AGE STRUCTURE, MORTALITY, AND SEX-RATIO OF THE RACCOON DOG IN FINLAND

We studied the age, sex structure, and mortality of a population of th e raccoon dog (Nyctereutes procyonoides) in southern Finland from 1986 to 1990. The sex ratio was 1:1. There were no sexual differences in a ge structure. In the course of the study, the population declined slig htly, which was taken into account when life tables were calculated. T he age structure of the captures in autumn were rather stable in succe ssive years. Life tables were calculated by two methods; by treating t he captures from the breeding season (March-April) as a random sample of the population, and by treating the year-round captures (from Augus t to May) as a sample of the animals that die in the course of 1 year. The two life tables did not differ statistically; the annual mortalit y rate of the population in southern Finland was 80.5% (54 and 51% for adults, and 88 and 89% for juveniles, respectively). According to the life table based on the random sample of the population, the mortalit y rate was lowest among 2-4-year-old raccoon dogs and increased after 5 years of age; maximum life span was 7-8 years. Because of heavy pres sure from hunting, mortality among juveniles was high, which may have resulted in a high rate of reproduction.