Like that of several other British mammals the distribution of the polecat has not yet been fully investigated. For one thing, being a creature of the night and mainly haunting sparsely inhabited uplands or the wilder parts of the lowlands, it is a difficult and often inaccessible subject for study. There is the further complication that ferrets, which are apparently not descended from our polecat but, some authorities say, from a North African species, have for many centuries been escaping and crossing with wild polecats so that perhaps nowhere can the polecat be claimed to be a “pure” species. Besides, rabbiters frequently interbreed tame polecats with ferrets. The resulting polecat-ferrets, usually piebald creatures, have been used for rabbiting in various parts of Britain, where many have escaped and formed local populations of “polecats”. This spread of polecat-ferrets has been much accelerated by the intensification of rabbiting which has taken place since 1939 and accounts for the many recent “polecat” records from areas known not to hold true wild polecats : the Home Counties, the Isle of Man, Mull, etc. Since these hybrids usually show much cream on back, head, or flanks, it might be thought that, being easily separated from genuine polecats, they would not complicate the distribution-map. Unfortunately some of these hybrids, and we do not know how numerous they may be, are all dark and indistinguishable from wild polecats. There are several apparently reliable accounts from central Wales of white female ferrets going wild for a few weeks and eventually returning to captivity leading families of absolutely dark young “polecats”. And since these may quite easily be sold elsewhere in Britain, it is not surprising that very genuine looking “polecats” turn up in unexpected places.
Taxonomic Results of the BRYOTROP Expedition to Zaire and Rwanda 29. Thuidiaceae, Thuidium
