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

[peter]

WOLVERINE


Many thanks for the link, the translation and the summary.

In the past years, Russian biologists more than once wrote that some large male bears deliberately follow and displace tigresses with cubs. The photographs and the article prove that they were right. 

Satellite bears

Male brown bears following and displacing Amur tigresses with cubs, if correct, are known as 'satellite bears'. It seems that some of them do not hibernate. The most likely reason is they solved the food problem. At least, the tigresses they follow and displace did. And they will continue solving them as long as the pressure is kept up.

This means that the tigress targeted has to hunt for both her family and the hangman. As he often is at least twice, if not three times, her weight, the tigress has no option but to hunt large animals for an extended period of time. When she fails to deliver, chances are the male bear will target one of her cubs. Or all of them. If she protects her cubs, she could be severely wounded or killed. In both scenarios, her cubs could perish.

Encounters between 'satellite bears' and tigresses with cubs or young tigers

In Band III of 'Mammals of the Sovjet-Union' , a number of incidents between tigresses and 'satellite bears' were described: 

" ... In a fight with a bear, the tiger isn't always victorious. In the 1959-1960 winter, a tigress with her two 2-year old cubs lived in a remote part of the Sichote-Alin Mountains. One day, she left them with a wild boar she had killed. When they were feeding, the tigress moved off. When she returned, she saw a large non-hibernating brown bear (also known as a 'Schatun') approaching the cubs and the wild boar. The tigress attacked the bear, but was killed in the fight that followed. In spite of his severe injuries, the 'Schatun' consumed both the wild boar and the tigress (Sysoev, 1960). In 1913, near the Great Sinantsch, a large brown bear killed a tiger. In 1960, in the Sichote-Alin Reserve, a young tiger was killed by a brown bear (V. Abramov, 1962). A similar incident happened in the Amur region (Krivopust, 1957) ... " ('Mammals of the Sovjet-Union', V.G. Heptner and A.A. Sludskij, German edition, Jena, 1980, pp. 150).  

The first incident happened in winter, meaning the bear involved most probably was a non-hibernating bear or Schatun. As Schatuns and satellite-bears often are one and the same, it's possible that the bear had been following and displacing the tigress and her two cubs for some time. The last incident (referring to the incident quoted from Krivopusk) wasn't discussed by Heptner and Sludskij, but by V. Mazak:

" ... Kaplanov (1948) and Abramov (1962) agree that an adult brown bear can kill and eat young tigers left on their own by their mother. In 1956, in the Schuchti-Pokto Reserve near Chabarowsk, a 3-year old tiger was killed by a brown bear near the wild boar killed by his mother (Krivopusk 1957, ex Abramov 1962). Two similar incidents happened in the 1959-1960 winter and in the fall of 1960 when a tigress resp. a young tiger were killed by a brown bear (Abramov 1962, Heptner and Sludskij 1972) ... ('Der Tiger', V. Mazak, third edition, 1983, pp. 120).  

This is a photograph of 2-year old Amur tiger killed and eaten by a brown bear (Mazak, 1983):

*This image is copyright of its original author

Based on these incidents and on recent observations of biologists, the conclusion is that tigresses with cubs are sometimes followed and displaced by large male brown bears. It's very likely that some of these bears also hunt young Amur tigers and tigresses in times of need (early spring and late autumn). More than one biologist wrote that male brown bears also hunt Himalayan black bears in this period of time.  

Tigresses without cubs, on the other hand, can be dangerous for female brown bears. Kaplanov (in 'Der Tiger', V. Mazak, 1983, pp. 89), following a tigress in the Kolumbe River Basin, found the tigress had dug up and killed a female brown bear and her two cubs in February 1940. Similar cases have been described by V.K. Abramov ('Der Tiger', V. Mazak, 1983, pp. 89). Early May 1951, a bear with a body length of 158 cm. and about 170 kg. killed and eaten by an Amur tigress was found close to the Tatibe River ('Mammals of the Sovjet-Union', German edition, Jena, 1980, pp. 149).    

This is the brown bear killed by a tigress near the Tatibe River in early May 1951 (Mazak, 1983). Mazak wrote it was an adult brown bear, but Bromley didn't provide any details about gender and age. Same for Heptner and Sludskij. Length and weight obviously were a result of an estimate, as a large part of the bear was eaten. If the bear really was about 170 kg. in early May, chances are he or she was 20-30% heavier just before hibernation. If so, it's likely it was an adolescent or young adult male (adult female brown bears average 140-150 kg.): 

*This image is copyright of its original author

Although the last incident proves that a tigress can kill a larger brown bear, one wouldn't fancy her chances in a fight with a large satellite-bear two or three times her weight. In order to give you an idea about the difference in size: 

Male brown bear from southeastern Russia. I have no details, but he seems to be average-sized -

*This image is copyright of its original author

Another well-built male -

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This is a large male (about 400 kg.) from the San Diego Zoo -

*This image is copyright of its original author

A brown bear recently captured and weighed in the Russian Far East. As only two males of 180 and 235 kg. were captured, I assume this is one of them -

*This image is copyright of its original author

The table with the weights of two male brown bears captured in the Sichote-Alin Natural Reserve - 

*This image is copyright of its original author

The male following and displacing tigress 'Rashel' is a very large individual, most probably close to 800 pounds. Although bears of this weight are uncommon, Ussuri brown bears (Ursus arctos lasiotus), as this photograph shows, can reach a great size - 

 

*This image is copyright of its original author

For comparison. This is tigress 'Zolushka' with her 2 cubs. A stocky tigress:

*This image is copyright of its original author

Here's another Amur tigress (2008, with Putin). In contrast to 'Zolushka', she has a more 'classical' appearance:

*This image is copyright of its original author

In early spring (just after hibernation) and late autumn (just before hibernation), bears need a lot of energy as fast as possible. Protein is the way to get there, but hunting isn't easy for bears. Cats, on the other hand, are natural hunters. When bears and cats co-exist, brown bears in particular often visit tiger kills. It's near these kill sites that tiger and bear most often meet and clash.

There are just over 500 Amur tigers and many thousands of bears in the Russian Far East. Nearly all bears, young or old, visit tiger kills. For Amur tigers, avoiding bears just isn't an option. They have to learn how to deal with bears and it starts when they are born. Cubs are protected by their mother, but when they disperse, at 18 months or a bit over, they are on their own. 

Although there is no information about the period between adolescence and adulthood, it's very likely that many Amur tigers don't make it to adulthood. Those that do are, bearwise, true survivors. Not a few of them have learned to hunt bears. Although many posters seem to think that only male tigers hunt bears, there's plenty of evidence of Amur tigresses hunting bears or training their cubs in this respect.

The story below, from November 2008, most probably is everyday reality for many Amur tigresses with cubs -    

*This image is copyright of its original author

Although an average captive Amur tigress is not much heavier than an average wild Amur tigress, some captive tigresses can exceed 160 kg. (353 pounds). One tigress shot because she had killed the owner of a (French) facility was just over 200 kg. (442 pounds). The heaviest wild Amur tigress I know of was 368 pounds (166,9 kg.), but it's likely that there were, or still are, heavier tigresses. The record tigress was shorter than average and also had a shortish skull. 

Wild Amur tigresses today average about 120 kg. (265 pounds), maybe a bit more. The heaviest weighed in the last decades was below 130 kg. (287 pounds). The range in weight in wild Amur tigresses is quite limited, which is not typical for wild tigers. Could point towards a shortage of food or to a population bottleneck not too long ago. There have been several in the last century.

Sexual dimorphism in Amur tigers is outspoken. Captive males average about 215 kg. (474 pounds), but the range is remarkable. Small adult males are just over 160 kg. (353 pounds), whereas the heaviest top 300 kg. (662 pounds). Two decades ago, wild male Amur tigers averaged about 177 kg. (390 pounds). As the historic average for wild males was about 215 kg. (474 pounds), it means that male Amur tigers, largely as a result of bad conditions and low numbers, lost about 80 pounds in a century.  

However. The sample resulting in 177 kg. a decade ago included a number of 'problem tigers' as well as a few 3-4 year old animals. Dale Miquelle thought that adult males today average about 430 pounds (195 kg.), but Guate's table suggested that 185-190 kg. (410-420 pounds) could be closer to the mark. I propose to use 190 kg. (420 pounds) for now. Compared to a century ago, this means they lost about 50 pounds. As prey depletion still is a problem, Amur tigers today probably hunt bears more often than they did a century ago. 

As the conditions in Russia have improved, the number of tigers has risen. As more tigers and better conditions should result in more individual variation, one would expect a 500-pound male Amur tiger sooner or later. A decade ago, Kretzschmar said he had seen tracks of very large male tigers. Although the heaviest male to date is a young adult of 212 kg. (468 pounds), recent photographs suggest that Kretzschmar could be right. I have no information about this male, but he seems healthy and has a large skull. Surprise captured -        

*This image is copyright of its original author

Tigress 'Rashel'

In the article you translated, you wrote that Alexander Sergeevitsch had observed the tigress targeted by the bear for some years. Last year, she had given birth to four cubs. I wonder if all of them survived, as it's likely the family faced periods of starvation. If tigress 'Rashel' can't find enough prey animals, chances are the bear will try to get to her cubs. 

Nature should run its course, but the number of wild Amur tigers is limited and they are still poached (about 20 every year). As tigresses in particular are vital, I can understand the decision to ease the pressure on 'Rashel'. 

Solving her problem, however, doesn't mean that the bear has to be taken out. If they can rehabilitate orphaned tigers, they should also be able to rehabilitate professional hangmen, one would think. Making little rocks out of big ones is a possibility, but why not use good old Pavlov?   

Amur tigers and male brown bears

Male brown bears are large animals. In the Russian Far East, they average about 580 pounds (263,09 kg.), but large individuals can reach 800 pounds (362,88 kg.). and quite a bit more at times. In order to hibernate, these giants need to fatten up severely in autumn. Protein would be best, but male brown bears are too heavy to hunt. In the Russian Far East, however, they use Amur tigers to get to protein. 

Although it's likely that a large male brown bear can displace any tiger, male Amur tigers apparently are not that often displaced. According to Kretzschmar, a well-known Russian hunter and biologist, an average male Amur tiger (410-420 pounds) and an average male brown bear (580-590 pounds) more or less compare in a fight, but tigresses with cubs, adolescents and young adults can be intimidated and displaced. My guess is that most Amur tigers killed in fights with brown bears are large cubs, adolescents and young adults. The details I could find more or less confirm this conclusion. 

Fights between brown bears and Amur tigers often happen close to kill sites. About half of them have a tragic outcome. Bears apparently initiate more fights, but tigers win most. During a debate on another forum some years ago bear posters agreed, but added that most bears killed were youngish individuals. Could be true, but the information needed to get to a conclusion often isn't there.

Rehabilitated Amur tigers released into the wild have collars, allowing researchers to track them. This is why they were able to find their kills. And the two bears killed by 'Boris'. The bears were youngish (2-4 years of age), but so was Boris when he fought them. This means that serious fights between immature tigers and bears apparently are not uncommon.    

In an article I read back then, a biologist wrote that he knew of 12 Amur tigers killed by brown bears. I did a bit of research some years ago and concluded that the real number of casualties is much higher. I'm not saying that the Russian Far East is a hidden battlefield, but it's very likely that the number of serious encounters between Amur tigers and brown bears far exceeds the estimates I saw.

A recent article on Amur tigers and brown bears strongly suggests that Amur tigers hunt bears more often than was assumed. In some regions and seasons (and summer in particular), bears are as important as wild boars and red deer. Some years ago, researchers wrote that largish bears would be too dangerous for Amur tigers, but Miquelle now thinks this assumption could have been incorrect.      

Kamsjatka

In Kamsjatka, not that far away, some male brown bears hunt cubs up to 4 years of age in spring and summer. Charly Russell and his wife Maureen ('Grizzly Heart', Random House, 2002) lost one of the three orphaned cubs they rehabilitated to a cannabalistic male. He nearly got another one during a long chase (about 8 km.) partly witnessed by Russell. This male had killed two of the three cubs of a wild female before he attacked the Russell cubs.

A photograph of the cub-killer -

*This image is copyright of its original author

A large male brown bear from Kamsjatka -

*This image is copyright of its original author

Updates on 'Rashel' and her cubs

As the article triggered the interest of many, we would be very interested in a follow-up on Rashel, her four cubs and the bear. Maybe you can find a bit more? Reply