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

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peter

Co-owner of Wildfact

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#2,475

04-08-2020, 11:40 AM

(04-08-2020, 12:49 AM)tigerluver Wrote: With all the data @peter kindly shared, a new, rather robust equation can be calculated. I counted specimens of all ages except those marked as starving. The sample size of 48 was statistically powerful and excellent given the limitations in recording measurements of the subject matter.

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Applying the computed formula, a 13.5 cm wide paw would weigh 295 kg. The 95% confidence interval would be between 259 kg and 337 kg, inclusive. In other words, the dataset indicates that there is a 95% chance the owner of a 13.5 cm wide paw weighs 259-337 kg, with the most likely weight closer to 295 kg.

Super effort, Tigerluver.

I admit I have some doubts on the predicted weight of a male with a heel width of 13,5 cm., but the table on the relation between heel width ('palm width') and weight in brown bears in northeastern Siberia, on the other hand, strongly suggests a relatively small increase in heel width over an, unknown, threshold can result in a very substantial increase in weight.

Another factor that resulted in doubt regarding the outcome of the prediction is recent information about the size of wild Amur tigers. The data collected in the last 28 years suggest adult male Amur tigers, depending on the season and the conditions, range between 170-212 kg. Although nothing can be excluded, there's no information of males exceeding 500 pounds (226,8 kg.), let alone, as the equasion predicts, 700 pounds (317,52 kg.).

Some captive male Amur tigers, on the other hand, have approached or even exceeded 650 pounds (294,84 kg.). As far as I know, all of them were Studbook tigers, meaning they're related to wild Amur tigers caught in the fifties, sixties and seventies of the previous century. Apparently, the genes to get to a large size are still there.

The question is if large males can be captured with an Aldrich footsnare. After reading 'The snare for tiger' (S. Kolchin and P. Maystrenko, 2013), I doubt if the Aldrich snare would be strong enough to restrict even an average-sized male. According to Kolchin and Maystrenko, Ivan Seryodkin was injured by a big male tiger who broke the snare binding when he was approached by people on June 17, 2008. Other male tigers were quite badly wounded while trying to escape. I don't know if conclusions were drawn after these incidents, but my impression is less tigers have been captured in the last decade. If there are tigers exceeding 700 pounds today, as the equation predicts, chances are they will not be captured. Not with a footsnare.

The only, indirect, way to test the equasion, therefore, is to go over the historic records once again. In Chapter 6 (Appendix 6.1) of 'Tigers in Sichote-Alin Zapovednik: Ecology and Conservation', 2005, 44 records were reviewed. Most of them were unreliable.

Baikov is well represented in Appendix 6.1: he shot 14 of the 44 tigers that made it to the Appendix. Of these 14 records, 11 were considered as unreliable, whereas two were considered as 'highly reliable'. The reason these 2 were considered as highly reliable is Baikov provided the necessary details. That, however, doesn't mean that the tigers of 320, 325 (twice) and 390 kg. he shot were a result of imagination, hearsay or inaccurate scales.

The historical records, if anything, suggest the predicted weight of a tiger with a heel width of 13,5 cm. (259-337 kg.) could be close. We'll never know how close, but tigers in the predicted range have been shot in the recent past.

And what about tigers the 3 tigers exceeding 340 kg. in Appendix 6.1? A century ago, more tigers had more room and more chances to live to old age. In large regions with good conditions and few people like Manchuria, some tigers might have reached a great size.

I've seen direct descendents of tigers caught close to Manchuria in zoos in western Europe in the late sixties and seventies of the previous century. Compared to captive Amur tigers today, they were not longer, but often a bit taller and nearly always more robust. Bigger limbs, bigger necks and limbs and, in particular, bigger skulls. I thought they were from a different world: