Description

Land use intensification caused severe population declines in many grassland bird species. For the Corncrake, a multi-brooded, ground-breeding rail that inhabits mostly agricultural grassland, more frequent mowing at earlier dates is a threat to nests and broods and induces dispersal of adults. We used an occupancy model that allows for staggered arrival and departure times to estimate within-season movements of male Corncrakes and analysed how departure probabilities, calling site occupancy and habitat suitability were affected by land use. This study covered two study periods before (1998–2000) and after (2012–2015) a change in the local management regime. Male Corncrakes showed continuous arrival and departure during the breeding season, but delayed mowing dates reduced departure probability in the second study period, which should enhance the probability for second broods because less calling sites were affected by mowing especially during early July. Late mowing, however, implies economical losses for farmers and cessation of land use expanded. On unused meadows litter heights increased and plant species richness and forb cover declined, thus preferred habitat conditions deteriorated. Calling sites in unmanaged meadows were abandoned by male Corncrakes after few years without land use. Postponing first mowing dates until broods fledge is effective in protecting Corncrake broods, because more chicks should have survived until fledging but habitat quality depends on annual management. Because currently mowing late in the season is unattractive to farmers, we suggest that future Corncrake habitat conservation should along with financial compensations promote and evaluate the utilization of late-cut biomass for energy production.