Partial arousals from hibernation in a pair of common dormice, Muscardinus avellanarius (Rodentia, Gliridae), in their natural hibernaculum

Abstract

A pair of common dormice discovered while torpid in their natural hibernaculum on December 5, was studied continously outdoors, exposed to natural fluctuations in temperature and rainfall. Temperature inside and outside the nest ball and motor activity were recorded. The first emergence from hibernaculum occurred on March 4, after which the dormice were daily active, chiefly during evening and night hours. Nest departures lasted on average 10.5 h (6.5-14 h) per day.During the 88 days while the animals remained in the hibernaculum ambient temperature ranged from -5° to 8.5° C. Nest temperature never fell below zero, being chiefly 1.0°C above ambient temperature during 68 of these days and thus reflecting deep hibernation in both animals. However, on 19 occasions nest temperature was raised steeply from average 5.6°C (2.0-8.0°C) to average 23.0°C (17.5-32.5°C). These increases of nest temperature, lasting roughly 4 h (3-8 h) are interpreted as partial arousals. The total duration of partial arousals was 76 h, i.e. 3.6% of the time during which the animals remained consistently in the nest.The interarousal time varied, being 16 days at the most and 12 h at the least. The frequency of arousals increased with rising maximum values of ambient temperature, and partial arousals never were recorded on days when temperature remained below 2°C. It is believed that partial arousals correspond to the periodic or spontaneous arousals previously recorded in laboratory experiments of some other hibernating mammals. However, the energetic expenditure seems to be smaller during periodic arousals because of their shorter duration and the fact that no departure from the hibernaculum occurs.Possible mechanisms governing partial arousals are discussed. As these events chiefly occurred during night they may partly be controlled by an inherent time sense.

Partial arousals from hibernation in hedgehogs in outdoor hibernacula

“…3) chiefly was much below 35-37 ~ C, previously reported as normal body temperature of the hedgehog during summer (Herter, 1934;Proctor, 1949). This hypothesis is supported by recent studies of the common dormouse, Muscardinus avelIanarius, in which nest temperatures were significantly lower during partial arousals compared to full arousals, when daily activity was resumed (Walhovd, 1976).…”

Effects of food availability and ambient temperature on hibernation in the Japanese dormouse,Glirulus japonicus

“…The Ta conditions in Experiment 1 (about 7-8~ fluctuation in a day and a maximum as high as 10~ on the average) were probably quite different from those in the animal's natural hibernaculum (Walhovd 1976) and unfavorable for the occurrence of torpor. We conducted Experiment 2, therefore, to determine whether the constant cold which is considered to be favorable for hypothermia can, by itself, raise the incidence of day-long torpor in the animals given ad lib food.…”

Thermoregulation and patterns of torpor in the spectacled dormouse,Graphiurus ocularis(A. Smith 1829) (Gliridae)

“…Hibernation throughout winter has been recorded in the temperate common dormouse Muscardinus avellanarius Linnaeus 1758 (WALHOVD 1976) and Glis glis (JALLEAGAS & ASSENMACHER 1986). In Eliomys quercinus, hibernation continues throughout winter with each torpor bout lasting 10 days (PAJUNEN 1984(PAJUNEN , 1986, whereas the percentile dormancy of Glis glis is 34-44 days per year (JALLEAGAS & AssENMACHER 1986).…”

“…Northern temperate dormice show distinct patterns of torpor and hibernation; activity is confined to spring and summer with hibernation occurring throughout the winter (NEVO & AMIR 1964, WALHOVD 1976. However, the forest dormouse, Dryomys nitidula Pallas 1779 of Israel, is active throughout the year, although during winter short bouts of hibernation occur ranging in duration from a few hours to 3 days (NEVO & AMIR 1964).…”