Nearly 200 years after bison were hunted to extinction in northern Mexico, 47 were reintroduced in 2025, and are now helping prevent wildfires and regenerate their lost ecosystem

For nearly two centuries, the American bison was missing from this corner of northern Mexico. The animals that once grazed across the region had been driven out by human activity and hunting, leaving behind a landscape without one of its most influential large herbivores. Then, in 2025, they came back.

A total of 47 American bison were reintroduced into the El Santuario Reserve in Cuatrociénegas, Coahuila, a protected area within the Chihuahuan Desert, according to an AS report. The reintroduction was carried out in two stages: three bison arrived in August, followed by 44 more in November. The larger group consisted of 38 females and six males. The initiative involved Fundación Pro Cuatrociénegas, the Museo del Desierto and the Mexican Fund for the Conservation of Nature, among other conservation partners.

What makes the return significant is not simply the sight of bison once again roaming Mexican grasslands. Conservationists regard the animals as “ecosystem engineers” because their everyday behaviour can alter the physical and biological conditions around them.

The bison are back in Cuatrociénegas

The bison's disappearance was not simply a natural population decline. Conservation accounts describe the animals as having been hunted out of the Cuatrociénegas region roughly 160-200 years ago. Their return therefore represents an attempt to restore a species that had historically been part of the landscape.

The reintroduction also connects Cuatrociénegas with Mexico's wider bison-conservation efforts. The 44 animals released in late 2025 came from the bison population associated with Rancho El Uno in Chihuahua's Janos Biosphere Reserve, an established conservation area where American bison have already been successfully reintroduced.

Cuatrociénegas itself is an unusually important conservation landscape. The protected area covers roughly 84,000 hectares and is famous for its gypsum dunes, springs and distinctive aquatic habitats. UNESCO highlights the area's exceptionally high endemism and its many protected species.

How 47 animals can influence a landscape

The key lies in what bison do while simply living and feeding. Their grazing removes vegetation, including dry plant material that can otherwise become fuel. Gerardo Ruiz Smith, director of Fundación Pro Cuatrociénegas, told CNN that this feeding behaviour can help reduce the amount of combustible vegetation available to wildfires, potentially limiting both their outbreak and spread.

Their enormous bodies also physically interact with the ground. As bison move across the landscape, their hooves disturb and loosen the surface. Ruiz Smith has said this creates openings through which water can penetrate the soil, potentially improving infiltration and creating more favourable conditions for vegetation.

They also move seeds. Seeds can become caught in bison fur and subsequently fall elsewhere as the animals travel, providing a natural mechanism for dispersal. Their dung adds another layer to the process: it provides organic material and attracts dung beetles, whose activity can contribute to nutrient cycling and soil aeration.

The return of other animals

The most striking signs of change may not belong to the bison themselves. According to Ruiz Smith, camera traps in El Santuario have recorded pumas, lynxes and collared peccaries, animals he said had previously been absent from the area. Local birds have also been observed using bison fur as nesting material.

That does not mean 47 bison alone have restored the entire ecosystem. Ecosystem recovery is a complex process involving water, vegetation, wildlife, climate and human land use, and longer-term monitoring will be needed to determine how durable these changes are.

But conservationists see the early signs as encouraging.

More than bringing back an animal

The larger idea behind the project is that conservation does not always mean protecting individual species in isolation. Sometimes, restoring a species also means restoring the ecological functions it once performed.

In Cuatrociénegas, those functions include grazing, disturbing soil, moving seeds and returning nutrients to the ground. After generations without bison, those processes are happening again.