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

peter Offline
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( This post was last modified: 06-03-2019, 06:21 PM by peter )

Good effort, Pod. Appreciated. I decided to add a few remarks.

A - Male tigers in India today and a century ago

Reliable information says male Indian tigers, at the level of averages, ranged between 182-209 kg. (402-461 lbs.) in the period 1860-1940. Today, male tigers average 210-220 kg. (463-486 lbs.). This average is without the Sunderbans. Without the correction factor used by biologists today, the average of adult male tigers in most of mainland India would be over 500 pounds.

The heaviest individuals, 'corrected' for food intake, seem to range between 250-260 kg. (552-575 lbs.), but two tigers weighed in Nepal in the seventies and eighties of the last century bottomed a 600-pound scale (272,16 kg.) and another male in northern India weighed a few years ago is said to be over 800 lbs. (362,88 kg.).  

There are quite many old records of tigers close to or exceeding 600 pounds. Some individuals shot by experienced hunters and Forest Officers were estimated at 700 lbs.. The heaviest actually weighed in Nepal was 705 pounds. This is without the enormous tiger shot by Hasinger in 1967 and a few very large individuals shot before 1860. Although old information isn't taken very serious, those who hunted tigers in the period 1820-1870 agree tigers shot before, say, 1850-1860 were larger than those shot later. One hunter who actually saw a tiger of 11 feet in northern India said he was dwarfed by an exceptional male shot in the early days.

Most hunters who wrote books in the 20th century didn't believe one word of stories about exceptional tigers. Like most biologists today, they said exceptional tigers were a result of skins, special tapes and Maharajahs interested in extra-large tigers. That, however, could have been a result of disappointment: nearly all giants were shot by early settlers, not those operating in the department of high status. Most high-ranking officers hunting tigers never saw even a 10-feet tiger. The reason was habitat destruction and rapidly declining numbers. Well before 1900, quite many already warned of the consequences. 

But destruction wouldn't affect the size of tigers in a relatively short space of time, would it? Yes it would. At least, that's what the information I have on Nepal and northern India suggests. In a few decades only, male tigers in northern India lost about 4 inches in total length. As total length and weight are strongly related in Indian tigers, weight would have been affected as well.

An indirect example is provided by tigers in India and Nepal today in that they are heavier than a century ago. This in spite of low numbers. The most likely reasons are better conditions (protected and well-stocked reserves), more competition and less stress caused by humans. Wild Amur tigers also seem a bit bigger than two decades ago. The reason seems to be more protection and less stress.     

B - The correction factor used by biologists today

It's true that 7 tigers shot by the Maharajah of Cooch Behar and his guests in the period 1871-1907 were gorged, but it's also true the sample had a few young adults and a few tigers considered to be quite 'light' for their size. Hewett's sample also had a few young adults and underweight tigers. Large samples, however, most probably reflect the actual natural conditions. All large samples strongly suggest that individual variation in wild Indian tigers was pronounced a century ago.  

There are more reasons to question the correction factor used today.

b1 - If field weights are to be corrected, biologists need to have a good idea about 'normal' and 'abnormal'. They also need to have an undisputed tool to correct field weights. Based on what I read, my guess is it wouldn't be easy to get to adequate definitions on 'normal' and 'abnormal'. As to the tool. It's known (referring to the book of the Maharajah of Cooch Behar) that a gorged male tiger of average length was 55-60 pounds heavier than a non-gorged male of similar length shot in northeastern India a century ago, but the question is what 'gorged' means. The next question is to what extent a weight should be corrected. A tricky affair at best, I think.     

b2 - If you correct field weights of gorged tigers, you also need to correct field weights of tigers considered as 'underweight'. The question is what method should be used to get to a 'normal' weight. In order to get to an answer, detailed information on individual tigers is needed. This means biologists need to dart, measure and weigh a lot of wild tigers for a considerable period of time in different regions. As far as I know, this has never been done. Not on a large scale, I mean.

There is, however, some information that could be used. The Sauraha tiger (Royal Chitwan) gained 8 cm. and at least 100 pounds as an adult. We also know tiger 'Dale', known for his peculiar interest in bears, was 445 pounds when he was first darted. Some time later, after losing 3 of his 4 canines, he was 375. This, mind you, was on a full stomach. Curtains, one would think. But when he was weighed a third time, he was about as heavy as the first time. This one 1 canine only. 

Based on these 2 individuals, on could conclude the range in weight in more or less (the Amur tiger no doubt was affected by an injury when he had lost 70 pounds, but he apparently recovered) healthy adult male tigers is 70-100 pounds. In the (injured) Amur tiger, the range was 15-16%. In the (uninjured) Nepal tiger, the range was at least 20%.    
The male tigers shot in Cooch behar, the Duars and Assam a century ago averaged 461 pounds and about 9.8 'over curves'. Gorged tigers were about 60 pounds heavier than non-gorged male tigers of similar length. A gorged male tiger, therefore, was about 13% heavier than a non-gorged male tiger. Quite a difference, but the range in weight in the 2 male tigers mentioned above was 15-20%. My guess is it was closer to 20%, because the second time the Amur tiger was weighed, he only was 375 on a full stomach. On an empty stomach, he could have been 315 pounds only. This means he lost about 130 pounds (about 30%) of his 'normal' weight in the period he was injured.   

Considering the significant weight range in these 2 tigers, the question is what a full stomach really means. Is it justified to correct the weight of a gorged tiger? Is it justified to correct the weight of every wild male tiger when you know wild male tigers, both injured and uninjured, are subject to quite violent changes in weight over time?     
        
b3 - Even if biologists succeed to agree on definitions and tools, corrected weights will never compare to field weights. The reason is they are estimates, whereas field weights are accurate. No scientist should be willing to exchange accuracy for something else when there's no good reason.  

I agree one should add a bit of information on individuals when the sample is smallish and tigers have only been weighed once, but one has to remember that correction factors are of a subjective nature. Furthermore, they do not reflect the conditions faced by wild tigers. Conditions that can result in significant changes in weight over time.    

What I'm saying is corrections can result in inaccurate information, if not outright misinformation. If you add dismissals of old records, chances are biologists could underestimate the size of wild tigers. In India, it resulted in 500-pound scales when biologists decided to weigh wild tigers. Not quite adequate, they concluded. Same for the 600-pound scales used later. In India and Nepal, large male tigers can exceed that mark. 

The obvious conclusion is that not all exceptional individuals shot in the past were a result of 'special tapes', 'skins', hunters unable to count to three and Maharajahs interested in pleasing their guests no matter what. Tigers are large big cats showing a lot of individual and regional variation. They also respond to conditions. One or two centuries ago, when wild country dominated most of India and tigers often had the opportunity to reach their potential, exceptional individuals really exceeded 11 feet 'over curves'. They also could have been bulkier. Captive tigers say these old records can't be dismissed out of hand. At least, not all. In tigers, conditions really seem to affect size.  

Quite many consider captive tigers as mirrors of wild tigers. Captive Indian tigers are smaller than their wild relatives, but in Amur tigers it's the other way round. Reasons? Read post 281 in the thread 'Captive lion and tiger weights'.      

C - New series on Amur tigers in the Premium Section

In some time, I'll start a series on the size of Amur tigers in the new premium section. Not what we had in mind when we started five years ago, but we have no other option if we want to get rid of monopolists in the department of money. Yes, I was referring to Google. And we want to, as we're still unable to subscribe to magazins and pay our mods after exceeding 10 million views (...). It's quite incredible. One could conclude that tech monopolists are no different from other monopolists and be close. In the end, it isn't about 'more communication' and things like that, but profit. The more, the better. 

If you decide to join the Premium Section, remember the revenues will not be be used to develop the skills of the owners in the department of spending it in luxury places designed to attract monopolists. The aim is to develop the forum. 

It is needed. Those who know agree wild animals face extinction in unprecedented numbers. The process of extinction is accelerating. No question. We need to do something and we need to do it fast. If you post, remember that one in particular. It isn't about you being right or wrong: it is about informing people about the plight of those without a voice.
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Messages In This Thread
RE: ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris) - peter - 06-01-2019, 06:39 AM
Demythologizing T16 - tigerluver - 04-12-2020, 11:44 AM
Tiger Data Bank - Apollo - 07-28-2014, 09:54 PM
RE: Tiger Data Bank - Apollo - 07-28-2014, 10:02 PM
RE: Tiger Data Bank - Apollo - 07-29-2014, 12:56 AM
RE: Tiger Data Bank - peter - 07-29-2014, 07:05 AM
Tiger recycling bin - Roflcopters - 09-04-2014, 01:36 AM
RE: Tiger recycling bin - Pckts - 09-04-2014, 02:22 AM
RE: Tiger recycling bin - Roflcopters - 09-05-2014, 01:01 AM
RE: Tiger Data Bank - Apollo - 11-15-2014, 10:07 PM
RE: Tiger Data Bank - Apollo - 11-15-2014, 10:57 PM
RE: Tiger Data Bank - Apollo - 11-15-2014, 11:33 PM
RE: Tiger Data Bank - Apollo - 02-19-2015, 11:25 PM
RE: Tiger Data Bank - GuateGojira - 02-23-2015, 11:36 AM
Status of tigers in India - Shardul - 12-20-2015, 03:23 PM
RE: Tiger Directory - Diamir2 - 10-03-2016, 04:27 AM
RE: Tiger Directory - peter - 10-03-2016, 06:22 AM
Genetics of all tiger subspecies - parvez - 07-15-2017, 01:08 PM
RE: Tiger Predation - peter - 11-11-2017, 08:08 AM
RE: Man-eaters - Wolverine - 12-03-2017, 11:30 AM
RE: Man-eaters - peter - 12-04-2017, 09:44 AM
RE: Tigers of Central India - Wolverine - 04-13-2018, 01:17 AM
RE: Tigers of Central India - qstxyz - 04-13-2018, 08:34 PM
RE: Size comparisons - peter - 07-16-2019, 05:28 AM
RE: Amur Tigers - peter - 05-20-2021, 07:13 AM
RE: Amur Tigers - Nyers - 05-21-2021, 08:02 PM
RE: Amur Tigers - peter - 05-22-2021, 08:09 AM
RE: Amur Tigers - GuateGojira - 04-06-2022, 12:59 AM
RE: Amur Tigers - tigerluver - 04-06-2022, 01:08 AM
RE: Amur Tigers - tigerluver - 04-06-2022, 09:08 AM
RE: Amur Tigers - tigerluver - 04-06-2022, 11:30 PM
RE: Amur Tigers - peter - 04-08-2022, 07:27 AM



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