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Christian's Black Footed Ferret Research Report
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The Black-Footed Ferret

The black-footed ferret is a very lucky species because it has bounced back from presumed extinction multiple times in the last several decades.  Loss of habitat, reduction of prey and outbreaks of disease have caused a dramatic decline in population.  Re-population efforts have contributed to the resilience of this small carnivorous animal and has given researchers an opportunity to study the effects of near extinction.


The black-footed ferret gets its name from its dark colored feet.  It is from the kingdom of animals (Animalia), phylum of vertebrates (Craniata), class of mammals (Mammalia), order of carnivores (Carnivora), and family of weasels (Mustelidae) (Anonymous 2012, 1).  The scientific classification, Mustela nigripes, is Latin for black-footed weasel.  It can be compared to the American Mink and Long-Tailed Weasel (Anonymous 2012, 2).  The black-footed ferret migrated to North America over 800,000 years ago using the Bering Land Bridge between what is now Russia and Alaska (Wisely 2006, 1).  After migration, the black-footed ferret evolved separately from its sister species, the Siberian polecat (Wisely 2006, 2). 

The range of the black-footed ferret includes most of the grasslands in the Great Plains of western North America, in between the borders of Canada and Mexico (Anonymous 2011, 1; Owen 2000, 1).  For shelter, it forcibly takes burrows created by prairie dogs, including the black-tailed, white tailed and Gunnison's prairie dogs (Anonymous 2011, 2; Biggins 2006a, 3).   It takes an estimated 30 hectares (300,000 square meters) of prairie dog colony to support one female black-footed ferret, and up to 50 hectares if she has a liter of young ferrets, or kits (Anonymous 2012, 3; Biggins 2006a, 1; Biggins 2006a, 2).  As prairie dogs' habitats are being eliminated by farmers for use in planting crops, the range of the black-footed ferret is decreasing (Wisely 2002, 1).

The black-footed ferret is a yellowish weasel-like animal with dark legs, feet, tail and a dark mask around its eyes (Anonymous 2012, 4; Anonymous 2011, 3).  The coloring helps it blend into its natural habitat, making it harder to spot.  Mature ferrets weigh around 2.5 pounds and are about 2 feet long (Kivi 2010, 1).  The black-footed ferret is long and slim, with short legs and a long tail (Anonymous 2012, 4).  This helps it enter the prairie dog burrows when it is searching for food and shelter.  Other physical adaptations are its big eyes and ears, which allow it to have excellent eyesight and hearing (Kivi 2010, 1).

For its diet, the carnivorous black-footed ferret prefers prairie dogs, but it also eats rodents, voles, rabbits and squirrels (Owen 2000, 2; Anonymous 2012, 5; Biggins 2006b, 1).  On average, it can consume up to 100 prairie dogs per year (Kivi 2010, 2).  The ferret has long, sharp teeth accompanied by strong jaws (Kivi 2010, 2), which allows it to kill its prey with a bite to the throat or base of the skull (Eads 2010, 1; Owen 2000, 2).  The black-footed ferret is a nocturnal hunter, entering the prairie dog burrows at night to catch them off guard (Kivi 2010, 3; Eads 2010, 1).  They are also opportunistic scavengers when they run across a dead animal (Godbey 2006, 1).  Because the prairie dogs eat their surrounding vegetation, ranchers poison them to protect their cattle's food source.  When the black-footed ferret eats the easy prey, it gets poisoned and dies soon after (Kivi 2010, 4).

The black-footed ferret digs for food and shelter.  It shows a great preference for using prairie dog colonies for its habitat (Biggins 2006b, 3).  It seeks out burrows enlarged by badgers or that have a mound of soft subsoil at the entrance.  "Black-footed ferrets readily dig out (either from above or below ground) burrows plugged by prairie dogs without difficulty"  (Owen 2000, 3).  The black-footed ferret is not known to migrate (Anonymous 2012, 8), but it is known to be very territorial.  When it feels necessary, it will engage in a fight to the death to protect its mating and living grounds (Biggins 2006b, 4).  Scent marking is a common occurrence, especially during mating season (Biggins 2006b, 5).  

March and April is the mating season for the ferret.  It has a gestation period of about 45 days.  The average litter size for black-footed ferrets is 3.5 kits per litter.  The female ferrets give birth to the kits in the abandoned prairie dog burrows.  The kits appear above ground in July and go off on their own in the fall (Anonymous 2012, 6).

The black-footed ferret is a top-priority endangered species (Anonymous 2012, 7).   Its population was reduced by 99% over approximately 100 years due to destruction of habitat, prairie dog poisoning, canine distemper and sylvatic plague (Wisely 2006, 4).  Canine distemper is considered 100% fatal to ferrets (Williams 1988, 2).  Plague is very common in prairie dogs and commonly ends in a large number of deaths, impacting the ferret population (Godbey 2006, 2).  The black-footed ferret was considered extinct until 1964 when a small group was found in South Dakota.  The ferrets captured from that site all died in captivity.  After being presumed extinct a second time, another small group was discovered in 1981 near Meeteetse, Wyoming (Williams 1988, 1).  All 18 of the black-footed ferrets from that group were immediately taken into a captive breeding program to save them from extinction (Anonymous 2011, 5; Wisely 2002, 2; Wisely 2006, 3).  By 1986, there were no known black-footed ferrets in the wild and only 7 mature ferrets in the breeding program (Wisely 2002, 3). 

Most of the current research on the black-footed ferret is related to the multiple breeding programs after the near extinction.  One study was related to the effects of the plague on the ferrets.  It concluded that the plague could not be totally wiped out in the wild and that vaccinations would not be effective for the ferrets. The researchers concluded that protecting the black-footed ferret may depend on stopping the spread of the plague in the prairie dog colonies (Godbey 2006, 3).

Another study tried to look at the genetic diversity of black-footed ferrets after the near extinction by comparing the litter sizes of the ferrets in the wild and the ferrets in captivity.  The researchers found that the litter size was a good way to compare the genetic fitness of the population (Wisely 2002, 4).  The litter size was decided by the amount of kits that appeared above ground with their mother (Wisely 2002, 5).  The conclusion was that litter size did not change even through the near extinction.  Before 1985, there were about 3.2 kits per litter.  Between 1997 and 2000, there were about 3.1 kits per litter.  The 0.1 difference was too small to be considered as a change (Wisely 2002, 6). 

The next study took a look at the size and shape difference between in situ (wild) and ex situ (captive) black-footed ferrets (Wisely 2005, 1). The studies were measuring the length of the tibia (lower leg) bone (Wisely 2005, 2).  They found that ex situ adult ferrets had significantly shorter leg bones than the in situ ferrets, except in the CRC (Conservation and Research Center) site in Virginia (Wisely 2005, 3).  The difference in the bone length was about 9% (Wisely 2005, 8).  At the CRC site, the black-footed ferrets were kept in larger pens that simulated their natural habitat (Wisely 2005, 4). This provided the ferrets room for digging and other "mechanical stimuli" to aid the development of their leg bones (Wisely 2005, 5).  After the ex situ ferrets were reintroduced to the wild, their offspring eventually grew back to normal size within a few generations (Wisely 2005, 6). This led to the conclusion that the captive habitats were influencing the size and shape of the ferret's tibia bone and this was due to environmental factors and not due to genetic change (Wisely 2005, 7).

As of 2006, the breeding program was producing 200-300 kits a year and the approximate population was 240 ferrets in captivity and 500 in the wild (Biggins 2006b, 2; Wisely 2006, 5).  The ferrets were then placed into reintroduction sites that include Espee Ranch, Arizona; Logan County, Kansas; Lower Brule, South Dakota; Northern Cheyenne, Montana; Saskatewan, Canada; Vermejo Park Ranch, New Mexico; and Wind Cave National Park, South Dakota (Anonymous 2011, 7).  The breeding programs have had a lot of success with the reintroduction of the black-footed ferret.  Since 1987, there have been a total of 6,500 ferrets produced in captivity and 2,300 of them have been released into the wild (Anonymous 2011,  6).  According to the IUCN (International Union for Conservation of Nature), there are currently 1,000 ferrets in their natural habitat and 300 ferrets in captivity (Kivi 2010, 5).  In attempts to increase genetic diversity, each breeding program site collected sperm samples to be sent out to the other breeding programs (Kivi 2010, 6).   However, after decades of conservation efforts, the black-footed ferret still remains one of the most endangered species in the United States (Anonymous 2011, 4).

The black-footed ferret is significant to me because my uncle owned a ferret when he was in fighter pilot training in Texas.  He named his ferret Bogey, the same name that fighter pilots give to their adversaries.  Bogey was a fun and crazy bundle of fur that loved to run, jump and hide in tight spots around the house.  They also make a cute, squeaky chattering sound.  Now that I know how lucky these ferrets are to have survived, I have much greater respect for the smelly little beasts.


The black-footed ferret is still far from being safe.  Even though loss of habitat, reduction of prey and outbreaks of canine distemper and sylvatic plague have caused a near extinction of this ferret, it has been able to bounce back with no big change in the genetic diversity or physical characteristics.  With help from many reintroduction efforts, the range of black-footed ferret has extended from just one spot in Wyoming to 12 states from Canada to Mexico in the last few decades.  The population has grown from 18 in 1986 to over 1,300  ferrets now.  The black-footed ferret is a survivor. 


Works Cited

Anonymous. "Black-footed Ferret." Endangered Species of the Mountain-Prairie Region: U.S. Fish and Wildlife Service. 2011. Web. 06 May 2012. <>.

Anonymous. "Montana Field Guide." Black-footed Ferret. 2012. Web. 06 May 2012. <>.

Biggins, Dean E. "Evaluating Habitats of Black-footed Ferrets." Revision of an Existing Model. 2006a. Web. 1 May 2012. <>.

Biggins, Dean E. Habitat Preferences and Intraspecific Competition in Black-footed Ferrets. 2006b. Web. 1 May 2012. <>.

Eads, David A. "Nightime Aboveground Movements by Prairie Dogs on Colonies Inhabited by Black-footed Ferrets." 2006. Web. 1 May 2012. <>.

Godbey, Jerry L. "Exposure of Captive Black-footed Ferrets to Plague and Implications for Species Recovery." 2006. Web. 1 May 2012. <>.

Kivi, Rose. "Species Spotlight: Black Footed Ferret." Bright Hub. 2010. Web. 06 May 2012. <>.

Owen, Amela R. "Journal of Mammology." Fossils, Diet, and Conservation of Black-footed Ferets. 2000. Web. 1 May 2012. <>.

Williams, E. S. "Journal of Wildlife Diseases." Canine Distemper in Black-footed Ferrets (Mustela Nigripes) from Wyoming. 1988. Web. 06 May 2012. < html>.

Wisely. "Environment Influences Morphology and Development for in Situ and Ex Situ Populations of the Black-footed Ferret (Mustela Nigripes)." Animal Conservation. 2005. Web. 1 May 2012. <>.

Wisely, Samantha M. "Journal of Heredity." Genetic Diversity and Fitness in Black-Footed Ferrets Before and During a Bottleneck. 2002. Web. 06 May 2012. < html>.

Wisely, Samantha M. "The Genetic Legacy of the Black-footed Ferret: Past, Presant, and Future." 2006. Web. 1 May 2012. <>.