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peter · 05-19-2016, 09:06 AM

TIGERLUVER

Many thanks for the effort on the Duisburg Zoo male Amur tiger. I was there about half a year ago and asked a few questions about this tiger. As he was in his prime before the keepers were born, I got no answers. In some time, however, I will contact the director. He should be able to find out a bit more. I'm in particular interested in the skull.

Calculations based on the correlation between (total) length and weight and chest girth and weight in tigers always are a tricky affair. One needs to have a large and reliable database and it also is important to distinguish between wild and captive animals. Based on what I saw in skulls, I would definitely add age as a factor. Although some immature Indian and Amur male tigers can reach a great size, there's no question that older animals are larger as a general rule. They also seem to be more dense in all departments.

As it is likely you will get more orders in the near future, I decided to post a bit more on Indian and Amur tigers. Hope you can use it.

a - V. Mazak on Amur tigers

V. Mazak, who had contacts everywhere, thought the Duisburg male could have been the largest captive Amur tiger of his day. We better take his word for it. After he understood, and, in the third edition of his book, acknowledged he had been taken for a ride by Baikov and a few others on the size of Amur tigers, Mazak developed a mild obsession with size. We're very happy he did, as it resulted in a lot of information on the size of captive Amur tigers. Mazak also measured over 400 (lion and tiger) skulls in different museums. In the end, he was as informed as anyone.

His focus was on the maximum size of big cats. Although some lions and Indian tigers also reached a great size, Mazak concluded wild Amur tigers were the largest wild big cats of his day. We have to add that he based his conclusion on information provided by Russian experts (Mazak spoke Russian and also was in Russia). Most of the weights mentioned in the third edition of his book ('Der Tiger', V. Mazak, 1983, pp. 189), however, were considered 'unreliable' or 'moderately reliable' by experts in 2005. It also is a fact he mixed weights of both captive and wild Amur tigers.

His information on the size of captive Amur tigers, however, is reliable. We know 8 males ranged between 96-110 cm. at the tip of the shoulder while standing (females ranged between 82-88 cm.) and we also know 3 males ranged between 298-320 cm. in total length measured 'between pegs'. Male tiger 'Amur', who died in the Prague Zoo at age 11,5, was 220 cm. in head and body (tail 99 cm.) and was estimated at 250-260 kg. in his prime. His son 'Benjamin' died at age 7. He was 201 cm. in head and body and had a tail of 97 cm. (head length 42 cm. and hindfoot 38 cm.). The Duisburg Zoo tiger was 210 cm. in head and body (tail 110 cm.) and stood 110 cm. at the shoulder standing (head length 50 cm.). He was estimated at 280-300 kg.

Mazak concluded the largest captive Amur tigers ranged between 260-300 kg. and 300-320 cm. in total length measured 'between pegs' or even a bit more. In his opinion wild males could surpass these limits, but he admitted (pp. 189) there was no solid proof.

One could question Mazak or not. There's no question he was preferenced to a degree, but he based his opinion on good information he collected himself. I initially had a few doubts on his conclusions, but it is a fact they were largely confirmed.

b - Maximum size

Baikov and others reported on very large and heavy Amur tigers shot a century ago. Although most records on these large animals were dismissed in 2005 (Slaught et al), a few were accepted. The extra-large animals he and some others shot were remnants of a population that was nearly completely wiped out. Experienced hunters often target the largest individuals. The result is the population will be affected, especially when the total number of animals was quite limited to start with. It is, therefore, not remarkable that those left in the first decades of the last century were not exceptional. This is important to remember, as today's Amur tigers descend from a very limited gene poole. If we add low numbers, habitat destruction, prey depletion and poaching, we're close to an orbituary on size. This is what is seen elsewhere and eastern Russia most probably is no exception. Tigers respond to pressure by declining in size: small animals are more elusive and can live on smaller prey animals.

Case closed regarding size? If we use the information collected in the last 2 decades, the answer is yes. The question is if the captured animals represent the population. This question can't be answered, because there is not much known about wild Amur tigers. Is there another way to get to an answer? Not a few experts, including Yudakov and Krechmar, said they saw large individuals. Yudakov saw a male tiger similar in size to the Duisburg Zoo tiger and Krechmar saw prints of very large individuals. If the population grows, chances are Amur tigers will once again adapt to the situation they face. The reason isn't large prey animals and climate, but competition. More tigers will result in more competition and then there is bears. Male brown bears (Ursus arctos lasiotus) average 580-600 pounds and compete with tigers.

Some years ago, on AVA, a poster called 'Eagle Raptor' had created a thread on captive tigers. Although his experience related to UK-based Amur tigers, he also had good information about Amur tigers elsewhere. Most captive males (about 60%, he thought) were 480-500 pounds (217-227 kg.). Miquelle told him wild males averaged about 430 pounds (195 kg.). The difference (about 60 pounds or 27 kg.) could be the average difference between captive and wild male Amur tigers. The difference between the largest individuals, however, could be less. If what I have is indicative, the heaviest and most robust animals could be wild tigers.

So what is the maximum size of Amur tigers? The largest wild captive females range between 145-167 kg., whereas the largest max out at 170-180 kg., possibly even 204 kg. The heaviest wild female, however, was shorter than average. The heaviest wild male could have been the Sungari river tiger shot in 1943, who was estimated at about 300 kg. Sysoev, Filipek, Sludskij and Stroganov reported on males ranging between 340-384 kg., but they were not there when these tigers were weighed and measured.

c - The Duisburg Zoo male Amur tiger

In your post on the Duisburg Zoo tiger (of which PC posted a part in this thread), you compared him to 7 wild male Amur tigers captured in the last 2 decades. These males averaged 184 kg. and 196 cm. in head and body. Based on this assumption, you concluded the Duisburg Zoo tiger could have been 224 kg. You also compared him to the Sauraha male, who exceeded 600 pounds the last time he was weighed. This tiger was 197 cm. in head and body. Based on his essentials, you concluded the Duisburg Zoo tiger might have ranged between 280-320 kg. Let's say the average of different attempts worked out at 260-270 kg. (range 224-320 kg.). Finally, you added Indian tigers seem a bit more robust than Amur tigers. Here's a few things I saw:

- Length

Warsaw (in Carnivora) did a bit of reading and concluded wild Amur tigers are measured 'over curves'. WaveRiders contacted Miquelle and he confirmed Amur tigers are measured 'over curves'. This means the 7 male Amur tigers were measured 'over curves'. The Duisburg Zoo male tiger was 210 cm. in head and body, but he was measured 'between pegs'. This means he, at his size, would have been at least 225 cm. 'over curves' in head and body (as opposed to 196 cm. for the 7 wild male Amur tigers). The Sauraha tiger wasn't measured 'over curves', but he also wasn't measured in a straight line. If he would have been measured 'over curves', he could have been about 205 cm. This means the Duisburg Zoo tiger was significantly longer. At 110 cm. at the tip of the shoulder (measured while standing), he also was much taller than the 7 wild Amur tigers. Finally, he had an exceptional long and heavy skull and very heavy limbs.

- Robustness

The Amur tigers captured in Russia ranged between 'healthy' and 'unhealthy'. Most healthy tigers range between 180-212 kg. If we include all male tigers, the range is 125-212 kg. Most males captured this century, however, were at the upper end of the range (180-212 kg.). My guess is Miquelle could have been right (about 195 kg. for an average adult male). If we deduct about 5 inches for an average male, one could conclude wild male Amur tigers, at about 183-185 cm. in head and body, average about 190-195 kg. Robusticy index about 1,05-1,10. Captive male Amur tigers range between 180-220 cm. in head and body length and 160-280 kg. I propose to use 195 cm. (in a straight line) and 220 kg. for now. Robusticy-index 1,10-1,15.

Wild Indian tigers seem a bit longer and heavier than wild Amur tigers. Based on what I have, I propose to take 195 cm. for head and body length straight and 220 kg. (about 486 pounds). Robusticy-index 1,10-1,15. Captive male Indian tigers in Indian zoos, however, ranged between 165-210 kg. I propose to take 400-410 pounds as average. This average was confirmed in another survey. Assuming they were as long as their wild relatives, the robusticy-index is about 1,0 or just below that mark.

The conclusion is no real difference between Indian and Amur tigers. The image we have (Indian tigers larger and more robust), is mainly a result of pictures of very large wild individuals posted in different threads. Most of them, however, are prime animals with a territory. We seldom see photographs of males who didn't make it. Another difference is many Indian tigers live in protected reserves loaded with big prey animals.

- Relatives

Compared to other big cats, Amur tigers are less 'chesty', longer and often taller. They also have significantly bigger limbs. Indian tigers are denser (confirmed in skulls). The old Amur tigers, wiped out before World War Two, could have been as dense. At their size, it can't be excluded that some would have surpassed 300 kg.

All in all, I'd say there is a strong correlation between lifestyle, food and size in all 3 big cats. Lions have to share food and face a lot of competition. There's no reward for size, because of their lifestyle (prides). Amur tigers face empty stores, bears and long winters. There is a reward for size, but big animals would face long winters and nordic long distance walking too. There's no reward for bulk, that is. Indian tigers live in well-stocked reserves with a lot of competition. This resulted in large, heavy and robust animals. At times, lions and Amur tigers can be as big as a large Indian tigers. The difference between them is large lions are visible, whereas large Amur tigers are not: only a fool would show himself in a region where 60 000 have a hunting license.

d - A few pictures

1 - Wild Amur tigresses

Amur females average just over 120 kg. and do not seem as robust as Indian tigresses and most lionesses. The question is if the picture that emerged in tables is representative. This tigress was severely wounded by a car some years ago. She didn't make it. A large and big animal, she was: