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

Netherlands peter Offline
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( This post was last modified: 04-08-2020, 04:31 PM by peter )

(04-08-2020, 01:19 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.


*This image is copyright of its original author


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:


*This image is copyright of its original author
   

Some males photographed in the last 2 decades seem to be quite close. More protection and better conditions have an effect:


*This image is copyright of its original author



*This image is copyright of its original author


Thanks again for the equation. Good work. Maybe you can find time to go over the bear information.
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United States tigerluver Offline
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( This post was last modified: 04-08-2020, 10:14 PM by tigerluver )

Excellent as always @peter. I’ll share a few thoughts later. Until then, I had a question based on the big tiger who escaped the snare. This tiger seems to refer to T16, who per old posts seemed to have gotten away. On the snare escapes, I see the story of a tiger named “Ivan”, who escaped and later died due to injuries in Kolchin and Maystrenko. In Gilbert et al. (2015), there is a tiger named T16/PT90 who died  of “canine distemper”. This tiger seemed to have been permanently maimed by a snare he broke. I infer Ivan and T16/PT90 from Gilbert et al. are the same and this Ivan was about 200 kg before losing half its weight per a post I read by @GuateGojira on the old boards (@GuateGojira could you confirm this and the source?).
So, are there two T16s or is this tiger with a claimed 13 cm paw Ivan?:

*This image is copyright of its original author


Edit:
Looking the photo of Ivan from Kolchin and Maystrenko, indeed the tiger above is the same as the one in the work:

*This image is copyright of its original author


The reason I bring this up is that one, the above photo has often been touted to be from an exceptional male. But if this is Ivan, he may've been weighed and we can see at what weight a tiger can start breaking snares. But again, I cannot find a source to confirm beyond a lost old board post. Next, I am interested in the source and to see if we can add another large pawprint and weight to the database.
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ON THE EFFECTS OF ALDRICH FOOTSNARES - I

a - Introduction

In 2013, 'The Snare for Tiger' was published on BIGCATS.RU Forums. The article, written by Kolchin (S) and Maystrenko (P), was translated by Alexey Bizin. It was corrected by Vladimir Dinets and Sergey Kolchin. The first part ('Beginning') has 8 pages. The second part ('Ending') has 7 pages, including an Addendum written by G.P. Salkina. As far as I know, it's still on the internet. 

Anyone interested in tigers captured with Aldrich footsnares in the Sichote-Alin Nature Reserve in the period 1992-2010 should read it. Same for those interested in wild Amur tigers allegedly 'killed by other tigers and bears'. The article also has information about 2 tigers captured in other reserves (see -c3-). 

Platon Maystrenko (biologist) and Sergey Kolchin (Phd), to be sure, are not amateurs. Same for Galina Petrovna Salkina (Phd). As Senior Research Fellow, she studied Amur tigers for many years in the Lazovsky Reserve. When the article was published, Kolchin was a Research Assistent at the Laboratory of Ecology and Animals in the Institute of Water and Ecology Problems, Far-Eastern Branch, Russian Academy of Sciences. He was part of the 'Amur Tiger Project' from October 2007 to Match 2009.
 
b - Intention of the series

I want to make it clear right from the start that all involved in saving wild tigers in some way are unsung heroes. They're the ones who who collected vital information and made sure we still have wild tigers in some regions. In my opinion, all of them deserve respect no matter what. 

Collecting information about wild tigers without a rifle, however, is far from easy. Same for capturing tigers with footsnares. Although not all tigers captured with Aldrich footsnares responded in the same way, some tigers were seriously injured trying to free themselves. It also is a fact that not a few perished in shortly after they had been captured. Finally, it's a fact that this method of capturing tigers affected the tiger population in the Sichote-Alin Reserve. 

The road to knowledge often is rough and rocky. The only way to do it in the right way and, as a result, learn is to record everything you do, including mistakes. In many respects, mistakes and failures are as informative as anything else. Provided you record them and succeed to avoid the usual pitfalls (like denial). The article of Kolchin and Maystrenko is an attempt to uncover incidents that, later, proved to be part of a pattern. It also is a detailed attempt to describe the effects of Aldrich footsnares. 

c - Answers to the questions in the previous post

c1 - Tiger 'Ivan'

In 2008, tigress 'Galya' had 3 maturing cubs. Galya had been captured twice (in 2002 and 2005) and, therefore, succeeded in avoiding traps, but her cubs were not so lucky. Male cub 'Ivan' (no. 88) was caught on May 3, 2008. Ivan Seryodkin told Kolchin he suffered some damage (a dent in a canine) trying to get out of the trap. Ivan's brother 'Clay' was captured on May 23, 2008. When trying to free himself, one of the lower canines broke down to the gum.

On June 17, 2008 a large male tiger was captured. This tiger was also called 'Ivan'. When Seryodkin, Kolchin, Miquelle and Clay Miller approached the tiger, he attacked and broke the binding of the footsnare. Seryodkin, carrying the gun to tranquillize 'Ivan', was bitten in the shoulder. The tiger could have killed him but was afraid of the hand flares and left the scene with a steel snare around his leg. Kolchin found a piece of one of his canines later. Members of the WCS checked the memory stick in Seryodkin's camera. It revealed that Seryodkin had conducted a photo session before his colleagues arrived at the spot. Seryodkin took hundreds of photographs. 

After he had broken the binding and attacked Seryodkin, tiger 'Ivan' managed to get rid of the steel trap around his leg and remained neutral to humans. That changed after he was captured a second time on October 27, 2009. Again he wounded himself trying to get free. A camera-trap picture taken fifty days after he had been captured showed a severely injured and emaciated tiger. On January 15, 2010, he killed a local fisherman. A day later, after he had attacked cars, 'Ivan' was shot. WCS employees, regarding his injuries, said he " ... apparently got into a fight with a bear or another tiger ... " (pp. 6 of the first part) and vets of the Primorskaya State Academy of Agriculture affirmed that view. But they, according to Kolchin and Maystrenko, lacked knowledge of wild animals and were sponsored by the WCS. 

c2 - Were 'Ivan' and tiger T-16 one and the same?

At the moment, I'm unable to answer the question, @tigerluver. I have to read the article you referred to first. There are more documents published in the period 2008-2012 I have to read, as the tigers mentioned in the article of Kolchin and Maystrenko feature in other publications as well. I'll get back to you on that one.

c3 - At what weight does a male Amur tiger start breaking snares?

In the second part of their article, Kolchin and Maystrenko say 'Ivan' wasn't the only male tiger who broke an Aldrich footsnare. In October 2009, John Goodrich was injured by a male tiger who broke the snare in the southwestern part of Primorye. In spring 2011, a mature male tiger also broke the snare and attacked the car with members of the of CAE RAS (they probably refer to members of the Russian Amur Tiger Project started in 2008). 

I don't know which tigers were involved and if they were weighed, but chances are they were not. For now, one has to assume they were not larger than the heaviest weighed in the period 1992-2020 (200-212 kg.).
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( This post was last modified: 04-12-2020, 12:05 AM by GuateGojira )

(04-08-2020, 05:45 PM)tigerluver Wrote: This tiger seems to refer to T16, who per old posts seemed to have gotten away. On the snare escapes, I see the story of a tiger named “Ivan”, who escaped and later died due to injuries in Kolchin and Maystrenko. In Gilbert et al. (2015), there is a tiger named T16/PT90 who died  of “canine distemper”. This tiger seemed to have been permanently maimed by a snare he broke. I infer Ivan and T16/PT90 from Gilbert et al. are the same and this Ivan was about 200 kg before losing half its weight per a post I read by @GuateGojira on the old boards (@GuateGojira could you confirm this and the source?).

The document that I have is this: Goodrich et al., 2012. CHAPTER 11 - Tooth breakage in tigers: cause for conflict? in "Diseases and parasites of wildlife in Siberia and the Russian Far East - Monograph". In page No. 113 they mention this male tiger of 200 kg and about 7 years old but they did not identify him.

In a document of Dr Miller of 2012 (his thesis) I found the male tiger named "Ivan" with Id Pt-90 that weighed 200 kg and had an estimated age of 10 years and captured in the Fall of 2009, that is the information that I used for my table of 2015. In the report of the WCS-STP of July 2007-June 2008 they mention a tiger identified as "T-09" that was radiocollared and tagged as "PT-85", that male weighed 200 kg and had an age of about 8 years old and was radiocollared in this period. The report also mention the male T-16 but it was not captured.This is the picture of the  male T-09 latter known as PT-85 with 200 kg:

*This image is copyright of its original author


So, as far I know T-16 was not captured but I remember a webpage that says that it was huge (supported by the picture that you have). About the other two male tigers (T-09--Pt-85 and Pt-90--Ivan, both of them weighed 200 kg. That is the information that I have.
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( This post was last modified: 04-12-2020, 11:49 AM by tigerluver )

Thank you @GuateGojira for the information. With that I have been able to put together who I think this "T16" is (camera trap from 2008):

*This image is copyright of its original author


First of all, thanks to Kolchin and Maystrenko (2013), we have a second image of T16. I came to this conclusion based on the identical stripe pattern between these two pictures. Take a close look at the area circle in yellow:

*This image is copyright of its original author


The pattern is unique and identical in that region. Looking at other areas also showed a near perfect match.

Kolchin and Maystrenko (2013) detail the story of the tiger on the right, in turn detailing the story of the tiger on the left. This tiger was named Ivan, tagged as PT90. We can verifty PT90's identity as T16 via the timeline described by Kolchin and Maystrenko (2013). In mid-2008, a tiger who would later be known as Ivan (PT90) escaped its snare and attacked a researcher. At this time, the tiger lost a piece of its canine.:


*This image is copyright of its original author


This same tiger was later snared successfully in October 2009. He looked like this a couple weeks before the life-changing moment:

*This image is copyright of its original author


After the snaring, Ivan (PT90) received debilitating injuries to his left foot, emaciating him. By January 2010, he was put down after killing a human. At that point, this was all that was left of him:

*This image is copyright of its original author


Now we can verify that the 200 kg male PT90 in Miller (2012) is the same Ivan discussed by Kolchin and Mastrenko (2013) and therefore the same specimen as the mythical T16. Per Miller (2012), PT90 was captured in "fall 2009", matching Kolchin and Maystrenko's reported date of capture. He then died after human conflict in January 2010, again matching both the date and reason of death as described by Kolchin and Maystrenko (2012). We can further verify that PT90/Ivan is T16 by the note in Gilbert et al. (2015) which noted PT90 has also been described as T16 in prior reports and literature who died of "canine distemper" after tiger-human conflict. With timelines and stories from multiple sources matching each other, irrefutably the mythical T16 is PT90/Ivan. Moreover, the photo comparison above leaves no doubt.

This means T16 was weighed, and weighed 200 kg. This is quite average. However, perhaps T16/PT90/Ivan was indeed a bit more exceptional in the camera trap in 2008. T16 was weighed at the older age of 10, about a year and half after losing a canine due to the Aldrich snare. Very clearly, T16 was not as robust in 2009 as he was in 2008. Below I show a comparison of T16's mythical photo and 2009 photo:

*This image is copyright of its original author


Without any measurements, it is apparent that 2008 T16 (on the left) was bulkier. Already an older tiger and then further debilitated by the loss of a canine, T16 understandably lost mass. In this comparison photo, I scaled both photos to the same shoulder height. Shoulder height does not ideally change when mass is lost with age in quadrupeds and therefore is an appropriate tool for scaling both images to equal body frame size. At the same shoulder height, we can see that T16 had greater chest and forearm diameters in 2008 as compared to 2009. Specifically, his chest diameter was 1.12x greater and forearm antero-posterior diameter was 1.15x greater. With these ratios, we can estimate how much heavier T16 was in 2008 as compared to 2009.

I will try to explain the theoretical basis of the mathematics the best I can, but please do ask for clarification if needs. When estimating mass between two separate individuals, the individual with the larger say chest diameter should also be equally larger in length and shoulder to shoulder width (I will call this depth from hereon). This results in an scale exponent of 3. Therefore we have the equation:

Mass  specimen 1= (Chest diameter 1/chest diameter 2)^3 * mass specimen 2

However, when we are comparing diameters from the same individual, body length will not change. Theoretically, increasing the width of a muscle (sarcomere at the smaller level) should also be associated with an equal increase the depth of the muscle. The same idea is likely for adipose tissue. Therefore, the scale exponent when comparing diameter changes within the same individual should drop to 2 and the equation is as follows:

Mass  specimen at diameter 1 = (Chest diameter 1/chest diameter 2)^2 * mass specimen at diameter 2

If we apply this above equation to the measurements in the photograph, we get the following estimates for T16's 2008 mass using his 2009 mass for comparison:

Using chest diameter:

2008 mass = (184/164)^2 * 200 kg
2008 mass = 252 kg

Using forearm diameter:
2008 mass = (91/79)^2 * 200 kg
2008 mass = 265 kg

Average 2008 mass = 259 kg

Now it is possible that if a diameter increases in one direction, the diameter does not increase in the perpendicular direction. This would drop the scale factor to 1. Therefore, we have one more theoretical equation for mass estimation:

Mass  specimen at diameter 1 = (Chest diameter 1/chest diameter 2)^1 * mass specimen at diameter 2

Applying this formula, we have the following estimates:

Using chest diameter:

2008 mass = (184/164)^1 * 200 kg
2008 mass = 224 kg

Using forearm diameter:
2008 mass = (91/79)^1 * 200 kg
2008 mass = 230 kg

Average 2008 mass = 227 kg

When (vertical) chest diameter increases due increase muscle mass and adipose tissue, the chest depth probably does increase as well but not to the proportional degree of (vertical) chest diameter due to the vertical pull of gravity. Similarly, when a forearm grows in antero-posterior depth, it likely grows in lateromedial diameter as well but not to the same degree as the chest wall would limit the medial expansion of the muscle belly. Therefore, I feel the actual scale factor for estimating the weight of an individual at different diameter measurements lies between 1 and 2. If we average together the two weights in bold, we are essentially using a scale factor in the middle of 1.5. The estimated 2008 weight with a scale factor of 1.5 would thus be 243 kg. All in all, T16 was likely not 270-300 kg mythical giant, but still in his prime a large Amur tiger by modern standards.

Regardless of which scale factor one prefers, what is apparent is that the 2008 form of T16 was heavier than the 2009 form. At the least he was probably 20 kg heavier, and at the most around 60 kg heavier. Seasonal changes in body fat may in part explain the such a difference. However, Kolchin and Maystrenko's description of the damage caused by Alrich snares cannot be ignored. An old tiger already, both aging and a broken canine probably took T16's spot away as the heaviest scientifically weighed Amur tiger during the Siberian Tiger Project. By the end, his condition resulted in him losing another estimated 100 kg per Salkina (Kolchin and Maystrenko 2013). A very somber end to possibly one of the larger Amur tigers of today.
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( This post was last modified: 04-25-2020, 05:03 PM by peter )

IS THE CORONOVIRUS A THREAT TO WILD TIGERS?

Captive tigers and lions have been affected by the coronovirus (Bronx Zoo, New York City), but it wasn't known if the virus could affect wild tigers. That recently, at least to a degree, changed when a Pench tiger showed signs of illness. Although treated with antibiotics, he died near a water hole. 

A few days before it was determined a giant hairball had likely killed the cat, Indian officials put the country's 50 wild tigers reserves on high alert. A bit premature, some concluded. 

But tigers are vulnarable to rabies, anthrax and canine distemper and can also fall victim to infectious peritonities, a disease caused by another coronavirus strain that affects the gastrointestal tract. 

Furthermore, Chinese researchers recently demonstrated that the virus reproduces efficiently in domestic cats and can be transmitted by respiratory droplets between animals. The results have not yet been subject to peer review, but Anup Kumar Nayak of the National Tiger Conservation (" ... This coronavirus could turn out to be very dangerous ... ") doesn't want to take any risks. 

Ullas Karanth, however, is more worried about the indirect effect of the virus. He thinks desperate locals, hunting tiger prey species for meat during the lockdown, are a bigger threat than the disease: " ... There is a real surge in this kind of hunting ... ":       

https://www.nytimes.com/2020/04/22/science/india-tigers-coronavirus.html?referringSource=articleShare

Here's the New York Times article written by Gloria Dickie for those not involved in links (thanks, Shelly). I added a few colours. Hope you don't mind:


*This image is copyright of its original author


*This image is copyright of its original author
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( This post was last modified: 04-25-2020, 11:30 PM by peter )

MEASUREMENTS AND WEIGHTS OF TIGER AND GAUR SHOT IN THE NORTH COIMBATORE JUNGLES IN OR BEFORE 1937

a - Introduction

When I was reading all volumes of the Journal of the Bombay Natural History Society (JBNHS) published in the period 1885-1960 once again, I found a lot of information about the size of big cats and many other mammals. Most records are dismissed by biologists, but those who measured and weighed big cats were accurate. Not seldom, they explained in what way the method used was applied in great detail.   

In some regions of what used to be British India big cats were measured 'over curves', but in other regions they were measured 'between pegs'. Most of those informing the members of the JBNHS measured big cats 'between pegs'. 

The main advantage of this method is it reflect the true length of a big cat. This is why zoologists in (most) natural history museums in western Europe still use this method. Another advantage is the outcome of a measurement taken in this way by different people is more or less similar. This is not the case when a cat is measured 'over curves'.    

Some years ago, when I measured (sedated or deceased) captive big cats every now and then, I often used the opportunity to test the differences between both methods ('over curves' and 'between pegs'). A big cat measured 'over curves' by different people always produced quite different results. A cat measured 'between pegs' by different people did not. 

Biologists today measure wild big cats 'over curves'. The most probable reason is it isn't easy to find a flat surface in wild country. Furthermore, it isn't easy to move a big cat not seldom well exceeding 400 pounds. 

Although biologists say the method in use today is used in a more or less uniform way, descriptions offered by those involved in measuring big cats suggest the method seems to be applied in different ways.

b - On a letter of R.C. Morris published in the JBNHS in 1938

In the days of the British Raj, officers in particular often recorded the length and weight of big cats they shot. Not all of them sent letters to the editors of magazines like The Field, The Indian Forester or the Journal of the Bombay Natural History Society, but quite a few did. One of the main contributors in the department of measurements and weights was R.C. Morris. 

In Volume XL (40), Part 1 (Miscellaneous Notes, No. II, pp. 114-115), I found this letter:


*This image is copyright of its original author
 

*This image is copyright of its original author


The undated letter (most probably posted in the autumn of 1937 and) published in the spring of 1938, doesn't have a nice story and isn't very long. Chances are you'll just take a brief look and then move on. The letter, however, offers a wealth of information on the size of three species often hunted in those days. 

As his letter can be used to find out a bit more on the size of tigers, leopards and gaurs in that region about 80-90 years ago, I decided for two tables. The table on leopards was posted in the leopard extinction thread. The table on tigers was posted in this thread.  

c - The length of tigers and the weight of gaurs shot in the North Coinbatore jungles in or before 1937

The table below is based on the letter discussed above. Two tigers, a female with a total length of 7.5 and a male with a total length of 6.6, were not used for the table (1). The reason is both, most probably, were immature. Feet and inches were exchanged for cm. and pounds were exchanged for kg. (2). I assumed the animals in his letter were shot in or, more likely, before 1937 (3). All tigers were shot in the North Coimbatore jungles (4). Same for the 4 gaur bulls: 


*This image is copyright of its original author
   

One more thing. In his letter, Morris didn't say in which way the tigers were measured. He, however, did in other letters. Tigers and leopards were measured 'between pegs'. 

d - Conclusions

Those of you interested in size will remember that male tigers in Central India (referring to Dunbar Brander's 'Wild Animals in Central India' published in 1923) averaged 9.3 (281,94 cm.) in total length, whereas tigresses averaged 8.4 (254,00 cm.). The 3 longest males shot in Central India taped 10.3 (312,42 cm.), 10.2 (309,88 cm.) and 9.11 (302,26 cm.).

Male tigers shot in the North Coimbatore jungles were a bit shorter (just over 8.11 in total length 'between pegs' as opposed to 9.3), but females (8.4) were as long as those shot in central India. The longest male shot in the North Coimbatore jungles taped 9.10 (299,84 cm.), but the sample of Morris is quite limited. In other letters published in the JBNHS, I found reliable records of male tigers shot in the Nilgiris exceeding 10.0 (304,80 cm.).  

When discussing southern India, one has to distinguish between the Nilgiris and, for example, the Deccan. Nilgiris tigers were, and still are (referring to recent information of Ullas Karanth), quite large, whereas those shot on the Deccan were smaller. The two longest male tigers shot on the Deccan I know of (referring to information provided by Brig.-Gen. R.G. Burton), were 9.8 'between pegs'.

Coimbatore seems to be on the border. Here's map of 1909. Coimbatore is just below Mysore (watch the red marker):


*This image is copyright of its original author


   
e - More information on the size of tigers in southern India

Those interested in the size of tigers in southern India can find a lot more in the JBNHS. Apart from that, you can find a number of free e-books. When you can, order a few books published a century ago. Most reprints are quite cheap.  

As stated above, Nilgiris tigers are quite large, whereas those shot in Mysore and what was known as the 'Madras Presidency' in the days of the British Raj were smaller. 

Over the years, I found a lot of books about Sumatran tigers published in the days of the former Dutch East Indies (now Indonesia). Some hunters visited southeastern India. They thought there wasn't much to choose between tigers in southeastern India and Sumatra. Those in southeastern India were generally a bit bigger, but the difference was limited. This, of course, was in the days Sumatra had much more tigers.
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A new study on the prey habits of Bandhavgarh tigers. Here is their key table:


*This image is copyright of its original author


The weight of prey eaten per scat is another interesting point that could be of use for those "empty belly" estimations. It is based on this equation from Ackerman et al. (1984):

*This image is copyright of its original author


From my understanding (which may be off the mark), the equation was derived by comparing prey mass and how much of the prey was consumed by 3 captive cougars. Navaneethan et al. (2020) apply this equation to tigers. If this equation holds true, tigers don't seem to eat as much per kill perhaps. The limitation of this method is that it as a calculated estimate and not actually weighing what is left of consumed prey.

Digging deeper into the Ackerman et al. (1984), the test cougars produced 9 kg of scat total (average scat of 203 g x n of 45) and consumed about 40 kg of prey (summing from the graph above) throughout the study. This would be about 75% of intake is digested and assimilated and 25% is defecated. Therefore, when correcting body mass for food intake, simply subtracting the entire mass of prey consumed from the measured body weight of the cat is inaccurate as such does not account for absorption and assimilation of intake. If we assume tigers have similar efficiency of digestion as cougars, we could infer that 14 kg of consumed prey would need a mass correction of 3.5 kg (25% of consumed biomass).

I have attached both papers. Please let me know your thoughts.

Attached Files
.pdf   AJCB-Vol8-No2-Navaneethan et al.pdf (Size: 532.06 KB / Downloads: 3)
.pdf   ackerman1984.pdf (Size: 1.23 MB / Downloads: 2)
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United States Pckts Offline
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(04-29-2020, 01:00 AM)tigerluver Wrote: A new study on the prey habits of Bandhavgarh tigers. Here is their key table:


*This image is copyright of its original author


The weight of prey eaten per scat is another interesting point that could be of use for those "empty belly" estimations. It is based on this equation from Ackerman et al. (1984):

*This image is copyright of its original author


From my understanding (which may be off the mark), the equation was derived by comparing prey mass and how much of the prey was consumed by 3 captive cougars. Navaneethan et al. (2020) apply this equation to tigers. If this equation holds true, tigers don't seem to eat as much per kill perhaps. The limitation of this method is that it as a calculated estimate and not actually weighing what is left of consumed prey.

Digging deeper into the Ackerman et al. (1984), the test cougars produced 9 kg of scat total (average scat of 203 g x n of 45) and consumed about 40 kg of prey (summing from the graph above) throughout the study. This would be about 75% of intake is digested and assimilated and 25% is defecated. Therefore, when correcting body mass for food intake, simply subtracting the entire mass of prey consumed from the measured body weight of the cat is inaccurate as such does not account for absorption and assimilation of intake. If we assume tigers have similar efficiency of digestion as cougars, we could infer that 14 kg of consumed prey would need a mass correction of 3.5 kg (25% of consumed biomass).

I have attached both papers. Please let me know your thoughts.
Add to that the issues with Scat sampling.
Most likely you will not know the actual age, sex or weight of the prey taken from scat.
You will also probably be monitoring a limited number of Cats since finding scat samples is generally very difficult unless you know where the cats territory is. 
I'd also wager heavily that Bandhavgarh now has far more Cattle present as well as the reintroduction of Gaur, both would contribute quite a bit to those numbers.
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Guatemala GuateGojira Offline
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(04-29-2020, 01:00 AM)tigerluver Wrote: A new study on the prey habits of Bandhavgarh tigers. Here is their key table:


*This image is copyright of its original author


The weight of prey eaten per scat is another interesting point that could be of use for those "empty belly" estimations. It is based on this equation from Ackerman et al. (1984):

*This image is copyright of its original author


From my understanding (which may be off the mark), the equation was derived by comparing prey mass and how much of the prey was consumed by 3 captive cougars. Navaneethan et al. (2020) apply this equation to tigers. If this equation holds true, tigers don't seem to eat as much per kill perhaps. The limitation of this method is that it as a calculated estimate and not actually weighing what is left of consumed prey.

Digging deeper into the Ackerman et al. (1984), the test cougars produced 9 kg of scat total (average scat of 203 g x n of 45) and consumed about 40 kg of prey (summing from the graph above) throughout the study. This would be about 75% of intake is digested and assimilated and 25% is defecated. Therefore, when correcting body mass for food intake, simply subtracting the entire mass of prey consumed from the measured body weight of the cat is inaccurate as such does not account for absorption and assimilation of intake. If we assume tigers have similar efficiency of digestion as cougars, we could infer that 14 kg of consumed prey would need a mass correction of 3.5 kg (25% of consumed biomass).

I have attached both papers. Please let me know your thoughts.

You done it, you hit the nail!!! This is what I tried to explain but I did not manage to do it. That part of the amount ingested by the tiger is absorved, so it is incorrect to "adjust" the body weight of an animal taking in count the entire amount ate, as part of that is going to be absorbed. Also we must take in count the time of the digestion, which in cats is very fast, in fact they can be empty-belly is less than 6 hours after a large meal.

Also, again, we must remember that the estimation at simple sight for the stomach content is not accurate, as Dr Chundawat (2018) proved with the tiger M-91: the field team members estimated that the tigers could eat between 25 - 30 kg in one sitting, but when the large male M-91 vomited and emptied his belly after a full meal the last night, the amount was actually "just" 19 kg, a big diference from the estimated figures.

Thank you for sharing this information @tigerluver.
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( This post was last modified: 04-29-2020, 06:09 AM by Ashutosh )

@GuateGojira, doesn’t the Chundawat case prove that they actually can eat 25-30 kilos in a sitting. Think about it. A tiger finishes up eating at night, about 6 hours the next morning, it throws up 19 kilos of content. You yourself said that total digestion in some cats takes 6 hours implying that the tiger digested some content while throwing up the rest (not accounting for the content that was absorbed) essentially concluding that there was more than 19 kilos in its stomach possibly in the 25-30 kilos range that Chundawat claimed.
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United States tigerluver Offline
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So the data on absorption begs question on whether it's worth correcting for food weight when the animal is not gorged. For instance, in a 19 kg meal, within the next 24-48 hrs 14 kg of that would be assimilated into maintaining tissue mass and other processes. Then there'd be about 5 kg of stool and colonic contents. Pretty much every mammal that is not in a starvation state has colonic contents at baseline. Therefore, colonic contents are essentially part of the organisms functional weight and removing them would be an unnatural modification. 

Of course for gorging the subtraction would be warranted, but likely we have to subtract less. Remember, the hunters who liked to subtract gorged bait weight from cats never gave the animal a chance to assimilate 75% of the bait in baseline body functions, as well... they killed the animal.
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Guatemala GuateGojira Offline
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(04-29-2020, 06:08 AM)Ashutosh Wrote: @GuateGojira, doesn’t the Chundawat case prove that they actually can eat 25-30 kilos in a sitting. Think about it. A tiger finishes up eating at night, about 6 hours the next morning, it throws up 19 kilos of content. You yourself said that total digestion in some cats takes 6 hours implying that the tiger digested some content while throwing up the rest (not accounting for the content that was absorbed) essentially concluding that there was more than 19 kilos in its stomach possibly in the 25-30 kilos range that Chundawat claimed.

Dr Chundawat did not claimed anything, it was just an estimation with the staff in the park. Also, remember that contrary to normal perception, tigers do not eat constantly the full 6 hours, in fact, the time at the bait may be less, depeding of what hour the tiger killed the animal.

Based in the case of Chitwan, the baits were put in the evening (between 6 to 7 pm) and the kills were not made just one hour after, but normally in the night (sometimes even after 12 am, as tigers hunt more in the night) and the tiger eat about 1 hour and rest, leave the place and take water and after that brake it eats again. That is why the average food intake in a day is between 14 to 19 kg in Nepal. So there is no reason to think that Panna tigers eat a different amount.

Other error is to think that the tiger ate the 20-30 kg in one sitting, or in just 6 hours. The issue is that the figures of up to 34 kg are for one entire day, a period of 24 hours, in the case of the Nepalese tigers (Tamang, 1982). Normally, when the tiger is captured it is disturbed at the baits and they do not eat in full, but just partially, that is why the average figure is about half of the full amount that a tiger can eat. So, although Dr Chundawat do not provide any other detail, the only thing that we can know is that the amount of that tiger, that was captured in the morning (normal time of captures are after 6 am, when the killed bait is located and when all the capture process is ready), was of 19 kg in the belly and if there was other amount, or if it was already allready absorbed is just speculation. However, as tigers eat in intervals, it will be very weird to imply that the tiger did absorved something or maybe, if the animal eat something more during the breaks between meals.

An example where we can apply this case is the hunt of a tiger in Rajasthan made by Colonel Kesri Singh. The tiger was bated in the morning, but the kill lasted the entire day until dawn when they finally killed the tiger. In that period the tiger was persecuted and he did not manage to eat anything, so whatever the amount that ate was, the tiger by that time was empty belly and all the amount of food was probably absorved.

So yes, tigers can eat up to 30 kg, but normally, in discturbed baits and with less than 12 hours at the kill, they will eat much less. M-91 was with a full belly in that moment, but the belly was of less than 20 kg and he could eat probably more if it was not disturbed.
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Guatemala GuateGojira Offline
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(04-29-2020, 07:38 AM)tigerluver Wrote: So the data on absorption begs question on whether it's worth correcting for food weight when the animal is not gorged. For instance, in a 19 kg meal, within the next 24-48 hrs 14 kg of that would be assimilated into maintaining tissue mass and other processes. Then there'd be about 5 kg of stool and colonic contents. Pretty much every mammal that is not in a starvation state has colonic contents at baseline. Therefore, colonic contents are essentially part of the organisms functional weight and removing them would be an unnatural modification. 

Of course for gorging the subtraction would be warranted, but likely we have to subtract less. Remember, the hunters who liked to subtract gorged bait weight from cats never gave the animal a chance to assimilate 75% of the bait in baseline body functions, as well... they killed the animal.

I think that the assimilation of the food will be in less time, specially in cats, because they had a high metabolic rate and its intestines had a good digestive process. Now, the colonic content is also correct, it is imposible to "correct" it as there is going to be allways an amount, so you have a good point on that.

In few words, the "empty belly" concept is just hipotetical, as while the stomach is going to be probably "clean", there is going to be content in the intestines, or even fat. So, never is going to be 100% accurate.

However, what is funny is that the "tiger-haters" in other forums complain about the Nepalese tigers but they do not say anything about the Etosha and Hobatere lions, which also were bated and that also ate a lot of domestic cattle. So, if we are going to compare "apples with apples", the same "puritanism" should be apply in both species. Interesting, this is not demanded in other species, by this same small group of people.
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( This post was last modified: 05-15-2020, 12:23 AM by peter )

THE RELATION BETWEEN HEEL WIDTH AND WEIGHT IN WILD MALE AMUR TIGERS - V (continuation of IV)

i - Additional information

In 1996, 'Numbers, distribution and habitat status of the Amur tiger in the Russian Far East: Express-Report', Matyuskin (EN) et al. (USAID) was published. 

Chapter 3 ('Methods') has some information about the relation between heel width, gender and age:

" ... Delineating the sex-age structure of the tiger population was based on measurements of track size. There is a considerable database for estimating sex of tigers from track sizes, based on measurements of the width of the main pad of the front paw of know sex and age tigers. Besides information from zoos (Matyuskin and Yudakov, 1974), there are data on tigers in the wild that died or were killed in nature (Nikolaev and Yudin, 1993), and also on animals captured and radiocollared (Miquelle and Smirnov, unpublished). Thanks to help of Ms. S. Christie, EEP Tiger Coordinator, this year we obtained additional track size data from captive tigers. Data from 130 tigers of determined sex and age confirm previous assessments (Matyuskin and Yudakov, 1974). We summarize the main points here.

With very few exceptions, tracks with pad width equal or exceeding 10,5 cm represent males. Tracks ranging in size from 8 to 10,5 cm include both adult (and subadult) tigresses and subadult males, although females are the predominant sex in this category. Many zoo-raised males exceed 10,5 cm in their second year; similar measurements have been made on young males still traveling in a family group in the wild (Miquelle and Smirnov, unpublished). In general, pad size stabilizes when males reach 3-4 years of age. Identification of tigresses is reliable when smaller tracks (representing cubs) are found in association with them, and in these cases, all measurements of tigress pads width are within the 8 to 10 cm range. track measurements of cubs in association with mothers in winter usually range in size from 6,5 to 8 cm, but as already noted, can reach 10.5 cm ... " (pp. 8). 

Chapter has information about the pad width of two adult tigers and two cubs:

" ... For the entire winter period of 1995-1996, tiger tracks were located near the Chinese border in the upper basin of the Right Komissarovka River. Two adult individuals appeared here at different times: a male tiger with a pad width of 10,5 cm, and a female (9,0 cm) with two cubs (8,5 and 8,0 cm) that wandered independently. All four individuals periodically crossed the country border into China ... " (pp. 9).
   
j - Conclusions

1 - There is information about the relation between heel width, sex, age and weight of captive Amur tigers in 'Tracks of the Amur tiger', E.N. Matyushkin and A.G. Yudakov, 1974, in: Hunting and Hunting Economy 5, pp. 12-17. It's likely the publication of Matyushkin and Yudakov is in Russian. 

2 - Miquelle and Smirnov have unpublished information about the heel width of wild Amur tigers

3 - The heel width of wild male Amur tigers nearly always exceeds 10,5 cm. Apart from a few exceptions, the heel width of wild adult females ranges between 8,0-10,0 cm. 

4 - The heel width of male Amur tigers stabilizes when they reach 3-4 years of age.

5 - I found three records of wild male Amur tigers with a heel width of 13,5 cm. According to @tigerluver (see posts 2,468 and 2,475 of this thread), a tiger with a heel width of 13,5 cm. ranges between 221-291 kg. if all tigers would be used for the equation. If only males would be used, the predicted range is 259-337 kg. (most likely outcome 295 kg.). 

6 - The heaviest wild tiger actually weighed in the period 1992-2020 was a young adult male of 212 kg.
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