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

[GuateGojira]

(03-11-2020, 02:56 PM)peter Wrote: GUATE

First of all many thanks for the overview on the size of wild tigers.  

As to the connection between the averages and the additional remarks: I agree with the question of Bornean Tiger on the average weight of wild male Amur tigers. I assume you decided to include a few historical weights, but I could be wrong. Could you inform us on the reasons?

There's a bit more. I'm referring to your info on skulls and length and the difference between wild and captive tigers. 

a - Body length

My advice is to add a remark on the method to measure tigers. In the recent past (1860-1955 roughly), hunters and naturalists in what was then British India distinguished between measurements 'between pegs' and measurements taken 'over curves'. The first method, as far as I know, was only used by some hunters in some parts of British India. Apart from a few exceptions (I have a dozen measurements of Indochinese tigers taken 'between pegs'), tigers were measured 'over curves'. Today, biologists measure wild tigers (and other big cats) 'over curves' just about everywhere. In order to prevent confusion, my proposal is to use measurements taken 'over curves' only. You could add a table with measurements taken 'between pegs' later. 

b - Skulls 

You said V. Mazak's tables (referring to the tables published in 'Der Tiger', third edition, 1983) pop up in just about every book about tigers and added his tables are a bit confusing, because he mixed measurements of skulls of captive tigers with those of wild tigers. I agree regarding Amur tiger skulls, but I'm not sure about the other subspecies. My proposal is to add a remark on Mazak's conclusions on the skulls of Amur tigers. 

The remark on the 385,00 mm. skull of a Caspian tiger in your overview can be removed, as it is confusing. In his book, Mazak said the owner of the skull was not a large animal. He added the information about that particular skull was unreliable. Furthermore, the skull was lost. 

As to the skulls of tigers in Malaysia. More than a century ago, an interview with the Sultan of Johore was published. The interview had a number of photographs and was discussed in this thread. Some of the tigers he shot well exceeded 9 feet 'between pegs'. Remarkable, as the males shot by Locke in Trengganu half a century later averaged about 8.7 'between pegs'. Locke ('The tigers of Trengganu') saw the records of the Sultan and confirmed large individuals had been shot by the Sultan. 

One of the tigers the Sultan shot had a skull with a greatest total length of 365 mm. A few years ago, a skull with a greatest total length of 370 mm. was discovered in the Helsinki Natural History Museum (Finland). This skull was from the southern part of Malaysia, meaning it can be used in your overview. 

My proposal is to use information published by the one who adopted Mazak's name (referring to J.H. Mazak). His samples are quite large, meaning the averages he found are reliable. I'm referring to the skull size of P.t. sondaica, P.t. sumatrae and P.t. corbetti. 

c - The difference between wild and captive tigers

Recent information strongly suggests there are significant differences between wild and captive tigers. Apart from Amur tigers, wild tigers often are larger and heavier than their captive relatives. In adult males, at the level of averages, the difference in large subspecies could be 10-20%.  

Between 1940-1980 roughly, four tiger subspecies (P.t. balica, P.t. sondaica, P.t. virgata and P.t. amoyensis) have been exterminated. Those involved in overviews, regarding the subspecies I referred to, therefore, have no option but to use old information. The problem is, the distinction between old and new information isn't always easy to spot in tables. For this reason, overviews need quite a few additional remarks. 

I know there isn't much room for additional remarks in your overviews, but maybe you could change a few things here and there. In the end, it isn't about the pictures, but the quality of the information.   

d - New information

You know most tables and overviews are based on a limited sample. This means the conclusions are moderately reliable at best. In the near future, to a degree, things will change. I measured about 400 skulls of big cats in natural history museums and private collections. In a few months from now, I'll have more time to visit museums and private collectors. Apart from the skulls I measured myself, I found a lot of good information elsewhere. All in all, I have about 1,000 skull measurements I consider reliable. 

I will post a number of tables this year. The aim is to distinguish between captive and wild and young adults and adults and every table will have individual entries only. I will contact you when I'm ready. 

In the meantime, some of us could contact field biologists or wildlife organisations in Indonesia, Malaysia, Thailand, India, Nepal, Bhutan and Russia. We need recent and reliable information about the size of wild tigers.

Hello @peter, thanks for your replay, I will answer the remarks:

a - Body length:
In fact, the image did explain which animals were measured "between pegs" and which "along the curves". In fact, as I say and also you confirm it, it seems that only Bengal tigers and a very few other specimens for the other subspecies/populations were actually measured "between pegs". Now, sadly I only have measurements "between pegs" as I discarted all those taked "along the curves" in litterature for obvious reasons. In fact, the only one that I still conserve the measurements "over the curves" are some tigers from India and those from the Caspian, that is all. Amur tigers, for obvious reasons are included only those "over curves" as that seems to be the method used by Russian Biologist in the old and apparently also in the new records, so there is no option. About Bali tigers, Mazák believe that the other measurements, which are two females as far I remember, were probably "over the curves" or maybe even "skin measurements", which is even more unreliable.

b - Skulls:
About Mazák, it is not a secret that I greatly admire him and he is still one of the main sources, so my remarks were only for education, not for other thing, I want to make that point clear. About the Amur tigers, I was not talking about skulls but about the weights, as we know that the heaviest tiger of 306 kg reported by Mazák was a captive one. About the skull of the Caspian tiger, I decided to use it because been honest, is in the same position like the other large skulls of the Bengal and a Amur tigers, those are huge skulls that can't be confirmed, or at least the one of 406 mm from Manchuria is the more reliable, but the other ones, we can only believe in the original report. In fact, I think that a size of 385 mm is posible for the Caspian tiger, as they were just slightly smaller than the Amur and Bengal populations:

*This image is copyright of its original author

I still remember this image and I can only wonder how large was this specimen.

About the Malayan tiger, Locke was the main source for body size and I also mention in the image the large skull of 370 mm that based in DNA it was classified as a Malayan tiger (check the remarks under the weight and skull lenght figures). 

Finally I used the average of skull length from Yamaguchi et al. (2009) because the sample is larger and I used the ranges from Mazák (2013) as it shows the maximum and minimum reported in all litterature. For Indochina and Malaysia, I used the averages from J. H. Mazák (2008) which separated the two subspecies in the case of the males, check this:

*This image is copyright of its original author

Ranges were taken from Mazák (2013) to complete the figures.

c - The difference between wild and captive tigers:
It was a hard decision to use captive weights for the tables, but it was the only form to fill the gap, however I clearly showed it when I use it to avoid confusion (red letters). I think that what we can do is maybe to add a remark explaining that captive specimens normally weight less than wild specimens (except for Amur tigers, for some reason). Now, other thing will be to exclude them, but I think that it will be unfair for those that gathered that data and at the end, is usefull at least for the record, in thise case Slaght et al. (2005) which contacted the zoos.

About old and new information, check that we already had the same problem with Bengal and Amur tigers in the past, so now we already know the methods to classify the reliable information. So you can be sure that the few information available for tigers of Caspian, Java and Bali posted in the image is the only reliable one. About South China and Malayan tigers, I used captive weights just to fill the gap, but like I told you, there are remarks in red color showing the difference.

d - New information
I am very excited to know that you have more information about skulls of tigers. I really appreciate your effort. I was thinking about that and also that you said that you have more measurements, so when you are ready to publish your information, I can help you to create tables or even comparative images. About to contact experts of other countries, I have tried to do it but no results for the moment, sadly.


Greetings. Reply