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

[peter]

1 - THE RELATION BETWEEN CHEST CIRCUMFERENCE AND WEIGHT IN NORTH-INDIAN TIGERS

a - North-east India

We know male tigers in the Duars, Cooch Behar and Assam, well over a century ago, averaged 129-130 cm. in chest circumference and 460,68 pounds (208,96 kg.). Empty males averaged 452,61 pounds (205,30 kg.) and gorged males of similar length averaged 512,56 pounds (232,50 kg.).

b - North-west India

We also know tigers shot in north-west India in roughly the same period averaged 435 pounds (197,32 kg.). Hewett's sample, however, was smallish and included at least two young adult males. Furthermore, most tigers shot were not weighed. Hewett described 12 of them as 'heavy' or 'very heavy'. As there, again, was a strong correlation between total length and weight, I decided to use those that were not measured to get to a new average. I got to 475 pounds. Many years later, this average was confirmed by Sunquist, who got to 221 kg. (488 pounds) for 7 males in Chitwan (Nepal). Nepal tigers are a bit longer, and therefore heavier, than those in north-west India, so 475 pounds could prove to be just about right for north-west India.

c - Conclusion

About a century ago, male tigers in northern India and Nepal, at 460-475 pounds or even a bit more than that, probably were the heaviest big wild cats. A the weights mentioned, they averaged 129-130 cm. in chest circumference in the north-eastern part of India.    

2 - ZIMBABWE LIONS AND COOCH BEHAR TIGERS COMPARED

Below is the famous table of Smuts (sorry about the bad quality, but I couldn't find a better version). I propose to compare the heaviest local type (Zimbabwe) with Cooch behar tigers. Zimbabwe males, at 125,9 cm. in chest circumference, averaged 193,3 kg., whereas Cooch Behar male tigers, at 129,5 cm. in chest circumference, averaged 208,96 kg. I know Cooch Behar tigers included 7 gorged individuals, but there's nothing known on the Zimbabwe lions in this respect. As I don't know, I assume both averages can be compared.

What do we see? Cooch Behar tigers have 2,86 % larger chests. This difference results in a significant weight difference (8,12 %). When we would construct a figure, the line would show a steep angle upwards. Is this typical? Not quite. Over a certain limit, however, a difference of 1 cm. results in a more than proportial increase in weight.     

Is the difference in chest circumference in both big cats a result of a difference in total length?

According to those who measured lions 'between pegs', South Africa has the longest lions. Stevenson-Hamilton wrote they averaged just under 9 feet in total length straight, but others, including himself (...), thought the average could be just over 9 feet. Let's say they are right. I propose to use 9.1 (276,86 cm.) for adult males.

Now let's move to tigers in north-east India. According to the Maharajah of Cooch Behar, 89 males averaged 294,41 cm. 'over curves'. He also measured about 10 males both 'over curves' and 'between pegs'. The difference between both methods was 5,45 inches (13,84 cm.). If we deduct this from 294,41, the result is 280,57 cm. in a straight line. Compared to lions in South Africa, the difference, therefore, is 3,71 cm. or 1,34%. The copnclusion is the difference between both is close to zilch.

This means the difference found, most probably, was not a result of longer and 'chestier' tigers. They were a trifle longer and somewhat bigger, but that, I think, couldn't have been the major reason for the difference in weight. The best explanation is that Cooch Behar tigers, at about similar size (roughly), were a bit more robust.    

Here's the Smuts-table:         

*This image is copyright of its original author

 


3- BROWN BEARS

This is the often used appendix on the correlation between chest circumference and weight in McCloud Lake brown bears. It is, or rather will prove to be, quite similar to the figure on big cats. The line shows a steep angle after, say, 200 kg. and 130 cm. in chest circumference.

More impressive than Cooch Behar tigers? No. Very similar. The difference is in exceptional animals in that brown bears produce more of them:

*This image is copyright of its original author

 

I now propose to move to Siberian male brown bears. The table below suggests they, chestcircumferencewise, are superior to their McCloud relatives. A circumference of 160 cm. isn't exceptional. A weight of 250 kg. and over, however, is:  

*This image is copyright of its original author

Why the difference in weight? I don't know, but I could think of two good reasons. One is no dumps in Siberia and two is tougher conditions. This would result in a longer animal (size is necessary to retain heat) using more energy to find less productive food. The large chest could be a result of more need for oxygen, but that seems unlikely as Amur tigers, although longer than all other big cats and also active in nordic long distance walking, have slightly narrower chests than Indian tigers, not known for long walks.
 
4 - BROWN BEARS AND BIG CATS COMPARED

Zimbabwe male lions average 125,9 cm. in chest circumference for 193,3 kg., whereas Cooch Behar and Assam male tigers average 129,5 cm. for 208,96 kg. I don't know about the McCloud male brown bears, but those in northeast Siberia average 144,05 cm. in chest circumference (n=20) for 231,1 kg. (n=10). If we remove the 600 kg. giant (he was estimated), we get to 141,68 cm. for just over 190 kg. (n=19).

The conclusion has to be that both tigers and lions produce more kg. per cm. chest circumference compared to brown bears of northeast Siberia, meaning both are more robust. Another myth gone, perhaps? Not quite. In order to find out more, we need to know more on body length.

This is impossible with Zimbabwe lions (no details known), but we know Cooch Behar and Assam male tigers averaged 203,01 cm. 'over curves' (n=54) in head and body length, whereas male Siberian brown bears averaged 195,61 cm. 'over contours' (n=23) with the estimated 600-kg. giant and 192,32 cm. without him (n=22).

What is 203,01 cm. 'over curves' when measured 'between pegs'? The answer is 203,01 - 13,84 cm = 189,17 cm. How about the bears? This is a table that could shed some light on the matter. It's about the difference between 'length' and 'contour length':

*This image is copyright of its original author

    
The difference between 'length' and 'contour length' in a male brown bear of 5 years and over of 196 cm. is no less than 32,2 cm. The Siberian male brown bears, averaging 195,61 cm. 'over contours' with the 600-kg. giant and 192,32 cm. without him, therefore, had to be 160-164 cm. 'between pegs'. I propose to use 162 cm. for head and body.

Now we have 189,17 cm., in head and body length straight, 129,5 cm. for chest circumference and 208,96 kg. for Cooch Behar and Assam tigers on one hand and 162,00 cm. for head and body length straight, 141,68 cm. for chest circumference and 190,11 kg. for northeast Siberian brown bears (without the 600-kg. giant). This means Cooch Behar tigers have an advantage of 16,77% in head and body length, a weight advantage of 9,91% and a deficit of 9,41% in the chest department. This means the correlation between chest circumference and weight in Cooch Behar tigers and northeast Siberian brown bears is different. In absolutes, the bears should pose no problem, but in relatives the situation is quite different. I'll leave that one to Tigerluver.

5 - TIGERS AND BEARS IN THE ARENA

The outcome of all calculations above clearly show why it is so difficult to say anything sensible on the outcome of confrontations between male tigers and male brown bears in eastern Russia. Bears are relatively more robust, even when they are smaller, but the difference in absolutes clearly is in favour of the tiger. The case would be clearcut in northeast Siberia, but bears also show much more individual variation than tigers.

Every male Amur reading this post and changing his mind about hunting male brown bears would start a risky business. I mean, he could meet a miniture male or his brother, who qualified for the national wrestling team. You just never know. 

Also remember Ursus arctos lasiotus is a much heavier animal than his relative in northeast Siberia. Although similar in total length (also 196 cm. 'over contours') and chest (just over 140 cm.), they average 270 kg., as opposed to 190,11 kg. for northeast Siberia (...). This time, the difference isn't a result of more dumps and easy food.    
  
Male Amur tigers are longer than most male brown bears in eastern Russia and will tower over their opponent in a fight, which is a distinct advantage. They seem to be as strong, more agile, faster and better armed (canines), but one has to remember that engaging a shorter animal with a 42% weight advantage, no neck and a terrible temper will most often result in a drawn-out fight, exhaustion and, for this reason, many breaks in most cases. I think an average male Amur tiger can severely damage an average male brown bear and keep him at bay, but if a bear is able to prevent significant damage, the male tiger, I think, has no option but to call it a day in the end and leave. This is why I am surprised that male tigers are not more often displaced. I have no clue as to why that is. It could be they are not willing to risk life and limb and it could be they know they are vulnarable as a result of violent weight fluctuations as a result of hibernation.   

At any rate. There is, like the Russians authorities in this matter said, a point where the balance shifts. Most thought it was close to 200 kg., but chances are it will depend on the size of the tiger. No male tiger in his right state of mind would start a fight with a dangerous animal of similar size and weight unless he has no option. For now, I think the limit would range somewhere between 175-225 kg., but the bear killed by a tigress in May 1951 near the Tatibe River (Bromlej) suggests tigers could be able to kill a heavier bear in circumstances that suit them. 

6 - THE TATIBE RIVER BROWN BEAR

Below is a photograph of a brown bear killed and partly eaten by a tigress in May 1951. Heptner and Sludskij (1980) published a drawing, but V. Mazak (1983) published the photograph he got from Abramov. Mazak wrote it was an adult bear, but there were no details on gender and age in Bromlej's book (the source). The only thing Bromlej wrote was the bear, at about 170 kg., taped 158 cm.   

Way too short to be an adult, Warsaw tried during the debate we had on AVA, but this argument was invalid as we know (see above) that adult male Ussuri bears average only 160-165 cm. in head and body length (in a straight line). Maybe the bear was measured in a straight line (Bromlej was a biologist and they usually measure animals in a straight line) and maybe the bear, as Warsaw argued, was measured by hunters, who measure bears 'over contours'. One of the question I had was how the bear was measured in the first place. The photograph clearly shows that the fattiest part (around the loins and the lower back) were eaten. This would have to result in a lot of improvisation when measuring the bear, one would think.  

At about 170 kg. in early May, chances are the bear was well over 200 kg. before hibernation, as it is known brown bears can lose 20-30% of their weight during hibernation. For this reason, I initially concluded the bear probably was a subadult or a young adult male (3-5 years of age or thereabout), but it's also possible the bear was a large female. Adult females average 145 kg., but some are well over 200 kg. (up to 280 kg., according to Kucerenko).

The debate was never quite concluded, but maybe that was too much of an ask. Everyone interested should try to get to his own conclusions:  
            

*This image is copyright of its original author

  
Even if it was a male, it wouldn't account for much. The difference between a young adult and a mature male in brown bears often is significant. Big old males, even after death, will not be touched by younger and smaller animals. Reply