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

[peter]

CAPTIVE AND WILD AMUR TIGERS

Amnon posted in the thread about Amur and Assam tigers in the debate section. He said wild tigers in both regions could be about similar, but captive Amur tigers usually are larger than captive Indian tigers. I agree.

The question is why captive Amur tigers are larger than all other captive big cats. Another question is why wild Amur tigers do not reach that size. The last question is why wild tigers are larger than captive tigers in India. In this post, a few ideas.  


A - WHY WILD AMUR TIGERS ARE NOT AS LARGE AS THEIR CAPTIVE RELATIVES

Amur tigers face tougher conditions than tigers living in other regions. They have to walk in snow for six months of the year. Prey densities are lower and prey animals also are smaller. The cold is pronounced for long periods of time. Furthermore, they face more competition. Amur tigers have to compete with other tigers, humans (omnivores), wild pigs (omnivores) and bears (omnivores) and all have to work harder to get the food they need.  

In fights between tigers, size is important. In fights with wild boars and bears, it seems to be a bit different. Size of course helps, but my guess is a combination of strength, endurance, agility and coordination could be a crucial. 

A competitive wild tiger, weightwise, just can't afford to get to his potential because it would have a negative effect in the departments discussed. He needs a large body to stay warm, long legs to walk, large paws to move in the snow and athleticism to hunt and engage competitors of similar or larger size. The information I have suggests most male tigers have about 1 kg. per square cm. in length. Some, like 'Luke' (212 kg.) and 'Banzai' (207 kg.), are short and stocky, but the norm is long and not over 210-215 kg. in good periods and not below 160-170 kg. in bad times. I think 190 kg. would be a good average. About similar to Kruger lions.   

A captive male Amur tiger, on the other hand, isn't tested. There's no need for limitations of any sort. In captivity, he could get to his potential. I saw small adult males just over 150 kg. and a few close to double that weight. My guess would be around 220 kg. or thereabout for most. Perhaps a trifle below that. And captive tigers don't have to go through violent changes in weight.    


B - WHY WILD AMUR TIGERS COULD HAVE BEEN A BIT LARGER A CENTURY AGO

Manchuria probably didn't have a lot of large animals 150 years ago as well. That was in the days of hunters writing about exceptional animals. So if it wasn't prey animals, then what was the reason tigers were, possibly, a bit larger a century ago?

One reason is more tigers would have resulted in more competition. This would have resulted in a larger size, as large tigers win more fights and have more access to females.

There is another reason. More tigers also would have resulted in more kills and more kills would have attracted more bears. Male bears, black or brown, often are large animals of 200 kg. and well over. If a big cat is displaced by male bears on a regular basis, he needs to hunt more often to get the same amount of meat. This means loss of energy and, in some cases, starvation.

Some tigers faced with displacement on a regular basis would not be willing to engage a bear, whereas others would. Of those willing to engage a male bear, some will be killed and some will kill their opponent. Those able to win a fight would probably try it again. If they survive longer than those displaced, chances are they pass on their genes more often. Natural selection as a result of the ability to overcome competition of bears, that is.

Although size, in this respect, would be less important than character and athleticism, a tiger would need size to be able to get to the vital parts of a bear while wrestling. He also would need agility and strength. Weight, however, could impede movement and agility. All this, I think, would have resulted in selection for long and tall animals with muscular fore-arms and the means to overcome large muscles in the neck of the bear, meaning large canines.

Everything I have on the size of Manchurian tigers a century ago suggests they were very similar to today's Amur tigers. Most large males were tall, very long and muscular. The largest according to Jankowski could have been 250-260 kg. empty or just over. There could have been freak tigers, but not one report on these giants was substantiated. Not as heavy as one would expect, that is.

In the days of plenty, chances are there would have been more exceptional animals. They would have affected the average in a similar way as small tigers. My guess is the average was a bit higher, but not to the extent often discussed. In the conditions up north, weight would have been a problem as often as not. The average could have been close to the average of today's captive Amur tigers (220 kg.), but I think it was a bit below that. About similar to the average for Assam a century ago, I think (205-215 kg.).           
 

C - WHY WILD INDIAN TIGERS ARE LARGER THAN THEIR CAPTIVE COUNTERPARTS

The only country that has captive Indian tigers, as far as I know, is India. I have information on 35 captive males in Indian zoos. The range was 160-210 kg. and the average was about 405 pounds (183,70 kg.). There is not much on wild Indian tigers, but the lightest was 200 kg. exactly. This tiger, from Chitwan, probably wasn't adjusted, but the photographs I saw when he was captured suggest he wasn't even close to gorged. Maybe the captive animals were malnourished and maybe there were not. Maybe small wild males are way below 200 kg. and maybe they are not. For now, I propose to use the information we have and it says there's quite a difference between wild and captive animals in India. Why is that?

India has many reserves, but most are not interconnected and there's humans everywhere. Every young male who wants to disperse has to be very lucky to reach a new safe place. There probably are many tigers like 'Broken Tail', who was hit by an express train.

Most reserves are well-stocked, meaning tigers do not need to starve. In many reserves, for this reason, tigers are healthy and quite large. A healthy population will produce many cubs. The problem is adolescents and young adults have nowhere to go. The only solution is to find a place in the reserve where you was born. That won't be easy, as those with prosperous farms and cattle don't want you on their turf. The result is conflicts and that's what we see all too often. Infighting is one of the major causes of death in tigers in India. What we see in most parts in India, therefore, is prosperous cities, large individuals, overcrowding, many struggles for territory and many victims.

In captive big cats, size often determines the outcome of a fight. If we assume it wouldn't be different in wild big cats, the conclusion has to be most large males will probably outcompete smaller males. If this pattern continues for a long time, we would expect to see larger tigers in the end and we are not disappointed. 

Tigers, as solitary hunters, have to be adapters by nature. If a tiger can't adapt to the local conditions, he will perish. In captive tigers, this drive is not there. The result is less competitive animals who seem prone to degeneration. Amur tigers are the exception to this general rule, because they need length, endurance, character and athleticism in order to overcome difficult conditions and competition of large omnivores. Weight would be counterproductive. Captive Amur tigers, however, are not impeded and the result is they often get to their potential. The result is long and tall tigers often a bit too heavy.


D - OMNIVORES AS COMPETITORS

I posted some stories on fights between wild boars and tigers. Tigers win most fights, but they are far from invincible. I didn't post a lot on bears and tigers in Russia yet, but the info I have suggests it also is a close call in most cases. Tigers win most fights, but they struggle against large males. Brown bears win on points, most Russian authorities think. I think it could be a bit closer than that, but chances are large male bears often go unchallenged. They are just too big for an average male tiger. Could have been a bit different in the days of plenty, but exceptional tigers have not yet been captured today. Why that is, is anybody's guess.  

Below are a few pictures of bears. No wild boars, as they featured some posts ago. The first three are Amur brown bears. The last one is a Himalyan black bear. Male Amur brown bears average about 260-270 kg. Male Himalayan black bears are much smaller, but you never know with bears. Some males are as heavy and robust as a big male Amur tiger. Bears, to quote a poster from AVA, are no joke. I'm sure we all agree:

4.1 - This is what some hunters really saw themselves (first posted by Warsaw on AVA):

*This image is copyright of its original author

4.2 - Just taking a walk (WCS):

*This image is copyright of its original author

 

4.3 - A captive Amur brown bear from the San Diego Zoo, if I remember correctly. First posted by a member of AVA who opened his own store some years ago (Grahh):
    

*This image is copyright of its original author

4.4 - Male Himalayan black bear shot by one of the Jankowski's. This photograph has no angles and the bear is as large as they come:
 

*This image is copyright of its original author

Reply