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

[peter]

ON THE SIZE OF CAPTIVE AMUR TIGERS - II

II.1 - Introduction

In this post, the dissertation for the degree of Master of S. Weilin, 'Study on growth and development of Amur tigers raising dispersedly' (Northeast Forestry University, 2005), will be briefly discussed. 

Before posting a few scans, I want to let you know our member 'Betty' (many thanks!) was the one who sent me the link to the dissertation and answered a number of questions.   

The dissertation is in Chinese. Only the title page, the abstract and table 3.27 were scanned. The reason is these pages were translated into English. It isn't always easy to understand everything. If you have questions, my advice is to contact 'Betty'.  

II.2 - Location, sample and methods used

The first thing you need to know is the study was conducted in the Hengdaohezi Feline Breeding Center (the Siberia Tiger Park and the Hengdaohezi Wildlife Farm) in the Heilongjiang Province in the northeastern part of China. This facility had about 400 Amur tigers in the summer of 2021. 

I selected one table for this post. This table (Table 3,27, 'Measurement of body size and weight of Siberian tiger') is based on measurements of 114 male tigers and 93 tigresses. All tigers ranged between 6-66 months of age.

According to 'Betty', the tigers were measured in a straight line ('between pegs'). I'm, however, not sure about the method used to measure the height at the shoulder. 

II.3 - Scans

II.3a - Title page

*This image is copyright of its original author

II.3b - Abstract

In total, 224 Amur tigers were measured. Of these, 207 were used for the table below (see II.3c). 

The tigers used for the study lived in the Hengdaohezi Wildlife Farm and the Siberia Tiger Park near Harbin. Although Weilin states there isn't much to choose between both populations, there is a marked difference between male tigers from Hengdaohezi and those from Harbin. Hengdaohezi male Amur tigers (HB 188,5 cm) were significantly shorter than those from Harbin (202,7 cm). The difference in weight (172,7 kg for Hengdaohezi as opposed to 192,1 kg for Harbin) also is remarkable. 

Recent photographs also suggest (referring to ground colour; stripe colour; number of stripes; stripe width; relatively size and shape of the head, and general appearance) both populations seem to be different from each other.   

In immature captive Amur tigers, there is a quite strong relationship between total length and weight. This relationship changes when they, to use the words of Weilin, enter 'puberty'. Females enter 'puberty' at about 30 months, whereas males do so at about 42 months of age. This finding is important, as it's known wild Amur tigers disperse between 18-24 months of age (closer to 18). This means young Amur tigers disperse well before they reach 'puberty'. 

According to 'Betty', the relatively low weight of male Amur tigers living in both facilities could have been a result of a number of problems. Back then (referring to the period 1990-2005), diseases were quite common in both facilities.    
 

*This image is copyright of its original author

II.3c - Table 3.27 

The table says captive Amur tigresses reach their greatest size (referring to HB and weight) at 30 months of age (just before they enter 'puberty'). Captive male Amur tigers reach their greatest size (referring to chest circumference and weight) at 42 months of age. 

In the period they change into adults (between 30-66 months for females and 42-66 months for males), both males and females lose quite a bit of weight. After reaching adulthood (66 months of age), females, although a bit shorter than in the period just before they entered 'puberty', regain the weight lost. This is not the case in males. Adult male Amur tigers are not as large (referring to total length, chest circumference, weight and standing height at the shoulder) as males entering 'puberty' at 42 months of age.   

If the averages in the table are confirmed in other studies, it means captive Amur tigresses need more time to develop into adults than males. Adult Amur tigresses average about 136-137 kg (301 pounds) and 270-271 cm in total length measured in a straight line. Adult males average 187-188 kg (413 pounds) and 309-310 cm in total length measured in a straight line. 

*This image is copyright of its original author

 
II.4 - Conclusions 

I've measured about 20 captive big cats, seen a lot more and have information about the size of captive Amur tigers I consider very reliable. What I saw and read strongly suggests captive Amur tigers, at the level of averages, are the largest (referring to weight, standing height at the shoulder and total length measured 'between pegs') big cats in captivity. This to say I wasn't surprised to find adult females in Hengdaohezi and Harbin to average about 300 pounds and 8.10-8.11 in total length measured 'between pegs'. Same for the total length (10.2) of adult male Amur tigers.  

I was, however, surprised at the average chest circumference (adult Amur tigresses average 122,9 cm and adult males average 142,7 cm). Not one of the big cats I measured, although some exceeded 442 pounds in weight, reached 135 cm. The Amur tigers in the two Chinese facilities are quite robust in this respect. As it's not a result of a large weight (adult females averaged 301 pounds and males 413 pounds), the conclusion is the large chests are a result of constitution. This conclusion later was confirmed in another study conducted in a Chinese facility.  

All in all, I'd say captive Amur tigers in Hengdaohezi and Harbin were (referring to the situation before 2005) quite long and, referring to chest circumference, quite robust. Although the average weights do not seem to confirm this conclusion, it has to be remembered weight often is a result of conditions. If diseases, as 'Betty' said, were indeed quite common in Chinese facilities in those days, it's quite likely it would have shown in the (average) weight of adult tigers.   

II.5 - Photographs 

It seems fitting to conclude the post with a few photographs (from Xinhua). The first photograph was made in July 2021, wehereas the second one was taken in July 2020.

*This image is copyright of its original author

*This image is copyright of its original author

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