The distribution of rufous hawk-cuckoo (HC) Hierococcys hyperythrus and oriental cuckoo (OC) Cuculus optatus was surveyed by line transect census in central and southeastern Hokkaido from late April to early July, 1976-2015. The census was conducted at 1,029 transects each 2-km long situated in 917 quadrats (4.5km×5km). HC occurred in 48 quadrats (5%) and 66 transects (6%) and the corresponding values for OC were 634 quadrats (69%) and 667 transects (65%). The occurrence frequency of HC in Siberian dwarf pine Pinus pumila forests, ever-green coniferous forests, mixed forests, deciduous broad-leaved forests, larch Larix leptolepis plantations, agricultural lands with woods, agricultural lands and residential areas, was 0, 7, 15, 8, 0, 4, 0.7, and 0%, respectively, and that of OC was 18, 80, 70, 89, 73, 70, 47 and 10%, respectively. The occurrence frequency of HC at less than 200m above sea level (asl), 201-400m asl, 601-800m asl, 601-800m asl and 801m asl or above was 3, 9, 10, 8 and 9%, respectively, and that of OC was 61, 76, 70, 67 and 49%, respectively.
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