Abstract
The Lanceolated Grasshopper Warbler Locustella lanceolata was censused along one to three 2-km transects (a total of 989) situated in 876 quadrats (4.5×5 km), in Hokkaido from late April to late July, 1976-2010. Warblers were recorded mainly in grasslands along lower and middle reaches of rivers, and those surrounding shallow lakes in Iburi, Ishikari, Tokachi, Kushiro, Nemuro, Abashiri and Soya districts. They occurred in grasslands and agricultural lands, and did not occur in woodlands and residential areas. Occurrence rates (No. of transects of occurrence/No. of transects censused) were 24.0% for grasslands and 3.4% for agricultural lands, and changed significantly in grassland during the study period.
