Populatieonderzoek naar de Hazelmuis in de Voerstreek

The Hazel dormouse (Muscardinus avellanarius) is a habitat specialist that prefers dense shrub
and tree vegetation and needs a high diversity of food plants on a limited area. Due to habitat
degradation and fragmentation the Flemish distribution area of this critically endangered
species has been reduced to the eastern part of the municipality of Voeren, where it forms a
cross-border population with the Dutch Hazel dormice. Since 2003 the Mammal Working
Group of Natuurpunt studies the remaining Flemish population to find out more about
population parameters, habitat use, the influence of habitat quality and management actions.
In 2007 a standardised monitoring started by counting autumnal nests along fixed transects.
In 2013 an intensive capture-mark-recapture study was set up based on nest box and nest
tube checks and live-trapping on custom made hanging platforms; also a first test with radiocollars took place. The information gathered from the combination of all these methods will
be used to validate the monitoring method and to formulate better protection measures. First
results show that late summer and autumn should not be considered as the main reproduction
period, at least not in an early year like 2014 when first young were already born at the
beginning of May. Hazel dormice do not only cross significant barriers like the railway during
dispersal, but also do this regularly during their nightly movements within their home range.
Expansion of the population on a location with sufficient connectivity seems to be hampered
by a too low population density resulting from insufficient habitat quality and (in this case) a
high predation pressure by house cats. On the scale of the Meuse-Rhine Euregion, genetic
analyses carried out by the University of Liège reveal four genetically isolated clusters, for
which a vision to interconnect these was computed in the Interreg-project ‘Habitat Euregio’.