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

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Betty

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06-15-2017, 09:57 PM

(06-14-2017, 06:27 AM)peter Wrote: PANTHERA TIGRIS ALTAICA 6

6a - Tigers and bears in the Russian Far East

The second post of the series on Amur tigers had a recent report about a male Amur tiger who, experts think, was killed by a brown bear on February 17, 2017. The report was from THE AMUR TIGER PROGRAMME, meaning it is reliable.

Although those who saw the tiger concluded he had been attacked by a brown bear, there are some reasons for doubt. Brown bears hibernate in winter. As the tiger was killed on February 17 (a very cold day), the bear had to be a large non-hibernating brown bear, meaning either a 'Shatun' (a hungry bear unable to hibernate as a result of a lack of fat) or a 'satellite-bear' (a non-hibernating bear routinely following tigers). Schatuns and satellite-bears, both focussed on food, are known to displace tigers. At times, they attack them in order to eat them.

The problem is the tiger wasn't consumed. Very strange, especially when it is known that bears suffered severely from two crop failures in a row.

For this reason, it can't be excluded that tiger 'Uporny' died in a fight with a male tiger. Amur tigers mate in winter and fights are not uncommon in that period. At times, one of the two is killed. Those killed are mutilated, but rarely eaten. We have to wait for the autopsy report.

Anyhow. This post has a bit more on the relation between tigers and bears in the Russian Far East.


6b - Bear numbers and density in the RFE

This table was posted on AVA some years ago. It has interesting information about bears in the Russian Far East. Brown bears, that is. Not black bears. Amur tigers live in two, maybe three, regions (Khabarovsk, Amur and Primoria). These regions have 12 000 - 14 000 brown bears in total. Primoria and Khabarovsk in particular have high densities:

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Here is a map of the RFE with brown bear densities. Regions with vertical stripes have most brown bears:

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Conclusion. There are about 500 Amur tigers in the RFE. The part in which they live has about 13 000 brown bears. This means that there are about 25-26 brown bears for every Amur tiger. If we add the number of black bears, the conclusion is that bears severely outnumber tigers. No wonder that tigers consider bears as an important source of food.

6c - Bears as a source of food

Over the years, many studies about food habits of Amur tigers have been published. In some of them, bears hardly featured, whereas they were a major food source in others. I got to unclear.

Not so long ago, I posted a number of pages from a recent study on, surprise, food habits of Amur tigers. This study is different from others in two ways. One is scats were collected for a number of years in 3 sites. Two is the effect of pseudoreplication (multiple scats collected from a single kill site) were eliminated. Could be one of the most reliable studies I read.

Below, you'll find the most important pages and tables. Quite a read, but interesting and very informative:

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6d - Linda Kerley on tigers and bears in the RFE

The scan below was posted on AVA by a member some years ago. It could be she changed her opinion in the last years, but it isn't likely, especially if we know that she was one the researchers who published the report on food habits of Amur tigers discussed in the previous paragraph.

Linda Kerley, with about 20 years of experience to her credit, is very much 'in the know' regarding tigers and bears in the Russian Far east. I hope the mail is still readable:

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What you need to remember is this:

- Bears are an important food source for Amur tigers, especially in summer
- Bears are not only hunted by specialists (old male tigers); tigresses also hunt bears
- Non-hibernating brown bears ('Shatoons' in Kerley's mail) harass, hunt and eat tigers (in winter)
- Anything can happen between tigers and bears.

6e - Two photographs of bears killed by tigers

The first photograph is from V. Mazak's book 'Der Tiger' (third edition, 1983). Mazak wrote that the bear (an adult, he added) was killed by a tiger. There was a lengthy discussion about this photograph in AVA some years ago.

The bear was killed near the Tatibe River in early May 1951 by a tigress. She ate most fatty parts and stayed with the bear for a few days. The bear was 158 cm. in length and weighed 170 kg. As a considerable part of the bear had been eaten by the tigress, it's likely the weight was estimated.

Assuming the estimate wasn't too far off, the bear could have been well over 200 kg. in late autumn (bears lose 25-35% of their weight during hibernation):

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This photograph was also first posted on AVA. The bear is second from the left. Have a look at the tusks of the wild boar (bottom, left):

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In the next post on tigers and bears, the focus will be on interactions near kill sites, tables with information on mortality (tigers), and observations of those 'in the know'.