标题：Population trend and breeding density of corncrake Crex crex (Aves: Rallidae) in the Alps: monitoring and conservation implications of a 15-year survey in Trentino, Italy
摘要：Corncrake has been poorly studied in the southern part of its range. We investigated population trend and breeding density of the species in Alpine meadows of northern Italy (Trento province), between 1996 and 2010. We separately assessed trend and density for early and late season. This is virtually the first quantitative detailed estimate of Italian populations of the species. In the selected study areas, corncrakes occurred at high density and showed fluctuations, but the general trends clearly suggest a decreasing population (with a decline of 6–9% per year), with significant declines in several sites/periods. Relative abundance and density greatly varied among different areas in the same year, suggesting that local effects could be important in determining habitat suitability for corncrake and thus its abundance. The area where grasslands appeared to be mostly partitioned among different owners and thus most likely to be mown at different times (Tesino area) was the only one where the species occurred at all years at good density, and qualified as the most important site for corncrake among the different study areas surveyed. Conservation strategies for the species should include conservation of mountainside grasslands, implementation of compatible farming practices, and annual monitoring to obtain safe assessments of the demographic trend.
