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

[peter]

ON THE SIZE OF AMUR TIGERS

Nice photographs, Amnon. They show that captive Amur tigers are both tall and long, in some cases well over 200 cm. in head and body length. The tiger in the third photograph could compare to the tiger that left these scratch marks:

*This image is copyright of its original author

Regional variation in captive Amur tigers (...)

I often noticed that Amur tigers in the Czech Republic and Slovakia are large. Apparently, these countries still have quite a few large Amur tigers. Friends who often visit Slovakia and the Czech republic told me they had seen a number of giants. 

When you see Amur tigers of that size all the time, it no doubt will have an effect. For you, it's clear that captive Amur tigers are the largest big cats by a margin. V. Mazak, who saw a lot of large Amur tigers in the Prague Zoo in the sixties and seventies of the last century, also thought that Amur tigers were the largest big cats.

Although I agree with Mazak's conclusions, captive Amur tigers show more individual variation than their wild relatives. In western Europe, I saw a few below par. One of the Amur tigresses I measured and weighed, although very healthy, compared to an average captive Sumatran tigress in nearly all respects. Pronounced variation is also seen in the skull department.

Population bottleneck

Based on what I read, I'd say that the effects of habitat destruction and overhunting, like in India, were already well visible in the period 1890-1910. By then, tigers had already largely disappeared in many regions. In the period 1910-1940, destruction was everywhere. 

V.K. Arseniev "... undertook twelve (...) major scientific expeditions in the Russian Far East between 1902 and 1930 and authored some sixty works on the geography and ethnography. Among these, 'Dersu the trapper' has earned a privileged place in Russian literature ... " (foreword of the English reprint of 'Dersu the Trapper', published in 1996).

Arseniev arrived in the Russian Far East in 1900, three years after the Trans-Siberian Railway had been completed. Between 1902 and 1907, he undertook three surveying expeditions described in 'Dersu the trapper'. Arseniev and Dersu, who met in 1906 and parted in 1908, both knew that the vast wilderness they saw would quickly disappear. According to Dersu: " ... All round soon all game end ... Me think ten years, no more wapiti, no more sable, no more squirrel, all gone ... " (Preface, pp. vii). That was in 1907-1908 (...). 

A few decades later, when there were less than 50 wild Amur tigers left, Kaplanov rang the bell. Some years later, the Sovjet authorities decided to protect Amur tigers.

Loss of size

In the period they walked the edge, Amur tigers might have produced a number of exceptional individuals. Although not one was confirmed by a biologist, there were quite a few reports about Amur tigers well exceeding 650 pounds in the period 1940-1970 (see 'Der Tiger', V. Mazak, 1983, and 'Die Säugetiere der Sowjet-Union', V.G. Heptner and A.A. Sludskij, German translation, 1980, Band III). Remarkable, as wild tigers facing pressure and a loss of numbers often quickly respond by losing size.  

In the sixties of the last century, when the situation had somewhat improved, it was decided to capture a limited number of cubs every year. Quite a few of these were sent to zoos in countries in eastern and central Europe, then occupied by the former Sovjet-Union. Some of them grew to a very large size. For some reason, zoos in the former Czecho-Slovakia in particular often had large Amur tigers.

Some years ago, I read an article in which reports about large Amur tigers were discussed. Apart from the 560-pound male shot near the Korean border in 1911 by Baikov, all of them were classified as 'unreliable'. The biologists involved also noticed a decline in size after 1970. Remarkable, as the situation in the Russian Far East had improved quite a bit in the sixties and seventies. 

Based on the information I had back then, I got to a similar conclusion on Amur tigers in zoos in western Europe in the late eighties of the last century. If the information on wild and captive Amur tigers is combined, coincidence seems unlikely. 

In the first decade of this century, a table with information on the size of wild Amur tigers was published. Although it, to a degree, was polluted by a number of young adults and 'problem tigers', the conclusion on the loss of size was confirmed. Not one of the males exceeded 200 kg. In the years that followed, more large males have been measured and weighed. Although some of them exceeded 200 kg., it wasn't by much.  

Questions        

Although some biologists expressed doubts about the alleged size of Amur tigers in the recent past, wild males shot and weighed before, say, 1940, averaged about 475 pounds. Today, according to Miquelle, males average 420-430 pounds. They also seem a bit shorter than before the population bottleneck. The first question is if the conclusions on size are right, as the samples are very small. 

The second question is why wild Amur tigers didn't lose size in the period they walked the edge but nearly half a century later, when the situation had improved and the number of wild tigers had increased.  

The third question is why facilities in the Czech Republic and Slovakia in particular seem to have more large Amur tigers than elsewhere.

As it isn't easy to answer the first two questions, I propose to start with the third question. Are captive Amur tigers in the Czech Republic and Slovakia as large as they seem? Are they larger than those in western Europe and the US? Based on what I know, I think they are. The most likely reason is they got Amur tigers in the period before they lost size. Another reason is they were not mixed.  

What's your opinion, Amnon? Reply