Seasonal Rhythms of Body Temperature in the Free‐Ranging Raccoon Dog (Nyctereutes procyonoides) with Special Emphasis on Winter Sleep

Abstract

The raccoon dog (Nyctereutes procyonoides) is the only canid with passive overwintering in areas with cold winters, but the depth and rhythmicity of wintertime hypothermia in the wild raccoon dog are unknown. To study the seasonal rhythms of body temperature (T_b), seven free‐ranging animals were captured and implanted with intra‐abdominal T_b loggers and radio‐tracked during years 2004–2006. The average size of the home ranges was 306±26 ha, and the average 24 h T_b was 38.0±<0.01°C during the snow‐free period (May–November). The highest and lowest T_b were usually recorded around midnight (21∶00–02∶00 h) and between 05∶00–11∶00 h, respectively, and the range of the 24 h oscillations was 1.2±0.01°C. The animals lost approximately 43±6% of body mass in winter (December–April), when the average size of the home ranges was 372±108 ha. During the 2–9‐wk periods of passivity in January–March, the average 24 h T_b decreased by 1.4–2.1°C compared to the snow‐free period. The raccoon dogs were hypothermic for 5 h in the morning (06∶00–11∶00 h), whereas the highest T_b values were recorded between 16∶00–23∶00 h. The range of the 24 h oscillations increased by approximately 0.6°C, and the rhythmicity was more pronounced than in the snow‐free period. The ambient temperature and depth of snow cover were important determinants of the seasonal T_b rhythms. The overwintering strategy of the raccoon dog resembled the patterns of winter sleep in bears and badgers, but the wintertime passivity of the species was more intermittent and the decrease in the T_b less pronounced.

• Canids
• Carnivores
• Hypothermia
• Seasonal rest
• Wintering strategy

Notes

This study was supported financially by the Academy of Finland, the Alfred Kordelin Foundation and the Finnish Game Management Fund.