Modern Weights and Measurements of Jaguars

[Balam]

(08-04-2020, 05:28 AM)peter Wrote:

(08-04-2020, 03:35 AM)Balam Wrote: From the jaguar directory thread, I posted a story on a Chaco jaguar who's pugmark width measured 10 cm, and I have felt is the same pugmark that measured close to 15 cm in length that I posted some time ago. @peter I wanted to ask you, based on the knowledge you have of the paw sizes of tigresses and small tigers, would a pugmark of a similar dimension compare? I've been under the assumption that tigresses usually have pugmarks of 10-12 cm in width. It would be interesting to draw the parallel because Chaco jaguars have been compared in the past to Sumatran tigers by hunters and comparing them to the data that we do have on tigers would give us a better idea of their size potential. Chaco jaguars are severely understudied and highly threatened.

BALAM (Onca?)

a - Difference between heel width and a pugmark
 
Before answering the question, I decided for a few words on the difference between a print (pugmark) and the heel width. In this photograph (pugmark of a male Amur tiger first posted by Rage), you can see the difference between a complete print and the heel width: 

*This image is copyright of its original author

Here's the tiger who left the print:

*This image is copyright of its original author

   
b - Heel width of wild Amur tigers

In wild Amur tigresses, the heel width ranges between 8,0-10,0 cm. In adult wild male Amur tigers, it ranges between 10,5-12,8 cm. 

The heel width in exceptional males can reach 13,5 cm. According to Tigerluver, a male width a heel width of 13,5 cm. ranges between 259-339 kg. One captive male Amur tiger in a UK zoo just over 600 pounds (272,16 kg.) had a heel width of 14,1 cm.

I don't remember if it's this tiger, but I do know he was just over 600 pounds as well:

*This image is copyright of its original author

c - Further reading

A few months ago, I posted extensively on the relation between heel width and weight in wild Amur tigers in the tiger extinction thread (posts 2,467-2,481 and post 2,492). Heel width, to keep it short, is one of the best indicators of weight in wild big cats (and brown bears). 

d - A wild male Amur tiger with a heel width of 13,5 cm.

For different reasons (discussed in the tiger extinction thread), researchers today are hesitant to dart healthy wild male Amur tigers. This means we have no option but to use data collected before, say, 2013. The heaviest weighed was a young adult male of 212 kg., but he still had some growing to do and chances are some individuals recently seen well exceed that mark. The male below had a heel width of 13,5 cm. 

Watch the short and very robust fore-limbs and the deep chest. I know the snow accounts for some loss of length, but it's clear this male is as robust as they come:     

*This image is copyright of its original author

 

Although the conditions in the southern and southeastern part seem to be a bit better, the northern part of Sichote-Alin seems to produce the largest males.  

e - A few pictures

Tracking a male Amur tiger. When this photograp was taken, not one of the captured males exceeded 205 kg. in weight:  

*This image is copyright of its original author

Based on what I have (old and new information), I'd say tigers living just south of the Himalayas could be the largest wild big cats today (averages). This photograph (taken in Rajaji) was first posted by Roflcopters. I do not doubt some males in that part of India are close to 650 pounds (294,84 kg.):

*This image is copyright of its original author

 

Here's one from Bengt Berg (northern India, close to Bhutan). The heaviest tiger he shot was 565 pounds. He didn't shoot the male that left the print below in order to allow him to pass on his genes. Berg saw the 565-pound male and the Bhutan tiger from very close range. The tiger he didn't shoot was quite a bit bigger (well over 600 pounds). 

Although known as the 'Killer of Man', the giant from Bhutan hunted male wild buffalos only. Every buffalo he killed was found with his enormous horns sticking in the ground. Berg was very impressed and wrote he must have been immensely powerful:

*This image is copyright of its original author

f - Chaco jaguars

The table you and Dark Jaguar posted in this thread says wild male jaguars in the southern part of Brazil are very robust for their length. Same for the photographs i saw. Weightwise, the heaviest no doubt compare to the largest Amur tigresses. As these range between 8,0-10,0 cm. in heel width, it's very likely the Chaco male with a heel width of 10,0 cm. was about as heavy as the heaviest tigress. 

What's heavy in wild Amur tigresses today? There's not much information, but the heaviest captured in the period 1992-2012 ranged between 125-130 kg. In that period, the heaviest males ranged between 200-212 kg. 

About 50-100 years ago, when Amur tigers were on their way out, individuals well exceeding that mark (males and females), have been shot. One of the largest females I know of, although still youngish, was 367 pounds (166,47 kg.). 

As a result of the population bottleneck of the thirties, forties and fifties of the last century, Amur tigers today are a bit smaller. Individual variation also has been affected. But the Russians are very serious about protection and the number of tigers is increasing all the time. As the conditions have improved as well, chances are wild Amur tigers will produce more large individuals in the near future. 

Back to jaguars. When measuring skulls, I noticed that skulls from jaguars shot in the southwestern part of South America were larger (and more robust) than those of jaguars shot in the northern part. I saw a large skull from Argentina and a few large skulls from Bolivia. Those who hunted them (referring to a few people I met) confirmed jaguars in the southwestern part of South America, apart from a few exceptions (like the jaguar recently poached in Surinam), are bigger than their relatives living in the northern part. 

Same for pumas, so it seems. Some males and females seen in Patagonia and the southern part of Chili seem to be in a different league. Weight- and lengthwise, large pumas in Canada and the northwestern part of the USA compare, but the Patagonians seem to have bigger, more rounded and more robust skulls.   

I hope you'll be able to find out a bit more about jaguars living in the northern part of Argentina. My guess is they more or less compare to Pantanal jaguars. Same for Bolivia. Anything known about Paraguay?

To finish the post, two pictures. This male definitely compares to a large male Sumatran tiger:

*This image is copyright of its original author

Skull of a male rainforest leopard (central part of western Africa, left) and a male jaguar from Bolivia (right). The skull of the leopard is flatter, but not much shorter (just over 1 inch). The upper canines of the leopard are missing, but my guess is they would have compared for length. The main difference between both skulls is the jaguar skull is more elevated and more robust (heavier). Photograph taken by 'Wanderfalke' in the Staatliches Museum für Naturkunde Stuttgart, 2012. 

The largest leopard skulls can exceed 280 mm. in greatest total length, whereas large jaguar skulls exceed 300,00 mm. Although generally a bit shorter, large jaguar skulls compare to skulls of male Sumatran tigers in quite many respects. One of the largest jaguar I know is (was) in the Netherlands. Unfortunately, the owner of the skull got cold feet just before we were supposed to meet:  

*This image is copyright of its original author

Hi Peter, excuse the late reply I had not read the last portion of it where you brought som very interesting points I'd like to discuss further.

First in regards to skull length as a tool to gage or compare body sizes between different species, the reason why I believe using skull length is unreliable is because different species have evolved to develop different morphological traits in regards to body proportions. Seymour indicated in his scientific paper on jaguars that jaguars are characterized by having a rather shorter skull, which becomes broader in the zygomatic arches, with a pronounced forehead (which explains why the picture above shows a more elevated skull) and dense bones and canines. This adaption makes sense for an animal that's known for piercing through harsh bones and thick shells to dispatch it preys:

*This image is copyright of its original author

A shorter but tall skull allows the back portion of it to accumulate larger pressure. This is why you're going to see that jaguars who may overlap in body mass with other felids such as Sumatran tigers will present shorter skulls, and it may give the false impression that leopards (who in contrast to jaguars present very long skulls proportionally, but narrower zygomatic arches) with closer skull length might rival them in size when looked exclusively through skull comparisons of dead animals.

One of the longest skulls for Llanos jaguars, for example, was a male that weighed "only" 114 kg, which is not huge for a jaguar from that biome (at least historically), with skull measurements of 31,25 centimeters long 22,50 centimeters wide, shared by @epaiva

*This image is copyright of its original author

At 114 kg, you may see Sumatrans surpassing 310 cm in length, and it may seem close to a leopard with a skull length of 280 cm, but who may yield around 70 kg of body mass.

About Bolivian jaguars, it makes total sense for Jaguars from southern Bolivia to have heavier and bigger skulls, northern Bolivia is part of the Amazon biome, where jaguars very rarely surpass 80 kg in weight. The southern part is the biome known as Chaco, where historically jaguars who rival Pantanal population in size are said to have existed (some still do, but their population has been close to annihilated). The Chaco extends from southern and eastern Bolivia, to western-northern Paraguay and northern-western Argentina. In terms of historical weights, as far as I know, there aren't any records, but we do have a very large skull record of 30 cms in length from Paraguay. Here is a table with historic skull measurements, which include several Paraguayan Chaco jaguars of very large skulls:

*This image is copyright of its original author

Panthera estimated a jaguar from the Bolivian Chaco known as Samson to have weighed 130 kg, and another male from the same area known as Aries was estimated to be between 120 to 130 kg by the scientists who track them.

Samson:

*This image is copyright of its original author

Aries:

*This image is copyright of its original author

Aries compared to Sumatran male:

*This image is copyright of its original author

We do have one weight from the Argentine Chaco of a male named Qaramta who yielded 107 kg, he doesn't really look anywhere near as big as Aries or Samson (who unfortunately were poached), so I don't think their size estimations wouldn't be reliable.

Much like Llanos jaguars, Chaco jaguars have been subjects to overhunt, to the point that only about a dozen are said to be left in Paraguay and Argentina. The very low genetic material, combined with the destruction of habitat and prey deficiency would have an impact on their sizes, and yet still we are able to report a male of 107 kg, who isn't necessarily big.

If I had to make my guesses, historically I believe that Llanos, Cerrado, Pantanal, and Chaco jaguars all overlapped in size. Nowadays the hierarchical of sizes would go this way:

1. Pantanal
2. Llanos
3. Cerrado/Chaco
4. Middle Magdalena basin/Maracaibo lake basin
5. Atlantic forest

With enough conservation efforts, these other populations can reach their former glory in sizes much like how is happening in the Pantanal. Reply