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

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(11-20-2020, 03:15 PM)peter Wrote: THE USSURI BROWN BEAR OR BLACK GRIZZLY (Ursus arctos lasiotus) - NEW INFORMATION ON LENGTH AND WEIGHT 

a - Introduction

A few days ago, our member 'Nyers' informed us about a new book on Amur tigers ('The uncrowned lord of the taiga') in the thread 'Amur tigers' (post 646). The online version (in Russian) is already available. The English translation will be published next year. The book, written by Yuri Dunishenko and Sergey Aramilev (General Director of the Amur Tiger Center) and published by the Amur Tiger Center, is based on recent scientific information. Both are undisputed authorities on wild Amur tigers, meaning the book is a 'must' for those interested in Amur tigers. 

The title of the new book no doubt will result in a few questions. Amur tigers and Ussuri brown bears more or less compare in head and body length, but Ussuri brown bears are more robust and heavier animals. For many, the question is who dominates who. 

Reliable information says male Amur tigers in particular hunt Ussuri brown bears up to the size of, and including, adult females. Some male Ussuri bears, and non-hibernating bears ('Schatuns' or satellite bears) in particular, however, follow, and sometimes hunt tigresses with cubs and immature tigers. It has to be added, however, that no such incidents have been recorded in the period 1992-2020.  

No incidents apart from two, I mean. One of them was an immature tigress found in the snow. Researchers arrived too late to get to solid conclusions. They assumed she had been killed by a bear, but the evidence they presented was inconclusive. Nearly all tigers killed by brown bears are eaten, but this tigress wasn't. In the period she was found, a number of Amur tigers had been affected by a disease. Some of those affected showed unusual behaviour. It could be she was one of them. 

There's no information about the second incident, but adult tigress 'Vera', also allegedly killed by a bear, is mentioned in an article about the (disadvantages of) Aldrich footsnares. The article, first published on a Russian forum, will be discussed in the near future.   

Interactions between males seem to be few. What we know, suggests male tigers and male brown bears avoid each other. A few incidents between large male brown bears and young adult male tigers have been described by Sysoev and Rukovsky. Their observations are considered as reliable, but most other stories about interactions between males of both species, as far as I know, have been dismissed. 

My guess is the situation won't change any time soon. The Russian Far East is a large and almost empty region. Most interactions between tigers and bears go unnoticed, that is. The only way to collect good information is to collar adult tigers and bears and monitor their behaviour for a prolonged period of time.        

b - A new document on Ussuri brown bears

Less than a year ago, a new document on Ussuri brown bears written by Seryodkin (IV), Kostyria (YK), Goodrich (JM) and Petrunenko (YK) was published in the Journal of Siberian Federal University Biology 12(4), Dec. 2019 (pp. 366-384): 'Space use by brown bears (Ursus arctos) in the Sichote-Alin'. It has an interesting table on the size of Ussuri brown bears captured in the period 1993-2001. 

The abstract is in Russian and in English. Here's the scan of the English translation:  

*This image is copyright of its original author

Here's a scan of the table mentioned above: 

*This image is copyright of its original author

I used the table to get to 2 others: a table on adult male bears and a table on adult female brown bears. Bears III (a 2-3 year old male), IX (a 4-year old female) and XV (a 3-year old female) were not used for the tables on account of their age (immature).  

Here's the table on adult females. They averaged 181,17 cm in total length (most probably measured 'over curves') and 163,75 kg (361 pounds). The sample, however, is very small:

*This image is copyright of its original author

And here's the table on adult males. They averaged 211,63 cm in total length (most probably measured 'over curves') and 257,50 kg (almost 568 pounds). The heaviest male (No. V) was weighed in May. It's very likely he would have been over 400 kg. in late autumn: 

*This image is copyright of its original author

The difference between young adults (5-8 years of age) and mature adults (9 years and over) is pronounced. Mature bears are not longer, but heavier. In males in particular, the difference is outspoken. Individual variation in both males and females is significant. 

c - More information on the size of Ussuri brown bears

A decade ago, on the former AVA Forum (now Tapatalk), an article written by N. Kucherenko (published in a Russian magazin in 2003) was discussed more than once. The reason was it has a table on the size of adult Ussuri brown bears. I'm referring to this well-known table:

*This image is copyright of its original author

The table is a bit suspect (it isn't likely that 10 adult males ranging between 260 and 321 kg produce an average of 264 kg), but the confusion could be a result of a typo (likely). 

Both males (196 cm as opposed to 211 cm) and females (160 cm as opposed to 181 cm) seem to have been somewhat shorter (referring to total length) in Kucherenko's day, but that could have been a result of the method used to measure them. The difference between measurements taken 'over curves' and measurements taken in a straight line is considerable in brown bears (see -d-). Another disadvantage of this method (referring to a measurement taken 'over curves') is it can be applied in different ways.   

The main difference between both tables, however, is the difference in (average) weight. Kucherenko's females in particular were significantly heavier. The difference could have been a result of the aim of his paper (written to lure hunters to the Russian Far East), but it's also likely large individuals were more common back then. In the first decades after WWII, bears were not often hunted. 

There's more information about exceptional female brown bears in a few threads of the former AVA Forum (now Tapatalk). A member from China (KTKC) posted what seemed to be reliable information on a few large females. Here's a scan of one of his posts. The female brown bear, from northeastern China, was 275 kg:

*This image is copyright of its original author

Some years ago, another document on Ussuri brown bears was published. Seryodkin was involved in that one as well. Here's a scan of table 1. Two of the three male brown bears were collared in the Sichote-Alin Nature Reserve. The young adult male (6-7 years of age) was 180 kg, whereas the adult male (8-10 years of age) was 235 kg: 

*This image is copyright of its original author

d - Difference between curve and straight line measurements in brown bears

The two iriginal tables posted above (see -b-) say adult female Ussuri brown bears average 181,17 cm in length, whereas adult males average 211,63 cm: a difference of 30,46 cm or about 1 foot. Assuming they, like most brown bears, were measured 'over curves', the question is how long they were in a straight line. This is necessary in order to be able to compare them to adult wild Amur tigers. 

Unfortunately, there's no information about the length of Ussuri brown bears measured in a straight line. Assuming they more or less compare to brown bears in the Americas, the question is if there's a bit more about American bears. The answer is affirmative. 

About a decade ago or so, I scanned and printed a table about the dimensions of American brown bears posted in a thread of AVA (now Tapatalk). As a result of problems with the PC, I lost a lot of information. This means I'm unable to tell you anything about the source of the table. The print, however, survived. Here it is:

*This image is copyright of its original author

 
The table has detailed information about the dimensions of male grizzly bears by age class measured in the period 1975-1985. My guess is the table is about brown bears captured in Yellowstone, but I could be mistaken. 

Anyhow. We're interested in 'Length (A)' and 'Contour length (A1)'. Length (A) is the straight line length, whereas contour length (A1) is the total length measured 'over curves' ('contours'). In adult male grizzly bears, that is to say bears of 5 years and older (bottom of the table), the average difference between both methods is 32,2 cm (164,3 cm as opposed to 196,5 cm). 

The question is if male grizzly bears can be considered as adult at age 5. My guess is most authorities consider a male brown bear as adult when he reaches 8-9 years of age. Males of 5-7 years of age would be considered as young adults. In order to be able to compare American male grizzly's with male Ussuri brown bears (see the table in -b-), I only used male grizzly's of 8 years and older in order to get to a comparison. 

The conclusion is the average difference between straight line and curve measurements in adult male grizzly's (8 years and older) is 36,2 cm per age class (range 7,5 - 60,9). There are significant differences between age classes. In two 13-year old male grizzly's, the average difference between both methods was 14,0 cm and in two 16-year old male grizzly's the average difference was 7,5 cm only, whereas it was as much as 60,9 cm in five 11-year old males. Strange.  

Anyhow. In 30 (the 15-year old bear was left out of the equasion as he was measured in a straight line only) adult male grizzly bears, the average difference between both methods was 36,2 cm (14,25 inches). 

Assuming they more or less compare to adult male Ussuri brown bears (a) and the method used to measure them 'over curves' ('contours') in the Russian far East was applied in the same way (b), the conclusion is adult male Ussuri brown bears, averaging 211,63 cm in total length measured 'over curves', are 175,43 cm measured in a straight line ©. This conclusion, however, is based on averages of age classes, whereas individual variation in adult male brown bears is pronounced. 

The American male grizzly's, by the way, averaged 95,7 cm (range 83,0 - 105,0) in height and 135,1 cm (range 116,0 - 150,0) in chest girth. 

Do American male grizzly bears and Ussuri male brown bears, as was assumed (see above), really compare? Not quite. What I have suggests Ussuri male brown bears are a bit larger in all departments. 

The two 8-year old males weighed in October were just over 200 kg and the 8-year old weighed in May was 220 kg. The other four male bears, all weighed in the period May-September, averaged 298 kg (range 256 - 363 kg) or 657 pounds. Big by any standard.

e - Difference between curve and straight line measurements in Amur tigers

In this post, the focus isn't on Amur tigers (Panthera tigris altaica), but Indian tigers (Panthera tigris tigris). One reason is there is much more information on the length (and weight) of tigers shot in what used to be British India. Another is there is good information about the methods used to measure tigers in that part of the world in both magazins and books. 

Tiger hunting always was quite popular in British India. From 1860 onward, the number of hunters more or less exploded. A few decades and tens of thousands of dead tigers later, hunters concluded regulation was badly needed in order to prevent total destruction. This, mind you, was well before the turn of the century (referring to the period 1880-1900). 

In this respect (destruction of the natural world), British India and Russia (referring in particular to the regions, ehh, aquired from China in 1858 and 1860 (nowadays the Russian Far East) definitely compared. 

If you want to know more about the situation in the Russian Far East, my advice is to read 'Taming tiger country: Colonization and environment of the Russian Far East, 1860-1940'. The dissertation of Mark Sokolsky (2016) is extensive and very interesting. 

Here's a map showing the territory gained by Russia in 1858 and 1860: 

*This image is copyright of its original author

The destruction of the natural world in the Russian Far East is also described in 'Dersu The Trapper'. In the first decade of the 20th century, Vladimir Klavdievich Arseniev and Dersu thought the slaughter they saw would result in mass extinctions in a few decades only. They were right. In the twenties and thirties of the last century, Amur tigers (as well as many other species) really walked the edge.  

Returning to British India, tigers and the methods used to measure them. As far as I know, only Forest Officers and a few experienced hunters measured tigers in a straight line in the period 1860-1890. Nearly all tigers shot in that period were measured 'over curves', that is. As this method, which can be applied in different ways, not seldom produced tigers of exceptional length, debates about the reliability of these records erupted quite often. 

Sterndale ('Natural history of the mammalia of India and Ceylon', 1884, pp. 162-163) was the one who proposed to measure tigers in a different way. His proposal to measure tigers in a straight line ('between pegs') was adopted in most parts of Central India, but in northern India, Assam and southern India many hunters continued to measure tigers 'over curves'. 

Here's a scan of pages 162-163 of his book:

*This image is copyright of its original author

The Maharajah of Cooch Behar ('Thirty-seven years of big game shooting in Cooch Behar, the Duars, and Assam. A rough diary', Bombay, 1908) and his guests measured all tigers they shot in the period 1870-1908 'over curves'. Just before and after the turn of the century (1898-1902), however, 12 male tigers were measured 'between pegs'. Of these, 10 were measured both 'over curves' and between pegs':

*This image is copyright of its original author

The table, an original for Wildfact posted in this thread in January 2016, shows the average difference between both methods in 10 male tigers shot in the period 1898-1902 was 5,45 inches or 13,84 cm (range 5-7 inches). These 10 tigers, largely as a result of one long tiger, averaged 290,17 cm in total length measured 'over curves' (range 274,32 - 317,50) and 276,35 cm 'between pegs' (range 261,62 - 300,99). The average head and body length of 9 males was 199,53 cm measured 'over curves' (range 186,69 - 210,82). Of these 10 males, 8 were weighed, of which one was 'gorged'. They averaged 455 pounds (range 385 - 504) or 206,39 kg.

Compared to the average of all male tigers shot in the period 1877-1908 (n=89), they were a bit shorter (290,19 cm as opposed to 294,84 cm). They also lacked a little over 6 pounds (455 as opposed to 461,34). Not one of the 89 males measured and the 53 weighed was exceptional.   

Why is this table posted in a post about the length of wild male Amur tigers? The reason is it, to a degree, can be compared to a table with the dimensions of 10 wild male Amur tigers captured in the Sichote-Alin Biosphere Reserve in the period 1992-2004. 

I'm referring to Table 7.3 in 'Tigers in the Sichote-Alin Zapovednik: Ecology and conservation', Miquelle (DG), Smirnov (EN) and Goodrich (JM), 2005. This much discussed document is in Russian only, but the table is in English as well: 

*This image is copyright of its original author

The tigers captured in this reserve were measured in the same way as the tigers shot in Cooch Behar, the Duars and Assam in the period 1870-1908 ('over curves'). In total length, they more or less compared to the 10 male tigers shot in northeastern India a century ago (294,00 cm as opposed to 290,19 cm). 

If the method used in Russia in the period 1992-2004 was applied in the same way as in northeastern India a century ago, it means we have to deduct 5,45 inches (13,84 cm) from the total length 'over curves' to get to the total length in a straight line. The result (294,00 - 13,83 = 280,17 cm) suggest wild male tigers measured in northeastern India in the period 1870-1908 and wild male Amur tigers measured in the Sichote-Alin Biosphere Reserve in the period 1992-2004 more or less compared in total length 'between pegs'. 

As the wild male tigers shot and measured in northeastern India and those shot and measured in Central India in roughly the same period (referring to 'Wild animals in Central India', A.A. Dunbar-Brander, 1923), the conclusion, regarding total length 'between pegs', is there's little to choose between wild male tigers in northeastern (n=10) and Central India (n=42) on one hand and wild male Amur tigers on the other (n=10). 

Wild male tigers shot in Central India averaged 420 pounds (190,51 kg), whereas those shot in northeastern India averaged 461 pounds (209,11 kg). In order to find out more about the weight of wild male Amur tigers captured a century later, we need more information. 

Here's a table with more details about 10 wild Amur tigresses and 10 wild male Amur tigers. It could be they are the tigers used for the table above, but I'm not sure. As a result of the problems mentioned above (referring to crashes that resulted in the loss of information), I'm also unable to tell you the source of the table. I only remember it was posted in one of the threads of the former AVA Forum (now Tapatalk):     

*This image is copyright of its original author

To be continued.

Good posting, some remarks.

What comes to those weight of the bears it was interesting to see some new figures. When looking at male bears I found it quite interesting that out of sample of only eight bears, there were two which were pretty big ones. First was that bear weighed May 19th and weight was 363 kg. By getting only 10% weight increase it would be a 400 kg bear which is a lot for so called ”inland grizzly”. I dare to claim, that just before hibernation it could weight at least anything in between 400-440 kg. To compare with biggest weighed wild bears ever in Scandinavia and Finland heaviest bear has been 372 or 373 kg (I always forget which was exact number).

Another big bear was weighed July 19th and 305 kg. What makes it interesting is, that while people often think that bears are in their lightest condition right after hibernation it isn´t the whole story. Some bears can be, but many are as light as they are right after mating time. Male bears move hundreds of kilometers while searching female bears to mate and they are quite aggressive and naturally fighting for mating rights. So a bear weighed in July can be pretty light when comparing what it is before hibernation. A 300 kg in July bear can be expected to gain 100 kg more weight before it starts to hibernate without being unrealistic. It can be less or more, but that bear could be in November something like 375-415 kg, imo.

I find this interesting also because of the study I noticed recently concerning brown bears living in Hokkaido (I shared it in brown bears thread). They are considered by some to be same subspecies as Ussuri brown bears and some think, that different population. They had a lot of bears around 400 kg and a few even bigger (up to 520 kg). These things seem to back up claims, that Ussuri brown bears are, what comes to size, somewhere in between ”normal” inland brown bears and brown bears with access to salmon rivers. While Hokkaido brown bears have been quite isolated it´s natural to assume that the bears living in Russian far east have more genetic variation nowadays. But maybe still producing some really big ones more often than most other brown bear subspecies/populations.


Then what comes to that one tigress suspected to be killed by a brown bear, but which wasn´t eaten. Looks to be somewhat unclear case, but most of the fights between brown bears and tigers are known to end to dispersion. It of course doesn´t mean, that all indivduals would survive long after fight, even though not dying on spot. So that tigress could have got lethal injuries while fighting and then dying some time later. Or not.

If it would have died during fight, bear would have eaten it without a doubt, bears aren´t picky and eat what they kill of course. But some cases remain unclear and looks like that case remains as possible, but not sure.


This part was then again one, which I´m not sure what you meant:
”Some male Ussuri bears, and non-hibernating bears ('Schatuns' or satellite bears) in particular, however, follow, and sometimes hunt tigresses with cubs and immature tigers. It has to be added, however, that no such incidents have been recorded in the period 1992-2020.”

When you write that no such incidents have been recorded in the period 1992-2020, you mean cases that bears would have hunted some tiger to kill it? And maybe non-hibernating bears following tigers in winter, which is rare too?

I ask because Asiatic black bears and brown bears both are known to follow tigers in order to have their share of tiger kills or usurping those kills. And this, as far as I know, happens all the time from spring to autumn more or less. Like that famous case with tigress Rachel which was practically persecuted by a brown bear to the point, that group of hunters were gathered in order to shoot the bear and help Rachel to keep her kills. I found that case a bit odd, that people were intervening, but of course brown bears aren´t endangered (yet) while tigers are and Rachel had that time cubs too. It s´naturally just one example. I mention this because, imo, that text could be understood in wrong way what comes to bears following tigers.

While that new book didn´t seem to bring in anything new to this tiger-bear topic, one interesting thing giving some new data are camera trap photos. Some already shared ones show tigers and bears captured to photos in same places, but looks like, that not too many of these photos are published yet. Hopefully in future more of these photos come out and more information about it which bears and how often there are etc. Reply