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

[peter]

ON THE SIZE OF CAPTIVE AMUR TIGERS - VI

VI.1 - Introduction

It may sound a bit strange, but it isn't easy to find information about the size of captive big cats. If you find something, chances are the information is unreliable. I'm not only referring to estimates (often indicated by rounded numbers), but also to selection. Not seldom, you'll find information about the largest individuals only. It's much more difficult to find information about average-sized or small tigers and tigresses.  

In contrast to what you would expect, zoos and big cat facilities contribute in this department (selection) as well. Nearly all big cats measured and weighed in zoos suffer from problems (neglect, old age or a disease) severely affecting their weight. 

In what way is a table about the size of captive big cats produced? 

One first has to find reliable information. The article has to be printed and additional information has to be added. You then need to develop a system to store the information. Months later, a table is produced. It's only then you realize important information is lacking. You also realize the goal to use adults only is very difficult to achieve. If you want a decent sample, you often have no other choice but the drop the standards to a degree. 

When you have a table meeting a few thresholds (referring to reliability, a decent sample, a good spread and overview), you'll notice it's necessary to include the additional information you collected. As you don't want to produce an unreadable table, decisions have to be taken. And then you realize the table has no averages, meaning more work is needed. How get to averages? Should every record be included? And what about individuals of which you have different weights? 

What I'm saying is it took me a long time to get to a result. With a 'result', I mean a table offering good information and overview at a glance. 

A few words about the sources wouldn't be out of place. Most of the information was found in books and articles. I also found quite a bit in local newspapers (referring to the USA in particular). Information 'Betty' found on a few (Korean and Japanese) blogs was included as well. The vital statistics of the Amur tigers and skulls I measured were added. I also used information I found in a number of posts in the thread 'Captive lion and tiger weights'. This means our members also contributed to the table. Last but not least, I used a few videos.  

VI.2 - About selection

VI.2a - Introduction

Selection has different faces. No matter what you do, it can't be avoided. This has to be accepted. Experience says those interested in a particular species tend to select information confirming their ideas. Most members of forums know all about it and try to keep their feet dry. A bit over the top, I think. There's nothing wrong with a bit of preference. Not seldom, it's the drive behind all kinds of quests. Furthermore, most of us learn to deal with the tendency to select the most impressive records over time. 

But most is not all. Some of those interested in big cats continue to develop in the department of preference. So much so, they, many years later, graduate with honour. When they reach that stage, preference developed into bias. This means they no longer control the urge to produce extra-large lions or tigers out of nowhere. Not seldom, they also invest a lot of time in dismissing records of exceptional representatives of the 'wrong' species. When they join a forum to enter 'debates' about big cats, problems are bound to erupt. Their outspoken opinions often prevent a productive exchange. Sooner or later, the climate is affected. Those posting good information usually are the first to go. When that happens, the owners of a forum have no choice but to intervene. 

The efforts of those driven by outspoken opinions, however, also have a positive effect in that members interested in good information become more aware of the consequences of preference. In the end, the result often is a wider scope and more balanced exchanges.    

VI.2b- About the tables in the next post 

The tables in the next post have information about both large and small individuals. Both tables, in fact, are well-stocked in the department of small tigers. In order to offer you a bit more about the way information was selected and used, I'll discuss a few tigers used for the tables. One of them is the smallest adult male Amur tiger I know of, whereas the other made headlines because of his large size. I'll also discuss an average-sized male.  
 
VI.2c - About 'Pavel'

Finding information about average-sized males, like I said in the introduction (VI.1), is far from easy. Information about the length and weight of captive Amur tigresses is even more rare. And then there is the department of small male Amur tigers. I'm referring to adult male Amur tigers not much, if at all, larger than a decent adult male Indochinese tiger.  

Tigers like 'Pavel'. He most probably was the smallest of the litter when he was born ('Pavel' means 'small' in Russian). I'm not sure, but think he was born in the Lincoln Park Zoo in Illinois. In October 2017, when he was about 9 years of age, 'Pavel', partly as a result of his interesting genes, was sent to the Smithsonian National Zoo in Washington. Two years later, tigress 'Nikita', from the Bronx Zoo in New York and also valuable, joined him. The attempt to introduce 'Pavel' to 'Nikita' didn't result in problems, but their meeting, as far as I know, also didn't result in offspring. 

When they met, 'Pavel', at age 11, was 341 pounds (154,68 kg), whereas 6-year old 'Nikita' was 297 pounds (134,72 kg). Did his size have an effect? I don't know, but it seems very unlikely. When a male and a female are introduced to each other in a zoo, you never know what will happen. Tigers decide at the very last moment. Not seldom, their choice surprises all involved. If they don't like each other, anything is possible. Females have been killed by males more than once.   

Anyhow. Less than 2 years later, 'Pavel' was moved to the Indianapolis Zoo. According to that zoo, 'Pavel' was 315 pounds (142,89 kg). This means he lost 26 pounds (11,8 kg) in about 2 years. Compared to the other male Amur tiger in the Indianapolis Zoo, 'Maxim', he lacked 35 pounds. This means 'Maxim' was a small male Amur as well (350 pounds). I can almost hear you say adult male Amur tigers of that weight surely are few and far between. The answer is negative. I found quite a few newspaper articles with precise information about adult male Amur tigers well shy of 400 pounds. 

For some reason, adult male Amur tigers in American zoos seem to have lost quite a bit of size after the turn of the century. This is not the case in females.    

VI.2d - About 'Igor' 
 
Most of you no doubt heard about tiger 'Igor' of the Odense Zoo (Denmark). He featured in quite a few newspaper articles and videos. Some of them were posted in the thread 'Captive lion and tiger weights'. Tiger 'Igor' wasn't exceptionally long or tall, but robust. Unfortunately, he was never measured and weighed in his best years. When he got older, he was troubled by problems affecting his health. 

In 2010, when he was treated for dental problems, he wasn't weighed. Some years later, just before his death, he was. In bad shape, 'Igor', then thin as a rail, still was " ... around 230 kilos ... " (quote from a PM of the Odense Zoo - see the List of References). As I was unable to find anything about his weight in his best years, 'Igor' entered the table at 230 kg. This although it's very likely he exceeded 600 pounds (272,2 kg) in his prime. In one article, they said he was 250 kg. In another, he was 300. We'll never know, but I do know large male Amur tigers like 'Igor' often exceed 600 pounds in their prime.  

Here's 'Igor' when he was treated for tooth problems. This photograph is from 2010, when he already had lost quite a bit of weight:

*This image is copyright of its original author

In his best years, he was a bulky male:

*This image is copyright of its original author

VI.2e - About 'Semyon'

In November 2014, in the thread 'Captive lion and tiger weights', our member 'Amnon242' posted a newspaper report about a male tiger in the zoo of Dvur Kralové (CZ). A few days later, I found another article about the same tiger. Both newspaper articles had a few photographs. 

In the first article, tiger 'Semyon' was " ... a 150-pound cat ... " (...). In the second, published a day later, he was 190 kg. Same for length. In the first article, he was 299 cm (HB 203 cm, tail 96 cm), whereas he was 325 cm in the second. A significant difference. And a problem, as I had to find the correct information. 

Using the photographs, I concluded the information in the first article most probably was correct. This, however, wasn't true for the weight. The weight in the second article was correct. The conclusion was 'Semyon' was 299 cm in total length measured 'between pegs'. In the second article, the length, most probably, was measured 'over curves'. His weight was 190 kg. A bit below expectation for a male of that size, but 'Semyon', at 17, was an old tiger and it's known captive male Amur tigers often lose a lot of weight when they get older. 

Here's 'Semyon':

*This image is copyright of its original author

VI.2f - About multiple weights, decisions, calculations and averages

Before I started on the averages, a lot of decisions had to be taken. Decisions depend on your goal. My aim is to produce a table reflecting the (range in) size of healthy captive male Amur tigers. I can hear you say that shouldn't be a problem. Select healthy adults and you have your answer. 

Wrong. There're so many problems I wouldn't know where to start. What is adult in captive Amur tigers? And what about large youngsters used for breeding purposes? Do I want to include tigers severely affected by disease, old age or abnormal conditions (referring to neglect and obesity)? Do I want to include exceptional individuals? What is exceptional? And what about tigers of which different weights are available? 

What I'm saying is selection, like I said at the start of this paragraph, is difficult to avoid. The question, therefore, is which criteria are used. The answer is it depends. There's no general rule that can be applied in the same way each time. In order to give you an idea, I'll to discuss a few tigers used for the tables.  

When you read the table, you'll notice some tigers have different weights. Tiger 'Amur' (no. 03 in the table), for example, was 192 and 255 kg. Both weights have a deep black colour. This means decisions were taken. In this case, I decided to use both weights. There were two reasons. In his prime, 'Amur' was estimated at 250-260 kg. I didn't decide for 250 or 260, but for 255 kg. Directly after death, he was 192 kg. The significant loss of weight was a result of a disease. A disease that killed him. As most captive Amur tigers perish as a result of a disease, I decided to use that weight as well. Using both weights (255 and 192), the result was 223,5 kg. This weight is far from correct (in his prime, 'Amur' was a long, tall and robust tiger), but it's the best I can do in the circumstances.  

His son 'Benjamin' (no. 05 in the table) also died as a result of a disease. Directly after death, he was 128 kg. In this case, I decided against using that weight. One reason is he perished in his prime. Another is he was badly affected by the disease that killed him. Although a bit smaller than his father, he no doubt doubt would have been well over 200 kg in 'normal' conditions. Using the weight of a tiger badly affected by a disease won't contribute to a realistic picture of healthy captive Amur tigers. That doesn't mean the weight will be erased. It will be recorded, because it shows a disease can have significant effects. This is important for zoos.  

Tiger no. 82 in the table is exceptional. The weight (442,4 kg) is reliable, but I don't know if he was very large or a very obese tiger. As he's over 100 kg (221 pounds) heavier than the second heaviest, I decided against using the weight. This, however, doesn't mean it was an imaginary tiger. He's very real. According to 'Betty', who has an extensive and reliable database, some male tigers in Chinese zoos well exceed 300 kg. At least 3 of them are over 400 kg (...).    

Tiger 'Rocky' (no. 69 in the table) seemed (referring to the video) to be an average-sized Amur tiger. At age 14, he was 216 kg. At age 18, he was 190 kg. I decided to use the average of both weights (203 kg) for the table.    

Tigress 'Nikita' (no. 31 in the table) ranged between 124,7-139,7 kg in her prime. The average (133,0 kg) was used for the table. Tigress 'Ai' (no. 37 in the table) was 159 kg in her prime. At age 18, she was 113,3 kg. The significant loss of weight not only was a result of her age: she suffered from many health problems. For this reason, I decided against using her weight at age 18.

VI.3 - Conclusions

This post is an introduction to the next. That one has the tables I referred to in this post. The aim of this post is to tell you a bit more about (finding and assessing) data and how to use them for, say, a table.  

The first thing you need to remember is you have to learn to learn to distinguish between estimates and accurate information. The second thing you need to remember is most information is a result of some kind of selection. You have to be aware of the effects. My advice is to use as many sources as possible. When the sample is large enough, chances are the effects of selection, to a degree, will even out. 

Information about the size of captive Amur tigers in Chinese facilities (referring to the dissertation, the study and the article discussed in the previous posts) is reliable, but the spread in all samples I saw is limited. This has an effect. Same for the conditions. The tigers in the Harbin Siberian Tiger Park and Hengdaohezi live in large groups. The decision to keep them in this way has disadvantages. One of them is diseases spread easily. According to our member 'Betty', tigers in Hengdaohezi and the Siberian Tiger Park in China suffered from diseases in the recent past. This resulted in relatively low averages. The problems were solved, but the new approach had unforeseen consequences (referring to photographs of obese tigers that made headlines not so long ago). I don't doubt this problem will be solved as well, as the Chinese are serious about (wild and captive) Amur tigers. 

All in all, I'd say captive Amur tigers, at the level of averages, really are the largest big cats in captivity. This, of course, is without the products of selective breeding (referring to white lions and tigers, all kinds of crosses and lions bred for hunters on quite a few 'farms' in South Africa). 

When going over the tables, one has to remember most captive Amur tigers are never measured and weighed. This includes exceptional individuals. Here's one of them to finish the post:

*This image is copyright of its original author

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