Low temperature effects and social influences on physiological condition of subadult wild rabbits

The effects of low ambient temperature and of social factors on the physiol ogical condition of subadult European wild rabbits (Oryctolagus cuniculus L .) during the winter season were studied in a population living under semi- natural conditions. Total serum protein, serum concentration of beta -hydro xybutyrate and body mass were monitored monthly and percentage of glycated haemoglobin was determined once in late winter. Social integration of subad ults was assessed by direct observations. A close relationship between fluc tuations of ambient temperature, serum protein levels and body mass was fou nd. The results indicate that protein reserves rather than body lipids but were the important energy resource of subadult rabbits during the winter se ason. Negative effects on physiological parameters were closely related to higher mortality rates and to a shortened survival time respectively. The p ercentage of glycated haemoglobin and levels of serum protein were correlat ed with the degree of social integration whereas the relation to serum prot ein was only apparent in dispersers. I hypothesize that the negative physio logical effects of the cold on subadults can be reduced either by mechanism s of social support and/or by thermoregulatory benefit.