ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris)

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(12-13-2018, 10:49 PM)peter Wrote: KUCHERENKO

I saw the famous Kucherenko-table in an article written for hunters. American trophy hunters, to be precise. Based on what I read, I'd say it was written to encourage them to visit the Russian Far East. 

Hunters like size. The bigger, the better. For this reason, Kucherenko could have selected large individuals only. Recent research says adult males, like he said, really average 590-600 pounds in the Russian Far East, but the range most probably isn't as limited as in Kucherenko's table (260-320 kg. or 565-722 pounds).

The table below, first posted by Warsaw in AVA, about the size of brown bears in the northeastern part of Russia could be more accurate. The sample is larger and the range is much more outspoken:

*This image is copyright of its original author

 

I know the bears in the table do not quite belong to Ursus arctos lasiotus, but it has adult males only and in size they more or less compare to their relatives in the Russian Far East. Individual variation, as you can see, is very pronounced. Whereas some of them, at least weightwise, are within the predatory reach of male Amur tigers, the great majority is not. A few are very large. 

A good table should have distinctions between age classes, especially in large and long-lived mammals like brown bears. The table Guate today posted about averages in Kodiak brown bears clearly shows the outspoken differences between age classes.

There are different ways to get to age classes. In the thread about male tigers and male brown bears in old AVA, I posted about a paper written by B.P. Zavatsky (1976). He studied skulls and teeth to get to age-based distinctions in brown bears: 

https://www.bearbiology.org/wp-content/uploads/2017/10/Zavatsky_Vol_3.pdf

There's much more where this came from (the internet), including recent articles about skulls of brown bears in Bulgaria and Iran. 

Based on everything I read, I'd say that one has to distinguish between young adults (5-8), adults (9-12), mature adults (13-18) and old adults (> 18) in large brown bear subspecies like Kodiak bears. At the level of averages, the difference between the age groups is considerable. Like tigers, brown bears seem to keep on growing nearly all their life. Skulls of old bears nearly always are larger and heavier than those of younger individuals. 

Male Amur tigers involved in brown bears occasionally attack adolescent males, but I never read anything about tigers preying on young adult males, let alone adults and older males. This although young adult males are not much bigger than mature females. 

According to Kerley, male Amur tigers hunt female brown bears " ... up to the largest and healthiest (individuals) ... " (from her mail to Junglesprout in September 2011). Her observation was confirmed by others. The question is why they do not hunt young adult male brown bears similar in size and weight (150-200 kg. or 330-441 pounds). My guess is it could be a result of a combination of strength and disposition. In the Russian Far East, brown bears are known for their disposition. Pikunov said they're more dangerous than Amur tigers.     

As to posts about bears in this thread. I don't mind good info about bears, provided it's related to the Russian Far East. The reason is Amur tigers, brown bears and Himalayan black bears live in close proximity in southeastern Russia. Info about the way they interact is of interest, that is.

There was this part of your posting which was in a way especially interesting for me: 

"According to Kerley, male Amur tigers hunt female brown bears " ... up to the largest and healthiest (individuals) ... " (from her mail to Junglesprout in September 2011). Her observation was confirmed by others. The question is why they do not hunt young adult male brown bears similar in size and weight (150-200 kg. or 330-441 pounds). My guess is it could be a result of a combination of strength and disposition. In the Russian Far East, brown bears are known for their disposition. Pikunov said they're more dangerous than Amur tigers."

Of course male bears can be aggressive in certain situations even though usually bears are towards humans pretty harmless.

Anyway it is interesting if/when bears in Russian far east are known for their disposition. Does this concern all brown bears there or is this the matter among Ussuri brown bears living at same areas as tigers. Just thinking, that have Ussuri brown bears evolved to be more aggressive because have to deal with tigers. It sounds sensible, because that could be a way to minimize a risk for a fight with tiger. Of course if that concerns all brown bears from Ussuri area to Kamchatka peninsula, then looks to be some other reason, maybe they are just all "mental" :)

It just is interesting to know if there are differences between brown bears living in "tiger areas" and other brown bears. Olga.boshoi also had interesting posting about brown bears and tigers recently in Bear and Big Cat interactions in the wild thread.. 

So now what I am thinking is, that is there partial expelling of bears at areas where tigers are. And this issue about male bear disposition at same area, could these things connect in some way and be pieces of puzzle giving more information about interactions between Ussuri brown bears and Amur tigers. Females and cubs going to outer regions of areas with higher tiger density and then leaving there less bears, but then again are those bears inside tiger areas then mostly more fierce male bears with attitude (alongside big size) keeping them safe from tiger attacks?

One thing about bears which should be also remembered when thinking their movements. During breeding time male brown bears are very aggressive (from May to July, mostly on June). At that time female bears with cubs try usually to avoid them and leave areas where male bears. Reason is, that male brown bears can kill cubs in hope to make female bear again in heat. If male bear manages to kill cubs of a female bear, that female bear is soon ready to breed. Otherwise females aren´t eager to do that until former cubs are independent. So at that time of year there is movement among bears. Especially at June tigers are not only problem for female bears and cubs. There is even research indicating, that female bears with cubs move closer to human habitats during breeding time and avoiding in that way male bears which even at that time avoid humans. Quite interesting when thinking how animals can adapt their behavior. Reply