No, alone they are not a feasible solution, although they have a key importance.

From everything I have seem, a mix between private reserves and public areas would be best, especially when private areas can act as a natural corridor, making it possible for jaguars to move, as they requires large areas for survival, and also avoid interbreeding.

A 13 years long jaguar study in Mexico

Our data did not strongly support our primary hypothesis that apparent survival of jaguars would increase after the first land purchase and cattle removal in 2003…

While the survival estimates increased after the first 4 years of the study, this change was not statistically significant…

Thus, we cannot conclude that a measurable change in survival is the result of the conservation strategy.

[3]

But still private owned areas are important:

The conservation agreement action in the cattle ranches (hunting ban) may provide benefits for long-term jaguar conservation without the need for large land purchases. [3]

And this is also confirmed by another Mexican study at La Papalota—a 368-ha natural protected area in Nayar. Although not as broad as the study above and being held at a natural preserve (not private area), it states that even small preserved areas count and can have an impact.

We suggest that, although a small protected area like our study site cannot provide an entire home range for even a single jaguar, it and similar reserves can play a crucial role as stepping-stones for jaguars moving across highly modified landscapes.

[4]

As I said in the begging, if private reserves, even small, can be place in the right places, they can be very useful in jaguars preservation.

There have been in fact a successful project in other country, Colombia, where private and public reserves acted together to preserve jaguar with success in the Sierra Nevada de Santa Marta National Natural Park, a place where jaguar population are among the mostly threatened, specially after big fires that destroyed their habitat.

Image: Severe fires in the upper reaches of Sierra Nevada de Santa Marta led the jaguars to concentrate in the coffee belt. Image courtesy of ProCAT.

They discovered that the jaguar population had been concentrated mainly in the Sierra coffee belt, that its territory had shrunk, and its usual prey had diminished, forcing the jaguars to resort to hunting livestock.

Under the Jaguar Friendly label, for which they can sell their coffee at a premium, the farmers allocate a hectare of protected forest as jaguar corridor for every hectare of coffee they cultivate.[5]

Again, as said before, the conjunction on natural reserves and private areas, creating corridors, is essential:

In this way, habitat for the big cat is guaranteed, and the coffee plantations serve as corridors that allow the jaguar to move between patches of forest that were previously disconnected. Zárrate says there are already more than 280 hectares (690 acres) of forest protected by the Jaguar Friendly label, and this year they hope to increase the number of certified farms to 20. [5]

But let’s move now to the land of larger jaguar populations, Brazil, with 4 key areas for jaguars: the Amazon, the Pantanal, the Cerrado (the Brazilian savanna) and the remains of the Atlantic Rainforest.

There has been a united project for the Atlantic Rainforest to monitor jaguars in both natural reserves and private areas:

The Great Mammals of Serra do Mar Program aims to generate data to support conservation plans for tapir (Tapirus terrestris), peccary (Tayassu pecari) and jaguar (Panthera onca).

The program's differential is its large-scale monitoring. There are 17 thousand square kilometers (km²) of operations in the states of São Paulo and Paraná – an area equivalent to 11 cities in São Paulo –, which make up the territory of the Great Atlantic Forest Reserve, the largest continuous remnant of preserved Atlantic Forest in the country.

[6]

What I like in the project besides considering natural forests and private reserves is the fact that it aims the preservation not only of jaguars, but also the integral monitoring of other large mammals, their preys. The Atlantic Rainforest is one of the areas with the largest biodiversity in the globe, surpassing by far the Amazon, a natural focus on conservationism.

One of the private reserves in the above mentioned project is called “Legado das Águas”(or “Legacy of the waters”), the largest private reserve of the Atlantic Forest in Brazil.

In Pantanal there is already several initiatives, in special prior ranches that became hotels and preserved their areas not only to attract visitors, but also preserve wildlife, with collar monitoring of jaguars. But jaguars move frequently from private reserve to private ranches, where they are shot in many occasions, once they prey on cattle. This is another long history, read more at Sergio Diniz's answer to Has a jaguar ever preyed upon an imported water buffalo in Brazil or anywhere else in South America?

In the Brazilian Amazon most of the land is public yet and is likely the only place jaguars are not threaten, yet. Thus, I am not aware of private reserves focused on jaguars preservation there.

But again, I will once more come back to the importance of corridors and how can private reserved be a key on that. One of this initiatives is in Brazilian Cerrado, the most biodiverse savanna in the world, carried by Jaguar Conservation Fund (JCF), a Brazilian NGO at Emas National Park in the country’s southwest.

The 131,400-hectare (324,700-acre)park, a UNESCO World Heritage Site since 2001, is home to at least 13 endangered mammal species. But on its own it’s not large enough to sustain a viable jaguar population, and the jaguars moving in and out of the park could be exposed to substantial extinction risk in the future, according to the survey…

In the Cerrado, jaguars have home range sizes of up to 15,000 hectares (37,000 acres), so for a park to sustain a viable jaguar population just within its borders, it needs to cover an area greater than 1 million hectares (2.5 million acres) — or nearly eight times the size of Emas National Park. The park is about half the size of Luxembourg…

Lead author Shannon Finnegan, from the State University of New York’s College of Environmental Science and Forestry, told Mongabay that jaguars travel outside the protected area in search of prey.

“Jaguars in this region move outside the boundaries of the park and onto agricultural lands regularly,” she says, adding she believes there is strong potential for the implementation of dispersal corridors into the Emas population.

[8]

This corridors could be arranged by private reserves, enough to allow jaguars’ migration.

Even though the Cerrado is a region with relatively low jaguar densities, creating effective dispersal corridors is crucial to ensuring the long-term survival of large carnivore populations. The study concludes that only a few immigrant jaguars are required to substantially mitigate the jaguar’s extinction risk in small populations. [8]

But fortunately, there are other corridor initiatives, where private reserves could be very useful. Let’s then talk a bit of the Jaguar Corridor Initiative:

The Jaguar Corridor Initiative is preserving the genetic integrity and future of the jaguar, which plans to connect and protect core jaguar populations from Mexico to Brazil, uniting public and private initiatives:

Panthera’s Jaguar Corridor Initiative is the only conservation program that seeks to protect jaguars across their entire six million km2 range. In partnership with governments, corporations, and local communities, Panthera’s Jaguar Corridor Initiative is working to preserve the genetic integrity of the jaguar by connecting and protecting core jaguar populations in human landscapes from northern Mexico to Argentina.

Panthera is currently leading or supporting efforts in eleven of the 18 jaguar range states, including Belize, Brazil, Bolivia, Colombia, Costa Rica, Guatemala, Honduras, Mexico, Nicaragua, Panama, and Suriname.

[9]

Back to the beginning, private reserves alone are not enough.

Some large-scale visions for multi-country ecological networks focus on wide-ranging umbrella species such as the jaguar. Ecological corridors in these networks can encompass multiple land uses and different land ownership, from federal entities to individual landowners.

[10]

Figure 1. Jaguar populations and corridors across its range. Populations and ecological corridors were prioritised according to ecological importance, network integrity and vulnerability. They were combined to identify all priority areas across jaguar range. © Kathy Zeller [10]

ADDITIONAL NOTE:

See also

Footnotes