Who is the "king" of tigers? - Bengal or Amur

[GuateGojira]

This topic was made with the purpose to finally state with of these two tigers is/was the largest, using the available data and the reliable records. Also, it will clarify what characteristics make the Amur and the Bengal tiger an unique animal and what adaptations were made in order to create a completely adapted form. Enjoy the reading and help with information.
 
Which is the largest of the tigers? The better form to understand this question is to state the three points of view: 1-the skull size, 2-the body size and 3-the body weight.
 

 

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1. Skull size:
Very few people have investigated the skull of the Amur tiger, and the only large database has been provided by Dr Vratislav Mazák. Although he is the only one that presents a large more or less representative sample, he made the mistake of including captive specimens, so his figures, although reliable, have this little problem; I don’t know if his sample of Bengal tigers suffer of this situation, however what it is sure is that the largest skulls recorded by him came from wild specimens. According with the investigation of Dr Vratislav Mazák, the Amur tiger is the largest of the tigers and his measurements on 227 skulls shows that the Amur tigers have the largest overall skulls. The average figures (greatest skull length) that he published in his book “Der Tiger” of 1983, were of 367.1 mm (n=8; range: 341-383 mm) for Amur males and 353.4 mm (n=36; range: 329-378 mm) for Bengal males. However, at least for the Bengal tigers, there are other scientists that have calculated other average figures.
 
I manage to collect 63 Bengal tiger skulls measurements from reliable sources, and 20 Amur tiger skulls (including those from Mazák, in the last case). The problem with the Bengal sample is that old records mostly present only greatest length and zigomatic wide, while only the pure scientific sources presents other important measurements like the condylobasal length. This seems not the case with the Amur tiger skulls. For the female side, I collected 12 Bengal females and 15 Amur ones.
 
With the Bengal tigers, there are three sources for the records:
1. The scientific sources: These are the measurements taken by scientists and naturalists from wild specimens, this are automatically accepted. Among this sample I can quote Pocock and Sterndale, among others.
2. The first hand sources: These measurements came from well know hunters and from first hand sources. As they were not taken by scientists, its accuracy is open to question by some people, but the reputation of the collectors make them highly reliable. At this field I included Hewett, the Maharaja of Cooch Behar and Burton, among others.
3. The second hand sources: These figures are reliable, but they are open to question as they have been not verified by scientists. The records of Rowland Ward are included here.
 
For comparison purposes, I will use only the scientific sources for comparison with those of the Amur tiger, because they have the three principal measurements, but check all the results:

*This image is copyright of its original author

The range of averages change between 352 to 374 mm, but it must be taken in count that just in the three last samples, we can be sure that the specimens used were fully wild. Including the average of 351 +/- 2.5 mm (n=37) from Yamaguchi et al. (2009), the overall average will be of 359.2 mm (n=134). This figure will be smaller than that of the Amur tiger, however we don’t know where Yamaguchi get his measurements (it is possible that he used the same specimens from European museums like Mazák), so using only wild specimens we get an average of 363.9 mm (n=61), which is about the same than the average for the Amur tigers.
 
These are the figures for the females, only for the scientific sources. I did not found other sources. Check the figure:
* Bengal tiger:             GSL                            CBL                        ZW
Females:                    295.6 mm (10)           266.4 mm (12)           196.2 mm (10)
                                271 – 312 mm            250 – 285 mm            185 – 203 mm
 
For comparison purposes, I am going to use an average mix of Mazák and the scientific sources, as these are the only ones that had poses the full set of measurements for comparison. The scientific sources for the Bengal are: Sterndale (1884), McDougal (1977), Pocock (1929-1939), Feiler & Stefen (2009) and Christiansen & Harris (2012).
 
The raw averages presents interesting figures check this out:

*This image is copyright of its original author

 
Extreme records support the Bengal for the title, as the largest skull for the Amur males was a Manchurian specimen of 406 cm (Kitchener, 1996), while the largest Bengal skull measured 412.8 cm (Hewett, 1938). However, on average, it seems that Amur tigers have the largest measurements and based on this, it is easy to see why Mazák strongly stated that the Amur tiger is the largest subspecies of tiger. However, using all the data for the Bengal tigers, the difference between these and those from Russia is of no more than 8 millimeters.
 
These results summarize all the data on skulls that I have found in literature. Peter will present more measurements in the future, so my results presented here must be taken as preliminary until more data could be shown.
 
As far I know, there is no data about bone sizes of “pure breed” Bengal tigers, only about the Amur ones. Christiansen & Harris (2005) published the measurements on two “Bengal” specimens, but judging by the body size and weight, or they were very young specimens (specially the male, 145 kg) or they were just hybrids. However, the bones of the Amur tigers presented by them, rank among the largest in record and compete in size with the largest felids in fossil records (372.5 mm and 429.5 mm for the largest humerus and femur respectively).
 
Finally, in the canines department, Mazák (1981) report a maximum canine length of 74.5 mm, although he quotes Dr Gewalt for a canine of 90 mm in a captive specimen. Dr Christiansen report a maximum canine length of 59.4 mm for a skull with a CBL of 337.8 mm (CN6049), which suggest a larger canine for the specimen CN5698 which have a CBL of 350.9 mm. However, he quotes a canine length of 71.4 mm for a Bengal specimen (CN4552), which is practically of the same length than the largest canine reported by Mazák.
 
Dr Sunquist captured a huge male known as Sauraha (T-105), which have a canine length of 65 mm from the tip to the gum line. In the skull, this canine probably measured up to 70 mm. However, I recently bought the book “Tiger: the ultimate guide” of Valmik Thapar (2004), and in an article “Filming Tigers” from Mike Birkhead, he states that the large male known as “Madla” that was estimated at 250 kg with a neck of 90 cm, had upper canines that were about 75 mm! (Page 213). This is a new record among Bengal tigers and taking in count that this was measured to the gum line, this means a length of no less than 80 mm in the skull, surpassing any wild Amur tiger canine recorded.
 
In conclusion, the skull size suggest that the Amur tigers are slightly larger than those from Bengal, however the differences are between 20 to 8 millimeters, which is hardly significant for animals that are known to reach over 2 meters long and weighs over 250 kg. So, in a raw manner, we can conclude that Amur tigers do have larger skulls than the Bengal ones, but the extreme records suggest parity in sizes, in both skull and canine size.
 
In my next post, the point No. 2 – The body size.
 
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