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 degrees 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 degrees 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 degrees 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 degrees 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.

Adaptation to cold and predation—shelter use by invasive raccoon dogs Nyctereutes procyonoides in Białowieża Primeval Forest (Poland)

“…Seasonally available food items constitute up to 50% of raccoon dog diet (Jędrzejewska and Jędrzejewski 1998), so to survive periods of food shortage raccoon dogs store fat reserves (Kauhala 1993, Kowalczyk R., unpublished data), settle into good shelters such as badger setts Kowalczyk et al 2008, this study) and undergo winter lethargy, at least in the northern part of the distribution area (Mustonen et al 2007;Kitao et al 2009). Raccoon dogs may compensate for seasonal limitation of food by carrion consumption (Jędrzejewska and Jędrzejewski 1998;Sidorovich et al 2000;Selva et al 2005), but this resource is limited and unpredictable in space and time.…”

“…Raccoon dogs are omnivorous carnivores and their diet strongly varies between different locations Jędrzejewska and Jędrzejewski 1998;Drygala et al 2000;Sidorovich et al 2000Sidorovich et al , 2008. They are also unique among canids as their overwintering strategy involves long periods of inactivity and winter lethargy (Asikainen et al 2004;Mustonen et al 2007. Kitao et al 2009).…”

Rabies in Northeastern Europe—the Threat From Invasive Raccoon Dogs

“…However, even in the north, active raccoon dogs have been observed in warm periods during winter. Temperature, snow depth and day length affect their winter activity (Kauhala et al, 2007). Hibernation may also alter rabies pathogenesis.…”

“…They may also change their den site during winter. During hibernation, the average body temperature decreases by 1.4-2.1 C (Mustonen et al, 2007). Raccoon dogs gather large fat reserves in autumn and lose about 43% of their body mass during winter (Kauhala, 1993;Mustonen et al, 2007).…”

“…Omnivory, large litter size, and hibernation were suggested as explanations for their high reproductive success Kauhala, 1996;Kauhala et al, 1998). Raccoon dogs start hibernation in November and wake up in March in southern Finland (Kauhala et al, 2007). They usually stay in their dens when temperature is below 210 C, snow depth .35 cm and day length ,7 hr.…”