The European Polecat population in Norway

 

by Hanne Karlsen

 

The European Polecat (Mustela putorius) can be found in most of Europe, the south of Norway, Sweden and Finland, representing the northern border for it`s extensiveness. The western border is made up by the Atlantic ocean, east; the Ural-mountains, and south; the Mediterranean sea and the Black Sea.

 

The European Polecat have been a part of the Norvegian fauna since the Postglaciale heat- period started, for around 8000-8500 years ago, and for example, a Polecat-jaw were found at a famouse Norvegian stone-age settlement (Vistehulen i Jæren). When the climate got colder and wetter, for around 2500 years ago, the Polecat, among other warm-loving species, were forced to withdraw to southern parts of Europe. After this, the climate have changed back and foreward, and have probably affected the Polecat-population all over Scandinavia. There are reasons to believe that the Polecat-population in Norway were quite stable up till the 1700 century.

 

 

Physical description

 

The Polecat have a long, slender body, and a characteristic “mask” in their face. They have short feets and small faces with rounded ears. The only difference between the look of the sexes, is the size, with females being quite smaller. They use their sense of smell for hunting, reckognising territory and for finding mates.

 

 

Home Range and territory

 

The availability of food decides the size of the home range. Female territory varies between 0,3-0,83km2, and male territory lies in between 0,2-3,55km2. They have several dens, usually not made by them self. Rabbit holes are often used. They prefer forest habitat, but can be found elsewhere when food is scarce.

 

They are often found around farm buildings on the edge of settlements, and were actually used by man i Europe to protect granarys and other foodstocks from rodents and other pests in the same way the Egyptians used cats. This is believed to be the origin of the domestication of Polecats, which have led to modern days domestic ferrets, which are kept as pets.

 

 

Feeding habits

 

The polecat is a carnivore. There have been many studies about the polecats feeding habits, some claim that it is a specialist, while other says it is a typical generalist. All over, the polecat eat a great variety of food, depending on season, the place it lives, age of the animal and so on. But small rodents, frogs, toads, birds and eggs seem to be the main diet. It is known for stockpiling, and storing live frogs that they paralyze by biting their neck.

 

They hunt by scent rather than sight, and their long, thin bodies are perfect for hunting burrow-living prey.

 

 

 

 

 

Polecat vs. mink

 

In France, they studied if there were any food-competition between the European Polecat and the American Mink. The conclusion they got was that amphibians were of greater importance for the Polecat than for the Mink, while the Mink eat more fish and birds. So the nicheoverlap was not so big between the species. An important factor was a heterogenous area, so that alot of different prey-species were represented.

 

So why is the mink so widespread and succsessful in Norway? The mink and the polecat is very similar both in looks and way of life, so one could believe that their population should be of the approximate same size. On top of this, the minkfur are much more popular, so alot more mink have been killed in Norway. There is no key answer known, but my opinion is that it migth be because the mink is more adapted to cold weather, and since the mink live largely of fish, Norway with all the fjords are perfect.

 

 

Social life and reproduction

 

The biology of the European Polecat have not been studied in Norway, so all the knowledgs and facts are from other countries.

 

The adult polecat has a solitary lifestyle, and they only meet for mating. They have a promiscuously polygamous mating system, and both the male and female mate with several individuals.

 

The matingperiod varies after geografical aspects, but usually from the end of march to may. As spring is approaching, males gets more aggressive, which might be to stop others from entering their territory. One set of cubs a year is normal, and the polecat usually reaches sexual maturity around their second year. The fetusdevelopment happens without delayed implanation, as of most mustelids. The pregnancy lasts for 42 days, and the litter size vary from 5-10. The cubs stays with their mother usually until september/october, even though they are capable of surviving on their own after 2-3 months.

 

Mortality and morbidity

 

Since the population in Norway are very little, there is no research done on this. But studies from Britain and Netherland show that animals killed in traffic is the biggest cause of death. Usually wild polecats dies within the age of five (due to human interferrence), while animals in captivity can easily reach the age of 8-10. Mortality among young are believed to be high too.

 

The polecat were formely killed for their fur, and big polecat-farms could be found several places in Norway. After World War 2, people were paid for every polecat they killed, and in 1953, 944 animals were registered killed. The numbers sunk in the years after, and in the end of sixties the payments stopped. Few polecats have been observed in Norway after that time-period, and there is no evidence that the population ever increased again. Since the ferret have becomed more and more popular as a pet, most observations done the last 15-20 years probably are of domesticated animals.

 

Conclusion

 

The polecat population all over Europe is diminishing, but it is not on the list of endangered species. Habitat alteration and direct persecution seems to be the main causes. Rough and cold winters have also made the Norwegian climate unsuitable for them, and also the modernisation of houses and farm buildings. It is probably the climate that will determine wheter or not the polecat population in Norway will survive.

 

Even though there have been several reports of observation of the European Polecat in Norway the resent years, it is not certain that  these are of a wild one, since the popularity of tame ferrets have increased, and these resemble their anchestors, and can therefore be mistakenfor one when they run away.  Also animals origin from farms might escape, and be mistaken for a wild one. Actually, alot of farm-animals escaped or were freed when farms went bankrupt, and those induviduals we have in Norway could just as well origin from these, or have been interbreeded with some.

 

Since there anyhow are few of them, and they are pretty much nocturnal, it is hard to get a clear picture of the size of the population. Their prints are quite similar to the mink, which are found in great extent over most parts of Norway, so it is not a easy job to get a clear picture on their existence in Norway. But their population seems to be narrowed down to small places in the south of Norway, near the Swedish border (where the polecat-population is bigger and more stable).

 

No one can predict how the loss of one specie will affect the rest of the natural ecosystem in that specific area. Future conservation plans should incorporate consideration when agricultural- and landscape alterations are made. The population in rest of Europe must be protected to prevent extinction of the wild European Polecat, and better awareness of this animal should be taken.

 

 

Sources

 

Professor Kjetil Bevanger, a Norwegian polecat-scientist

 

http://www.zoologi.no/fakta/ilder.htm

 

http://europa.eu.int/comm/food/fs/sc/scah/out67_en.pdf

 

http://nidaros.nina.no/

 

http://www.bbc.co.uk/nature/wildfacts/factfiles/274.shtml