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

[peter]

(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 average of adult males is a bit lower, whereas female brown bears are almost 100 pounds heavier. How explain? 

The table above, regarding the average weight of brown bears, is based on recent research of biologists, whereas the other table 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. Her answer, posted on September 12, 2011, was printed. Unfortunately, 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 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.  

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', 1925, pp. 4), males " ... quite often ... " got to " ... 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 most of the weights he mentioned were qualified as 'unreliable', some were accepted in an evaluation 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) about a century ago. The 'historical' average of adult females was 137,5 kg. (303 pounds).

I'm not too sure about the outcome of the evaluation. Apart from the 560-pound male shot by Baikov near the Korean border in 1911, all records of tigers exceeding 550 pounds were classified as 'unreliable'. This although experienced hunters like Baikov and Jankowski agreed that large individuals well exceeded 600 pounds in their day. Tigers exceeding that mark have also been shot in the 20th century.

In 1943, a very large tiger was shot by a member of V. Jankowski's team near the Sungari river. 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, V. Jankowski said the tiger was 350 kg. (772 pounds). In spite of the photograph published by V. Mazak, those evaluating old records ignored the report.

The photograph, by the way, showed a robust and large-skulled tiger that could have compared to the Duisburg zoo tiger. The Duisburg zoo tiger was 320 cm. in total length in a straight line (head length 50 cm.) and estimated at 280-300 kg. in his prime. V. Jankowski said the tiger shot in 1943 was the largest he saw by a margin. About as large as they get, he thought.       

Baikov wrote that 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 often seen 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 - IMMATURE MALE BROWN BEARS

According to the table above, two-year old male brown bears average 169 kg. (374 pounds). Significantly heavier than an average adult female brown bear, that is. In spite of their weight, male brown bears of that age are no match for an adult male Amur tiger. The reason is that tigers are experienced hunters, whereas brown bears of that age are not.

Any cases known of immature male bears killed by tigers?

Tiger 'Boris', also known as 'Putin's tiger', was partly raised in a rehabilitation facility. When he was released, researchers were able to follow him. At a relatively young age, Boris killed 2 brown bears. It wasn't possible to determine the gender of the bears, but researchers concluded that both were immature (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. The bear had been killed by a tiger. Assuming that the bear was about average in size, it's likely he was about as heavy as his killer, if not heavier.

In early May 1951, a brown bear was killed and partly eaten by an adult tigress (Bromlej, 1965). V. Mazak ('Der Tiger', 1983) said the bear had been an adult male, but the length (158 cm.) and weight of the bear (approximately 170 kg. or 375 pounds) point towards an immature male or an adult female. 

Here's a photograph of the bear killed in May 1951 ('Der Tiger', V. Mazak, 1983, pp. 91):

*This image is copyright of its original author

 

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, not one of the bears was measured and weighed. The estimates were based on sight, that is.

Warsaw said that estimates based on sight can result in significant exaggerations. I agree, but not to the degree he suggested.  

In the days I often visited a big cat facility in the northern part of the Netherlands, I did a few experiments. In one of them, I asked a number of visitors to estimate the length and weight of 4 adult captive big cats (1 adult male lion and 3 adult male Amur tigers). The distance between the visitors and the cats, before they were drugged, was 2-4 m. (7-13 feet roughly). Their estimates were recorded and the experiment was repeated more than once. To keep it short: not one of them got close. 

Most visitors overestimated cats with (relatively) big skulls and underestimated big cats with (relatively) smaller skulls (and stripes). 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. A keeper or vet who has weighed big cats very often is quite a bit closer than a pro without experience.    

Adult brown bears have relatively large skulls, meaning it's likely that they could be overestimated. It's, however, also likely that the rangers and biologists who saw them had some experience.  

CONCLUSIONS

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

2 - Individual variation in adult female brown bears is pronounced. Whereas some barely exceed 200 pounds, others well 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. Two-year old male brown bears, averaging 169 kg. (374 pounds), are significantly heavier than adult female brown bears.

6 - Amateurs often overestimate the weight of captive big-skulled mammals like brown bears. Professionals, however, often are quite close. Within this group, there's a significant different between those who have measured and weighed animals and those who have not. 

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. Reply