Mowing is the greatest threat to Whinchat Saxicola rubetra nests even when compared to several natural induced threats

Abstract

Birds in agroecosystems are among the most threatened in Europe, largely due to intensification of agricultural production. For the Whinchat (Saxicola rubetra), an indicator species of high nature value grasslands, and whose population is decreasing over most of Europe, mowing was reported as the most significant threat several times. However, no studies to date compare mowing to other potentially significant threats to confirm this. We investigated mowing and four additional nature-related threats simultaneously and used them to construct a set of models to explain which factor has the most significant impact on Whinchat nest survival. Our study was done on a type of a grassland often found in protected areas with moderately improved production, where the density of Whinchat is high, yet influenced by human activities and natural factors. Date of mowing explained nest failure the best, followed by predation and weather, confirming mowing as the most significant problem to nest survival. Changes in mowing regime were identified as an important conservation measure. To increase breeding success of grassland birds, some of these measures (e.g., mowing postponement) were already suggested and used in EU through Agri-Environmental measures (AEM) program, but with little effect. We believe this is due to the little known indirect effects of mowing on birds during the post-fledging and pre-migration period, which is one of the least understood parts of their life cycle.