Japanese Journal of Veterinary Research;Volume 50, Number 4


Growth pattern and seasonal weight changes of the feral raccoon (Procyon lotor) in Hokkaido, Japan

Asano, Makoto;Matoba, Yohei;Ikeda, Toru;Suzuki, Masatsugu;Asakawa, Mitsuhiko;Ohtaishi, Noriyuki

Permalink : http://hdl.handle.net/2115/2964
JaLCDOI : 10.14943/jjvr.50.4.165
KEYWORDS : body size;growth;Procyon lotor;raccoon;seasonal change


The growth pattern and seasonal weight fluctuations of feral raccoons in Hokkaido were evaluated between 1999 and 2001. The growth rates in body length and body weight were described for juveniles (young of the year) and yearlings (animals born in the previous season) using the Gompertz growth model. The asymptotic body sizes for males were greater than those for females. Young raccoons born during spring in the study area could potentially grow up to their asymptotic size at the beginning of their first winter, but they would not reach their full adult sizes until at least their second fall. Adult raccoons (animals ≥ 2-year-old) had seasonal weight fluctuations with annual weight loss of 25% to 28% of mean maximum weights in west-central Hokkaido, but these result would be an underestimate of the degree of annual weight fluctuations. Juvenile raccoons can be distinguished from the older animals by measuring body length or body weight during fall in Hokkaido.