The only endemic species confined to North America is the black-footed ferrets. The U.S Fish and Wildlife Services have marked them as endangered species from the year 1967. They belong to the genus "Mustela" and subgenus "Putorius". The sub genus consists of only three species which includes Mustela putorius known as the European polecat, Mustela eversmanni also called the Steppe or Siberian polecat and Mustela nigripes known as black footed ferrets.

The origin of ferrets took place in Europe about six million years ago. They evolved from the weasel like ancestors. It was during the middle Pleistocene, Mustela stromeri which was the earliest known ferrets lead to the origin of Mustela putorius and Mustela eversmanni. During the late Pleistocene stage, the ferrets came into North America from Siberia by passing the Bering land bridge. It was through the ice-free passageways they deviated towards the southeastern region to the Great Plains.

The evolution took place for over thousands of years feeding on the prairie dogs as prey and thus came the black footed ferrets which are recognized as endangered species today. The first appearance of the mammal has not been stated yet, but it has also told that the animal was found almost 100,000 years back in North America. It has been estimated that the deviation of the species from Siberia took place almost 2 million years ago.

The black footed ferrets has been found in the grassland habitats along the Great Plains in almost 2 Canadian provinces, 12 states and also in some northern parts of Mexico. Ferrets were to cover a larger area for their living when they lived on their prey to be the prairie dog. Today the situation has changed as the geographic distribution has been reduced to less than 2 percent which has lead to the decreased population of ferrets. They are presently denoted as the depreciated and encroached ecosystem where they live in.

The relation and co-existence of the ferrets and prairie dogs for thousands of years has been widely known by the Native Americans. The camps formed by prehistoric Indians have found out skeletons of both the prairie dogs and ferrets.

Active steps has been taken by the private landowners, native Americans, conservation groups and the North American Zoo community to bring back the ferrets into their natural habitat since 1991. The sites referred for this purpose are mainly parts of Utah and Colorado. The efforts have had benefits and the species are also presently claimed to be having an 'Astonishing Comeback'.

Black footed ferrets are considered to be one of the endangered species of North America. A species is considered to be endangered when it is in the edge of immediate extinction and needs proper security and implementation of protection services for its survival. Ferrets depended on prairie dogs for their survival and it has been estimated that almost 250 prairie dogs is needed for a ferret family throughout the year.

The black footed ferrets hunt their prey in open and vast grasslands. For turning their habitat into farmland, the farmers have tried their hand in the elimination of the prairie dogs by destroying their burrows with poison. The ferrets depend entirely over the prairie dogs for their complete living apart from their food. They rest in the burrows of their prey during day time and this is how they were poisoned accidentally. The reduced number of prairie dogs has been considered as the major cause of decreasing ferret population as they depended entirely on them for their living.

There are two major reasons for considering the ferrets to be endangered. These are due to their habitat loss where they need acres of land thriving and the land was transformed into field by the people of the village. The loss of their food or reduced number of prey was considered to be the other reason.

At first, the ferrets were just listed as endangered animals and further developments were not encouraged by the team. But recently severe action has been adopted in saving these animals from extinction. For this, the animals are captured and breaded by providing the perfect platform for them to live by setting their habitat. It has also aimed at making the population to a census size of 200 breeding adults by 1991 and they have accomplished the goal well and fine.

With re-introduction of the ferrets into their habits, captive breeding has been ensured to be increasingly popular. And according to the studies, it has been stated that a total of 228 ferrets has been released after 1991. With the active steps taken and proper management updated for the protection of the animals, successful results have been obtained in conserving them.

With proper adoption of conservation techniques and passing of laws and acts, the population of ferrets has been rising. These plans are affected by several interactions whereby several measures are taken to counteract them.