Determination of landscape parameter
Both landscape parameters, cover arable fields and landscape
heterogeneity, were determined on the basis of the biotope mapping of
the federal state Brandenburg
(lfu.brandenburg.de/lfu/de/aufgaben/natur/biotopschutz/biotopkartierung/).
The map distinguishes a large variety of habitats. However, for this
study, we used only the twelve main habitat categories: arable fields
(64% cover within the study area), forests (13%), grasslands (11%),
swamps (2%), built-up areas (3%), standing waters (3%), anthropogenic
immature soils (2%), deciduous copse and avenues of trees (1%), parks
and cemeteries (1%), dwarf shrub heaths (<1%), streaming
water including shores (<1%) and special biotopes
(<1%). For small parts of our study area in the federal state
Mecklenburg-Vorpommern, we conducted a biotope mapping by ourselves with
the help of aerial images. Arable field cover is defined as the
percentage of arable field cover around the traps for a specific radius.
Landscape heterogeneity is defined as the Shannon-Diversity of main
habitat types weighted by their coverage (Maskell et al. 2019). We
calculated both landscape predictors for continuous radii from 60m –
3000m. Cover of arable fields and landscape heterogeneity were shown to
have a scale-dependent correlation (Supplementary information, Appendix
2). At small scales (<500m) no significant clear correlation
was found, whereas at larger scales (>500m) both measures
tended to be negatively related to each other.