Distribution of Siberian blue Robin Luscinia cyane and Grey Bunting Emberiza variabilis during the breeding season in Shiga Prefecture, Japan

Abstract

Currently, the number of confirmed locations for Luscinia cyane during the breeding season is decreasing nationwide, while Emberiza variabilis is increasing. Both species are locally observed during the breeding season in the mountains of Shiga Prefecture, but their distribution is not fully understood. In order to confirm the distribution of these species, we conducted a survey of the number of singing males at 48 survey sites in 7 mountain ranges throughout Shiga Prefecture between May and July from 2020 to 2023. As a result, Luscinia cyane was confirmed in 23 survey sites on 5 mountain ranges, and Emberiza variabilis was confirmed in 8 survey sites on 3 mountain ranges. Regarding Luscinia cyane, there was no change in the distribution of mountain ranges compared to records from the 2000s, but a decrease in habitat was suggested for two mountain ranges. Regarding Emberiza variabilis, there are no records of the breeding season before 1990s, so it is thought that the distribution of the breeding season has expanded in recent years.