.
The number is too low to consider.

Anyways, I found the link for the study of the following chart...

*This image is copyright of its original author

Source: https://www.researchgate.net/publication/284678859_Brown_bear

However, this study doesn't mentioned the ages of bears in the study. But we can get it if we use logical thinking.

It gave some interesting points, and corrects our claims.

From the study...
"Size and Weight. Size varies greatly across the North American
range, among sex and age classes of bears, and seasonally. Body
masses from various populations are reviewed in the Interagency
Grizzly Bear compendium (LeFranc et al. 1987) and supplemented
with additional information (McLellan 1994). These records
illustrate variation in body mass among populations (Table 26.1).
Brown bears occupying coastal habitats of Alaska and British
Columbia are the largest representative of the species in North
America.
Bears from coastal Alaska with access to salmon are the
heaviest. For example, males from the Alaska Peninsula (Miller and
Sellers 1992) average 357 kg, whereas males from the Yukon
(Pearson 1975) average 145 kg. Females from the same areas
average 226 and 98 kg, respectively.
Popular literature often sensationalizes the “1000-pound bear.”
Although brown bears have been documented to reach and exceed
this weight (Craighead and Mitchell 1982), most are smaller. Mass in bears is related to diet (Hilderbrand et al. 1999a)."

So according to this study, it was considered that Alaska peninsula brown bears are the largest species of Brown bears. 

Also on other hand it seems the 9 year old Brown bear is reaching it's full size in summer according to this chart (from the same study). It loklo different for females. 

*This image is copyright of its original author

And the following quote gave different age for sexual maturity in male brown bears from Alaska...

"Male Reproductive Characteristics. White et al. (1998) provide an
excellent review of the reproductive characteristics of male grizzly
bears. Based upon presence or absence of spermatozoa in the lumen
of the seminiferous tubules, mean age of sexual maturity in a sample
20 grizzly bears from the continental Unites States was 5.5 years
(White et al. 1998). The youngest bear with fully-formed spermatozoa
was 3.5 years old and killed in July. Only 1 of 11 bears that were ≤4.5
years of age had spermatozoa, whereas 8 of 9 bears ≥5.5 years of age
did (White et al. 1998). Erickson et al. (1968) reported spermatozoa
in seminiferous tubules of brown bears in Alaska at 4.5 years of age,
whereas Pearson (1975) reported them in bears 5-7 years of age."

So according to this adult male brown bears from Alaska reach sexual maturity half year later than the grizzlies (inland population) of united states. 

And I already explained to @brotherbear, that the bears in this study are definitely older & larger than the bears of the another chart claiming 300kgs average which is starts from 6+ year old individuals. 

So, they're older than 6+ individuals means 7+(or 8) individuals. Although, i don't really think a 8 year old male Brown bear is not adult. 
The calculation is alright, both based on 10 specimens. Believe me.

So, I really don't think 9 year old male Kodiak bears aren't gonna surpass 800lbs mark on average. But of course individuals vary, especially in Alaskan Brown bears where they can pack more fat throughout their lives...

Quote:

"So, they're older than 6+ individuals means 7+(or 8) individuals. Although, i don't really think a 8 year old male Brown bear is not adult. 

The calculation is alright, both based on 10 specimens. Believe me.

So, I really don't think 9 year old male Kodiak bears aren't gonna surpass 800lbs mark on average. But of course individuals vary, especially in Alaskan Brown bears where they can pack more fat throughout their lives..."

My last posting here was exactly about this part of your message. I disagree with you and I explained why in my posting. I leave it up to others to consider which one is giving more reasonable opinion and explanation here. I have nothing to change to my posting at this point, I wrote about my observations and gave reasoning.

I know this other chart in your posting here and it has many problems too as it is explained in that chart itself and there is warning to be cautious in making comparisons based on that. Alone it should tell to anyone, that not making too big conclusions based on it. Still writers of that book write based on that, that bears on Alaskan peninsula are biggest :) I find it quite odd and it raises a lot of questions how credible that book is what comes to that claim, especially when there is other research giving so different results.

Then again you say: "Also on other hand it seems the 9 year old Brown bear is reaching it's full size in summer according to this chart ..." Difficult to understand, that what on earth you are trying to say with that.

9 year old bear as a bear in any age is light in spring and after breeding time if sexually mature and then heavy in late autumn. 9-10 years old brown bear can be considered as fully grown even though it can continue up to 11 years and if I remember right even to 14 years old sometimes. But it is quite common agreement, that bear aged 9-10 years old can be considered as fully grown, even though they gain more weight after that too. Reply