Populations of Muscardinus avellanarius in north-western Europe can survive in forest poor landscapes, when there are enough hedges (Rodentia: Gliridae)

Abstract

The hazel dormouse (Muscardinus avellanarius) is a strictly arboreal species. In its European lowland range, the forest coverage was heavily reduced during historical times, e.g. down to ca. 4% in the northern German federal state of Schleswig-Holstein in the 18th century. This low forest cover remained for 200 years. According to habitat models, hazel dormice cannot survive in the long-term in habitats with low levels of forest cover (<5–10%). To answer the question, how hazel dormouse populations survived in almost deforested areas the recent species distribution map for north-west Europe was analysed with a GIS-overlay of different habitat data. Additionally, historical maps for north-west Germany were analysed to find crucial historical landscape elements. The history of a site apparently influences the present status of hazel dormice. Forest cover of younger woodlands is still of importance but less determinant. Habitat tradition and continuity are important for habitat suitability for the hazel dormouse and identifying historical hedgerow systems and historical woodlands can help to find places with hitherto unknown presence of hazel dormouse. Apparently, for the hazel dormouse the lack of forest habitats in north-western Europe was successfully compensated by the creation of a hedgerow network. Hedgerows function as a habitat by themselves, not just as a connecting structure. A density of 50 m continuous high quality and well-connected hedgerows per hectare seems to be a minimum for the survival of hazel dormice in northwest European landscapes. The preservation of ancient habitats and the restoration of new habitats as core habitats and connections is a key strategy to facilitate the long-term survival and re-colonisation of species.