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

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(11-27-2018, 11:05 PM)peter Wrote:

(11-24-2018, 04:24 PM)brotherbear Wrote: Peter says: And sorry about the length of the post. I know it has a lot of info posted before, but I felt it was needed to get to a kind of conclusion. In the next posts, I will focus on the size of Amur tigers a century ago and today. In between, the Sungari river tiger will be discussed one more time. This time, I'll add info from V. Jankowski himself.
 
Length of the post not a problem. We all know that you favor the tiger and me the brown bear. But what we have in common is the fact that we both want the truth; the accurate facts. Today, I learned more.  I had assumed that when a tiger ambushed a bear weighing upwards to 440 pounds, it was a miscalculation by the tiger. Evidently not so. Also, that a tiger can kill a bear of this size with a single well-placed bite. Interested in learning more. Not about winning -  about knowing. 
Oh, about noses, a bear is very aware of protecting his nose in any skirmish. Very sensitive. 

Point taken, my friend. Preference always is a factor to consider. The only way to oppose it is to focus on reliable and accurate information. This post is an attempt to get to a bit more accuracy on the observation of researchers regarding the size of the largest female brown bears killed by tigers in the Russian Far East.

1 - THE AVERAGE SIZE OF ADULT FEMALE BROWN BEARS IN THE RUSSIAN FAR EAST
 
Recent research says that experienced, often older (referring to Schleyer's observation - see my previous post), male Amur tigers hunt brown bears up to the size of an adult female. Anything known on the size of adult female brown bears in the Russian Far East?

This table (from a recently published document) was posted by Guate a week ago. It says that adult female brown bears today average 145 kg. (321 pounds):

*This image is copyright of its original author

 
2 - INDIVIDUAL VARIATION IN ADULT FEMALE BROWN BEARS IN THE RUSSIAN FAR EAST

A decade ago or so, I saw a table with weights of adult male and female brown bears in the Russian Far East. Adult male brown bears averaged 264 kg. (about 580 pounds), whereas adult female brown bears averaged 189 kg. (420 pounds). Compared to the table above, the main difference is the average of adult female brown bears. How explain?

The table above, regarding the average weight of brown bears, is based on recent research of biologists. Their info hasn't been published. The table in which adult female brown bears averaged 189 kg., however, could have been based on bears shot by trophy hunters. As trophy hunters tend to select the largest individuals, tables based on their records should be taken with some care. 

The Russian Far East has many thousands brown bears. If we add that individual variation is pronounced in large mammals like brown bears, one never quite knows what to make of averages. Based on what was published, however, I do not doubt that a large female brown bear can severely outweight an average adult male Amur tiger.

In AVA, a Chinese poster with access to good information (KTKC, if I remember correctly) said female brown bears well exceeding 700 pounds had been shot not so long ago in the northeastern part of China. I've also seen reliable reports about exceptional females shot in the Russian Far East. Poster WaveRiders recently said he has seen skulls of very large female brown bears.

3 - KERLEY 

In 2011, Linda Kerley was contacted by a poster called 'Junglesprout' from AVA about brown bears and tigers. She responded. Her answer, posted on September 12, 2011, was printed, but the quality of the print was well below par. For this reason, I decided for a few quotes:

" ... I have been studying tiger food habits for the past 14 years and have found several bears killed and eaten by tigers. Some tigers specialize in eating bears and they will (part of the sentence is missing) ... larger brown bears. We radio-tracked one male tiger who ate bears all summer and lost weight in the winter presumably because he couldn't find his favorite food ... " (post of poster 'Junglesprout' of September 12, 2011).

" ... Bears are an important food source for tigers in summer ... " (do.).

" ... I have seen tigers prey on all shapes and sizes of black bears and up to the largest and healthiest female brown bear ... " (do.).

" ... what we know is there are no rules - anything can happen between bears and tigers ... " (do.). 

4 - BAIKOV

In 1925, 'The Manchurian tiger' was published. About 75 years later, it was translated into English by Alex Shevlakov. I have the translation. It's an interesting document written by a man who hunted tigers himself. On foot, that is. 

In the days of Baikov, Amur tigers ranged between the central part of what's now South-Korea to the northwestern part of Manchuria. Back then, Amur tigers were larger and heavier than today. In Baikov's opinion, the Manchurian tiger " ... quite often ... " (The Manchurian tiger, pp. 4) weighed " ... 20 poods ... " (about 320 kg. or 706 pounds). The measurements of a full-grown male given on page 9 are exceptional.  In his opinion, " ... the muscular system of the body is extremely massive and perfectly developed ... " (do., pp. 9).

Although some of the weights Baikov mentioned in 'The Manchurian Tiger' were qualified as 'unreliable', others were accepted in an overview of old records published a decade ago. Based on records regarded as 'highly reliable', it was concluded that adult male Amur tigers could have averaged 210-220 kg. (460-481 pounds), whereas adult females averaged 137,5 kg. (303 pounds).

I'm not too sure about the outcome of the survey, as the tiger shot near the Sungari river in 1943 by a member of V. Jankowski's team was exceptionally robust as well. In his letter to V. Mazak in May 1970, V. Jankowski wrote the tiger was at least 300 kg. In his book 'Tiger, deer and ginseng', published in 1993, he said the tiger was 350 kg. (772 pounds). The photograph published by V. Mazak showed a very robust male tiger.

According to Baikov, Amur tigers had been pushed out of most of Korea and the southwestern part of Sichote-Alin. The home range of the Manchurian tiger was Guiring Province in northeastern China, where it was seen often in the

" ... extensive primeval woods of the upper Sungari, the Lalinkhe and Ashikhe, and also following river basins: the Mudan-jan, Muren and Sui-foung. Some points in this forested area which has a Chinese name Shu-Kai (the wood sea), have names which are relative to the tiger, for example, the Tiger Mountains, the Tiger lowlands, the Tiger ravines, and so on. Even now (1925), this area is covered with almost continuous virgin forest, although significantly thinned recently on the borders and on the KVZhD (Chinese Eastern Railroad), but 25 years ago it was actually a continuous green sea of impassable primeval Woods, where every animal lived at ease, and where the tiger alone reigned ... " (do., pp. 6).

As to tigers hunting bears:

" ... A rather big tiger would defeat a bear of almost the same weight. For this purpose, the predator tracks down the bear and makes an ambush, ordinarily on a rock or in windfallen trees, taking the side against the wind. Carelessy a bear slowly goes by an ambush, suspecting nothing, and the tiger rushes out on it from above, its one paw claws under the bear's chin, the other paw at the throat, and the tiger bites through the neck vertebrae ... " (do., pp. 14).

5 - THE WEIGHT OF ADOLESCENT MALE BROWN BEARS

Immature and adolescent male brown bears can be as heavy as an average adult female brown bear, if not considerably heavier: the table above says that 2-year old male brown bears average 169 kg. (374 pounds). Male brown bears of that age, in spite of their weight, are no match for an adult male Amur tiger. The reason is they are no experienced professional predators.

Any cases known of adolescent male bears killed by tigers?

Tiger 'Boris', also known as 'Putin's tiger, was raised in a rehabilitation facility. When he was released, he was collared. This means that researchers were able to follow him. When still immature, Boris fought and killed 2 brown bears. It wasn't possible to determine the gender of the bears, but both were adolescents ranging between 2-4 years of age.

In the article about interspecific relations between tigers and bears recently discussed in this thread, researchers said they found a male brown bear in his third or fourth year killed by a tiger. Assuming he was about average in size, it's likely that he was as heavy as his killer, if not heavier.

Bromlej mentioned a brown bear killed by an adult tigress near the Tatibe river in early May 1951. The bear was 158 cm. in length and estimated to have weighed about 170 kg. Although he didn't say anything about it, there have been many debates about the gender. V. Mazak (1983) also referred to the incident. He said the brown bear had been an adult male, but quite a few posters doubt his conclusion. 

6 - WEIGHT ESTIMATES BASED ON SIGHT: THE DIFFERENCE BETWEEN PROFESSIONALS AND AMATEURS

Researchers think that the heaviest adult female brown bears killed by male Amur tigers ranged between 150-200 kg. (330-441 pounds). As far as I know, the bears were not weighed and measured. The estimates were based on sight.

Warsaw said that estimates based on sight can result in significant exaggerations. I agree. But. 

In the days I quite often visited a big cat facility in the northern part of the Netherlands, I did a few experiments. Before I measured and weighed 4 captive big cats (1 adult male lion and 3 adult male Amur tigers), I asked a number of visitors to estimate the length and weight of the big cats they saw. The distance between the visitors and the cats, before they were drugged, was 2-4 m. (6-13 feet). Their estimates were recorded. To keep it short: not one of them even got close. The experiment was repeated more than once.

The conclusion is that people tend to overestimate cats with big skulls and underestimate big cats with stripes. By a margin, I have to add. Any difference between amateurs and those with experience? Yes. Significant? Yes. Amateurs are nearly always way off, whereas professionals usually are quite close. Within professionals, experience is important. Someone who has weighed big cats and bears very often is much closer than a pro without experience.    

Adult brown bears, males and females, have relatively large skulls, meaning it's likely that they could be overestimated. As we're talking about wild brown bears, it's very likely that the distance between the observers and the bears would have been significant. It's, however, also very likely that those involved had experience. This, I noticed in captive big cats and bears, is important.

CONCLUSIONS

1 - Adult female brown bears in the Russian Far East average 145 kg. (321 pounds).

2 - Individual variation in adult female brown bears in the Russian Far East is pronounced. Whereas some barely exceed 200 pound pounds, others exceed 700.

3 - According to Kerley, experienced male Amur tigers hunt brown bears up to the the size of the healthiest and largest female.

4 - According to Baikov, a " ... rather big tiger would defeat a bear of almost the same weight ... " ('The Manchurian Tiger', 1925, pp. 14).

5 - Adolescent male brown bears, ranging between 2-4 years of age, have been killed by tigers. Recent information says that two year old male brown bears, averaging 169 kg. (374 pounds), are significantly heavier than adult female brown bears.

6 - It's likely that weight estimates of big-skulled mammals (like brown bears) seen from a distance will result in significant exaggerations. There is, however, a significant difference between amateurs and professionals. Within professionals, there's a significant different between those with experience and those without.

7 - All in all, I'd say that it's more than likely that the estimates of experts regarding the weight of adult female brown bears killed by tigers (150-200 kg. or 330-441 pounds) could have been quite accurate. Furthermore, it's known that experienced tigers have killed brown bears ranging between 150-200 kg.

If someone some day would find statistics about bears so, that there would be explained, what is meant by adult in that statistic. It would be interesting to see statistics about bears so, that not too much open questions.

Then also would be interesting to see statistics about bears, which are full grown. That means bears 9-11 years old. Because bears grow size for so long time, there can be many opinions and points of views how to look at statistics. Maybe it would be pretty fair to talk about adult bears, when those are about 5-6 years old even though not full grown yet (?). But of course if talking about adult tigers only when those are old enough to be full sized (not weight), then of course same should be with bears. But does someone have that kind of statistic information is another question :) Reply