Nesting behaviour and seasonal body mass changes in a rural Irish population of the Western hedgehog (Erinaceus europaeus)

There was previously no information on nesting, seasonal body mass or the hibernation behaviour of the hedgehog in Ireland. Between 2008 and 2009, hedgehogs were caught, weighed weekly and monitored by radio tracking at a rural Irish site. Day nests were recorded in the active period and hibernacula thereafter. Arable land has been reported to be poorly utilised by hedgehogs in the UK and Denmark. In Ireland, day nests and hibernacula were constructed in the hedgerows of arable land indicating that these areas will be exploited if hedgerow is maintained and highlights the importance of maintaining hedgerows in arable areas. Individual females returned to the same day nest significantly more than males. Over the 2 years, individuals were found to occupy a mean of 1.8 (+/- 0.9; SD) hibernacula (maximum of 3) and they rotated between nests up to four times (mean of 2.5 +/- 1.6). When hedgehogs occupied multiple hibernacula, those occupied in mid winter (December and January) were occupied for significantly longer than those occupied at the start (October and November) and end (February and March) of hibernation. Studies in the UK and Denmark have reported on hedgehog hibernation. However, the winter climate in southern Ireland is milder than other areas of Europe and thus it was expected that hibernation characteristics would also differ, i.e. shorter hibernation periods, earlier emergence, lower body mass loss and the ability to survive hibernation at a lower body mass. This proved to be the case with a mean hibernation period (+/- SE) of 148.9 (+/- 0.5) days, a mean body mass loss of 17.0 (+/- 0.53) %, emergence in March and the ability of late juveniles to survive at a pre-hibernation body mass of 475 g.