Rewilding the Prairie: A Conversation With Aaron Facka on Black-Footed Ferrets

Rewilding ecosystems comes in many shapes and sizes; it’s a collective process involving many people and many species. It also often requires starting small and focused – one species can be a critical piece to a much larger puzzle.  

As part of our rewilding efforts, we are researching one of these critical puzzle pieces: the black-footed ferret, a small carnivore that once roamed western North America. For the last four years, we’ve been working to support this ferret’s reintroduction by using deep-learning technology alongside on-the-ground research in prairie and grassland ecosystems throughout New Mexico and Utah.  

Hear from Aaron Facka, PhD, our Senior Wildlife Biologist, below for details on our research, the fascinating ferret, and rewilding in the West.  

A black-footed ferret in its native grassland habitat. Photo by Kerry Hargrove

The black-footed ferret has a tumultuous history – how has their population fluctuated over time? How are they doing now? 

Aaron: The black-footed ferret originally lived in western North America from Canada to Mexico, evolving to thrive in miles of flat grasslands and prairies east of the Rockies. Over the last 100 years, people, development, and disease drove the species to near extinction in the wild in the 1970s.  

In 1981, the ferret was thought to be extinct when a ranch dog in Wyoming brought home a long, skinny animal with black fur banding its eyes and feet. The family took it to a local taxidermist, where it was excitedly identified as a black-footed ferret, leading biologists to find a small colony that ultimately saved the species after a remarkable comeback in captivity. 

Over the last 50 years, they’ve remained one of the most endangered mammals in the world. Since then, the U.S. Fish and Wildlife Service designated the species as endangered and began reintroduction efforts across this historic range, helping their population grow to what is now between 400 and 500 individuals. We still have a lot of work to do to increase and stabilize this at-risk population. 

This map illustrates the approximate historic black-footed ferret range, which has been reduced to ~30 reintroduction sites shown as dots above. Map by Wildlands Network

Why are black-footed ferrets important to their native grassland ecosystem?  

Aaron: These small carnivores are the only ferrets native to the continent, found nowhere else on the planet but the grasslands and prairies of western North America. They’re known as an indicator species, meaning that their presence signals healthy grassland ecosystems as they serve as both a key predator and prey on the prairie.  

A black-footed ferret peeking from a burrow. Photo by Kerry Hargrove

What is the relationship between black-footed ferrets and prairie dogs?  

Aaron: Black-footed ferrets have an extremely specialized diet. They don’t just hunt prairie dogs – prairie dogs actually make up 90% of the food they eat. As a result, the ferret population is entirely dependent on large, stable prairie dog populations. As prairie dog numbers declined by up to 98% in North America due to agriculture, hunting, poisoning, and disease, so declined the black-footed ferrets.  

Prairie dogs are themselves keystone species that have an enormous effect on nutrient and water cycling, are prey bases for other species, and they create burrows for invertebrates and species like burrowing owls. Their colonies may also increase the forage quality for species like pronghorn and bison. Ferrets also use prairie dog burrows for shelter and raising young – and an occasional alternative food source when other species share the burrows. 

Prairie dogs and their grasslands in our Valles Caldera National Preserve project. Photos by Donny Kelley-Currens/Bosque School.

What is the biggest challenge to rewilding these ferrets? How do conservationists think about reintroduction? 

Aaron: Conservationists are actively looking for new grassland locations to reintroduce black-footed ferrets across the West, including in New Mexico and Utah where we’re conducting research. The biggest challenge conservationists face is maintaining and identifying large and stable prairie dog populations to reliably sustain new black-footed ferret populations given how intertwined the species are.  

Another important and difficult part of this equation is identifying and mitigating disease in prairie dog colonies, as disease decimates prairie dog populations and can be passed to ferrets – a double whammy.   

Finding ideal locations requires actively monitoring prairie dogs and their intricate burrowing networks across miles of grasslands for consistent, year-over-year data that 1) tracks populations that sustain over long periods of time, 2) gives up-to-date information, or 3) identifies locations of intact grasslands which could support prairie dogs and ferrets.  

This map illustrates the approximate historic ranges for the black-footed ferret and several prairie dog species. Each dot represents a ferret reintroduction site. Map by Wildlands Network

Why is deep-learning technology important in ferret and prairie dog research?  

Aaron: Despite their importance to ferrets and other species, prairie dogs are not well monitored across their range or large landscapes. Given the need to track their populations and their total extent on the landscape, deep-learning models are potentially critical tools to help us consistently monitor large landscapes to identify reliable prairie dog colonies. It also helps us find grassland areas without prairie dogs that may be suitable to reintroduce prairie dogs and subsequently black-footed ferrets.  

As a result, we’re using deep-learning models to map and monitor prairie dog populations by using AI to decipher aerial footage of large landscapes and estimate the numbers of existing prairie dog colonies.  

A map of one of our project sites in New Mexico using a deep-learning model. Map by Wildlands Network

How well have deep-learning models predicted prairie dog burrow locations so far? 

Aaron: As part of our prairie dog monitoring project, we recently worked with students at the Bosque School in New Mexico to validate our deep-learning model by comparing the model’s predicted prairie dog burrow locations with the burrows we identified in the field.  

We found that the model accurately predicted where prairie dog burrows existed 65% of the time, with the other 35% of its predictions misidentifying boulders or tree snags. As a result, we found the models to be accurate for identifying existing prairie dog colonies while these misidentified areas could often be corrected by minimal desktop validation from a trained scientist.  

We used this information to refine our models and both 1) improve the model’s accuracy and 2) teach the technology to better distinguish between burrows, trees, and boulders.  

What progress have we made so far in restoring ferret and prairie dog populations? What are the next steps? 

Aaron: We’ve been actively using and refining our methods in several areas with different prairie dog species. We’re working with biologists in Utah to help identify potential colonies of the endangered Utah prairie dog, at Valles Caldera National Preserve to assess Gunnison’s prairie dog populations, and across eastern New Mexico where we’re about to begin a mapping project for black-tailed prairie dogs. Our work at Valles Caldera National preserve could provide an initial assessment for the possibility of reintroducing black-footed ferrets in that area – though that work is still in early inception.  

Projects like the ones above have helped us improve our capability to regularly monitor prairie dog populations over time. Over the next five years, we will continue to collect data on these populations and work with agency and nonprofit partners to assess new black-footed ferret reintroduction locations. 

A collared black-footed ferret in one of Aaron Facka’s prior research projects in Arizona. Photo by Aaron Facka 

What does a rewilded future look like for these species?  

Aaron: Ideally, we can collectively identify enough locations across the ranges of prairie dogs to support sustainable populations of prairie dogs and black-footed ferrets independent of human support. With that foundation, we can increase the population size and distribution of both ferrets and prairie dogs so that these ferrets are no longer endangered but are thriving across the continent.  

In turn, reintroducing these species creates a ripple effect that supports a wide variety of animals and plants that rely on them, from raptors and badgers to insects and grasses. This ultimately creates a future not just for individual species but a rewilded future in its essence: the restoration of entire ecosystems.  

Cover photo by Kerry Hargrove.