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

[peter]

LARGE CARNIVORES AND THE CONSERVATION OF BIODIVERSITY (edited by Ray J.C., Redford R.H., Steneck R.I. and Berger J. - Island Press, 2005).


Chapter 10 - Amur tigers and wolves (Miquelle et al.)

Our new member Bremhji posted a link to the book mentioned above. I read chapter 10, which is about Amur tigers and wolves in the Russian Far East. Well written and very interesting, I think. Recommended. While reading, I made some notes. This post has information about the things I liked best. 

In order to prevent problems, I decided to use quotes whenever possible. Remember some parts were left out in order to improve readability. The parts left out were either references or sentences that served as illustrations of statements. In between the quotes, I will add a few remarks. The titles of the paragraphes (and Chapter 10) are mine.   


a - Why wolves numbers have fallen in Sichote-Alin: tigers

As was stated before, rumours about wolves and Amur tigers compare to those about bears and tigers. What is known, is wolves and tigers do not use the same areas. Not today. This paragraph has a few quotes as to why that is: 

" ... Based on fieldwork ... through the early 1970s, Gromov and Matyushkin (1974) argued against the perception, common in Russia, that wolves are driven to low densities or extinction in the presence of tigers ... " (pp. 188).

" ... Despite the clear inverse correlation between wolf and tiger numbers, the mechanism driving population declines of wolves is unclear. Gromov and Matyushkin (1974) reported both usurpation of wolf kills by tigers and scavenging of tiger kills by wolves. The former has probably not been a primary factor influencing wolf distribution. Gromov and Matyushkin (1974) believed that tigers did not prey directly on wolves, and along with others (Yudin 1992) proposed that wolves actively avoid areas used by tigers, resulting in spatial separation of the two species as tiger abundance increases, with wolves remaining only in peripheral areas. However, simple displacement and avoidance seem unlikely to explain the dramatic decrease in wolf numbers across such large areas ... " (pp. 188-189).

" ... Although there are only four records of a tiger killing a wolf (Miquelle et al. 1996; Mokovkin 1999), Amur tigers are notorious for killing dogs. Although rarely observed, direct killing of one predator by another is suspected to play an important role in limiting many predator species (Palomares and Caro 1999; Woodroffe and Ginsberg, this volume). Thus, despite the lack of clear evidence, we propose that direct killing of wolves by tigers has likely been an important element in reducing wolves to a functionally insignificant role in the Sikhote-Alin ecosystem ... " (pp. 188-189).    

What they are saying is Amur tigers and wolves use different areas in the Russian Far East today. Nobody knows why that is. Tigers could have been involved, but there is no strong evidence to suggest they habitually prey on wolves. The number of wolves killed in half a century is very limited. If we add the one killed by tigress Ilona recently, the total number is five only. In spite of that, biologists think tigers are partly responsable for the decrease of wolf numbers. Hmmm. 


b - Why wolf numbers have fallen in Sichote-Alin: hunters

" ... In Russia, ..., large carnivores are primarily viewed as competitors to human hunters. The general conclusion in Russia is that wolves can significantly depress ungulate populations and should be controlled to maintain high ungulate yields for hunters ... " (pp. 203).

" ... Our conclusions that tiger predation is unlikely to limit ungulate populations to the same extent as wolf predation concur with opinions of local biologists (Kucherenko 1974; Dunichenko 1987) ... " (pp. 203).

" ... Nonetheless, the relationship between tigers and Russian hunters is less than amicable, and 'intraguild' killing of competitors extends to the hunter-tiger relationship. Abundant evidence suggests competition killing is one of the primary motivations for poaching in Russia (Miquelle et al. in press). Due to this inimical relationship, and because new regulations provide nongovernmental hunting groups with wide-ranging responsabilities to manage game species, hunters will be key stakeholders in determining the future of tigers in the Russian Far East (Miquelle et al. in press). Finding common ground with hunters must therefore be a primary task for those wishing to conserve the Amur tiger. Paraphrasing one argument for tiger conservation, local conservationists and biologists have proposed to local hunters that 'while tigers may not be desirable, they prevent wolves from becoming abundant ... and we all know that wolves are worse worse than tigers in depressing prey numbers, so it is to your advantage to tolerate the tiger' ... " (pp. 204).      
        
These quotes strongly suggest that hunters largely determine the future of animals, and large carnivores in particular. Although it isn't stated with so many words, there's no question that wolves are a prime and legitimate target of hunters. The reason is wolves are more destructive than tigers:

" ... Nevertheless, our simulations suggest that wolves can limit prey to a much greater degree than can tigers ... " (pp. 203).  


c - Why wolf numbers have fallen in Sichote-Alin: conditions not favouring social hunters


" ... Estimates of energy requirements ... suggest that wolves eat more than would be expected for their body mass, whereas tigers eat less than would be expected ... " (pp. 202).

In order to explain the high requirements of wolves, hunting mode and sociality are discussed:

" ... As ambush predators, tigers hunt by stalking followed by very short rushes (Yudakov and Nikolaev 1992), with high success rates (Hornocker 1970). Chases by tigers rarely extend beyond 150 m (Miquelle et al., unpublished data). Yudakov and Nikolaev (1992) reported 54% and 38% success of Amur tigers hunting wild boar and red deer, respectively. Because tigers are solitary, intervals between kills are high (six to nine days). Collectively, high success rates, short chase distances, and long intervals between kills result in low energy expenditures for tigers.

By contrast, wolves have low success rates, averaging 14% over 14 studies (Mech and Peterson 2003). As cursorial predators, they may chase prey for kilometers. Although living in groups provides wolves the capacity to kill large prey and obtain greater biomass per kill (Gittleman 1989), group living also has costs. In particular, sharing kills results in less energy acquired per individual per kill. Consequently, kill rates must be higher for wolves, leading to greater travel distances as packs search for prey. An additional cost of group living is the time and energy expended on social interactions, a cost that solitary species like tigers largely avoid. In summary, higher kill rates (a consequence of sociality), as well as greater energy expended in cursorial hunting (greater chase distances) and social interactions, all result in greater energy demands for wolves. These factors likely explain much of the difference in food consumption between wolves and tigers ... " (pp. 202).       

This factor, I think, is more important than all others. In the Russian Far East, wolves, as a result of their way of living, struggle to make a living. Sociality also doesn't help.


d - Why wolf numbers have fallen in Sichote-Alin - conclusions

1 - Conditions in the Russian Far East do not favour social carnivores like wolves. The reason is their way of life results in a more or less permanent energy deficit. In the long run, this can only result in adaptions and they didn't disappoint us. Wolves in the Russian Far East usually live alone or in small groups. The days of large packs are past and gone, that is. 

2 - Although direct predation by tigers doesn't happen often (only five incidents in half a century), wolves most probably avoid tigers because they are able to kill them. As a result, wolves and tigers use different areas.    

3 - Another factor not to be underestimated is hunters. Large carnivores are considered as competitors of hunters in Russia. Tigers have a small advantage because they limit wolf numbers, but wolves have no credit at all. As hunters eliminated tigers, there's no question they will eliminate the one not supported by anyone at every given opportunity.

All clear, I think. There are, however, two questions:

a - Why is it wolves were seen in large packs in a region known for tigers (the eastern part of the Sichote-Alin Mountain Range) about a century ago by Velter and his companions? I mean, they caught 26 in a wolf trap in 6 weeks only.

b - Why is it timber wolves in the Russian Far East, known because of their large size, seem unwilling or unable to take on tigers if we also know they do not hesitate to harass and attack brown bears, who can grow to a larger size than tigers?    
 
 
e - A few pictures

1 - Winter Ecology of the Amur tiger (Yudakov and Nikolaev): Great study. Buy it when you can:

*This image is copyright of its original author

 


2 - Ussuri forest: 

 

*This image is copyright of its original author

3 - The actors featuring in this post side by side: 

*This image is copyright of its original author

4 - Tiger and wolves in the RFE (Bisley). This probably never happened, but it's a nice painting anyhow:

*This image is copyright of its original author

5 - Moonlight wolf. Can't get enough of this one:

*This image is copyright of its original author

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