The Black-Footed Ferret
After a decade of work, cloning of black-footed ferrets has produced five captive ferrets with no timeline for breeding integration, while genetic engineering for plague resistance remains entirely speculative. Even if these technologies succeed, they cannot solve the underlying problem: ferrets still require suitable habitat, including prairie dogs, which continue to face persecution.
A species saved, but still struggling
The black-footed ferret (Mustela nigripes) was once a widespread small carnivore across North America’s Great Plains. Its historical range includes 12 US states, the Canadian provinces of Saskatchewan and Alberta, and the Mexican state of Chihuahua.
Presumed extinct in the late 1970s, a Wyoming population was rediscovered in 1981, which led to recovery efforts. Traditional captive breeding programmes and habitat protection have increased wild populations to an estimated 325 individuals across 13 sites, all descended from seven founders.1 However, wild populations have been stagnant for about a decade.2 The IUCN lists the species as Endangered.3
Why is the black-footed ferret still endangered?
One of the main ongoing threats is the decline of prairie dogs (Cynomys spp.). Prairie dogs are the ferret’s primary food source and provide shelter, as black-footed ferrets live and raise their kits in old prairie dog burrows.
Additionally, the loss of contiguous shortgrass prairie habitat has isolated the remaining ferret populations. Black-footed ferrets currently occupy 300,000 acres of North America. To leave the endangered-species list, they would need about three times that area.2
Further threats include sylvatic plague and reduced genetic fitness from inbreeding.1 Sylvatic plague, caused by the bacterium Yersinia pestis and introduced to North America in the early 1900s, is the primary threat to reintroduced populations.
Can genetic engineering help save the species?
Scientists are now cloning ferrets to boost genetic diversity. Three black-footed ferrets have been cloned from frozen tissue belonging to a female outside the original seven founders. One of the clones has given birth to two kits, expanding the genetic founding pool from seven to eight.4
To protect rare black-footed ferret females, domestic ferrets (Mustela putorius furo) were used as egg donors, surrogates, and foster mothers. This marked the first cloning of a U.S. native endangered species.4
There are no public plans to release the cloned ferrets – or their offspring – into the wild.5 The primary goal of the project may be to pave the way for the genetic engineering of black-footed ferrets, which carries additional risks.6
To achieve heritable plague resistance, two genetic engineering approaches are being considered: duplicating the black-footed ferret’s own antibody genes to enable lifelong expression of a plague-neutralising antibody, or introducing genes from domestic ferrets for which sylvatic plague is not fatal.7
Both strategies would require many years to develop, and significant uncertainties remain. Approaches would first be tested in laboratory mice before transferring them to black-footed ferrets. An experimental ferret population would then be established to evaluate both plague resistance and long-term fitness across multiple generations.7
No prairie dogs, no ferrets: Habitat loss blocks recovery
The recovery of black-footed ferrets ultimately depends on the conservation of prairie dogs, which faces serious challenges. Today, prairie dogs occupy just 2% of their historic range,8 due to sylvatic plague – which has a 90% mortality rate in prairie dogs9 – as well as widespread legal poisoning and shooting.
As a result, finding suitable sites for ferret reintroductions is increasingly difficult. Of the 34 North American locations where captive-born ferrets have been released, nearly half no longer support any ferrets.2
Who decides? Gaps in regulation and oversight
The black-footed ferrets were cloned under a specific USFWS Endangered Species Recovery Permit, but this does not cover incorporating their genetics into breeding populations.10 Reintroduction efforts span eight U.S. states, Canada and Mexico11 – making international coordination of any future efforts to introduce their genetics into breeding populations essential but complicated.
The same 2018 permit also authorised genetic engineering of cell cultures. If genetic engineering for plague resistance eventually succeeds, it would introduce yet another layer of regulatory and cross-border complexity.
Equity and ownership: Who controls genetic conservation?
The cloning of the black-footed ferret has come about through collaboration with a private company, ViaGen Pets & Equine, raising questions about ownership and access to genetic resources from a US endangered species.
Funding and publicity directed toward high-tech interventions risk overshadowing community-driven habitat restoration and prairie dog management, which are essential for ferret survival.
Captive breeding and habitat protection have increased wild populations
What’s working now: Proven tools for ferret recovery
Proven conservation strategies are already demonstrating success. Traditional captive breeding programmes have increased wild populations from 18 individuals to 325 by 2019.1
Some practical tools to control sylvatic plague exist. Dusting burrows with insecticide to kill fleas remains effective, and an oral vaccine has improved prairie dog survival during outbreaks.12 Combined with habitat restoration to expand and connect prairie dog colonies, these efforts offer durable, ecosystem-level benefits.
Importantly, protecting prairie dog colonies supports not just ferrets but entire prairie communities, including burrowing owls, foxes and eagles.13
Sources
- US Fish and Wildlife Service. (2020). 5-year review for black-footed ferret (Mustela nigripes) https://ecos.fws.gov/docs/five_year_review/doc6326.pdf [↩] [↩] [↩]
- Wu KJ. (2024). How long should a species stay on life support? The Atlantic https://www.theatlantic.com/science/archive/2024/03/black-footed-ferret-vaccine-conservation/677733 [↩] [↩] [↩]
- IUCN Red List of Threatened Species (2015). https://apistaging.iucnredlist.org/es/species/14020/45200314 [↩]
- Novak BJ et al (2024). First endangered black-footed ferrets, Mustela nigripes, cloned for genetic rescue. bioRxiv. https://www.biorxiv.org/content/10.1101/2024.04.17.589896v1 [↩] [↩]
- Thomson J. (2024). Endangered cloned ferret has babies in a world first. Newsweek https://www.newsweek.com/endangered-species-black-footed-ferret-clone-babies-milestone-1979799 [↩]
- GeneWatch UK. (2025). Chimera: The Genetic Modification of Nature https://www.genewatch.org/sub-578277 [↩]
- Redford KH et al (Eds) (2019). Genetic frontiers for conservation. IUCN. https://portals.iucn.org/library/sites/library/files/documents/2019-012-En.pdf [↩] [↩]
- Boulerice J. (2025). Understanding the effects of plague treatment for prairie dogs. Smithsonian’s National Zoo & Conservation Biology Institute https://nationalzoo.si.edu/conservation/great-plains-science/plague-treatment-prairie-dogs [↩]
- USGS website. https://www.usgs.gov/programs/fish-and-wildlife-disease/sylvatic-plague [↩]
- Revive & Restore website. https://reviverestore.org/projects/black-footed-ferret-old/major-milestones [↩]
- Association of Zoos and Aquariums website. https://www.aza.org/reintroduction-programs [↩]
- Rocke TE et al. (2017). Sylvatic plague vaccine partially protects prairie dogs (Cynomys spp.) in field trials. EcoHealth https://link.springer.com/article/10.1007/s10393-017-1253-x [↩]
- US National Park Service website. https://home.nps.gov/articles/000/prairie-dogs.htm [↩]