Mapping an elusive arboreal rodent: Combining nocturnal acoustic surveys and citizen science data extends the known distribution of the edible dormouse (Glis glis) in the Czech Republic
Abstract
Surveying mammals is always a challenge for field biologists. When those mammals are nocturnal and mostly arboreal, as in the case of the dormice (Gliridae), the task proves even more difficult.
During the summers of 2015 and 2016 we carried out a national survey of edible dormouse (Glis glis) distribution in the Czech Republic. Twenty-one trained surveyors conducted acoustic nocturnal surveys in 640 mapping squares (a national 11.2 x 12 km mapping grid) for the presence of typical dormice loud squeaks and churring calls.
Additionally, we published articles in newspapers and magazines, and conducted radio interviews to raise awareness among the public and to invite them to contribute their own observations, as dormice commonly inhabit people's homes. This led to over 360 public observations, of which 237 belonged to edible dormouse and were precisely georeferenced.
The nocturnal surveys detected presence of dormice in 175 out of 1830 surveyed sites. When data from public and nocturnal surveys were combined, edible dormouse was detected in 192 mapping squares.
During a previous data collection period, 1950-2011, edible dormice were only detected in 137 mapping squares. Our study substantially extends the known distribution of the species, including several isolated populations.
It also confirms the presence of healthy populations in the NW and E of the country and validates a new species distribution model. Thanks to its characteristic night calls, we show that nocturnal surveying is a very efficient mapping tool for the edible dormouse and we suggest its use whenever there is a need for distributional data.
In addition, we show that citizen science data have a great potential to supplement surveys of this species but on its own cannot replace targeted surveys by wildlife biologists. Thus, our recommendation is to use records from the public as a supplementary data source, unless considerable effort is devoted into raising the public awareness about the species.