Talk Absurdity or reality Roadside verges are a premium habitat and act as a largescale corridor while even motorways are a minor barrier for the hazel dormouse Muscardinus avellanarius

On the one hand roads and their impacts are recognized as one of the main factors threatening mammal biodiversity especially in the crowded areas of central Europe (Benítez- López et al. 2010). On the other hand, all kinds of roads usually imply roadside habitats, which a) can be highly connected landscape elements, b) can cover a significant high proportion of land and c) are regularly managed by road administration. In the northern German federal state of Schleswig-Holstein, road verges must actually be managed as a component of the habitat system (§18a StrWG SH). So roadsides have the potential to play a noteworthy role in habitat and species conservation, but good examples, where roadside habitat managements have led to an improvement of a species status are rare or amiss.

The hazel dormouse is a strictly protected species in Europe (Habitats Directive annex IV, Bern Convention annex III), endangered in our study region in Northern Germany (Borkenhagen 2014) and missing in most neighbouring regions. It is known as a strictly arboreal species living in the canopy at the edge of forests and in shrubs (Juškaitis 2014). Movements onground are a rarely observed behaviour (Bright 1998) and movement studies show that even small pathways are a significant barrier (Bright et al. 2006). Only few studies have given proof, that the hazel dormouse can traverse longer distances on ground (Büchner 2008,Juškaitis 2014) and that roads are not a total barrier (Chanin & Gubert 2012).

But recently we found more and more evidence of hazel dormouse living in Schleswig-Holsteins roadside habitats.

Therefore we conducted several studies to answer these questions:
1. Do dormice regularly live in roadside habitats and on traffic islands?
2. Does road crossing take part and if yes, is it an exceptional behaviour or does it happen regularly? Is there a close genetic relationship between populations on either side of the road?
3. Do continuous roadside habitats over a longer distance function as migration corridors? Is this roadside habitat network as suitable as habitat networks in adjoining cultural landscapes? Capture-mark-recapture-study showed that hazel dormice reproduce at roadside verges habitats and 30 crossings over roads were proved. An additional telemetry-study proved 27 crossings over roads; so road crossing can be a relatively frequent behaviour.

A large scale genetic study showed, that populations in habitats on both roadsides are genetically close related. Genetic differences via longer distances along roadsides were lower than via agricultural landscape. In summary a comparison of dormouse habitats a) along roads, b) in cultural landscapes and c) in forests show a high importance of roadside habitats for the both survival and dispersal of this species in Northern Germany. Road authorities are well aware of this responsibility and consider the species’ need in management plans and management practice.

dormouse, mammal, roadside habitats, roadside verges, road crossing, habitat corridor, barrier effect, Northern Germany, genetic differences