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

[peter]

AMUR TIGER RESEARCH - THE CLAYTON S. MILLER THESIS - V - CONCLUSIONS


1 - Amur tigers have 156.000 square km. of contiguous forests with low human density at their disposal. This is without North-Korea and north-east China. Of all remaining subspecies, Amur tigers, in this respect, have the best future.


2 - The problem is only about 15% of it is protected. Amur tigers have to share 85% of their territory with 60.000 hunters in Russia alone (...). As both more or less hunt the same prey animals, conflict is close. Many Amur tigers die directly (poaching) or indirectly (prey depletion, traffic and canine distemper) as a result of conflicts with humans. Take this study. Of the 5 tigers collared and monitored, 2 were killed by humans. The third was out of action for two months as a result of a poaching attempt. This means 60% of the collared tigers suffered as a result of conflict. Way too high.

Also remember quite many Amur tigers are 'problem tigers'. These tigers often are well below the average weight and many of them, often as a result of an injury they picked up in a conflict, end up dead sooner or later. I don't know how many 'problem tigers' there are, but the list I saw some years ago was a long one.  


3 - If the aim of doubling the number of tigers in 2022 is to be reached, more protection is needed. The question is how much more. In order to answer this question, Miller developed a model enabling researchers to quantify the energetic needs of Amur tigers. He concluded it is good enough to be used by those involved in advice and decisions regarding (the protection of) tigers anywhere in Asia. 


4 - The risk with a model based on the minimum requirements of tigers severely affected by conflict and prey depletion is underestimation of the real energetic needs. One could, however, make a case for a model based on healthy tigers, not one adapted to limitations.

These limitations are real and expressed in different ways. Apart from the number of tigers killed during conflicts and the large number of 'problem tigers', there is the question of weight. Wild Amur tigers, although often longer and taller than Indian tigers, are well below the Indian average. There also is little variation. Captive Amur tigers are heavier than most of their wild relatives. at least in Europe and in the US. In this respect, they are very different from other subspecies.

It is known Amur tigers face tough conditions, severe competition and empty forests. For this reason, they need large territories. We also know about 15% of their energetic need is used for thermoregulation. This means many wild Amur tigers often are unable to get to their potential. In spite of that, Amur tigers are large and robust animals with large skulls. There's no question they are the largest subspecies. Based on everything I have, one would expect 0.9-1.3 kg. per cm. in head and body length for a healthy wild adult male. Translated into numbers, I would get to 160-265 kg. for males and an average between 195-220 kg. Like in all other subspecies, we also expect to see outsized specimens about 30-40% heavier every now and then. It is, however, a fact that the heaviest of those actually weighed in the last two decades were 200, 204, 207, 212 and possibly 215 kg. (referring to a photograph of L. Kerley collaring a 474-pound male), whereas the average is close to 190 kg.

One can't say the lower average probably is a result of genes when it is known Amur tigers, even without the giants many referred to in the recent past, were 10-15% heavier a century ago (Slaght et al, 2005). A lower average weight (combined with the other factors mentioned above) could be an expression of a structural problem, especially when it is known that 41% of the energetic need of Amur tigers is strongly related to weight. 

Should a model be based on unnatural conditions (those of today), or should a model start from a different track? Surviving on a minimum wage or moving to promotion, that is the question. I think Miller could have added a bit more on this issue, but I readily admit it would be less than practical and time-consuming. Size is something for posters. But researchers could and should deliver a bit more in this department, I think.


5 - Apart from the points discussed in -4-, Miller's thesis is well written, to the point and, above all, relevant. As there can be no doubt he was supported by people 'in the know', the thesis also can be seen as an appeal. What they're really saying is Amur tigers need more protected reserves and more large ungulates. And they need it fast if the goal of twice as many tigers in 2022 is to be reached. 

From what I read on the site of the Russian Amur Tiger Team, the Russians are prepared to act. There will be more reserves and they also seem prepared to address the problems regarding hunters and legislation. 

In the end, it's just another battle between humans and animals. I'm optimistic about the outcome. There is plenty of room, many Russians seem willing to accept tigers as neighbours, there is a lot of knowledge and the political representatives have the will to act. If there's one country able to sustain a population of, say, 1000-1500 wild tigers, it's Russia. If the Chinese are prepared to help out, Amur tigers could recover. It would be quite an achievement. Reply