Modern weights and measurements on wild tigers

[GuateGojira]

Short note: on the body mass of the Sumatran tiger.

As you know, in my last comparative image the average weight of the Sumatran tigers is of 123 kg (n=10; range: 104 - 148 kg) for males and 98 kg (n=5; range: 75 - 110 kg) for females. Now, we have more weights and is important to corroborate and explain some information that we have.

Information about the Sumatran tiger is very scarce and few hunting and scientific records are available. Based in the information that I have, and the new one provided here, I collected 19 weights from males, but actually is not that simple as we may think.

The first 6 males came from hunting records gathered by Sody (1949) and Mazák (2013), these weights are: 104, 104, 115, 123, 130 and 140 kg. Based on this and the captive specimens that he knowed, Mazák (1981) stablished a range of 100 - 140 kg for male Sumatran tigers. Latter in 2005, Slaght et al. (2005) reported only one wild male of 140.2 kg and the average weight of 21 captive males of 109.4 kg (SE 3.1) and 21 females of 86.7 kg (SE 2.8); including the wild male Slagth et al. (2005) stablished an average of 110.8 kg (SE 3.3). Barlow et al. (2009) provided more details as he published the ranges used, but while we know now that the lightest of the males was of 91 kg, the heaviest is the wild male of 140.2 kg, so we don't know which is the heaviest captive male in the original sample. As far I know, the heaviest pure Sumatran tiger weighed 131.4 kg (Juma tiger in the Australia Zoo, at 2007). There is a mention of a male of 181 kg from the DreamWorld park, but I am not quite sure if that tiger is 100% pure Sumatran.

Based on this, the captive male tigers may weight between 91 - 131 kg, while the wild males may weight between 100 to 140 kg, not big diference. Now we have new weights from wild males, all except one problematic specimens in not quite good conditions and that were captured for relocation or because were injured. The 11 males range from 62 to 130 kg, the lower figures reflect specimens not in they best form.

Priatna et al., 2012 reported three males over 4 years old that weighed 73, 98 and 122 kg, and althoug the document says that the three were in good conditions, do not specify if this was during the capture or before its release. Kompas & Fransisca (2008) mention four adults males of 62, 105, 105 and 106 kg, but two of those males (the ones of 105 and 62) are mentioned again by Mardiastuti (2019), this time with weights of 119 kg and 74 kg respectively. So, why there is a difference of 14 and 12 kg respectively? This shows that in the 9 months that they were is captivity they gained weight, corroborating that they initial weights were not normal and when they mention that they were in good conditions, it is clear that this was after the time of recovery in captivity. Here is where we found the problem of using the weigths of animals that presented problems as they do not reflect the status of a wild and healty animals. The weights of 73, 74 and 62 must be discarted (specially the one of 62 as is the same as the one of 74 kg) as do not reflect healthy males, check that even adult captive males do not weight as low. This leave us with all the other 15 wild males between 98 to 148 kg, which at least match the weights of healty adults in captivity and the old records, also from the wild. Other three wild males found injured, one from 110 kg (Jarkasih, 2019), other male of 130 kg confirmed by Veteriany Erni Suyanti Musabine were also included (Suyanti, 2015), and the record male of 148 kg captured in the Jambi region and named "Slamet" (ZLS, 2003), which was not injured but captured for study purposes.  

Using the 15 wild "healty" adult males we get an average of 119.6 kg, which seems realiable for a species with an average skull length of 314.8 mm, probably should be a little more, as @"Pathio" confirmed that the adults animals that we can see in camera traps in the deep of the jungle looks very heavy. The weights used are 98, 105, 106, 110, 119, 122, 130, 140.2 and 148 kg, plus the old records of 104, 104, 115, 123, 130 and 140 kg.

In conclution:
* Wild Sumatran male tigers: 119.6 kg - n=15 - range: 98 - 148 kg.
* Captive Sumatran male tigers: 109.4 kg - n=21 - range: 91 - 131 kg (?).

This means that I will need to update my image on the size of the tigers, but this provide us to a closer idea of what is the real weight of the Sumatran tigers.

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