Tuesday, January 15, 2008
The Spread of Tanukis (Raccoon Dogs)
The Tanuki or Raccoon Dog is an interesting animal that is hunted with terriers in Finland and, increasingly, in other European countries as well.
Originally from Japan and China, this 13-22-pound animal has migrated through Russia and into Finland (where it was imported for fur and sport), and is now found as far west as France. While some sources claim this animal was once hunted to near extinction in Japan, numbers there seem to have rebounded with a vengeance (if in fact they were ever low), as road impacts now are estimated to be in the range of 110,000 - 370,000 a year.
The secret to the Tanuki's success seems to be that it occupies an ecological niche that was heretofore unoccupied in Europe. The red fox specializes on small mammals (mice and voles), the raccoon dog on plant material (berries and seeds) and the badger on invertebrates (worms, snails and beetle grubs).
Though primarily a plant eater, the Tanuki is an opportunistic omnivore that will eat just about anything if given a chance, and is willing to live in a wide variety of homes, including old fox, badger and rabbit dens -- as well as under sheds, and in locations very near human residences.
Unlike the Raccoon, the Tanuki is a true canid ( Canus Nyctereutes procyonoides). The "procyonoides" species name is a tip of the hat to the genus name of the North American Raccoon, Procyon.
Where the Tanuki differs from other canids. is that it is fairly slow, and has a jaw structure that is too weak to take down larger prey. Like the raccoon, Tanuki will scavenge baby birds from nests and might catch an occasional mouse, but their weak carnassials and well developed molars mean they have a diet heavy in plant matter supplanted by eggs, lizards, roadkill, frogs, mice, insects and human refuse.
Like Fox, Raccoon, Possum, and Groundhog, the average Tanuki has a short life span, rarely living past three years in the wild.
Of course, as with any successful species with a short life span, reproduction rates are high. The average Tanuki litter is 5 to 9 pups born in a ground burrow after a gestation period of about 60 days.
The raccoon dog carries the highest average litter weight of any canid, with the mean weight of a litter being 24% of the weight of the female. Males stick around and help raise the young -- a good thing since the female Tanuki is no doubt exhausted from carrying her load!
Home ranges for a Tanuki are quite large (10-20 sq kilometres) and overlap, reflecting the seasonal nature of food sources. As food in one area declines, the Tanuki waddles off to another area where the berries, insects or seeds are in greater supply.