Modern weights and measurements on wild tigers

[GuateGojira]

Average weight of the male tiger (Panthera tigris) at species level:

I will try to clarify this issue of the weights with the tigers.

With the Bengal tigers, in old records, we have many weights to compare the tiger populations, but from modern records we have very few.  Using all the available figures, hunting and modern, I calculated an average weight of the Bengal tigers from India and Nepal at 211 kg (465 lb) - n=141; including Sundarbans it will be 200 kg (440 lb) - n=147. In the mainland all the populations are over  200 kg on average, except from the one of southeast India which  is about 182 kg, but from here we only have hunting records. I found that there is no significant diference in body length between the populations, just in weight which range between 182 to 243 kg.

I had a full list of at least 160 male specimens from hunting and modern records, but sadly I lost all that information, so I manage to recover this list of 147 specimens in order to get a good idea of the average weight of male Bengal tigers in the Indian Subcontinent:

Central India: 204 kg - n=55 - range: 160 - 255 kg.
Southwest India: 218 kg - n=6 - range: 206 - 227 kg
Southeast India: 182 kg - n=9 - range: 150 - 203 kg.
Northwest India: 243 kg - n=3 - range: 220 - 268 kg.
Northeast India: 205 kg - n=44 - range: 168 - 236 kg.
Terai-North India: 200 kg - n=17 - range: 161 - 259 kg.

Nepal: 224 kg - n=7 - range: 180 - 272 kg+.
Sundarbans: 123 kg - n=6 - range: 97 - 172 kg. 

I still need to recover lees than 10 weights that I had, but the difference in the average figures will be minimal, I still remember that the average in the Southwest will be smaller and that in Northeast India will be higher. This list excludes all the specimens over 272 kg, including them in a group of "exceptional specimens" that range from 276 kg (Kumaon) to 320 kg (Nepal), and is a list of 6 males, please take in count that these records are tied to its acceptance and not all are accepted as "reliable", however at liest in the case of a huge male of 282 kg in Kumaon it clearly says that was actually weighed. This sample includes only the 16 males recorded by scientists and published or corroborated by email. If we include all the other weights reported by news webpages in this topic the sample will be higher but I don't think that the average will be dramatically different.

The figure of 272 kg+ was stablished by the two big males from Chitwan, Nepal, males tigers 105-Sauraha and 126. Interestingly, while only 4 males were captured in that area between 1974 to 1980, 2 of them are already heavier than any tiger or lion in the wild recorded by scientists (the male of 272 kg in Kenya was a cattle killer and consequently very bulky and at some point abnormal), which suggest that most of the males in that area reached big weights. They calculated weights "empty belly" are of at least 260 kg, and Smith et al. (1983) presented a figure of 261 kg, which is the one quoted in modern books.  

Dr Jhala says that the tigers in Ranthambore NP are among the largest in India, but it seems that he have just captured 8 specimens (other source says 10) in the area between 2007 and 2009: 3 adult males, 1 adult female, 3 subadult males and 1 subadult female. From the 3 adult males, we know the weight of two males: T10-Darra with 220 kg and T-24-Ustad with 240 kg; the other male T12-Tikkoo is still not clear, but people that saw him estimated that it could not weight less than 200 kg. The area of Kumaon and Gwalior presented huge tigers in the old records, in fact 4 of the exceptional males came from that area (272, 276, 282 and 292 kg, respectivelly), and we must not forget that the modern tigers that live in Ranthambore are decendents of a population reintroduced from Gwalior (Thapar et al., 2013). 

About the Amur tigers, we have less information, however, with the few old and verified old records and the modern scientific records we can present figures of 216.5 kg (n=10, range: 164 - 254 kg) for males in old records and 190 kg (n=23, range: 155- 212 kg) for the modern ones. The overall average using all the weights will be of 203 kg for the entire subspecies/population.  

The Caspian tigers are calculated to be as large as the Bengal ones, but the few skulls available suggest a smaller size. The only three weights from males records a figure of 197 kg (range: 170 - 240 kg). One skull is said to have measured 385 mm in total length (Heptner & Sludskii, 1992) but a follow investigation suggested that the other measurements presented suggest a specimen much more smaller and that probably the skull was measured over the bone, saldly the skull is lost forever (Mazák, 2013).

The Indochinese tiger was about the same than the Caspian tiger, if not slightly longer based in the skulls. The biggest skull from a Caspian tiger was of 369 mm while a new skull apparently from Malaysia (based in DNA) was  of 370 mm. In the weight department very few figures are available in litterature, with just three males: one of 173.3 kg (Pocock, 1939), other of 182 kg (Mazák, 2013) and a big one of 259 kg (Bazé, 1957). Modern records are available thanks to the scientists working in Thailand at this moment, and based in 4 males (with 5 captures) the average weight is of 182 kg (range: 164 - 209 kg), about the same body mass than modern Amur tigers. So using the modern records plus the old records we got an average figure of 193.5 kg (n=8, range: 164 - 259 kg).

The South China tiger is the smallest of the mainland tigers, if we take them as a single subspecies, and only lives in captivity. Slagth et al. (2005) present a a list of captive specimens and the males from this population had an average weight of 130.7 kg (n=13, no range). A list of wild specimens from hunting records shows an aveage of 152 kg (n=8, range: 108 - 190 kg). The biggest specimens seems to be from the northern are and the smallest ones from the southern, se there was a cline in the weight of this population. I don't have figures from the tigers that are in semi-wild status in South Africa, but I guess that they are heavier than those in China zoos and maybe clouse to those from the old wild records.

Finally, the only other subspecies/population from which we have body mass records is the Sumatran tiger, the smallest tiger in modern days. Using modern scientific records we have an average weight for males of 127 kg (n=4, range: 98-148 kg). That sample also includes a male of 75 kg, it says tha was adult and in good health, but certainly there is an error in that figures. The smallest captive adult male recorded by Slaght et al. (2005; in Barlow et al. (2009=) is of 91 kg and came from a sample of 21 speciments, and also Mazák (2013) which recorded weights of wild and capivte specimens reported that the smallest male was of 100 kg. So the figure of "75 kg" came probably when the animals was first captured and probably in not a good shape, or there was a typo. Using old hunting records, the average weight for Sumatran male tigers is of 119.3 kg (n=6, range: 104 - 140 kg), and using all the records for this subspecies we get to 122.8 kg (n=10, range: 104 - 148 kg). There is a record of a male of 180 kg but if that is accurate it will be exceptional. Also @peter measured a skull from a male of 350 mm in greatest length, which suggest that in the past big males existed in the island. There is also other record from a captured male of 130 kg posted here by a member but as we don't have the main source of it, I did not included the records in the modern records.

About the Malayan tigers, we don't have reliable weights from the wild in the old records. I found only one records of a male of 120 kg, but other news reports shows males of up to 170 kg, which will be not out of question. The figures showed by a report on Malayan tiger conservation as just estimations and reach a maximum of 130 kg. Slagth et al, (2005; in Barlow et al. (2009)) present a list of weights of "Indochinese - Corbetti" tigers but in fact this weights are from Malayan tigers in captivity, the average weight for males is 120.6 kg (n=6, range: 109 - 132 kg), this is closer to the Sumatran tigers than to the mainland ones. Reliable measurements from old records give average lengths as large as the South China and Indochinese tigers (Locke, 1954), and the skulls reported are big, with an average greatest length of 339 mm - n=4 (J. H. Mazák, 2008) and now we have a new skull of 370 mm. This suggest that in the past the Malayan tigers were as big as South China tigers (average greatest skull length of 334.7 mm (n=10, range: 318 - 348) and in some case even as big as the Indochinese tigers. I had not calculated yet the average weight of this population based in the skull size, but certainly if we use the average figures from modern captive specimens, we will get a very low average weight for the tigers species, a one that will not reflect the real weight of the species in time.

For Java and Bali tigers, the situation is worst. We only have two weights for Javanese tigers and none for the Bali tigers. For Javanese male tigers, we have one wild male of 141 kg and other from captivity of 110 kg. The average of these two specimens will be 125.5 kg, which is slighly more than those from Sumatra and this is accurate as the skulls fromthe male tigers in Java and bigger than those from the other two islands. However, the weight of 141 belongs to an animal with a skull length of 331 mm, whcih is just a little over the average reported of 321.3 mm in the study of Mazák and Groves (2006) that also included inmature specimens. Also, the biggest skull measured for this subspecies is of 349 mm (Mazák, 2013) and he even concluded that based in the skulls, this tiger population was probably as big as the tigers in South China! Using the condylobasal length of several specimens I calculated an average weight of 134.5 kg (n=10, range, 110 - 158 kg), which I guess will be probably closer to the real average in the wild. For Bali tigers we don't have any weight, Mazák (1981) estimated a weight between 90 - 100 kg, but I calculated an average weight of 112.8 kg (n=3, range: 107 - 123), but we must take in count that Mazák did not know the large skull of 301.5 mm in greatest length reported by Buzás and Karfas (1996). Also, my estimations based in the condilobasal length are using only captive specimens, if we use wild and captive  specimens the average figures will be:
* Java male tigers: 141.8 kg - n=10 - range: 116 - 166 kg.
* Bali male tigers: 118.9 kg - n=3 - range: 113 - 130 kg.
This may be a little more reliable figures, by I dediced to use the captive ones as the result obtained with the male of 141 kg was closer to the original (I got 144 kg with that specimen with condylobasal length of 294 mm.). However is interesting to see that the largest Bali male tiger, which had a skull size of the about the same than the large jaguar males from the Pantanal, got a similar calculated weight.


We can try to estimate an overall average weight for the males of the species Panthera tigris, but we will need to use captive specimens and isometric calculations from skulls to fill the holes. Taking the risk, this is what I got:
* Bengal tiger: 200 kg - n=147 - range: 97 - 272 kg.
* Amur tiger: 203 kg - n=33 - range: 155 - 254 kg.
* Caspian tiger: 197 kg - n=3 - range: 170 - 240 kg.
* Indochinese tiger: 193.5 kg - n=8 - range: 164 - 259 kg.
* South China tiger: 152 kg - n=8 - range: 108 - 190 kg.
* Malayan tiger: 120.6 kg - n=6 - range: 109 - 132  kg - captivity.
* Sumatran tiger: 122.8 kg - n=10 - range: 104 - 148 kg.
* Java tiger: 125.5  kg - n=2 - range: 110 - 141 kg - one wild, one captive.
* Bali tiger: 112.8 kg - n=3 - range: 107 - 123 kg - isometrically calcullated.
** Overall average: 158.6 kg - n=220 - range: 97 - 272 kg.

This figure is pratically the same reported by Yamaguchi et al. (2009) and Kitchener & Yamagichi (2010), which says that the average weight for the male tiger at "species level" is c.160 kg. Now, remember that this list have many assumtions, specifically in the Malayan and Bali tigers. I used only to two known males for the Java tigers in order to use only true weights, but if I use the figure of 134.5 kg that I obtained from 10 skulls the average for male tigers overall will be 159.6 kg, practically the same figure with no diference. Now, if we use strictly only weights and only wild specimens, which will exclude the Malayan tigers (as they are captive), the Java tigers (as only one is wild) and the Bali tigers (as are calculated) from the sample, the average weight for male tigers as a species will be 178.1 kg (n=209, range: 97 - 272 kg).


Now, I did not included the male tiger of 389 kg from Guinness, well because something seems incorrect in that figure, the picture shows a bit tiger probably over 272 kg or maybe 290 kg, but that is all. The explanation that because a cat can eat a fifth of its weight is not satisfactory, specially by the fact that the highest amount ate by a tiger, actually record, is of 35 kg in Nepal and 27 kg in Kanha. Also, by no means we can take as "reliable" the reports of those lions of 700 and 800 lb, those are clear exagerations promoted by "fans" and we alread know that news reports are not reliable if are not corroborated. If not, it will be like to return to the old days and again acept the old records of Amur tigers of 360, 384 and even 400 kg! I think that if we try to get a good idea of the weight of these animals we must use a criteria and those selected-random-unreliabel figures should be discarted. In fact, the biggest male lion accepted by Guinness with 313 kg is also highly doubtfull, taking in count that the picture of that animal shows a quite small-to-average size male lion and the fact that was "checked by several people" is not guarantee, specially when we don't know what "people" was that, where they "experts", where they "officials", or where they just people that liked to please the guess? The method used but Slagth et al., (2005) seems reliable to me, and by this method, none of those huge lions from unverified news reports is remotelly reliable.

These are the figures about tigers that I have, if someone want especific information feel free to ask. Greetings. Reply