Modern Weights and Measurements of Jaguars

[Balam]

Hi @Maritimus77, good to see you here.

Good compilation on craniometric values divided by populations, I believe most of the data is conclusive in that statistically speaking Llanos and Pantanal jaguars are pretty much tied size-wise if we go by historical data, the heaviest reliable jaguar from the Llanos was a male hunted in El Rosero, Venezuela that weighed 148 kg, and was included in Rafael Hoogesteijn book, I believe "El Tigre Americano":

*This image is copyright of its original author

*This image is copyright of its original author

This is tied with Lopez, the jaguar which Rafael also participated in capturing in the northern Pantanal who topped out a scale of 136 kg with velocity and was later estimated to have fully weighed 148 kg by the biologists present. I made this comparison of Lopez next to a Bengal tiger that weighed 177 kg next to him to show how massive he truly was, both cats pretty much empty bellied:

*This image is copyright of its original author

If you scroll through the previous page you'll see our discussion about Joker, a jaguar that in my view is likely the heaviest weighed by scientists as he registered 140 kg on a digital scale while slipping from said scale and not fully lifted up, alluding to that he was likely much heavier than that, but I digress.

The heaviest jaguar from the Llanos captured by Dr. Hoogesteijn weighed 121 kg, a little heavier than Almeida's heaviest Pantanal male of 119 kg.

We've recently gathered plenty of weight data for Pantanal jaguars who are by far the most studied population, though unfortunately for their Llanos counterparts recent information on them in terms of sizes is almost completely null. The most recent data of Llanos jaguar weights come from the study: Jaguars, pumas, their prey base, and cattle ranching: Ecological interpretations of a management problem

*This image is copyright of its original author

Two males of unknown age weighed 87.5 kg, much lower than the value of 105 kg gathered by Hoogesteijn and Mondolfi in their study. Granted the sample size is minuscule and likely doesn't represent an accurate view of the jaguars at Hato Piñero as a whole. Here there are some individuals from Hato Piñero captured by biologist and Llanos jaguar expert Włodzimierz Jędrzejewski (more pictures in the Llanos jaguar thread):

*This image is copyright of its original author

There are some very big males on here like M18 or M33, it would be interesting to know their weights, but overall my impression from seeing these jaguars (and I could be wrong) is that they don't look as "well-fed" as those from the Pantanal or other hatos from the Colombian Llanos that may have greater prey biomass like Hato la Aurora. The thesis that many of us have proposed here is that the current situation in Venezuela has had an impact on jaguars as many are indiscriminately hunted which lowers their genetic quality, and as their main prey is also poached out, the jaguars lack the resources to grow to the same dimensions they likely attained a few centuries ago when they had almost complete undisturbed access not only to native prey, but also feral cattle and horses numbering in the hundreds of thousands across the Llanos.

We believe that this phenomenon took place in the Pantanal as well during the times Almeida performed his hunts since it was during the peak time of jaguar poaching, as well as their main prey the caiman. But thankfully protections from changed legislation and involvement from scientists have made the Pantanal population much stronger and the numbers of natural prey items have skyrocketed as well. We can confidently deduct that Pantanal jaguars are nowadays greater than during the times of Almeida because of the dozens of recent captures, there is a multitude of males that surpass Almeida's record of 119 kg. A full list of 181 recent jaguar captures from multiple populations can be accessed here.

We're expectant to see if Panthera will at some point release the data they have on jaguars captured at Hato la Aurora in the Colombian Llanos, an area that I believe has all the right pieces to produce some very interesting jaguars, like this one for example:

*This image is copyright of its original author

I made this comparison of two very large males, to the left one from Hato la Aurora in the Llanos, and to the left from Caiman Ecological Refuge in the Pantanal, to see how well they fare against each other. Both are massive and compare really well to each other, IMO:

*This image is copyright of its original author

Overall I think that all this weight data pretty much aligns with the skull values you posted as these two populations represent the largest of the jaguar populations studied, though it would be interesting to see how the jaguars from the Llanos de Moxos in Bolivia, the third-largest floodplain ecosystem in South America, would fare since the environment is pretty much the same as the Oricono Llanos and the Pantanal. We're just lacking a lot of data and even photos on them.

The rest of the analysis of the width/length of the skulls of jaguars from Central America is very interesting. Many jaguars from places like Costa Rica heavily prey upon sea turtles, so the relative wider zygoma might be advantageous for them in order to perforate the thick armor of the turtles. Reply