2020 年 52 巻 1 号 p. 1-9
The Rufous Hawk-Cuckoo Hierococcyx hyperythrus was censused along 1,169 transects (2 km in length) situated in 1,034 quadrats (4.5×5 km in size) in Hokkaido from late April to late July, 1976–2019. In addition to these, information about presence or absence of the species in another 602 quadrats were obtained from spot census, literature and personal records for illustrating a distribution map. Rufous Hawk-Cuckoos were recorded over almost all of Hokkaido except plains and the northern and eastern parts. They occurred in 16.9% of 1,034 quadrats. Proportions of quadrats in which Rufous Hawk-Cuckoos were recorded have a tendency to decrease in the northern and eastern areas.