This study in Lithuania showed that the abundance dynamics of the common dormouse (Muscardinus avellanarius) populations were comparatively “smooth”, without outbreaks and crashes. Decreases and increases of abundance continued for some years, and abundance differed no more than three-fold in two successive years. A close negative correlation was revealed between spring population density and percentage of juveniles in the autumnal population. The last parameter is a consequence of reproduction success, which determined the scale of population increase in autumn and was due to several factors. Among them, proportion of breeding adult females had the greatest significance and was inversely proportional to population density in spring. Some young-of-the-year females usually joined the breeding process, when population density was low. The proportion of late breeding cases, when juveniles were born in September, was also negatively correlated with spring population density. The number of litters produced by one female during the season, and the average litter size also influenced reproduction success. The negative correlation between population density and reproduction success shows the presence of a reproduction success based pattern of density dependent self-regulation in M. avellanarius in the populations investigated.
Roads are a threat to biological diversity. Especially the hazel dormouse (Muscardinus avellanarius) can be badly influenced by fragmentation due to its strictly arboreal activity. In this study a Northern German dormouse population living in roadside habitats and on road islands at crossroads was investigated to find out if road crossing is an exceptional behaviour or if it happens regularly. With capture-mark-recapture-method 30 crossings (mostly across a federal highway, three of them across a federal motorway) and via telemetry 27 crossings over federal highway and smaller streets were observed. Our study gives evidence, that road crossing can be a relatively frequent behaviour, as 18 % of the mark-recaptured and 60 % of the radio marked animals crossed roads, but it remains unclear, under which circumstances road crossing takes place.
In Lithuania, common dormice Muscardinus avellanarius destroyed 6.6% of 3807 bird nests with eggs in nestboxes at two study sites. M. avellanarius occupied nests of pied flycatcher Ficedula hypoleuca without eggs or nests with incomplete clutches most often, ate unhatched eggs, but did not kill or bite nestlings and adult birds. M. avellanarius were very seldom found in nestboxes with nests of tits Parus spp. Edible dormice Glis glis destroyed 14.3% of 498 bird nests with eggs or nestlings at two study sites, mostly nests of F. hypoleuca and great tit Parus major. G. glis ate birds’ eggs, killed and ate nestlings and adult birds. Forest dormice Dryomys nitedula made the biggest impact on birds nesting in nestboxes. They destroyed 20.5% of 171 nests with eggs or nestlings, ate eggs, killed and ate nestlings and adult birds. The most common impact of D. nitedula on birds in nestboxes was the killing of adults, either breeding or just looking for nest sites, and F. hypoleuca made a majority among birds killed. F. hypoleuca was most affected by all three dormice species in Lithuania, while P. major was impacted less and only by G. glis and D. nitedula.