Seasonal changes in body weight of the raccoon dog in Wakayama, western Japan

Abstract

In the temperate zones, mammalian body weight increases via fat deposition prior to the onset of winter. However, seasonal variations in the body weight of wild raccoon dogs (Nyctereutes procyonoides) have never been assessed. We assessed seasonal changes in raccoon dog body weight using 118 males and 77 females aged at least 1 year in Wakayama, western Japan. Mean body weight was lowest in May (3.4 kg) and peaked in November (4.1 kg), representing an increase of 21.2% from summer to autumn. This pattern of body weight change is likely to reflect caloric consumption and use throughout the year, given that raccoon dogs consume fruit to increase body fat in autumn, and then utilize their fat resources during winter.