Steppe Polecat, Mustela eversmanii
The steppe polecat (Mustela eversmanii), also known as the masked polecat or the white polecat, is a member of the Mustelidae family that is native to Eastern and Central Europe and Central Asia. It is a nomadic species, moving across its large range to follow its main prey item of ground squirrels. This species holds five recognized subspecies, and one extinct subspecies known as M. e. michnoi.
The steppe polecat is similar in appearance to the European polecat, but its body is longer due to the shorter guard hairs. Its size varies between males and females, with males growing slightly larger than females. Males can reach an average body length of up to 22.1 inches, with a tail length between 3.1 and 7.2 inches and an average weight of up to 4.5 pounds. Females can reach an average body length of up to 22.1 inches with a weight of up to 2.9 pounds.
The fur of the steppe polecat changes in the summer and the winter, after each coat is molted in the spring and fall seasons. The winter fur is soft and the base color is whitish yellow to yellow in color. The rougher guard hairs, which are thicker on the outer legs, tip of the tail, and along the spine, are brown to blackish brown in color. The head is white with black spots or almost completely white in color, and the neck can be yellowish white in color. The summer coat is thinner than the winter coat, and appears to be reddish in color, and the fur on the head is typically darker, creating a greater contrast between the lighter and darker fur.
Because the steppe polecat moves about so much, it is not thought to hold territories or home ranges. However, older males will sometimes establish loose territories during warmer months, if prey is abundant. Younger polecats move more frequently, inhabiting the burrows of the ground squirrels and other creatures they have eaten. Females that are nursing young will hold territories for the longest periods, but the typical stay for any polecat is between days and months. During the winter months, the steppe polecat will move between 7.4 and 11.1 miles per day.
The steppe polecat does not dig its own burrows, instead inhabiting those dug by voles, hamsters, moles, marmots, ground squirrels, and other creatures that live in underground dens. These polecats will expand the dens slightly, but because they will not stay long, the structure of the dens is not desirable for long periods. The nesting burrows of this species are expanded to hold at least three passageways, but can hold up to twenty, but burrows dug completely by the steppe polecat are shallow and cannot support these passages.
The mating season for the steppe polecat in captivity occurs in the month of March, but in the wild, mating can vary. In western Siberia, polecats began to mate in March, but in Transbaikalia the mating season occurs in late May. Females breed once a year, producing one litter, but if breeding was not successful or if a litter has died, breeding can occur again. After a pregnancy period of up to 43 days, a litter of three to six kits is born, although litters of up to eighteen have been recorded.
Kits are born both blind and hairless and weigh only .1 ounces. After about three days, the kits weigh 1.1 ounces and began to grow a white undercoat. By the twentieth day of age, the kits are dark in color and weigh 2.5 ounces. By thirty-four days of age, the kits will open their eyes and will attempt to feed on meat, although they do not reach full maturity until two and half months of age. Full maturity is reached at two years of age. Although its growth rate is fast in the first few months of its life, the steppe polecat’s skull is still growing at the time its relative, the European polecat, has reached full maturity.
The steppe polecat feeds primarily on ground squirrels or rodents, but it will consume pikas, hamsters, and other small mammals. During warm months, these polecats will hunt ground squirrels along the ground, but during colder months, they must extract the squirrels from burrows. Males typically must widen the entrance to a burrow before it consumes the squirrels, but young females can crawl inside the burrow to hunt during this time. Pikas, hamsters, or water voles become the steppe polecat’s main diet in areas where ground squirrels do not occur. Other prey choices include fish, chicken, and carrion along rivers and lakes. Birds, reptiles, and amphibians are occasionally consumed.
The steppe polecat can contract many diseases including tularemia, the sylvatic plague, pasteurellosis, and even canine distemper. This polecat can catch ticks and eleven species of fleas, a few of which are caught from prey.
In the former Soviet Union, the steppe polecat holds a significant economic value to humans that share its range. It hunts species that cause damage to crops and spread diseases, and can kill up to 1,500 mouse-like rodents or 200 ground squirrels within a year. It is also hunted for its fur in this area, and is highly prized in Kazakhstan. During the 1920’s and 1950’s, the population numbers of the steppe polecat decreased significantly due to habitat destruction and a decrease in prey. Fortunately, this species is common and relatively easy to farm. The steppe polecat appears on the IUCN Red List with a conservation status of “Least Concern.”
Image Caption: Mustela eversmannii (Steppe Polecat), dermoplastic specimen (taxidermy), origin: Dolní Němčí, Czech Republic. Credit: Jan Dušek/Wikipedia (CC BY-SA 3.0)