Size and weight siberian tiger

[GuateGojira]

Hi again @AlejoBravo96 , I see that you created another post about the same topic here: https://wildfact.com/forum/topic-weight-...#pid191750

Maybe it will be better if a moderator can delete it and we can continue with your questions in this same topic, to avoid duplicities.

So, this is what you put there:

"Hola chicos, espero que estén bien. Soy nuevo en este espacio pero estoy feliz de aprender como muchas personas. Me gustaría preguntarte sobre el verdadero peso y tamaño del tigre de Amur, ya que he visto varias publicaciones afirmando que el tamaño y peso de esta subespecie ha disminuido mucho, incluso por debajo de los 200kg. Pero para mi sorpresa, portales como la Sociedad Geográfica Rusa, el programa de conservación del presidente Putin o la Organización Mundial para la Conservación de Grandes Felinos mantienen sus estadísticas de peso en 300 kg. Mi duda surge ya que Russia WSC basa sus estadísticas en una muestra de población de menos de 100 individuos, unos 70 según su web oficial, y además afirman que todos han sido ejemplares en conflicto y en su mayoría casos muy jóvenes. Entonces mi pregunta es la siguiente. ¿Es válido asegurar que el tamaño y el peso del tigre de Amur han disminuido? Teniendo en cuenta que se ignoran casi 700 individuos que no han sido documentados, y de los cuales varios han sido vistos en cámaras trampa que pesan mucho más de 240kg, me atrevería a decir. Me gustaría preguntarte sobre el verdadero peso y tamaño del tigre de Amur, ya que he visto varias publicaciones afirmando que el tamaño y peso de esta subespecie ha disminuido mucho, incluso por debajo de los 200kg. Pero para mi sorpresa, portales como la Sociedad Geográfica Rusa, el programa de conservación del presidente Putin o la Organización Mundial para la Conservación de Grandes Felinos mantienen sus estadísticas de peso en 300 kg. Mi duda surge ya que Russia WSC basa sus medias en una muestra de menos de 100 ejemplares, unos 70 según su web oficial y que todos han sido ejemplares en conflicto y en la mayoría casos muy jóvenes. Entonces mi pregunta es la siguiente. ¿Es válido asegurar que el tamaño y el peso del tigre de Amur han disminuido? Teniendo en cuenta que se ignoran casi 700 ejemplares que no han sido documentados, y de los cuales se han visto varios en cámaras trampa que pesan mucho más de 240kg se atrevería a decir. Espero sus respuestas Gracias. "

I am not going to translate ALLLL that, BUT as I do understand it I am going to answer it, then the other posters will have an idea of what we are talking.

In 1992 a group of scientist from USA and Russia started one of the best conservation projects ever made, The Siberian Tiger Project (STP). They idea was to study, monitor and protect the las population of the Amur tiger, which after the fall of the Soviet Union it was again in great danger with poaching report increasing every year. Part of the project was also to place radiocollard to some specimens so they could study them just like the USA/Nepalese scientist do in Chitwan NP, Nepal between 1973 and 1983. So, they started capturing tigers but in this new terrain they needed new tecniques so it was a new feat to work with this population. In al that time, until 2005, several adult tigers ranging from 3 to 14 years (possible 16) were captured, measured and weighed for the first time and they found that they body size was not bigger than the Bengal tigers captured in Chitwan (Nepal) and Nagarahole (India). This is reported in several scientific publications, I remember at least four of them in this moment, but for some reason all this knowledge has been ignored by the rest of the people. Latter in 2005 a monograph was created that included ALL the details of these animals, including methods used and details of they status. The result were the following average figures:

Males - 176.4 kg, n=18, range: 125 - 205 kg
Females - 117.9 kg, n=13, range: 110 - 129 kg

So I started to dig about the specimens used and I found that some specimens were not in good shape or even sick, so I don't even remember since when I started to make my own tables adding not only the specimens from the STP but also those of the new The Amur Tiger Programme (TATP) which is the continuation of the conservations efforts for this tigers, this time just 100% Russian scientists. Interestingly I found that the new specimens since 2010, they were weighing over the 200 kg mark in the case of the  males, and latter I found that the body mass of the Amur tiger had fluctuated during the present and past century.

In the same monograph from 2005 of the STP, the scientist analized the body mass of the past records of the Amur tiger, you know, all those figures of specimens of 300 - 385 kg, and they found that all those figures, except one, were impossible to confirm, as most of them came from third hand sources, news papers and there could not corroborated by independent sources. The only specimen that kept the doubt was a male of 325 kg recorded by Baikov, but they found that the sorces available contradicted themselves, as the French one quoted the weight but the English one (older edition by two years) did not, so as they could not found the original source in Russian they left them as not confirmed. At the end, they concluded that the old Amur tigers prior 1940-1950, which where when the great tiger-tribulation happened, the specimens were bigger than modern ones, presenting these averages:

Males - 215.3 kg, n=9, range: 163.7 - 254 kg
Females - 137.5 kg, n=2, range: 115 - 160 kg

Of course, I do found other reliable first hand records in litterature and also challenged three female specimens that the monograph said that were unreliable for invalid reasons (frozen carcase of evicerated) and you can check the results in my tables, which are higher average figures.

Also there is another study from the Russian scientist Nicolaev & Yudin (1993) that showed a sample of Amur tigers found dead and the heaviest male in that sample was an specimen of 192 kg, clearly the tigers were slowly recovering from the slaghter thay suffered. If we use only the 8 male specimens that were not in such a bad shape, and including a male of 200 kg reported by Peter Mathiesen in his book, we got an average of 171.3 kg, and for the 4 more or less in good shape females the average was of 113.7 kg.

So, as you can see, there has been a great fluctuation in the body mass of the Amur tiger and now it seems that the increse continue, but for the moment only the male of 206 kg is confirmed and the other big three (225, 250 and 270 kg ) need to be confirmed yet.

Estimations based only in pictures from people and camera traps are not reliable, check this specimen for example:

*This image is copyright of its original author

*This image is copyright of its original author

This is the male PT-85 "Sergei" captured at 8 years old. Honestly, how much do you think that weighed? This is prime adult male and definitelly and handsome specimen. Many people estimated him at even 250 kg just based in the picture but guess what? This specimen weighed "only" 200 kg, still big, but not the giant that many imagined.

Check this other male:

*This image is copyright of its original author

If you know about Amur tigers maybe you already recognize it, but how much do you think it weighed? Whell this is no other than male PT-20 "Dale", the biggest Amur tiger captured by the STP. This picture is from his first capture, when he weighed 202 kg. At the end of his like this male reached the record of 205 kg, which was the heaviest figure for any modern Amur tiger until TATP started capturing tigers in 2010, reaching figures of up to 212 kg.

Now, I don't what to forget something interesting. While the body mass of the tigers fluctuated very abruptly from 216.5 kg before 1950, to 171 kg in the 80's to up to 190 kg after year 2000, the body size did not changed. In fact, checking the very few real body measurements from tigers taked by Zoologist in Russia (check my tables), you will see that they do not changed at all compared with those from tigers captured by the STP and TATP, the only that changed was the chest girth, which as we know, is synonimous is the body mass. So what happen with the HUGE tigers reported by the old litterature? Well, you will see some examples.

Check this male:

*This image is copyright of its original author

This is a big male by any standard and in fact is the heaviest Amur male tiger accepted by scientists and with good references at 254 kg, but the measurement that the author (Baikov) quote is too large, is of about 350 cm, when this animal probably do not surpassed the 310 cm in straight line. So this is the type of exagerations that happened. 

Now check this even worst example:

*This image is copyright of its original author

This is the famous "Great Van", a tiger was was a killer (or humans or cattle? I don't remember) and that was quoted to measure about 4 meters long! Now check again its picture, it was even smaller than the male of 254 kg. So, this is the problem with the old litterature and the records from it, and sadly this is worst in the Russian side where many of the "total length" measurements are actually skin measurements. 

Even then, this doesn't mean that big tigers do not existed in Russia, check this picture:

*This image is copyright of its original author

Probably the bigger ones in the left side of the picture weighed no less than 230 kg, but sadly we can only speculate.

So, in conclution, there has been a fluctuation in the body mass of the Amur tigers and a decrese in they chest girth, but not in they body length/height. Cammera traps are not a good form to estimate the size of an specimen, specially with no points of reference, and the conservationist websites are not interested in accuracy about morphology, but in the information about ecology and conservation.

Hope this helps with your inquiries. Reply