The dormouse surprises biologists


The hazel dormouse is not a pure woodland dweller, as biologists have discovered. © JRG/ Adobe Stock

The small hazel dormouse, which is strictly protected in Germany, was previously considered to be a strict woodland dweller, which is why it was only searched for there. But now a more detailed study with some radio-collared specimens of these rodents reveals that reed beds are also popular with hazel dormice. They stay there both to forage for food at night and to rest in their nests during the day – and do so almost as often as in the forest. This also has consequences for their protection.

Contrary to what its name suggests, the hazel dormouse (Muscardinus avellanarius) is not a mouse, but rather belongs to the dormouse family like the dormouse. Typical of this small, nocturnal rodent are its spherical nests made of tightly woven grass and leaves. The hazel dormouse spends the day in these nests, eating insects, fruit, flowers and buds. For its hibernation, it builds a special winter nest in burrows or under the litter. The hazel dormouse is also native to Germany but is under strict protection due to its low population density and shrinking habitat.

Woody plants preferred?

Until now, the hazel dormouse was considered a typical forest and hedge dweller and thus a characteristic species of species-rich and light forests with a well-developed shrub layer. It was assumed that the small rodent, as a strictly arboreal species, restricted its territories, nests and foraging to habitats dominated by woodland. For this reason, the occurrence of the hazel dormouse has so far only been checked in forest habitats and hedges – for example before construction work. However, in recent years there have been repeated indications that this habitat attribution for the hazel dormouse may be too narrow. The small rodents have been sighted in heathland, bushland and reed beds, among other places.

Raja Wipfler from the University of Bayreuth and her colleagues have now investigated more closely whether these are just isolated cases or whether there is more to it. They chose the Regnitz valley south of Bamberg as their test area, where woodland and reed beds border directly on one another. The team temporarily caught eight dormice and fitted them with a small radio transmitter. This enabled them to track where the animals were when foraging and during their resting phase during the day.

Day and night in the reeds

The analysis of the transmitter data revealed something surprising: the dormice used the reeds to a similar extent as the adjacent forest land,” report Wipfler and her colleagues. At night, 41.1 percent of the measuring points were in the reeds and 50.7 percent in the woodland. And during the day, while the small rodents were resting in their nests, the transmitter data also provided an unexpected picture: “On average, the dormice chose 42.5 percent of their resting places in the reeds, 45 percent were in the adjacent forest and 12.5 percent of the nests were on the border between the reeds and the woodland,” report the biologists.

Wipfler and her team suspect that staying in the reeds offers the dormice better protection from predators. The reeds are also the habitat of many insects that are a source of food for the dormice, and provide plenty of suitable nesting material. It is also conceivable that the dormice are moving from the forest to the reeds to avoid competition from the larger and stronger yellow-necked mice and wood mice, the researchers explain. The new findings are of great importance for nature conservation and the adaptation of protective measures. “It is important that authorities and state institutions now incorporate knowledge about reed beds as a habitat for the dormice into their protection programs and monitoring,” emphasize Wipfler and her team.

Source: University of Bayreuth; Article: Journal of Vertebrate Biology, doi: 10.25225/jvb.23118

Recent Articles

Related Stories